Jégo G, Martínez M, Antigüedad I, Launay M, Sanchez-Pérez J M, Justes E
Laboratoire d'écologie fonctionnelle, UMR 5245, CNRS-UPS-INP-ENSAT, Avenue de l'agrobiopole BP 107, Auzeville-Tolosane, 31326 Castanet-Tolosan cedex, France.
Sci Total Environ. 2008 May 15;394(2-3):207-21. doi: 10.1016/j.scitotenv.2008.01.021. Epub 2008 Mar 6.
The quaternary aquifer of Vitoria-Gasteiz (Basque Country, Northern Spain) is characterised by a shallow water table mainly fed by drainage water, and thus constitutes a vulnerable zone in regards to nitrate pollution. Field studies were performed with a potato crop in 1993 and a sugar beet crop in 2002 to evaluate their impact on nitrate leaching. The overall predictive quality of the STICS soil-crop model was first evaluated using field data and then the model was used to analyze dynamically the impacts of different crop management practices on nitrate leaching. The model was evaluated (i) on soil nitrate concentrations at different depths and (ii) on crop yields. The simulated values proved to be in satisfactory agreement with measured values. Nitrate leaching was more pronounced with the potato crop than with the sugar beet experiment due to i) greater precipitation, ii) lower N uptake of the potato crop due to shallow root depth, and iii) a shorter period of growth. The potato experiment showed that excessive irrigation could significantly increase nitrate leaching by increasing both drainage and nitrate concentrations. The different levels of N-fertilization examined in the sugar beet study had no notable effects on nitrate leaching due to its high N uptake capacity. Complementary virtual experiments were carried out using the STICS model. Our study confirmed that in vulnerable zones agricultural practices must be adjusted, that is to say: 1) N-fertilizer should not be applied in autumn before winter crops; 2) crops with low N uptake capacity (e.g. potatoes) should be avoided or should be preceded and followed by nitrogen catch crops or cover crops; 3) the nitrate concentration of irrigation water should be taken into account in calculation of the N-fertilization rate, and 4) N-fertilization must be precisely adjusted in particular for potato crops.
维多利亚-加斯泰斯（西班牙北部巴斯克地区）的第四纪含水层的特点是地下水位浅，主要由排水补给，因此在硝酸盐污染方面构成一个脆弱区。1993年对马铃薯作物和2002年对甜菜作物进行了田间研究，以评估它们对硝酸盐淋失的影响。首先使用田间数据评估了STICS土壤-作物模型的总体预测质量，然后使用该模型动态分析不同作物管理措施对硝酸盐淋失的影响。对该模型进行了评估：（i）不同深度的土壤硝酸盐浓度，以及（ii）作物产量。模拟值与测量值结果吻合良好。马铃薯作物的硝酸盐淋失比甜菜试验更明显，原因如下：（i）降水量更大；（ii）马铃薯作物根系浅，氮吸收量较低；（iii）生长周期较短。马铃薯试验表明，过度灌溉会通过增加排水量和硝酸盐浓度显著增加硝酸盐淋失。甜菜研究中考察的不同氮肥水平对硝酸盐淋失没有显著影响，因为其氮吸收能力强。使用STICS模型进行了补充虚拟试验。我们的研究证实，在脆弱区必须调整农业措施，也就是说：1）在冬季作物前的秋季不应施用氮肥；2）应避免种植氮吸收能力低的作物（如马铃薯），或者在其前后种植氮吸收作物或覆盖作物；3）在计算氮肥施用量时应考虑灌溉水的硝酸盐浓度；4）必须特别精确地调整氮肥施用量，尤其是针对马铃薯作物。
