Degradation Characteristics of Maize Straw under Different Buried Depths in Northeast Black Soil and Their Effects on Soil Carbon and Nitrogen

摘要

Incorporation of straw in the improvement of soil fertility via increasing soil organic carbon has become an important method. But in this process of decomposition, a considerable portion of carbon will be released into the atmosphere. The present research dealt with experiments to make more straw-carbon to stabilize in the soil and to maintain the decomposition of crop straw. Based on this concept, the effects of maize straw incorporation at different depths on the nutrient status of soil were observed via three experiments conducted for 3 years on a Black Soil in Northeast of China. Four soil depths were tested. These are D 0 (0–5 cm), D 1 (5–15 cm), D 2 (15–30 cm) and D 3 (30–45 cm). The results showed that maize straw residues incorporation to sub-surface (D 1 –D 3 ) layer had a significant difference compared with D 0 (68.7% C lost, P < 0.01) after 3 years of decomposition. The three treatments with buried residues into the soil had almost similar average diminution of C content (10.37–14.01%). Meanwhile, D 0 had a lower decomposition constant, straw lignin and cellulose decomposition than D 1 –D 3 treatments. The content of urease and sucrase declined with the deep soil, and straw return increased the enzyme activity in this study. The D 1 treatment also had a higher soil microbial biomass carbon (SMBC) and labile soil organic carbon (SOC) fractions. These components also increased significantly with the seasonal change in the D 2 treatment. The content of SOC showed significant positive correlation with C/N and soil temperature. While sucrose and moisture showed significant negative correlation between them. The present simulation study reinforces the importance of analyzing SOC fractions and SMBC into the deep soil. It had indicated that maize straw incorporation in deep soil was very important for the maintenance of soil fertility. At the same time, it suggested a solution to the problems of large quantity of straw production in the maize cultivation zones. The results bear significant importance for agriculture.