Content of inorganic nitrogen in soil under monoculture of maize

The influence of mellowing of soil and fertilisation on the content of inorganic nitrogen in the soil under monoculture of corn-maize was observed at the stationary field experiment during years 1998-2000 on brown loess soil prolluvial sediments. The experiments was set in warm and temperately arid climatic area in South-west Slovakia (average temperature during growing season is 16,4oC, average annual precipitation amounts to 561 mm). The experiment had two systems of mellowing of soil: A - deep ploughing in to 0.3 m in autumn, B - twice combined soil looser (to the depth 0.10 m) in autumn. Each system of soil mellowing had three fertilisation levels: K - unfertilised control, a - NPK fertilisation by a balance method according to nutrient requirements of maize for harvest 8 t and its content in soil, b - NPK fertilisation by a balance method according to nutrient requirements of maize for harvest 8 t and its content in soil + ploughing down after harvest residues and maize stalks. The plots had dimension 3,5 x 10 m and were in four times repetition. The treatments a and b were manured by superphosphate and potassium sulphate (in autumn before fallowing) and by nitrate ammonium with limestone (before seeding). The doses of fertiliser (shown in table 2) were determined according to soil agrochemical analysis and harvest 8 t maize. In the treatment b we used 0.5 kg of nitrogen (nitrate of ammonium with limestone) to each 100 kg of ploughing down residues. Before seeding and after gathering of corn-maize the specimens o soil were taken out from depth of 0 - 0,3 m to determine ammonium (colour method by Nessler test solution) and nitrate nitrogen (colour method by acid phenoldihydrosulphide). Acquired results were evaluated by programme Statgraphic 5.0. The most significant influence on the content of inorganic nitrogen had climatic conditions in the interference with agro-technical interventions during experimental years. The influence of years was statistically highly significant. Different mellowing of soil had no statistical significant influence on content of inorganic nitrogen. Ploughing down harvest residues and stalks maize was manifested by moderately augmentation of particulars inorganic nitrogen forms in the soil (before seeding in the treatment B). This augmentation was no statistically significant