Simulation of nitrate leaching for different nitrogen fertilization rates

Agriculture, Ecosystems and Environment 103 (2004) 59–73
Simulation of nitrate leaching for different nitrogen fertilization
rates in a region of Valencia (Spain) using a GIS–GLEAMS system
J.M. de Paz a,∗ , C. Ramos b,1
a
b
Centro de Investigaciones sobre Desertificación, Camı de la marjal s/n, Apdo. Oficial, 46.470 Albal-Valencia, Spain
Instituto Valenciano de Investigaciones Agrarias, Carretera Moncada-Náquera km 4,5, Apdo. Oficial, 46113 Moncada, Valencia, Spain
Received 14 January 2003; received in revised form 10 October 2003; accepted 27 October 2003
Abstract
The groundwater loading effects of agricultural management systems (GLEAMS) model coupled to a GIS was used to
evaluate the effect of different fertilization treatments on the total N leaching in a selected area of eastern Spain with intensive
agriculture. Four nitrogen fertilization rates (traditional or base, base rate reduced by 20%, reduced by 50%, and the rate
calculated by the Nmin recommendation system for vegetables, and reduced by 70% for citrus) were evaluated at a regional
scale to find the rate that minimized N leaching without reducing crop N uptake.
Nitrate leaching maps were obtained for the different nitrogen rates studied. A great reduction of N leaching (up to 68%
for vegetables, and 75% for citrus) was observed under the most reduced fertilization rates and this reduction was greater in
areas irrigated with surface water in comparison to those irrigated with groundwater.
The GIS–GLEAMS system was a useful tool to assess the N leaching at a regional scale for the different N management
considered. For example, it was shown that the Nmin recommendation system was the most efficient for vegetables, and for
citrus the most efficient fertilization rate was the reduced 50%, that is similar to that recommended by the Code of Good
Agricultural Practices.
The areas irrigated with groundwater with high nitrate content had a high leaching rate, and the nitrate applied in irrigation
water should be considered when planning the crop fertilization. A temporal analysis of the NO3 -N in soil, N leaching, crop
evapotranspiration and rainfall allowed to identify the influence of the soil NO3 -N and the rainfall on nitrate leaching.
© 2003 Elsevier B.V. All rights reserved.
Keywords GIS; GLEAMS; Nitrate leaching; Nitrogen fertilization