Efficiency of organic carbon sequestration in typical slightly eroded chernozem

Abstract

The research was carried out to study the efficiency of organic carbon sequestration (ESCS) in the arable layer of typical slightly eroded chernozem when biopreparations (based on Trichoderma viride and Pseudomonas aureofacieens) were applied with by-products of crops separately or together with nitrogen, nitrogen fertilizers, as well as to assess its relationship with indicators of transformation of plant residues and biological state of soil. The object of the study was typical slightly eroded heavy loamy chernozem on carbonate loess-like loams with humus content in the topsoil (according to Tyurin’s method) of 5.11. 5.36%; that of alkaline hydrolyzable nitrogen 160.2±2.6 mg/kg, mobile phosphorus and potassium (according to Chirikov’s method) 112.0±7.8 mg/kg and 102.2±9.8 mg/ kg, respectively, that of exchange calcium 223.5 ± 2.2 mg-eq/kg, with a medium reaction close to neutral (pHKCl 5.6±0.1).The research was carried out in 2018-2021 in a stationary field experiment with biopreparations in Kursk Region, in a grain-row crop rotation (sunflower-barley-soybeans-buckwheat). The experimental design included the following variants: crushed by-products (background) as a control; background + nitrogen of ammonium nitrate at the rate of 10 kg of PPN per 1 ton of by-products; treating seeds, soil before sowing, crops 2 times during the growing season and crushed by-products before embedding them in the soil (biopreparations + background) with biopreparations Gribophyte and Imunazot ; biopreparations + background + nitrogen of ammonium nitrate at the rate of 10 kg of PPN per 1 ton of by-products. The efficiency of organic carbon sequestration in the soil was calculated according to the formula proposed by the authors based on the study of the dynamics of humus reserves in the arable soil layer, the annual intake of crushed by-products into the soil and the content of crop-root residues in the soil. It was revealed that the use of biopreparations and crushed by-products contributed to an increase in ESCS in the arable soil layer 3.7 times, the combined use of biopreparations with N 4.9 times, and the application of only N10 kg of PPN with 1 ton of by-products 2.3 times compared with the control (by adding only crushed by-products). A direct, very close correlation of efficiency of organic carbon sequestration in the soil with an average rate of decomposition of plant residues (r=0.98), a close one with CO2 emission from the soil (r=0.88), and an average one with the cellulolytic activity of the soil (r=0.69) was established.