Matjaž Glavan

This investigation explores the impact of various management practices on nitrate leaching and crop yield in two specific areas in Slovenia. The issue of nitrate leaching from agricultural land is a worldwide threat to drinking water, and despite years of research efforts, universal solutions are still unknown. The two chosen study sites are significant because of their importance for agricultural production and because groundwater aquifers beneath are main sources of drinking water, which makes imposing mitigation measures challenging. One of the areas was reported to be of “bad” status according to the Water Framework Directive criteria, while the other is at risk of reaching this status if nitrate concentrations in groundwater continue to rise. This research used the SWAT model to simulate nitrate leaching and crop yield changes under different agricultural scenarios on different soil types. It aimed to accomplish two objectives: first, to identify parts of the case study areas where the existing combination of soil conditions and agricultural practices enables a high potential for nitrate leaching; second, to identify agricultural practices that decrease nitrate leaching from various soil types while maintaining crop yields in each area. By identifying the most vulnerable locations and the most promising practices, we generated a chart of best management practices for specific soil types as a guide that extension services can use to advise farmers on potential management improvements. The main findings demonstrate that reducing fertilizer application, both organic and inorganic, in areas where the rates exceed crop requirements may not have a significant impact on crop production. However, these reductions often resulted in a noticeable decrease in nitrate exports. The results also showed that soil type is crucially important and should always be considered when evaluating the effects of agricultural management on crop yields and nitrate leaching.