P-load in drainage water when slurry is applied

The paper presents study results on nutrient leaching in crop rotation fields where slurry was applied. The studies were carried out within the period of 2001–2003. As the study results have shown, phosphorus (P) concentrations much depend on drainage runoff. Increasing drainage runoff resulted in decreased P concentrations (r = 0.7). P leaching also depends on the precipitation amount (r = 0.83). Higher precipitation rates resulted in more intensive P leaching. P leaching more depended on the drainage runoff and the type of cultivated crops rather than on fertilization rates. P leaching decreased when higher amounts of phosphorus were accumulated in crop yield; the mineralization process of vegetative residuals that were left in the test field enhanced more intensive P leaching. When slurry was applied on crops of the test field, P concentrations never exceeded maximum allowable rates determined in normative documents of the Environment of Lithuania. From the point of view of the environment protection, it is more expedient to apply slurry in spring because in this season of the year the leached amount of total P input into the soil is 37.5% less compared to its leached amount when slurry is applied in autumnVytauto Didžiojo universitetasŽemės ūkio akademij