Effect of perennial grasses and fallow on the structural composition and mobilization of mineral nitrogen of chernozem soil of Krasnoyarsk forest steppe

The influence of perennial leguminous grasses and fallow on the structural composition and content of mobile forms of nitrogen of chernozem soil of Krasnoyarsk forest steppe is examined. An "excellent" structural composition was identified under eastern galega and hybrid alfalfa of the 10-11 and 5-6 years of use, respectively. The structural composition of the soil under eastern galega is dominated by pedov of magnitude 3-5 and 2-3 mm and the least content of the largest units (>10 mm), compared to alfalfa agrophitocenosis and fallow field. Two-factor analysis of variance revealed the dependence of the content of structural units and mobile nitrogen compounds from a number of the studied factors. A significant contribution to the variability of the structural composition of the factor "not examine factors" was found out- not the studied variables in the experiment. Granulometric soil composition has a significant impact on the formation of separate units. Apparently, the factors contributing to the least flow of valuable-size aggregates in the soil of fallow field are smaller humus content, relatively high content of coarse dust and the lack of plant root systems. The soil under fallow gave way to the perennial grass agrocenoses and corresponded to "good" level of structure. The degree of the influence of factors on the mobilization of nitrogen alcaline-hydrolizable compounds is in the following descending order: interaction (crop * period)> period> crop. It was shown that in the soil under eastern galega, maximum pool of easily hydrolizable nitrogen is formed, in comparison with alfalfa and fallow in the growing season with optimum moistening. Fallow soil was inferior to herbal agro-ecosystems, but trash cover background conditioned an increase in nitrogen up to the level of perennial grasses under arid conditions of the second growing season (2012 y.). According to the content of ammonium nitrogen, the variants were equal and corresponded to low level. A significant impact on the nature of the transitions of ammonium exchange was made by a factor period", apparently reflecting the variability of moistening conditions and temperature of growing seasons. The dynamics of nitric nitrogen revealed the advantages of the fallow field before grasses, whereas eastern galega - before alfalfa. The intensity of oxidized nitrogen compounds was determined by agrotechnical and bio-climatic factors, which is proved by statistics.

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