Management of the Agricultural Nitrogen (N) Pollution in the Bulgarian Groundwater Vulnerable Zones

摘要

Nitrogen pollution of the soils leading to pollution of the surface and subsurface waters is an essential water resource problem. Related to the issue is also the nitrogen pollution of the atmosphere. The main part in these processes belongs to the excessive use of fertilizers in the agriculture. The problem acquires particular importance for groundwater bodies situated in areas with intensive agriculture and natural preconditions making them more vulnerable to pollution. The study shows the N pollution and the response management activites trends in Bulgaria during the last two decades. The country has determined the boundaries of nitrate vulnerable zones and has set for them the maximum fertilizers norm equal to 170 kg N/ha. The performed analyses show that for achievement of the marked in the EU Nitrate Directive and the Kyoto Protocol targets for the period 2013-2020 and until 2050, further expansion of these zones and reduction of the norms should be done. This requires introduction of good practices with appropriate usage of fertilizers aiming at achievement of satisfactory yields with acceptable levels of nitrogen pollution of the soils and the air. The struggle with this challenge could be made more effective through employment of mathematical models. As illustration of such a possibility shown are the results from a pattern model study for estimation of optimal quantities of fertilizers applied to maize production on fluviosoils in Bulgaria.