Effectiveness of Organic Materials on Acidification Control and Organic Matter Enhancement of Red Soil

Objective In order to study the comprehensive effectiveness of different types of organic materials on controlling the acidification of Red soil and enhancing the organic matter.

Method This study selected the acidified Red soil developed in Quaternary laterite as the research subject, and investigated the changes in soil pH, exchangeable hydrogen, exchangeable aluminum, exchangeable base cations, particulate organic carbon and mineral-bound organic carbon after the returning of three types of crop residues, including corn, rice and rape, as well as the application of two types of organic matter (pig manure and biochar) through simulated cultivation experiments, and systematically evaluated the comprehensive effectiveness of soil acidification characteristics and carbon components by using the principal component analysis method.

Result The results showed that all the organic materials significantly increased soil pH and decreased soil exchangeable hydrogen, exchangeable aluminum and complexed aluminum. Among these, pig manure had the most significant effect, increasing soil pH by 0.9 units and decreasing exchangeable hydrogen, exchangeable aluminum and complexed aluminum by 64.0%, 92.1% and 30.5%, respectively. Besides, all organic materials significantly increased the contents of particulate organic carbon and mineral-bound organic carbon. Especially, biochar increased total soil organic carbon by 95.8%. The comparative analysis of the combined effectiveness of five kinds of organic materials on reducing soil acidity and increasing soil carbon showed that pig manure > rape straw > rice straw > biochar > corn straw. This indicates that pig manure exhibited the most effective combined impact on soil acidification control and organic matter enhancement, while among the three types of crop residues, rape straw was the best, while biochar and maize stover were less effective.

Conclusion Based on the previous results, this study recommends that pig manure and rape straw should be preferentially selected for the amelioration of acidified Red soil.