Study Of Organic Carbon Changes In Black Soils After Application Of Different Organic Materials With Equal Carbon Content

Soil Organic Carbon(SOC)is an important component of terrestrial carbon pool.Due to environmental and anthropogenic factors,black soils are facing a series of ecological and environmental problems such as decreasing soil organic matter content,thinning humus layer,decreasing fertility and structural damage,which lead to soil degradation and threaten the sustainable use of agricultural land and food security.Therefore,how to improve the soil organic carbon content and soil quality efficiently is an urgent problem to be solved.In order to solve this problem,five treatments,including no organic material(CK),biochar(Bc),Corn straw(CS),Woody peat(WP)and Herbaceous peat(HP),were set up in this experiment to investigate the changes of soil organic carbon,active organic carbon fraction and humus composition,and to reveal the influence of different organic materials with equal carbon application on the characteristics of soil organic carbon change,so as to provide a theoretical basis for the sustainable development of black soil.This study provides a theoretical basis for the sustainable development of black soil.The results of the study are as follows:1.Application of different organic materials with equal carbon content increased soil organic carbon content,active organic carbon content and carbon pool management index,and the effect of Bc treatment on improving soil organic carbon became more and more obvious as time became longer,with increases of 1.73 g/kg and 1.89 g/kg at 360 d and 540 d,respectively,and conversion efficiencies of 44.43% and 48.5%,respectively.the content of active organic carbon fraction and carbon pool management index increased more significantly with HP treatment.2.The humic acid carbon content was significantly higher than that of CK after application of different organic materials with equal carbon content,and the effect was more pronounced in WP and HP treatments,with an increase range of 26.45% to 35.95% and 17.77% to 31.40% in0-20 cm and 20-40 cm soil layers,respectively,and a significant increase in humic acid carbon content in Bc treatment compared to CK,with an increase range of 7.46% to 8.79%.The application of organic materials all increased the degree of soil humification,and the WP,HP,and Bc treatments significantly increased the PQ values as time became longer.3.The application of different organic materials with equal carbon content changed the structure of soil humic acid.Bc treatment was beneficial to increase the aromaticity of humic acid structure with time and increase the thermal stability of humic acid to make it more stable,while CS and HP treatments were more beneficial to increase the aliphaticity of humic acid molecules and make the structure simpler.4.The application of different organic materials with equal amount of carbon improved the soil physicochemical properties,and the improvement effect of physicochemical properties between different application treatments decreases with the increase of material application time.Bc treatment has the tendency to improve soil p H and significantly improve soil fast-acting nutrients,and has the tendency to improve crop yield.In conclusion,the application of different organic materials could improve soil organic carbon content,increase organic carbon conversion efficiency,and improve humus structure,among which biochar had the most significant improvement effect in the later stage of the experiment and had greater potential for improving soil properties.