The effect of straw on the humus state of chernozem

Abstract

Abstract. The purpose of the research is to present the results of studies obtained in the long-term stationary experience of the Geographical Network of Experiments with Fertilizers of the Russian Federation on the effect of various methods of straw, crop residues and nitrogen fertilizers utilization on the humus state of leached black soil. Establish the effect of the systematic introduction of straw and crop residues on the content of total and labile humus in leached black soil, provide data on the fractional composition of humus. Methods. There were used conventional methods: total nitrogen by the method of indophenol greens, humus according to Tyurin in Simakov’s modification; fractional group composition according to Ponomareva and Plotnikova; labile carbon – by the release of humic substances during treatment with 0.1n NaOH, soil treatment with sodium pyrophosphate 0.1m Na4P2O7 (Dyakonova’s method) and hot water (Schulz’s method). Results. The results of studies obtained in a long-term stationary experiment on the study of the effect of straw and crop residues on the humus state of the soil are presented. It has been established that the annual introduction of straw and crop residues into the soil makes it possible to maintain the humus state of the leached black soil at the level of the initial content. Significant differences in the humus reserves in the arable soil layer according to the methods of utilization of organic residues were not revealed, they were assessed as very high. On a long fallow, humus reserves were high, on virgin lands they were ultra-high. The results of the studies showed that the fractional composition of fulvic acids depended on the method of using straw and stubble residues; the fractional composition of humic acids did not differ from the method of utilizing straw and stubble residues. A decrease in the content of total humus was revealed against the background of burning and removing straw and stubble, while an increase in its content was noted during the systematic plowing of post-harvest residues. Scientific novelty consists in changing the fractional-group composition of humus when using organic residues (straw, stubble) for the reproduction of soil organic matter.