GLOBAL BIOGEOCHEMICAL CYCLES, VOL. 18, GB1009, doi:10.1029/2003GB002108, 2004 Geographic distribution of major crops across the world Billie Leff,1 Navin Ramankutty, and Jonathan A. Foley Center for Sustainability and the Global Environment (SAGE), Gaylord Nelson Institute for Environmental Studies, University of Wisconsin, Madison, Wisconsin, USA Received 6 June 2003; revised 8 October 2003; accepted 30 October 2003; published 16 January 2004. [1] Humans have transformed the surface of the planet through agricultural activities, and today, 12% of the land surface is used for cultivation and another 22% is used for pastures and rangelands. In this paper, we have synthesized satellite-derived land cover data and agricultural census data to produce global data sets of the distribution of 18 major crops across the world. The resulting data are representative of the early 1990s, have a spatial resolution of 5 min. (10 km), and describe the fraction of a grid cell occupied by each of the 18 crops. The global crop data are consistent with our knowledge of agricultural geography, and compares favorably to another existing data set that partially overlaps with our product. We have also analyzed how different crops are grown in combination to form major crop belts throughout the world. Further, we analyzed the patterns of crop diversification across the world. While these data are not sufficiently accurate at local scales, they can be used to analyze crop geography in a regional-to-global context. They can also be used to understand the global patterns of farming systems, in analyses of food security, and within global ecosystem and climate models to understand the environmental INDEX TERMS: 1699 Global Change: General or miscellaneous; 1640 consequences of cultivation. Global Change: Remote sensing; 1630 Global Change: Impact phenomena; 1694 Global Change: Instruments and techniques; KEYWORDS: land use, land cover, croplands, crop distribution, agricultural census, crop harvested area Citation: Leff, B., N. Ramankutty, and J. A. Foley (2004), Geographic distribution of major crops across the world, Global Biogeochem. Cycles, 18, GB1009, doi:10.1029/2003GB002108. 1. Introduction [2] Humans dominate the landscape in nearly every corner of the planet. Today, croplands occupy nearly 18 million km2 (an area roughly the size of South America), pastures take up another 34 million km2 (an area roughly the size of Africa), and urban areas use roughly 2.5 million km2 (an area roughly the size of a third of Europe) [Klein Goldewijk, 2001; Ramankutty and Foley, 1998; Turner et al., 1993]. Altogether, these three anthropogenic ecosystems currently occupy over a third of the global land surface. [3] Human land use practices have enormous consequences for the environment. While croplands and pastures provide food for the world’s population, agricultural practices have, to a large degree, led to the clearing of many forests [Goudie, 2000]. Human land use practices have also degraded many soils [Meyer and Turner, 1994], influenced global and regional climates [Betts, 1999; Bounoua et al., 2002; Brovkin et al., 1999; Pielke et al., 2002; Zhao and Pitman, 2002], changed the global cycles of carbon, nitrogen, and water [Houghton et al., 1999; Vitousek et al., 1997; Postel 1 Now at National Geographic Maps, Washington, DC, USA. Copyright 2004 by the American Geophysical Union. 0886-6236/04/2003GB002108 et al., 1996], induced the loss of biodiversity [Dale et al., 2000; Pearce, 2001; McNeely, 1992], affected geomorphic processes, and changed the quality of many natural waterways [Goudie, 2000]. [4] Characterizing the geographic extent and nature of human-dominated ecosystems is vital to understanding the environmental impacts of land use and land cover change. With the advent of remote sensing, there have been several efforts aimed at depicting regional and global patterns of land cover [Vogelmann et al., 2001; Cihlar, 2000; DeFries and Belward, 2000; Belward et al., 1999; Lobo et al., 1997; Brown et al., 1993; Loveland et al., 1991]. However, these studies have mainly focused on natural ecosystems, with only one or two land cover classes devoted to humandominated ecosystems. On the other hand, ground-based census data (routinely collected across counties, states, and nations) often contain detailed land use information, but lack the spatial detail and resolution of satellite-based data. [5] In order to characterize global agricultural land cover, Ramankutty and Foley [1998] developed a statistical ‘‘data fusion’’ technique to calibrate satellite-derived land cover data [Loveland and Belward, 1997] against agricultural census statistics. Their data represent the cropland land cover of the world on a continuous scale, depicting the percentage of each grid cell in cultivation (Figure 1). However, this data set is still limited in not delineating the distribution of GB1009 1 of 27 GB1009 Figure 1. Global cropland data set of Ramankutty and Foley [1998]. This data set was created by merging satellite-derived land cover data and administrative unit level agricultural census data. It represents the fraction of a 5-min resolution (in latitude by longitude) grid cell occupied by arable lands and permanent crops in 1992. See color version of this figure at back of this issue. specific crop types and cropping systems. Detailed information on agricultural land use practices (such as cropping systems) is necessary to understand the environmental consequences of cultivated ecosystems. For example, the distinction between C3- and C4-based physiology crops is important in studies of the global carbon cycle [Lloyd and Farquhar, 1994; Still et al., 2003]. In addition, Donner and Kucharik [2003] discuss the importance of differentiating between maize and soybeans on nitrate export through the Mississippi River, and the spatial pattern of rice paddy is important to estimate the distribution of methane emissions [Cao et al., 1996; Matthews and Fung, 1987]. Moreover, model-based estimates of historical and current crop production [Kucharik, 2003] and future crop production [Leemans and Solomon, 1994; Fischer et al., 2000] have made distinctions between different crops. [ 6 ] Here we use an approach, similar to that of Ramankutty and Foley [1998], wherein we combine national and sub-national agricultural census data, along with land cover data, to derive the spatial distribution of crop types across the world. Our focus is also on cultivation within permanent croplands, which follows the Food and Agriculture Organization (FAO) definition of arable lands and lands under permanent crops (Table 1). Other land use systems, including pastures and regions of shifting cultivation, are not considered in this study. 2. Methods [7] We derived the global distribution of 18 major crop types by synthesizing agricultural census data on harvested area, and the global cropland data set of Ramankutty and Foley [1998]. The crop categories were selected using distinct biogeochemical, phonological, and food resource characteristics. We arrived at 17 major crop categories (barley, cassava, cotton, groundnuts or peanuts, maize, millet, oil palm fruit, potatoes, rapeseed or canola, rice, rye, sorghum, soybeans, sugar cane, sugar beets, sunflower, Table 1. A Glossary of Terms Used in This Paper Term Cropland Major crops Cropland area Cropland fraction Crop area Crop fraction Relative crop fraction Cultivation intensity Region Description Arable land (including harvested cropland, crop failure, temporarily fallow or idle land, and cropland used temporarily for pasture) and land under permanent crops (such as cocoa, coffee, rubber, etc., including all tree crops except those grown for wood or timber). The harvested produce may be used for both human consumption and/or feed. One or more of the following: barley, cassava, cotton, groundnuts or peanuts, maize, millet, oil palm fruit, potatoes, pulses, rapeseed or canola, rice, rye, sorghum, soybeans, sugar cane, sugar beets, sunflower, and wheat. The area of each grid cell (in square kilometers) occupied by croplands. The fraction of each grid cell occupied by croplands. The area of each grid cell (in square kilometers) in any one of the major crops. The fraction of each grid cell that is in any one of the major crops. The ratio of harvested area of each crop to total harvested area. In this paper, intensity refers to the magnitude of the crop fraction, i.e., the higher the crop fraction in a grid cell, the greater its intensity of cultivation with respect to that particular crop. It does not refer to the land inputs such as irrigation, fertilization, multiple cropping, etc. An area in the world generally larger than a single country, but smaller than a continent (e.g., the Middle East, the conterminous United States). The area of our regions ranges from just over 200,000 km2 (the Caribbean) to 14,000,000 km2 (Northern South America). See Table 5 for a list of the regions discussed here. 2 of 27 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION GB1009 GB1009 Table 2. Crop Commodity Classifications and Definitions [FAO, 2002] Category Cereals barley maize millet rice rye sorghum wheat Pulses other cerealsb cassava potatoes other root/tuberb sugar beets sugar cane pulses Nuts nutsb Oil-bearing crops groundnuts rapeseed oil palm fruit soybeans sunflower other oil-bearing cropsb Vegetables vegetablesb Fruit fruitb Fibers cotton other fibersb Spices spicesb Other crops other cropsb Roots and tubers Sugar crops FAO Crop Definition and Commentsa Crop Hordeum spp. Varieties include with husk and without (naked). Zea mays. Includes hybrid and ordinary maize (with widely different yields). Echinocloa frumentacea, Eleusine coracana, Eragrostis abyssinica, Panicum miliaceum, Paspalum scrobiculatum, Pennisetum glaucum, Setaria italica. Small-grained cereals that include a large number of different botanical species. Oryza spp. Mainly oryza sativa. Rice grain after threshing and winnowing. Also known as rice in the husk and rough rice. Secale cereale. Sorghum spp. Includes hybrid and other varieties. Triticum spp. (T. durum and T. aestivum). Includes durum and common wheat, the latter includes the varieties: spring, winter, hard, soft, red, and white. Includes: oats, buckwheat, quinoa, fonio, triticale, canary seed, mixed grains. Manihot spp. Other names: manioc, mandioca, yucca, yucca dulce. Solanum tuberosum. Includes: sweet potatoes, yautia, taro, and yams. Beta vulgaris var. altissima. Saccharum officinarum. Includes: dry beans, dry broad beans, dry peas, chick-peas, dry cow peas, pigeon peas, lentils, bambara beans, vetches, and lupins. Includes: Brazil nuts, cashew nuts, chestnuts, almonds, walnuts, pistachios, kola nuts, hazelnuts (filberts), and areca nuts. Arachis hypogaea. Other name: peanuts. Brassica napus var. oleifera. Other name: Canola. Elaeis guineensis. Glycine soja. Helianthus annuus. Includes: coconuts, olives, karate nuts, castor beans, tung nuts, safflower, sesame, mustard, poppy seed, melon seed, linseed, hempseed, tallow tree seeds, kapok fruit, seed cotton. Includes: cabbage, artichokes, asparagus, lettuce, spinach, cassava leaves, tomatoes, cauliflower, pumpkins, cucumbers and gherkins, eggplants, chilies and peppers, onions, garlic, leeks and other alliaceous vegetables, green beans, green peas, green broad beans, string beans, carrots, okra, green corn, mushrooms, watermelons, and cantaloupes. Includes: bananas, plantains, oranges, tangerines, mandarins, clementines, satsumas, lemons, limes, grapefruit, pomelo, apples, pears, quinces, apricots, sour cherries, peaches, nectarines, plums, stone fruit, strawberries, raspberries, gooseberries, currants, blueberries, cranberries, grapes, figs, persimmons, kiwi fruit, mangoes, avocadoes, pineapple, dates, cashew apple, and papayas. Gossypium spp. Includes: flax fiber and tow, hemp fiber and tow, kapok fiber, jute-like fibers, ramie, sisal, abaca, manila hemp, and coir. Includes: pepper, pimento, vanilla, cinnamon (or canela), nutmeg, mace, cardamoms, cloves, anise, badian, fennel, and ginger. Includes: tea, coffee, cocoa, mate, tobacco, natural rubber, chicory roots, carobs, hops, peppermint and spearmint, pyrethrum, Arabic gum, and other resins. a For more detailed crop definitions, classifications and recommendations, visit the FAO Statistics Division web site at http://www.fao.org./es/ess/ rmcrops.asp. b Denotes a crop considered minor in this paper and one for which a separate data set was not generated, although census data, at least at the national level, were available for all crops listed here. and wheat), one major crop group category (pulses, which includes many beans, peas, lentils, etc.), and 10 other ‘‘minor’’ crop categories (fibers, fruit, nuts, oil-bearing crops, other cereals, other roots and tubers, others, spices, and vegetables) (Table 2). Agricultural census data were collected and regrouped into those categories and data sets were generated for all eighteen major crops, while all other crops and crop categories were grouped into a single ‘‘other crop’’ category (Table 2). [8] We collected agricultural census data from various census organizations (Table 3). At the national level, agricultural census data are available for every country in the world from the FAO in the FAOSTAT database [FAO, 2002]. This database contains harvested area data for over 100 individual crops, collected and reported annually for the time period 1961 – 2001. In addition, to achieve some level of uniformity in the size of administrative units, we collected sub-national (one administrative level below the nation: state or province equivalent) census data for a number of countries, based on either their land area or their share of global cropland area. These countries were Argentina, Australia, Brazil, Canada, China, India, Kazakhstan, Mexico, the Russian Federation, Turkey, and the United States of America (Figure 2). [9] We collected and averaged the census data for 6 years, 1990– 1995. This period centers roughly around 1992, the year for which Ramankutty and Foley [1998] developed their cropland distribution data set. Often the national totals obtained from the sub-national censuses did not match the FAO national data. After checking for consistency in definitions and for errors, we scaled all sub-national data to the FAO national totals. Similarly, scaling was done in cases 3 of 27 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION GB1009 GB1009 Table 3. Agricultural Census Data Sources for 1990 – 1995, Inclusivelya Location Data Source Comments Countries of the world Food and Agriculture Organization [2002] States of Argentina Instituto Nacional de Estadistica y Censos [1995, 1996a, 1996b, 1996c] States and Territories of Australia Australian Bureau of Statistics [1991, 1992, 1994] States of Brazil Instituto Brasileiro de Geografia e Estatı́stica, SIDRA: Banco de Dados Agregados, 1996 (available from the IBGE web site at http://www.ibge.gov.br) Statistics Canada [1992, 1997a, 1997b] Provinces of Canada Provinces of China States of India Oblasts of Kazakhstan States of Mexico Oblasts of the Russian Federation State Statistical Bureau, PRC [1991 – 1996] and U.S. Department of Agriculture [1999] Ministry of Agriculture [1993] Gosudarstveni Committet Kazahskoi SSR po Statistike [1987] Centro de Estadı́stica Agropecuaria [2000] Goskomstat Rusii [1995] and U.S. Department of Agriculture [1999] Regions in Turkey State Institute of Statistics [1994, 1995] States of the United States of America U.S. Department of Agriculture [2001] We selected 18 major crops and averaged the FAO harvested area data for those crops for 1990 – 1995 inclusively. Census data were available only for the five provinces in the Pampa for the calendar years 1993 – 1995 inclusively. No data were available on cotton. Data collected for 1990 – 1994 inclusively. For rapeseed/canola, data were available only for 1990. Only a single census for 1996 was available. Agricultural censuses were available for 1991 and 1996 only. The pulse category was limited to dry peas and beans and no data were available for other pulses. Census data were available for every year between 1990 and 1995 inclusively. Data were available for three crop years 1990 – 1991, 1991 – 1992, and 1992 – 1993. Census data were available only for 1986. No data were available on barley. Data were available only for 1991. Census data were available for 1990 – 1995 inclusively for most crops. Barley data were available only by regions (group of oblasts) for 1968 – 1970. For rye, only data on production (tons) were available. Data were available for 1991 and 1993, and it was by region rather than by state. There were 9 regions with 5 to 11 states each. Data were available for 1990 – 1995 inclusively for all crops, except for millet, for which only 1987 data were found. a We collected agricultural census data for all administrative units for the years 1990 through 1995 inclusively, unless otherwise noted in the comments. where sub-national data were not available for all six years (see Appendix A). [10] The census data for each crop were converted to a relative crop fraction (the proportion of a particular crop’s harvested area to the total harvested area) (see Table 1 for definition of terms used in this paper). This fraction was assigned to the administrative unit for which it was obtained (Figure 3). It should be noted that the harvested area data for Figure 2. Countries of the world for which agricultural census data were collected. For the countries in white, only national-level census data were collected from the FAO [2002], while for the countries in black (nations with large total cultivated area or total land area), we collected state-level data (see Table 3 for agricultural census data sources). 4 of 27 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION GB1009 RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION GB1009 Figure 3. Flowchart showing the methodology used to construct the major crop data sets. Boxes with rounded corners indicate geospatial data sets, while boxes with sharp corners indicate tabular data at the level of political units. We first collected agricultural census data on harvested area for crops at the national or sub-national level. From these data, for each administrative unit, we then estimated the proportion of each of the 18 major crops to the total harvested area. We then masked non-cropland areas and applied a smoothing algorithm (see text for details). Finally, we multiplied the resulting data of individual crop proportions by the cropland data set (Figure 1) to obtain the per-pixel proportion of each of the 18 major crops. all crops do not directly sum up to reported cropland area. This is because of multiple cropping (the practice where the same land is cultivated 2 or even 3 times throughout the same year). Here we assumed that all crops within a region have similar multiple cropping patterns. Thus, by expressing the harvested area for each crop as a proportion of the total, we obtained for every pixel the probability that a particular crop is cultivated. [11] Next we used the data set of the extent of the world’s croplands [Ramankutty and Foley, 1998] to mask out noncropland areas. Then we smoothed the data to eliminate discontinuities at the borders between political units. Although real crop discontinuities exist between some nations, all of the boundaries we have introduced are artificial and arise solely because of our use of administrative level data. Hence we smoothed these by applying a 41 41 pixel Gaussian filter. Since the smoothing may have introduced biases in the data, we rescaled the data equally for all crops to ensure that all fractions indeed added to 1. This smoothing and normalization significantly altered the census data in administrative units where both of the following conditions are met: the unit has a width in any direction smaller than the width of the filter, and the unit has a crop proportion significantly different from that of the surrounding administrative units. [12] Finally, to obtain the spatial distribution of each crop (fraction of grid cell occupied by the crop, what we define as ‘‘crop fraction’’), we multiplied the spatially distributed relative crop fraction from the previous step by the cropland data set of Ramankutty and Foley [1998]. The 18 crop data sets thus produced are gridded, global, and at a 5-min latitude/longitude resolution (10 km) (Figures 4a – 4f). [13] These crop data have been created using a very simple procedure (Figure 3), with multiple assumptions, and thus have several limitations. First, the use of national and state level data, without the ability to define cultivation intensities within administrative units, makes the data appropriate only for regional- to global-scale studies. Secondly, in regions where some crops have multiple growing seasons and others have single growing seasons, the assumption of the same number of growing seasons will lead to overestimation of the extent of the former (e.g., rice and pulses), and underestimation of the extent of the latter (e.g., millet, wheat, and barley). This is the case especially in the tropics where certain crops are planted and harvested multiple times, while others are not. Third, reporting errors in the census data may considerably alter the final results. This is especially true for countries where there may be political or economic incentives to over- or under-report cropland area (e.g., China [see Seto et al., 2000]). Fourth, the effects of the smoothing filter are difficult to quantify. Most frequently the affected areas are along the border between administrative units, across which cultivation intensities vary greatly because of cultural or environmental differences: small states and countries surrounded by larger administrative units, and long and narrow administrative units. Finally, errors in the Ramankutty and Foley [1998] croplands data set would carry over to these new data sets. [14] Despite the simplicity of the approach used to generate these data, they are the first of their kind. By merging the high spatial resolution of satellite-derived data and the high level of attribute differentiation in census data, these data represent a useful product to be used within numerical models (of the Earth’s climate, terrestrial ecosystems, and hydrological systems) and by land managers, planners, and policy makers. [15] One caveat to add is that the data, in their current form, do not identify some important phenological charac- 5 of 27 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License GB1009 RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION teristics of crops such as spring crops versus winter crops. Such distinctions are very important when assessing the environmental consequences of crops. We recommend that climate and ecosystem modelers use climate data in conjunction with our crop data sets to distinguish between the different crop phenologies [e.g., Leemans and Solomon, 1993]. In future updates of this product, we plan to incorporate these distinctions. 3. Data Evaluation [16] Although the geographic distribution of total croplands has been mapped on a global scale [Ramankutty and Foley, 1998; Wood et al., 2000], there are no independent geospatial data sets for the global distribution of the world’s major crops. This makes our effort unique, but also presents us with the challenge of performing a comprehensive quality assessment without comparable data. [17] To our knowledge, there have been three other efforts that have attempted to characterize the spatial distribution of crops on a global scale. The FAO, in collaboration with the International Institute for Applied Systems Analysis (IIASA), estimated the global land suitability for growing different crops [Fischer, 2000]. Although valuable, this product only indicates where crops could be grown, and is not a representation of where crops are grown today. Another effort by the National Institute for Public Health and the Environment (RIVM) in the Netherlands spatially allocated the FAO national agricultural census data into pixels by using a measure of land suitability for seven different aggregate crops [IMAGE-team, 2001]. Once again, while this is a useful product, it is not strictly comparable to ours because it reflects land suitability rather than actual cultivated areas, and also is based on data for the year 1970. Indeed, a quantitative comparison of the RIVM data set to our product showed that the two data sources have poor correspondence: the correlation coefficient ranged from a low of 38% (for soybeans) to 57% (for rice). [18] The only product comparable to ours can be found in a recent publication by the Joint Agricultural Weather Facility (JAWF) of the U.S. Department of Agriculture (USDA) [USDA/JAWF, 1994] (also available at http:// www.usda.gov/oce/waob/jawf/profiles/mwcacp.htm), where they presented the major crop growing regions of the world. However, the product is not digital or geospatially referenced, and we are thus limited to a qualitative comparison. The USDA/JAWF publication allows us to compare the global distributions of all but four (potatoes, cassava, pulses, and oil palm fruit) of the 18 major crops. Rather than presenting cultivation intensity per pixel, the USDA/JAWF data set delineates two levels of cultivation in each region: ‘‘major’’ and ‘‘minor.’’ While the publication does not cover the whole world, it is valuable in providing GB1009 climatological and crop calendar data for the world’s major crop growing areas. [19] Despite the different format and source materials, our data agree with the USDA publication on the distribution of a large number of the major crops throughout the world. However, there are also a significant number of crop growing areas in which the two data sets differ. In Table 4, we present the areas of agreement and disagreement, as well as those areas for which a comparison is not available because of the non-global nature of the USDA data. In most cases where the two data sets compare poorly, it is because of the lack of sub-national or sub-state level census data in our data sets. This is the case with the cultivation of crops in large administrative areas (e.g., the Canadian Prairie Provinces, the Australian states, Mongolia, Pakistan, Nigeria, France, Spain, Germany, and Poland) and with crops having narrow growing areas (e.g., cotton, sugar cane, rapeseed, and canola). In other cases, the two data sources differ even where census data are available with the same resolution (e.g., the cultivation of maize throughout Mexico). This might be related to inaccuracies in the Ramankutty and Foley [1998] croplands data set that forms the basis of our major crop data sets. 4. Global Cropping Patterns [20] Here we discuss the global distribution of major crop groups (Figures 4a – 4f, 5, and 6). 4.1. Cereals [21] The most prevalent group of crops across the world is cereals (Figures 4a – 4c). Taken together, cereals are the only group of crops with cultivation that exceeds 20% of global land area (Figures 5a – 5c), or 61% of the total cultivated land. In particular, wheat, maize, barley, rice, and millet are dominant over more than two thirds of the cropland of the world (Table 5). The only regions where a cereal is not the dominant crop are the Caribbean and central Africa. In the Caribbean, the dominant major crop is sugar cane; while in central Africa, the dominant major crop is cassava. However, in both regions, a cereal (maize) is the second most prevalent crop (Tables 6 and 7). [22] A breakdown by latitude also reveals the dominance of cereals (Figures 5a – 5c). Wheat is the most abundant crop, occupying 22% of the total cultivated area in the world. The most intensive wheat cultivation occurs in the temperate latitudes of both hemispheres. Wheat is most prevalent in the Great Plains of the United States, the Canadian Prairie Provinces, the Indus and the upper Ganges Valleys, along the Kazakhstan and Russian border, and in southern Australia (Figure 4c). Wheat is also found throughout Europe, in southern South America, in parts of eastern Africa, and in eastern China. Figure 4. Global distribution of 18 major crops. The 18 major crops were selected based on biogeochemical, phenological, and food resource characteristics. We first display seven cereals (barley, maize, millet, rice, rye, sorghum, and wheat), then two tubers (cassava and potatoes), two sugar crops (sugar beets and sugar cane), a single category for pulses, five oil-bearing crops (soybeans, groundnuts or peanuts, rapeseed or canola, sunflower, and oil palm fruit), and finally, a single crop for the fiber category (cotton). Note that a very compressed scale is chosen to better display the data in gray scale, although the data have continuous values from 0 to 100%. 6 of 27 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License GB1009 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License 7 of 27 GB1009 RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION GB1009 8 of 27 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Figure 4. (continued) GB1009 RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION GB1009 9 of 27 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Figure 4. (continued) GB1009 RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION GB1009 10 of 27 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Figure 4. (continued) GB1009 RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION GB1009 11 of 27 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Figure 4. (continued) GB1009 RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION GB1009 12 of 27 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Figure 4. (continued) GB1009 RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION GB1009 GB1009 Table 4. Qualitative Comparison of the Data From USDA/JAWF, 1994 and This Study Crop Wheat Areas of Agreement Areas of Disagreement Major Cultivation Zones Without USDA Data Rice USDA major growing areas in USDA minor growing areas in the North America and Europe (France, UK, USA and Canada (Saskatchewan); Italy, Romania, and Poland); all Pakistan, South Africa, parts of Europe cultivation in South America, Russia, (Spain and Germany); USDA major Kazakhstan, Northern Africa, India, growing areas in China and Australia USA, Brazil, and Southeast Asia Maize USA, Europe, India, and China Mexico, Brazil, Argentina Barley Sorghum Millet Rye Sugar cane Belarus and Russia, northwestern Africa Mexico, India India Former Soviet Union southeastern USA, Cuba, Brazil, India, and China Sugar beets Cotton China South America, former Soviet Union, Pakistan, and China USA, Canada, Brazil, India, and China North America and Europe (UK and Spain) USA, Argentina, and Australia China, Africa Russia, China, Africa Europe (Germany and Poland) Queensland in Australia, India, Pakistan, Central America and the Caribbean Philippines, and South Africa (other than Cuba), South America, central Africa USA, Europe, and Kazakhstan Chile and Turkey USA, Argentina, Spain, Egypt, Africa, Peru, Turkey, Afghanistan, Australia, and India and Thailand Italy, India, and Argentina Southeast Asia (other than India and China) southeastern USA Africa and Southeast Asia (other than India and China) Canadian Prairie Provinces, France, Ethiopia and Australia Germany, Poland, and UK Kansas in the USA, Italy, Hungry, southern Africa, Eastern Europe France, and Spain (other than Hungry and Ukraine), India, China, and Uruguay Soybeans Ground nuts/Peanuts China and India Rapeseed/Canola India and China Sunflower USA, Argentina, Russia, and Ukraine [23] Maize is the most geographically ubiquitous crop and the crop with the third largest extent in the world. It is cultivated over 13% of the world’s croplands, with the most extensive cultivation occurring from approximately 50°N to 45°S (Figure 5c). Maize attains its highest cultivation intensity in the U.S. maize belt, but it is also a major commodity in northeastern China (Manchuria), along the Rift Valley in Africa, and in eastern Europe (Figure 4a). Less intensive cultivation of maize can be found in South America, western Europe, India, and southeastern China. [24] Barley and rye are preferentially grown in colder latitudes, with the majority being cultivated around 55°N (Figure 5a) in Canada, the northern United States, and European Russia (Figures 4a and 4b). Barley is the crop with the fourth largest area, with 9% of the world’s croplands, while rye is cultivated over 2% of the world’s croplands. [25] Rice, sorghum, and millet dominate the tropical and sub-tropical belts, especially in the Northern Hemisphere (Figure 5b); these three crops occupy 11%, 3%, and 2%, respectively, of the global cultivated area. Rice is the second most extensive crop in the world, and is a major crop of south and southeast Asia. It is also cultivated in the Amazon Basin, the southern United States, and southern Australia (Figure 4b). Sorghum, the only cereal that does not emerge as a dominant crop in any region, is common throughout the Rift Valley and the Sahel region in Africa, the southern half of the Mississippi Valley, and India (Figure 4b). Millet appears in the Ethiopia Central and South America (other than Brazil), Africa Africa (other than South Africa), Central America (other than Mexico) same regions of Africa as sorghum and to a lesser degree throughout parts of Asia, and is most abundant in western India (Figure 4a). 4.2. Roots and Tubers [26] Although roots and tubers cover a much smaller area than cereals, they are another important human staple. The two major crops from this category, potatoes and cassava, are both tubers. Together they cover 4% of the world’s total harvested area. Geographically, they are cultivated in contrasting climates (Figure 5d). Potatoes are extensively grown in the colder temperate latitudes between 40°N and 75°N, with the highest potato cultivation intensity occurring at 55°N in the European part of the former Soviet Union and in northeastern Europe (Figure 4c). On the other hand, cassava is grown in the equatorial and tropical regions (Figure 4c). This crop is cultivated from 20°N to 30°S, but its cultivation intensity, even at its highest (5°S), is only half that of potatoes. Cassava also appears in northern Brazil, south central Africa, Thailand, Micronesia, and Polynesia; cassava is also the major crop cultivated in central Africa. 4.3. Sugar Crops [27] Although sugar beets and sugar cane both produce sugar, the similarities between the two crops end there. They prefer different climates, with sugar cane favoring yearround warmth, while sugar beets favor much cooler conditions (Figure 5e). The two crops also have different plant 13 of 27 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION GB1009 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License 14 of 27 GB1009 RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION GB1009 RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION GB1009 Figure 6. Regional distribution of major crops of the world. The world is divided into 24 agriculturally and culturally distinct regions. For each region, in a pie chart, we present the proportions of the top five most common crops (here we include minor crops, ones for which census data were collected, but for which no spatial data sets were generated). For completeness, we include the Islands as a region (defined as any island in the world with an area less than 5000 km2) although they are not part of our spatial maps or the discussion. The information for the Islands arises purely from the census data. See color version of this figure at back of this issue. physiologies: Sugar cane is a C4 crop, while sugar beets are C3, and in sugar cane the sugar is stored in the stalk, while in beets it is stored in the roots. The two sugar crops together take up slightly more than 2% of the cultivated croplands in the world. Sugar beets are cultivated in the temperate latitudes of the Northern Hemisphere from 40°N to 60°N, mostly in Europe and the European part of Russia (Figure 4d), while sugar cane is a tropical crop, cultivated mostly in the Caribbean and Florida, but also in Central and South America, India, and other parts of south Asia (Figure 4d). Minor cultivation areas for sugar beets can also be found in the American midwest and the northeastern tip of China, while sugar cane is also grown in Australia and South Africa. 4.4. Pulses [28] The FAO defines pulses as a group comprised of dry beans, dry broad beans, dry peas, chick-peas, dry cow peas, pigeon peas, lentils, bambara beans, vetches, and lupins. Pulses are very important economically and provide us with food, medicines, oils, chemicals, timber, dyes, and ornamental garden plants. They also have extremely high dietary Figure 5. Latitudinal distribution of 18 major crops. (a) Temperate cereals (barley and rye), (b) tropical cereals (sorghum, millet and rice), (c) most common cereals (maize and wheat), (d) tubers, (e) sugar crops, (f) pulses, (g) temperate oil-bearing crops (soybeans, rapeseed or canola, and sunflower), (h) tropical oil-bearing crops (ground nuts or peanuts, and oil palm fruit), and (i) cotton. 15 of 27 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License GB1009 GB1009 Table 5. Regional Distribution of the Relative Crop Fraction of the Top Five ‘‘Major’’ and Three ‘‘Other’’ Crops (in %) Region Major Crop 1 Major Crop 2 Major Crop 3 Major Crop 4 Major Crop 5 Sum of 5 Other Crop 1 Other Crop 2 Other Crop 3 Sum of 8 Canada and Alaska wheat barley rapeseed/canola maize pulses oats linseed mixed grain 48.1 15.9 15.0 3.9 3.0 86.0 4.6 2.2 0.9 93.7 Conterminous USA maize wheat soybeans cotton sorghum oats grapes oranges 28.0 25.5 23.9 5.3 3.9 86.6 1.8 0.3 0.3 89.0 Central America maize pulses sorghum wheat sugar cane coffee oranges bananas 46.6 12.8 8.4 4.8 4.6 77.2 7.2 1.4 0.9 86.7 Caribbean sugar cane maize pulses rice cassava coffee cocoa plantains 36.1 7.8 6.2 6.0 3.8 59.9 7.2 3.6 3.3 74.0 Northern South America maize soybeans rice pulses sugar cane coffee cocoa oranges 23.7 18.2 8.8 8.6 7.7 67.0 6.5 1.9 1.5 76.9 Southern South America wheat soybeans sunflower maize sorghum oats linseed grapes 27.0 25.6 12.3 11.7 3.4 79.9 2.2 1.7 0.5 84.3 Northern Europe barley wheat rapeseed/canola sugar beets potatoes oats linseed mixed grain 34.7 30.9 8.8 3.7 3.4 81.5 9.8 1.0 0.7 93.0 Western Europe wheat barley maize rapeseed/canola sugar beets grapes oats triticale 32.0 17.5 9.0 6.9 5.1 70.5 4.3 2.5 1.5 78.8 Southern Europe wheat barley maize sunflower pulses olives grapes oranges 21.0 16.1 6.1 5.9 1.9 51.1 15.1 9.4 1.0 76.6 Eastern Europe wheat barley maize potatoes rye oats mixed grains apples 24.7 16.8 11.2 8.2 7.2 68.2 3.6 2.1 1.6 75.5 wheat barley rye sunflower potatoes oats buckwheat apples European Russiaa 29.4 29.2 9.6 6.0 5.2 79.3 12.0 2.5 0.6 94.4 wheat barley potatoes pulses rye oats buckwheat apples Asiatic Russiaa 47.4 9.1 4.4 2.9 2.0 65.8 12.0 2.5 0.6 80.9 Northern Africa wheat barley maize pulses rice olives almonds tomatoes 30.6 18.8 6.9 3.8 3.5 63.6 11.4 1.3 1.3 77.6 Sahelian Africa sorghum millet maize pulses groundnuts oil palm fruit cocoa yams 20.0 18.9 10.5 8.3 5.2 62.8 4.1 4.0 3.2 74.0 Central Africa cassava maize groundnuts pulses sorghum plantains coffee cocoa 24.9 19.2 8.9 4.8 4.4 62.3 6.4 5.2 3.6 77.6 Eastern Africa maize pulses sorghum cassava rice plantains sweet potatoes coffee 27.1 9.8 8.6 7.9 5.1 58.4 5.9 3.2 3.1 70.7 Southern Africa maize wheat sunflower sorghum sugar cane grapes oranges pumpkins 53.6 15.0 6.3 4.9 3.8 83.6 1.2 0.5 0.3 85.6 Middle East wheat barley pulses cotton maize grapes olives dates 43.4 21.0 6.8 2.7 1.9 75.7 2.6 2.2 0.9 81.4 Central Asia wheat barley cotton millet rye oats buckwheat safflower seed 51.3 22.5 9.4 1.6 1.6 86.3 1.9 1.4 0.8 90.4 East Asia rice wheat maize soybeans rapeseed sesame sweet potatoes linseed 19.9 17.2 12.4 4.8 3.3 57.6 7.0 3.5 3.4 71.5 South Asia rice wheat pulses millet sorghum sesame seed coconuts mangoes 26.5 16.4 10.9 6.8 5.9 66.4 1.1 1.0 0.6 69.1 Southeast Asia rice maize cassava oil palm fruit pulses coconuts natural rubber coffee 45.8 10.4 4.0 3.7 2.7 66.7 8.0 6.5 1.4 82.6 Australia/New Zealand wheat barley pulses sorghum sugar cane oats triticale grapes 50.8 17.6 11.3 3.0 2.0 84.7 6.4 0.8 0.3 92.2 sugar cane maize rice cassava oil palm fruit coconut bananas sweet potatoes Islandsb 17.5 6.5 4.2 2.8 1.3 32.3 47.6 4.7 3.2 87.8 a The numbers under the other crops in European and Asiatic Russia are the same because sub-national data were unavailable (see Appendix A). For completeness, here we include the Islands as a region (defined as any island in the world with an area less than 5,000 km2) although they are not part of our spatial maps or the discussion. The information for the Islands arises purely from the census data. b value because they contain a higher percentage of protein than most other plant foods. [29] Most pulses prefer warm climates, but there are varieties that grow in temperate regions. Pulses are broadly cultivated from 60°N to 50°S (Figures 4d and 5f). On a global scale, they occupy 4% of the cultivated land and, as a group, they rank third in cultivation area, after cereals and oil-bearing crops. The most intense cultivation of pulses occurs around 25°N (in India, where census data on a dozen different kinds of lentils were collected), but pulses are also cultivated throughout Europe, parts of western Asia, the eastern half of China, Australia, the Rift Valley in eastern Africa, the southeastern states of Brazil, Central America, and even in Canada. 4.5. Oil-Bearing Crops [30] On a global scale, oil-bearing crops are grown over 10% of the cropland. According to the FAO, 10% of the total calories available for human consumption are derived from oil-bearing crops such as soybeans, groundnuts (or peanuts), rapeseed (or canola), sunflower and oil palm fruit. This percentage is slightly higher for developed countries (12%) and slightly lower for developing countries (9%). While oil-bearing crops are used mainly for processing into 16 of 27 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION GB1009 Table 6. Area and Relative Proportion of Seven Crop Groups a 2 Crop Group Area, 1000 km Relative Fraction, % Cereals Roots and tubers Sugar crops Pulses Oil-bearing Fibers (cotton) Others Total cropland 10,955 734 419 794 1,819 534 2,664 17,920 61 4 2 4 10 3 15 100 a The crop groups here are comprised only of the 18 major crops considered in the study. All other crops are included in the ‘‘Others’’ group. oil (about 79% of the world production), they are also used for direct food consumption (11%), for seed (2%), for feed (5%), and for industrial use (almost 1%), and 3% are wasted [FAO/GIEWS, 2001]. [31] Oil-bearing crops exhibit a distribution pattern similar to that of cereals: Soybeans, rapeseed (or canola), and sunflower prefer temperate latitudes, while groundnuts (or peanuts) and oil palm fruit are their equatorial and tropical counterparts (Figure 5g). Soybeans occupy 5% of the world’s croplands, while rapeseed/canola and sunflower each occupy 2% of the world’s croplands, groundnuts occupy 1%, and oil palm fruit occupies less than 1% of the world’s croplands. [32] The cultivation of soybeans, especially in North and South America, has been increasing rapidly in recent years, and this was the only crop that had a strong positive growth trend in the 6 years of census data collected. Soybeans are also unique in being the only oil-bearing legume. According to the FAO/GIEWS [2001], Asia and the Americas are the largest producers of oil-bearing crops. These crops amount to 50 and 34%, respectively, of the agricultural production of the two continents. Soybean rivals maize for domination in the maize belt of North America, but is also prevalent in central South America (southern Brazil and northern Argentina), eastern China, and central India (Figure 4e). The soybean belt in the United States alone is roughly the size of Bolivia (or 1.1 million km2). [33] Peanuts are grown in the southeastern United States and eastern China, but the greatest intensities are found in southern India and Gambia (Figure 4e). Rapeseed (or canola) is most prevalent in the southern Canadian provinces, but the crop is also cultivated extensively in the entire continent of Europe, in northwestern India, and in southeastern China (Figure 4e). Sunflowers are grown in southeastern Europe and the European part of Russia (Figure 4f), while oil palm fruit is characteristic of some equatorial nations, including Malaysia and Indonesia, and western Africa (Figure 4f). 4.6. Cotton [34] Cotton is the only major fiber considered here and the only non-food crop. It is cultivated over 3% of the croplands, mostly around 30°N (in the southeastern United States and Uzbekistan, and in Tajikistan, where cotton is the major agricultural commodity) and around 20°N (in India and Pakistan) (Figures 4e and 5). Smaller areas of cotton cultivation can also be found throughout southern GB1009 South America, the southern half of Africa, and in Australia. 4.7. Other Crops [35] While the top five major crops together constitute 65% of the cropland, this is not necessarily true for a few regions: the Caribbean, central Africa, East Asia, eastern Africa, Oceania, southern Europe, and western Africa (Table 5). To describe the agriculture of these regions better, we present the top three minor crops (Table 5). The top three minor (or other) crops add up to 26% of the cropland in southern Europe, 15% in central Africa, and 14% in the Caribbean. [36] Of the ‘‘minor’’ crop groups, the most dominant are fruit (with slightly more than 3% of the world’s croplands); other oil-bearing crops such as coconut, olives, safflower, sesame, and linseeds; other cereals such as oats and mixed grains; and other crops such as coffee, tobacco, and cocoa (all with slightly less than 3% of the world’s croplands) (Table 5 and Figure 6). Vegetables, other roots and tubers, nuts, other fibers, and spices each take up less than 2% of the world’s cropland area. [37] On a global scale, several minor crops have areas of cultivation larger than some of the chosen major crops. With over 220,000 km2, oats, a minor cereal, is 1.5 times larger in extent than rye, a major cereal. Coffee and coconuts are each cultivated over slightly more than 100,000 km2, an area larger than that of both sugar beets and oil palm fruit, both of which are considered major crops. Sweet potatoes cover an area of 90,000 km2, but their extent is half that of potatoes. Grapes and olives, each with over 75,000 km2, are two other regionally significant crops that cannot be disregarded on a global scale either. 5. Diversity of the Major Crops [38] Crop diversity is a critical factor in food security because having a variety of crops allows for the possibility Table 7. Area and Relative Proportion of the 18 Major Crop Categories Crop Area, 1000 km2 Relative Fraction, % Wheat Maize Rice Barley Soybeans Pulses Cotton Potatoes Sorghum Millet Sunflower Rye Rapeseed/canola Sugar cane Groundnuts/peanuts Cassava Sugar beets Oil palm fruit Total of major 18 crops Others Total cropland 4,028 2,271 1,956 1,580 927 794 534 501 501 331 290 288 283 265 247 235 154 72 15,256 2664 17,920 22 13 11 9 5 4 3 3 3 2 2 2 2 1 1 1 1 <1 85 15 100 17 of 27 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION GB1009 GB1009 Figure 7. Degree of diversification of agricultural commodities. Here we map an Agricultural Commodity Diversification Index (ACDI), which is based on the ratio of the relative crop fraction of existing crops to the average mean relative crop fraction (see text for details). This data set only represents the diversification in cultivation of the selected major crops in this study. See color version of this figure at back of this issue. that at least some crops will survive despite a poor climate, insect outbreaks, or other natural disasters. Social factors such as civil or economic strife, trade imbalances, and others can compound natural disasters to further threaten food security. [39] For a quantitative evaluation of the global distribution of the diversity of our chosen major crops, we define an Agricultural Commodity Diversification Index (ACDI). This index is based on the ratio of the relative crop fraction to the average crop fraction of the crops that exist in each grid cell. For each grid cell (i), the ACDI is calculated as follows: ACDIi ¼ 18 X Fi;k min ; 1:0 : Mi k¼1 Here, for each grid cell i, Fi,k is the relative crop fraction for each of the major crops (k), and Mi is the average crop fraction of the crops that exist in that grid cell; that is, Mi ¼ Ni 1 X Fi;k ; Ni k¼1 where Ni is the number of crops in grid cell i with Fi, k > 0. Note here that the ‘‘other crops’’ category is excluded from ACDI, otherwise Ni P Fi;k would always be 100%. Using a k¼1 map of ACDI, we can assess the agricultural commodity diversification for different parts of the world (Figure 7). [40] A caveat to note first is that ACDI is scale dependent. First, because our basic data come from administrative level census information, differences in administrative unit sizes will influence patterns of ACDI. By breaking down the largest countries into subnational units (Figure 2), we have tried to achieve a roughly uniform administrative size throughout the world. However, major differences in administrative unit sizes still exist. Moreover, ACDI is scale dependent even if we are able to obtain data uniformly for equal area units; the level of diversification can change with scale depending on the cropping patterns. Given these caveats, below we compare our ACDI estimates across the world, placing emphasis on the patterns and not the absolute values. [41] The highest levels of major crop diversification in the world can be found in the Andes region of South America, Uruguay, the African nations along Gulf of Guinea, parts of the Rift Valley, the Nile Valley, parts of the Iberian Peninsula, Ukraine, India, Pakistan, North China Plain, and Manchuria (Figure 7). Other regions with high ACDI values are the southeastern United States, parts of the northern Great Plains, Venezuela, eastern Brazil, the Pampas region, Chile, parts of western Africa, the Ethiopian highlands, eastern Africa, much of Europe, southwestern Russia, southeastern China, and eastern Australia (Figure 7). [42] On the other hand, among the world’s least agriculturally diverse places are: the midwestern United States, Montana, western Amazônia, coastal Algeria, semi-arid southern Africa, northern Kazakhstan, Mongolia, Indochina, Malay Peninsula, and western Australia. Relatively low ACDI values can also be found in most of North America, Mexico, Brazil, parts of North Africa, Sudan, Madagascar, northern Europe, the Middle East, Bangladesh, most of Southeast Asia, Japan, and most of Russia. Some of these regions are heavily cultivated, although with low crop diversification. For example, in the midwestern United States (and the Canadian Prairie Provinces) maize and wheat make up more than two thirds of the cropland, while in Vietnam, Laos and Cambodia, extensive rice cultivation is found. 6. Regional Cropping Patterns [43] In this section, we illustrate cropping patterns for different regions of the world. We attempt to delineate the 18 of 27 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION GB1009 RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION GB1009 Figure 8. Crop belts of the world. This map is derived from the three most dominant crops. A dominant crop is one with a cultivation proportion than exceeds the mean (using the ACDI from Figure 7). If more than three crops were dominant in a certain location (e.g., the Indian sub-continent), then we mention the two most dominant crops and report the remainder as being mixed. See color version of this figure at back of this issue. world’s major growing regions, focusing on what crops or crop combinations are dominant in each region. [44] We use our 18 crops data sets to delineate the world’s major crop ‘‘belts,’’ defined using a combination of the most dominant crops (those with relative crop fractions larger than the average relative crop fraction as calculated for ACDI). Regions with a single dominant crop are classified as a single-crop belt, while those with two dominant crops form a two-crop belt, and those with three dominant crops form a three-crop belt. In regions with 19 of 27 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License GB1009 RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION GB1009 Figure 8. (continued) more than three dominant crops, we label the two most dominant crops and label the remainder as being ‘‘mixed’’ (Figures 8a – 8c). 6.1. North America [45] North America is composed of large, agriculturally homogeneous regions (Figure 7). Three major features stand out: two wheat belts and a maize belt in the north gradually transitioning into a soybean belt in the south (Figure 8a). [46] The North American wheat belt dominates this region by far; wheat makes up 30% of the cropland in this region (Table 5 and Figure 6). There are two wheat belts extending west of the Mississippi and spanning the southern Prairie Provinces in Canada and the Great Plain states in the United States (the two belts being separated by the states of South Dakota and Nebraska) (Figure 8a). Winter wheat is cultivated predominantly south of Nebraska, where it is planted in September through October and harvested in June 20 of 27 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License GB1009 RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION GB1009 Figure 8. (continued) through July of the next year. In contrast, spring and durum wheat, which are cultivated predominantly north of Nebraska, are planted in April through May and harvested in mid-July through mid-September of the same year [USDA/JAWF, 1994]. Although wheat dominates these two belts, there are a variety of secondary crops cultivated; barley and canola are grown in the northern portions of the North American wheat belt, maize is grown in the central part, and sorghum and cotton are grown in the south. [47] The maize belt is dominant in the lower half of the Missouri River basin and the entire region east of the Mississippi (Figure 8a). Here maize is planted April through May and harvested October through November [USDA/ JAWF, 1994]. Throughout the maize belt, there is a single secondary crop, soybeans, which often rivals maize for dominance. In the Midwest, the maize belt in Wisconsin transitions into a maize-soybean belt in Iowa and Illinois, and then into a soybean belt in Missouri. [48] Soybeans make the third most prominent crop belt in North America. This crop dominates the lower half of the Mississippi as far east as the Carolinas (Figure 8a). This region has a similar but somewhat wetter and warmer 21 of 27 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License GB1009 RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION climate than that of the maize belt. Soybeans are planted slightly later than maize (May through June) but harvested around the same time (October through November) [USDA/ JAWF, 1994]. Throughout the soybean belt, the secondary crops are cotton and wheat. [49] The other important crops in North America are barley (which together with wheat forms a wheat-barley belt in the Canadian province of Alberta) and cotton (which dominates the cropland along the Gulf Coast with the exception of Florida, and forms a cotton or cotton-sorghum belt in Texas and cotton-groundnuts belt in Georgia). Florida is dominated by sugar cane, making this region agriculturally similar to the rest of the Caribbean, rather than to continental North America. The state of Georgia also contains a small groundnuts belt. 6.2. Central America and the Caribbean [50] Central America has varied agroclimatic settings. However, a single crop, maize, dominates the region from central Mexico to Nicaragua inclusively (Figure 8a). In the dry climate of northwestern Mexico, maize is planted in September and October and harvested January through March of the next year [USDA/JAWF, 1994]. In Mexico, maize forms crop belts with three other crops: sorghum in the state of Tamaulipas, pulses in Coahuila, and wheat in Sonora. Throughout the Central American maize belt, pulses are the next most dominant crop, followed by sugar cane. [51] Costa Rica’s croplands are a transitional area with a mixture of maize, pulses, and rice being cultivated throughout the country (Figure 8a). Rice forms a much smaller second crop belt in Costa Rica and Panama, with maize as the secondary crop, although the average annual temperature and precipitation in this region are not much different from those to the north. The Caribbean is dominated by sugar cane (Figure 8a). In this region with a steady yearround climate, sugar cane is planted and harvested almost throughout the entire year (November through May) [USDA/JAWF, 1994]. Rice and maize are the secondary crops throughout the Caribbean. Although not considered a major crop in this study, coffee is a key commodity in the Caribbean and accounts for 7% of the cultivated land (a percentage higher than that of the third most dominant major crop). 6.3. South America [52] South America has far more diverse cultivation than North and Central America (Figure 7). Here maize and soybeans rival for dominance in the northern portions of the continent, while wheat dominates in the south. [53] One maize belt is draped over the entire Andes and the lowlands to their west from the Columbian highlands all the way into Argentina’s Patagonia, and another centers on the Brazilian Highlands in southeastern Brazil (Figure 8a). Here maize is planted March through May and harvested October through December [USDA/JAWF, 1994]. While maize is a major dominant crop in Central America, the Andes, and the Brazilian Highlands, it is surpassed by wheat and soybeans in the La Plata region of South America. Throughout the Andean maize belt the secondary crops GB1009 are rice (in the Columbian and Ecuadorian lowlands west of the Andes), potatoes (throughout the Peruvian and Bolivian Andes), and sunflowers (in the southern Andes of Argentina). In the Brazilian Highlands, sugar cane and soybeans complement the maize belt. [54] Soybeans form the next largest belt in South America (Figure 8a). This crop is extensively cultivated in the central portion of the continent from the Brazilian state of Mato Grosso in the north to the Argentinean state of Cordoba in the south, in the Gran Chaco region and the area east of it. Soybeans in this region are planted in the beginning of the wet season (October through December) and harvested at the end of it (March through May) [USDA/JAWF, 1994]. The secondary crops throughout this soybean belt are maize in Brazil, cotton in Paraguay, and a combination of wheat, maize, and sunflower in Argentina. [55] Wheat forms the third largest crop belt in South America, but it is the major crop in the southern part of the continent in Argentina and Chile (Figure 8a). Wheat covers the pampas of Argentina and the Western Coastal Plain of Chile. As opposed to the maize and the soybean cultivation areas in South America, the regions of wheat cultivation do experience frosts. Wheat in this region is planted May through July and harvested mid-November through mid-January [USDA/JAWF, 1994]. Throughout the South American wheat belt in the pampas of Argentina, soybeans and sunflowers form the secondary crops, while throughout the South American wheat belt in Chile, the secondary crop is maize. [56] In addition to maize, soybeans, and wheat, there are several other major crop belts in South America. Although sunflowers are cultivated in other parts of the world, South America has the only sunflower belt (Figure 8a). In fact sunflowers are the third-ranking crop in southern South America, surpassing maize, with 12% of the cropland. Also, the northern coastline of the continent and the Tocantins river basin are regions of rice cultivation, while the Xingú river basin is a region of cassava cultivation (Figure 8a). In Brazil the region between Serra do Piaui and the town of Recife makes up a small pulses belt, while south of São Paulo has a sugar cane belt (Figure 8a). 6.4. Europe [57] Europe, like North and Central America, is also composed of large homogeneous agricultural zones (Figure 7). The top five most common major crops for the continent as a whole (wheat, barley, maize, potatoes, and sunflower) represent 63% of the croplands (Table 5). The top five most common major crops for the continent as a whole (wheat, barley, maize, potatoes, and sunflower) represent 63% of the croplands (Table 5). Most locations in Europe can benefit from two harvests. Winter grains (winter wheat, winter barley, and rye) are planted September through October and harvested mid-June through August of the next year, and spring grains (maize, spring barley, and most oats) are planted April through May and harvested September through October of the same year [USDA/JAWF, 1994]. [58] Wheat is cultivated across the entire European continent, except for the Iberian Peninsula, Belarus, and the Baltic Republics (Figure 8b). While most of the wheat 22 of 27 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License GB1009 RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION cultivated throughout this region is winter wheat, durum wheat is also grown here. Winter wheat is most often cultivated in combination with winter barley and rye, and is also most often cultivated on the same land (doublecropped) with maize, oats and to a lesser extent with spring barley [USDA/JAWF, 1994]. Throughout southern Europe, spanning France, Italy, Hungary, Moldova, and all countries south of there, the secondary crop is maize. To the north, in Croatia, Bosnia and Herzegovina, northern Serbia, and Romania, can be found a maize-wheat belt. In Poland, the much more cold-tolerant rye can be found as the secondary crop. In this northern sub-region, barley and rye are also found. Throughout Poland, the Russian oblast of Nizhny Novgorod, and the surrounding regions the croplands can be described as a mixture of wheat, barley, rye, and potatoes. [59] Second in size in Europe is the area of barley cultivation (Figure 8b). Winter barley is the dominant crop on the Iberian Peninsula, especially in Spain, and is surrounded by barley-wheat and wheat alone belts. The spring barley belt is found in Belarus, the Baltic Republics, and the European part of Russia. Ireland stands alone in having both spring and winter barley cultivation. Throughout the barley belts, the secondary crops are wheat, potatoes, and rye. [60] The region along the Mediterranean Sea has a distinct climate. While wheat and barley are the top crops, a minor crop, olives, occupies a large portion of the region’s cropland (over 43,000 km2 or 15%). In this region, fruits come next in the other categories with 40,600 km2, of which area 65% is in grapes, 7% in oranges, and 6% in peaches and nectarines. 6.5. Africa [61] With 13% of the global harvested area, Africa has less cropland than any other part of the world. The agroclimatological zones in Africa are very diverse, ranging from the dry and barren desert, through the rich soil of the Rift, Nile, and Niger Valleys, to the southern extremes. But unlike any other parts of the world, there are no large crop belts in Africa. Rather, there are agricultural regions within which different combinations of crops are cultivated (Figure 8b). [62] Northern Africa is characterized by a Mediterranean climate with the alternation of pronounced warm dry and cool wet seasons. Morocco, Algeria, Libya, and Tunisia have large crop areas along the coast, dominated by a mixture of wheat and barley (Figure 8b). With a single growing season, both winter wheat and barley are planted November through December and harvested May through June of the next year [USDA/JAWF, 1994]. In the Nile delta and Nile Valley, wheat, maize, and rice form a unique agricultural belt (Figure 8b). Again, akin to southern Europe, olives are a major crop in this region, representing 11% of the cropland. [63] The Sahel region, with low rainfall, is dominated by the drought resistant millet and sorghum. In Senegal, Gambia, and Guinea-Bissau another drought resistant crop, groundnuts or peanuts, is grown. Maize and a mixture of other crops are also found in northern Nigeria (Figure 8b). With a single growing season in the Sahel, most crops are planted May through July and harvested October through GB1009 November [USDA/JAWF, 1994]. Coastal West Africa has a more moderate climate because of the oceanic influence and thus benefits from two growing seasons. The dominant crops here are hydrophilic: rice from Guinea to Liberia and maize from the Ivory Coast to Nigeria. Here the first crop of rice is planted April through May and harvested August through October, and a second crop of rice is planted November through December and harvested March through April. Maize is also cultivated in two crops, with the first one being planted March through April and harvested June through August, and the second being planted August through September and harvested December through January [USDA/JAWF, 1994]. The secondary crop throughout Africa’s West Coast rice belt is cassava, while in the maize belt it is a mixture of sorghum, rice, cotton, and millet. Since the agricultural area along the western coast of Africa is much smaller than the one in the Sahel, rice is not one of the top five crops in Sahelian Africa (Figure 6). However, maize is the third most dominant crop, after sorghum and millet, occupying 11% of the cropland in this region (Table 5). [64] Directly east of the Sahel, in Ethiopia, is the northern tip of the African Rift Valley. Throughout the Rift Valley, maize is the dominant crop (Figure 8b). The only locations where maize is not dominant are Zaire (where cassava and cassava-maize-pulses are the prevalent combinations), Mozambique (where cassava dominates), and the drier Botswana and Namibia (where sorghum and millet, respectively, are the crops of choice). Throughout eastern Africa, maize is a winter crop generally planted March through June and harvested August through December, while in South Africa, maize is a summer crop planted October through December and harvested April through June. With water being the limiting factor throughout eastern Africa, the secondary crop is cassava (in Tanzania, Angola, Zambia, and Mozambique), pulses (in Uganda and Tanzania), sorghum (in Mozambique), and cotton (in Zimbabwe, with somewhat better irrigation facilities). South Africa, on the other hand, benefits from a second crop of winter wheat that is planted May through July and harvested October through December [USDA/JAWF, 1994]. The island of Madagascar benefits from two growing seasons, and the most dominant crop is rice, followed by cassava and maize. Rice here is planted November through mid-January and harvested April through June. The two winter crops in this area are wheat and sweet potatoes. The former is planted in May and harvested in November, and the later is planted mid-February through mid-May and harvested mid-May through midDecember [FAO/GIEWS, 2001]. There is a ’’minor’’ crop that should be included for a more complete regional picture; plantains occupy a significant portion of the croplands in both eastern and central Africa, representing about 6% of the cropland (Figure 6 and Table 5). 6.6. Middle East [65] The dominant crop in the Middle East is wheat, cultivated from Turkey in the west to Iran in the east and along the Mediterranean coast, briefly interrupted by a combination of barley and wheat in Syria (Figure 8b). Winter wheat and barley are planted mid-September 23 of 27 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License GB1009 RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION through December and harvested April through August [USDA/JAWF, 1994]. With a far smaller proportion (7% of the cropland) pulses are the third major crop in the Middle East, cultivated in the summer together with maize in northern Turkey, with cotton along the Turkey-Syria border, and with sunflowers in western Turkey. 6.7. Asia [66] Rice dominates this region with 24% of the cropland. The Asian rice belt stretches from India and Nepal on the west to Japan, South Korea, and Taiwan on the east, from the Yangtze River in the north to Timor in the south (Figure 8c). This area receives ample precipitation from the monsoons. Throughout this region, farmers plant a single crop of rice in April and May and harvest it in August through October; however, several sub-regions plant multiple crops of rice [USDA/JAWF, 1994]. Rice is double cropped in southeastern China, along the final stretches of the Xun Xi River, throughout most of Indochina, in the eastern half of India and the Ganges floodplain, and on the island of Java. Throughout parts of Bangladesh, in the Ganges-Brahmaputra floodplain, three crops of rice are cultivated. This large crop belt is dominated almost exclusively by rice, but there is a large number of diverse secondary crops: wheat, maize, groundnuts, and sugar cane in China; maize, cassava and pulses in Indochina; wheat in Nepal; wheat, pulses, and groundnuts in India; and maize in Indonesia. [67] With only a slightly smaller area (19% of the cropland), wheat forms the second largest crop belt in Asia. This crop is characteristic of the Indus River Valley in Pakistan, the Huang He River Valley in China, and most of Central Asia with the exception of Turkmenistan, Uzbekistan, and the southern parts of Kazakhstan (Figure 8c). In Pakistan and northwestern India, winter wheat is planted October through December and harvested March through May. In the Huang He River Valley, spring wheat is planted in March and April and harvested in mid-July through midAugust, but winter wheat accounts for 85 – 90% of the wheat and is planted mid-September through October and harvested in June. In Kazakhstan and the Russian oblasts north of it, winter wheat is planted in September and harvested mid-July through August, but spring wheat is the larger crop and is planted in May and harvested midAugust through September [USDA/JAWF, 1994]. Unlike in the Asian rice belt, secondary crops are far fewer in the wheat belt. In the Indus River Valley, the major secondary crop is cotton, in the Huang He River Valley it is maize, and in Kazakhstan and the Russian oblasts north of it the major secondary crop is barley. [68] In Asia, maize is grown in small pockets of dominance (Figure 8c). It is the dominant crop in two of the northeastern Chinese provinces of Jilin and Liaoning. To the north, this area transitions into a maize-wheat-soybean area and then into a soybean-maize-wheat area, while to the west, it progresses into a wheat-maize and later into a wheat cultivation area. The secondary crop throughout this area is rice. China has another maize pocket in the southern province of Yunnan; this stands alone in the middle of the Asian rice belt, and the secondary crop here is wheat. Finally, together with rice, maize forms the dominant crop GB1009 combination in the Philippines, where cassava and sugar cane compete for third and fourth place. While for Asia as a whole, maize represents 7% of the cropland, this crop is one of the top five only in East and Southeast Asia (Table 5 and Figure 6). [69] Together with rice and wheat, pulses form a dominant crop complex in western India. In Asia as a whole, they represent 6% of the cropland, but in India, this proportion is 12%. Here they are the third most important major crop after rice and wheat, and the area they cover is about half that of rice and about equal to the area of wheat. Pulses are also the secondary crop in Myanmar and a tertiary crop in North Korea and several southern Russian oblasts. [70] Several other crops form a number of small crop belts (Figure 8c). Potatoes dominate in far northeastern Russia, barley is the most dominant crop in parts of southeastern Kazakhstan, a combination of cotton and wheat dominates Uzbekistan, and oil palm fruit stands out in Malaysia. India alone has the most diverse combination of crop belts. Groundnuts stand out in Gujarat; millet in Gujarat and Rajasthan; a combination of pulses, rice, and wheat exists in Madhya Pradesh, with the agriculture of the rest of this state being a mixture of more than three crops; sorghum dominates the state of Maharashtra; while rice spreads along the southern and eastern coast. 6.8. Australia and New Zealand [71] The agriculture of this region closely resembles that of the other temperate regions of the world. Wheat dominates Australia (Figure 8c); it is interrupted only briefly by a combination of wheat and barley in the area around Adelaide. Winter wheat here is planted May through July and harvested October through December [USDA/JAWF, 1994]. In the western portion of the Australian wheat belt, pulses are the most prominent secondary crop, while barley is the secondary crop in the eastern portions. Winter barley is also the most dominant crop in New Zealand, forming its own belt there; it is planted April through June, and harvested November through January. Wheat is the secondary crop in New Zealand. Pulses are the third crop category with a significant enough proportion to be included here (11%). 7. Summary and Conclusions [72] Agricultural activities have been one of the most important drivers of global environmental change in recent decades and centuries. To assess the consequences of cultivation practices for global food production and the health of the environment, data sets of the worldwide extent and intensity of agricultural land use and land cover change are critically needed. While remotely sensed data are able to delineate some of the patterns of agricultural land cover, they are unable to distinguish some of the important features of agricultural land use practices such as the different types of cropping systems (crop varieties, crop rotations, intercropping, multiple cropping), agricultural inputs (irrigation, fertilization, machinery), and outputs (yield, production). Such information is critically needed for studying the consequences of food production systems on the global biogeochemical cycles, global and regional climate, and 24 of 27 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License GB1009 RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION food security; only ground-based data sources, such as agricultural censuses, contain the necessary information. [73] In this study we have synthesized crop specific agricultural census data and spatially explicit data on the extent of the world’s croplands to generate global data sets for the distribution of 18 major crops. Although the study uses a simplified approach with several assumptions, it succeeds in producing a ‘‘first cut’’ global data set that is generally consistent with common agricultural knowledge. Quantitative validation of the data set has not been possible due to the lack of good alternative data sources for many regions of the world. However, we have qualitatively compared our data sets to a recent publication on the distribution of major crops of the world by the U.S. Department of Agriculture; the comparison reveals the major consistencies between the data sets, as well as the deficiencies in our approach. [74] This study shows that the selected 18 major crops (barley, maize, millet, rice, rye, sorghum, wheat, cassava, potatoes, sugar beets, sugar cane, pulses, soybeans, groundnuts/peanuts, rapeseed/canola, sunflower, oil palm fruit, and cotton) are representative of the agriculture of most regions in the world. In certain regions however, one would need to include other crops to obtain a more complete picture (i.e., oats for many parts of the world and grapes and olives in the Mediterranean) (Table 5). Using the crop cover data, we were able to objectively delineate the major crop belts of the world (Figure 8). The location of these crop belts is also in concert with the rest of the agricultural literature. Some continents are composed of large agriculturally homogeneous zones (North America, Europe, Asia, the Middle East, Australia, and New Zealand), while others truly are tapestries of crop mixtures (South America and Africa). [75] These crop data sets have a wide range of applications. They can be used within global ecosystem models and climate models, to assess global food production systems (food production, food security), global water use (irrigation water requirements, impacts on water quality), and consequences for global climate and biogeochemical cycles. Digital versions of these major crop data sets will be made available through our web site (http://www.sage.wisc. edu) upon publication of this paper. Appendix A. Compilation of Crop Inventory Data: Assumptions Made in Countries With Unavailable Sub-National Data A1. Andora [76] There are no FAO data for Andora. Therefore, to obtain the proportion of harvested area of each crop to the total harvested area, we used an area-weighted average of data for each particular crop from France and Spain. A2. Argentina [77] In Argentina, census data were available only for the following states: Entre Rios, Buenos Aires, San Luis, La Pampa, Santa Fe, and Cordoba. For the remaining states, we used an area-weighted average of data from the known states. For cotton, only national level data were available. GB1009 This was distributed among the states in proportion to the total harvested area of the remaining major crops. A3. Australian Capital Territory [78] In the Australian Capital Territory, we assumed the proportions of each of the 18 crops to the total to be the same as those of the Australian state of New South Wales. A4. Brazilian Litigated Zone [79] In the Brazilian Litigated Zone, to obtain the proportion of each crop to the total, we used an area-weighted average of that particular crop from the Brazilian states of Ceara, Piaui, and Amazonas. A5. Canadian Northwest and Yukon Territories [80] In the Canadian Northwest and Yukon Territories, to obtain the proportion of each crop to the remaining, we used an area-weighted average from the Canadian provinces of Alberta and British Columbia. Also, state-level data for pulses were available only for dry peas and dry beans. The sum of these data was scaled up to match the FAO nationallevel statistics for pulses. A6. Kazakhstan [81] For Kazakhstan, only national level data on barley were available. This was distributed among the oblasts in proportion to the total harvested area of the remaining major crops. A7. Liechtenstein [82] In Liechtenstein, as FAO data were not available, to obtain the proportion of harvested area of each crop to the total, we used an area-weighted average of data for particular crop from Austria and Switzerland. A8. Luxembourg and Belgium [83] The agricultural census data for Luxembourg and Belgium were reported together; therefore, we assumed the two countries to have the same crop proportions for all crops. A9. Montenegro [84] In Montenegro, to obtain the proportion of each crop to the remaining, we used an area-weighted average of that particular crop from Albania, Bosnia, and Herzegovina. A10. Russia [85] In Russia, barley data were only available for regions (group of oblasts). This was uniformly distributed among the oblasts within each region. Only production data were available for rye (in tons). Knowing the total harvested area at the national level from FAO statistics, and assuming that yield is relatively constant among the different oblasts where this crop is cultivated, we estimated harvested area for each oblast. A11. San Marino [86] In San Marino, as FAO data were not available, we assumed the proportions of each of the 18 crops to the total to be the same as those of Italy. A12. Serbia [87] For Serbia, to obtain the proportion of each crop to the total, we used an area-weighted average of that partic- 25 of 27 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License GB1009 RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION ular crop from Albania, Bosnia and Herzegovina, Croatia, Bulgaria, Hungry, Macedonia, and Romania. A13. Taiwan [88] In Taiwan, we assumed the proportions of each of the 18 crops to the total to be the same as those of the Fujian province in China. A14. District of Columbia and Guantanamo Bay [89] The cropland area in the District of Columbia in the United States and Guantanamo Bay of the United States is negligible, and therefore we assumed the cropland proportions for all crops to be zero. A15. West Bank [90] In the West Bank, we assumed the proportions of each of the 18 crops to the total to be the same as those of Israel. [91] Acknowledgments. We would like to thank Tom Lillesand and Jun Zhu for fruitful discussions and advice during this project. We would like to thank Lex Bouwman for providing the RIVM crop data sets. The two reviewers of this paper provided very constructive suggestions that greatly improved the quality of the final manuscript. This work was supported by NASA’s Office of Earth Science (through Interdisciplinary Science (IDS) Program grant NAG5-9452). References Australian Bureau of Statistics (1991), Summary of Crops: Australia 198990, 19 pp., Canberra, ACT, Australia. Australian Bureau of Statistics (1992), Year Book: Australia 1992, Canberra, Australia, ACT. Australian Bureau of Statistics (1994), Year Book: Australia 1994, Canberra, ACT, Australia. Belward, A. S., J. E. Estes, and K. D. Kline (1999), The IGBP-DIS global 1-km land-cover data set DISCover: A project overview, Photogramm. Eng. Remote Sens., 65(9), 1013 – 1020. Betts, R. A. (1999), The impact of land use on the climate of present day, in Research Activities in Atmospheric and Oceanic Modelling: CAS/JSC WGNE Report, edited by H. Richie, pp. 7.11 – 7.12, World Meteorol. Org., Geneva. Bounoua, L., R. DeFries, G. J. Collatz, P. Sellers, and H. Khan (2002), Effects of land cover conversion on surface climate, Clim. Change, 52(1 – 2), 29 – 64. Brown, J. F., T. R. Loveland, J. W. Merchant, B. C. Reed, and D. O. Ohlen (1993), Using multisource data in global land-cover characterization: Concepts, requirements, and methods, Photogramm. Eng. Remote Sens., 59(9), 977 – 987. Brovkin, V., A. Ganopolski, M. Claussen, C. Kubatzki, and V. Petoukhov (1999), Modelling climate response to historical land cover change, Global Ecol. Biogeogr., 8(6), 509 – 517. Cao, M., K. Gregson, S. Marshall, J. B. Dent, and O. W. Heal (1996), Global methane emissions from rice paddies, Chemosphere, 33(5), 879 – 897. Centro de Estadı́stica Agropecuaria (2000), Sistema Municipal de Bases de Datos (SIMBAD), Sector Agropecuario, Resultados Definitivos: VII Censos Agricola-Ganadero y Ejidal 1991 [CD-ROM], Inst. Nacl. de Estadı́stica, Geogr. e Inf., Aguascaliente, Mexico. Cihlar, J. (2000), Land cover mapping of large areas from satellites: Status and research priorities, Int. J. Remote Sens., 21(6/7), 1093 – 1114. Dale, V. H., S. Brown, R. A. Haeuber, N. T. Hobbs, N. Huntly, R. J. Naiman, W. E. Riebsame, M. G. Turner, and T. J. Valone (2000), Ecological principles and guidelines for managing the use of land, Ecol. Appl., 10(3), 639 – 670. DeFries, R. S., and A. S. Belward (2000), Global and regional land cover characterization from satellite data: An introduction to the special issue, Int. J. Remote Sens., 21(6/7), 1083 – 1092. Donner, S. D., and C. J. Kucharik (2003), Evaluating the impacts of land management and climate variability on crop production and nitrate export across the Upper Mississippi Basin, Global Biogeochem. Cycles, 17(3), 1085, doi:10.1029/2001GB001808. Fischer, G., H. van Velthuizen, F. Nachtergaele, and S. Medow (2000), Global Agro-Ecological Zones (Global - AEZ) [CD-ROM], Food and GB1009 Agric. Org./Int. Inst. for App. Syst. Anal. (FAO/IIASA), Rome. (Also available at http://www.fao.org/ag/AGL/agll/gaez/index.htm) Food and Agriculture Organization (2002), FAOSTAT 2001: FAO Statistical Databases [CD ROM], Rome. Food and Agriculture Organization/GIEWS (2001), Global information and early warning system on food and agriculture, Rome. (Available at http:// www.fao.org/giews/English/giewse.htm) Goskomstat Rusii (1995), Selskoe Khoziaistvo Rossii: Statisticheskii Sbornik, Goskom Rossiiskoi Federatsii po Statistike, Moscow. Gosudarstveni Committet Kazahskoi SSR po statistike (1987), Narodnoe hoziaistvo Kazahskoi SSR: Iubileinii Statisticheskii Ejegodnik, Alma-Ata. Goudie, A. (2000), The Human Impact on the Natural Environment, 5th ed., MIT Press, Cambridge, Mass. Houghton, R. A., J. L. Hackler, and K. T. Lawrence (1999), The US carbon budget: Contributions from land-use change, Science, 285, 574 – 578. IMAGE-team (2001), The IMAGE 2.2 implementation of the SRES scenarios: A comprehensive analysis of emissions, climate change and impacts in the 21st century, [CDROM], Nat. Inst. for Public Health and the Environ., Bilthoven, Netherlands. Instituto Nacional de Estadistica y Censos (INDEC) (1995), Sector of the Ecocomy, in 1995 Statistical Yearbook Republic of Argentina, chap. 5, pp. 289 – 297, Buenos Aires. Instituto Nacional de Estadistica y Censos (INDEC) (1996a), Agriculture, in 1996 Statistical Yearbook of the Argentine Republic, Vol. 12, chap. 6.2, pp. 358 – 371, Buenos Aires. Instituto Nacional de Estadistica y Censos (INDEC) (1996b), Resultados Generales Ampliados, in Encuesta Nacional Agropecuaria 1995, vol. 5, pp. 24 – 38, Buenos Aires. Instituto Nacional de Estadistica y Censos (INDEC) (1996c), Resultados por Zonas Agroestadisticas, in Encuesta Nacional Agropecuaria 1995, vol. 7, pp. 20 – 24, Buenos Aires. Klein Goldewijk, K. (2001), Estimating global land use change over the past 300 years: The HYDE Database, Global Biogeochem. Cycles, 15(2), 417 – 433. Kucharik, C. J. (2003), Evaluation of a process-based agro-ecosystem model (Agro-IBIS) across the U.S. cornbelt: Simulations of the inter-annual variability in maize yield, Earth Interact., in press. Leemans, R., and A. M. Solomon (1993), Modeling the potential change in yield and distribution of the Earth’s crops under a warmed climate, Clim. Res., 3, 79 – 96. Lloyd, J., and G. D. Farquhar (1994), 13C discrimination during CO2 assimilation by the terrestrial biosphere, Oecologia, 99, 201 – 215. Lobo, A., J. J. Ibanez Marti, and C. C. Gimenez-Cassina (1997), Regional scale hierarchical classification of temporal series of AVHRR vegetation index, Int. J. Remote Sens., 18(15), 3167 – 3193. Loveland, T. R., and A. S. Belward (1997), The IFBP-DIS global 1km land cover data set, DISCover: First results, Int. J. Remote Sens., 18(15), 3289 – 3295. Loveland, T. R., J. W. Merchant, D. O. Ohlen, and J. F. Brown (1991), Development of a land-cover characteristics database for the conterminous U.S., Photogramm. Eng. Remote Sens., 57(11), 1453 – 1463. Matthews, E., and I. Fung (1987), Methane emission from natural wetlands: Global distribution, area, and environmental characteristics of sources, Global Biogeochem. Cycles, 1(1), 61 – 86. McNeely, J. A. (1992), The sinking ark—Pollution and the worldwide loss of biodiversity, Biodiv. Conserv., 1(1), 2 – 18. Meyer, W. B., and B. L. Turner II (Eds.) (1994), Changes in Land Use and Land Cover: A Global Perspective, Cambridge Univ. Press, New York. Ministry of Agriculture (1993), Area and Production of Principal Crops in India 1990 – 91 to 1992 – 93, Dir. of Econ. and Stat., Dep. of Agric. and Co-op., Min. of Agric., Govt. of India, New Delhi. Pearce, D. W. (2001), The economic value of forest ecosystems, Ecosyst. Health, 7(4), 284 – 296. Pielke, R. A., G. Marland, R. A. Betts, T. N. Chase, J. L. Eastman, J. O. Niles, D. D. S. Niyogi, and S. W. Running (2002), The influence of landuse change and landscape dynamics on the climate system: Relevance to climate-change policy beyond the radiative effect of greenhouse gases, Philos. Trans. R. Soc. London, Ser. A, 360(1797), 1705 – 1719. Postel, S. L., G. C. Daily, and P. R. Ehrlich (1996), Human appropriations of renewable fresh water, Science, 271, 785 – 788. Ramankutty, N., and J. Foley (1998), Characterizing patterns of global land use: An analysis of global croplands data, Global Biogeochem. Cycles, 12(4), 667 – 685. Seto, K. C., R. K. Kaufmann, and C. E. Woodcock (2000), Landsat reveals China’s farmland reserves, but they are vanishing fast, Nature, 406, 121. State Institute of Statistics (1994), Prime Ministry Republic of Turkey, 1991 General Agricultural Census: Results of the Agricultural Holdings (Households) Surveys, Ankara. 26 of 27 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License GB1009 RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION State Institute of Statistics (1995), Prime Ministry Republic of Turkey, 1993 Agricultural Structure and Production, Ankara. State Statistical Bureau (1991), Peoples Republic of China, Statistical Yearbook of China 1990, Econ. Inf. Agency, Hong Kong. State Statistical Bureau (1992), Peoples Republic of China, Statistical Yearbook of China 1991, Econ. Inf. Agency, Hong Kong. State Statistical Bureau (1993), Peoples Republic of China, Statistical Yearbook of China 1992, Econ. Inf. Agency, Hong Kong. State Statistical Bureau, Peoples Republic of China (1994), Statistical Yearbook of China 1993, Econ. Inf. Agency, Hong Kong. State Statistical Bureau, Peoples Republic of China (1995), Statistical Yearbook of China 1994, Econ. Inf. Agency, Hong Kong. State Statistical Bureau, Peoples Republic of China (1996), Statistical Yearbook of China 1995, Econ. Inf. Agency, Hong Kong. Statistics Canada (1992), Agricultural profile of Canada: Part 1. 91 Census, 93 – 350, Min. of Ind., Ottawa. Statistics Canada (1997a), Agricultural profile of Canada: 96 Agriculture census, 93 – 356-XBP, Min. of Ind., Ottawa. Statistics Canada (1997b), Historical overview of Canadian Agriculture: 1996 Agriculture census, 93 – 358-XBP, Min. of Ind., Ottawa. Still, C. J., J. A. Berry, G. J. Collatz, and R. S. DeFries (2003), Global distribution of C-3 and C-4 vegetation: Carbon cycle implications, Global Biogeochem. Cycles, 17(1), 1006, doi:10.1029/2001GB001807. Turner, I. I. B. L., R. H. Moss, and D. L. Skole (1993), Relating land use and global land cover change: A proposal for an IGBP-HDP Core Project, Rep. 24, Int. Geosphere-Biosphere Programme, Stockholm. United States Department of Agriculture/Joint Agricultural Weather Facility (1994), Major world crop area and climatic profiles, report, U.S. Dep. of Comm., Natl. Tech. Inf. Serv., Springfield, Va. GB1009 United States Department of Agriculture (1999), International agriculture, USDA Econ. and Stat. Syst., Springfield, Va. (Accessible via the web from the Albert R. Mann Library at Cornell University at http://jan.mannlib. cornell.edu/data-sets/international/) United States Department of Agriculture (2001), Historical data, USDA Natl. Agric. Stat. Serv., Washington, D. C. (Accessible via the web from the USDA NASS at http://www.usda.gov/nass/) Vitousek, P. M., H. A. Mooney, J. Lubchenco, and J. M. Milillo (1997), Human domination of Earth’s ecosystems, Science, 227, 494 – 499. Vogelmann, J. E., S. M. Howard, L. Yang, C. R. Larson, B. K. Wylie, and N. VanDriel (2001), Completion 1990s National Land Cover Data Set for the conterminous United States from Landsat Thematic Mapper data and ancillary data sources, Photogramm. Eng. Remote Sens., 67(6), 650 – 662. Wood, S., K. Sebastian, and S. J. Scherr (2000), Pilot Analysis of Global Ecosystems (PAGE): Agroecosystems, 110 pp., Int. Food Policy Res. Inst. and World Resour. Inst., Washington, D. C. Zhao, M., and A. J. Pitman (2002), The regional scale impact of land cover change simulated with a climate model, Int. J. Climatol., 22(3), 271 – 290. J. A. Foley and N. Ramankutty, Center for Sustainability and the Global Environment (SAGE), Gaylord Nelson Institute for Environmental Studies, University of Wisconsin, 1710 University Avenue, Madison, WI 53726, USA. ([email protected]; [email protected]) B. Leff, National Geographic Maps, 1145 17th Street NW, Washington, DC 20036-4688, USA. ([email protected]) 27 of 27 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License GB1009 RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION Figure 1. Global cropland data set of Ramankutty and Foley [1998]. This data set was created by merging satellite-derived land cover data and administrative unit level agricultural census data. It represents the fraction of a 5-min resolution (in latitude by longitude) grid cell occupied by arable lands and permanent crops in 1992. 2 of 27 GB1009 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License GB1009 RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION Figure 6. Regional distribution of major crops of the world. The world is divided into 24 agriculturally and culturally distinct regions. For each region, in a pie chart, we present the proportions of the top five most common crops (here we include minor crops, ones for which census data were collected, but for which no spatial data sets were generated). For completeness, we include the Islands as a region (defined as any island in the world with an area less than 5000 km2) although they are not part of our spatial maps or the discussion. The information for the Islands arises purely from the census data. 15 of 27 GB1009 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License GB1009 RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION Figure 7. Degree of diversification of agricultural commodities. Here we map an Agricultural Commodity Diversification Index (ACDI), which is based on the ratio of the relative crop fraction of existing crops to the average mean relative crop fraction (see text for details). This data set only represents the diversification in cultivation of the selected major crops in this study. 18 of 27 GB1009 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License GB1009 RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION Figure 8. Crop belts of the world. This map is derived from the three most dominant crops. A dominant crop is one with a cultivation proportion than exceeds the mean (using the ACDI from Figure 7). If more than three crops were dominant in a certain location (e.g., the Indian sub-continent), then we mention the two most dominant crops and report the remainder as being mixed. 19 of 27 GB1009 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License GB1009 20 of 27 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Figure 8. (continued) GB1009 RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION GB1009 21 of 27 19449224, 2004, 1, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GB002108, Wiley Online Library on [23/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Figure 8. (continued) GB1009 RAMANKUTTY ET AL.: GLOBAL CROP DISTRIBUTION GB1009
0
Puede agregar este documento a su colección de estudio (s)
Iniciar sesión Disponible sólo para usuarios autorizadosPuede agregar este documento a su lista guardada
Iniciar sesión Disponible sólo para usuarios autorizados(Para quejas, use otra forma )