Humus state of the soil under liquid manure application on Kuban rice crops

Abstract

Abstract The aim of the work is to study the effect of liquid manure application on the humus regime of gleyic and chernozem soil when growing rice. On the Maryano-Cheburgolsky irrigation area of the rice irrigation system of the Krasnoarmeysky district of Krasnodar Territory, field experiment was conducted with the autumn and spring application of slurry both separately and together with the nitrification inhibitor Entec FL DMPP against the background of mineral fertilizers. Soil samples were taken before sowing, during the growing season, and after harvesting rice from the plowing layer. The content of total and water-soluble humus, total nitrogen, humus composition were determined. The redox potential was measured in undisturbed samples. Autumn and spring application of liquid manure into the soil in the amount of 30 t/ha, as well as the joint application of organic matter with a nitrification inhibitor, contributed to the preservation and replenishment of humus, improving its qualitative composition. Under their influence, the recovery processes in the soil are intensified and the content of water-soluble humus increases by 0.88-1.66 × 10-3 % C compared to the control without fertilizers and by 0.59-0.137 × 10-3 % C relative to the mineral background. The greatest effect was observed when the nitrification inhibitor was included in the slurry and applied in the autumn. The agrotechnical method contributed to an increase in humic acids in the soil and the transition of humus from humate-fulvate to humate type (CHA: CFA=2.01-2.03), humus enrichment with nitrogen (C: N decreases from 8.7-9.0 to 8.0), and increasing the mobility of water-soluble organic matter during the growing season of rice.