Influence of mineral fertilizer on nitrogen leaching

In this paper we present results of a long-term crop rotation experiment established in 1971 in central Lithuania on morainic sandy loamy Epicalcari-Endohypogleyic Cambisols. The influence of regular fertilization with different NPK fertilizers in a crop rotation (winter wheat, sugar beet, spring barley, annual grasses and perennial grasses) and climatic conditions on the amount of N-compounds in lysimeter water (sampled at 40- and 80-cm depths) was investigated. Nitrate (NO3) concentration in lysimeter water depended mainly on the nitrate fertilizers application rate. Based on the 30-year mean (1976-2005), fertilization of agricultural crops with 112 kg N ha(-1) increased nitrate concentration in lysimeter water at 40-cm depth by 67.1 mg l(-1) to 112.1 mg l(-1). An N-fertilization rate of 224 kg N ha(-1) increased nitrate concentrations by 139.1 mg l(-1) to 187.2 mg l(-1). The effect of mineral fertilizers on ammonium (NH4+) concentrations in lysimeter water was insignificant. Increases in the nitrogen concentration in lysimeter water in response to N-fertilization were more substantial when agricultural crops were not fertilized with phosphorus. Correlation between the nitrate concentration and applied amount of N-fertilizers was more statistically reliable when grain crops (r = 0.65-0.67, n = 74, p<0.001), sugar beet (r = 0.63, n = 27, p<0.001) and perennial grasses (r = 0.40, n = 59, p<0.01) were cultivated on the experimental field. Higher amounts of nitrate were leached when annual plants were cultivated, compared with perennial grasses. The concentration of NH4 and NO2 in lysimeter water was minimal and the influence of mineral fertilizers negligible.