Peanut Straw Decomposition Products Promoted by Chemical Additives and Their Effect on Enzymatic Activity and Microbial Functional Diversity in Red Soil

Abstract

ABSTRACT The objectives of the present study were to determine the promotional effect of chemical additives on quality of peanut straw decomposition products and to evaluate the influence of the resulting products on soil biological properties. Straw was mixed with or without chemical additives, such as iron(II) sulfate (FeSO4), alkali slag, or FeSO4 combined with alkali slag, and decomposed for 50 days. The decomposition products were used as organic fertilizer and added to red soil for an incubation experiment. The chemical additives increased total organic carbon (C), total nitrogen (N), and available N content but decreased the C:N ratios in decomposition products compared to controls. Adding FeSO4 gave the highest humic acid content (HA, 30.34 g kg−1) and ratio of humic to fulvic acid (HA/FA, 0.53) and the lowest ratio of HA absorption value at 465 nm to that at 665 nm (E4/E6, 6.05), suggesting high humification of decomposition products. Application of the resulting products to soil increased soil urease and invertase activities. BIOLOG analysis showed that microbial C utilization ability, Shannon–Weaver diversity, and McIntosh evenness indexes were improved by the organic fertilizer promoted by chemical additives. Principal component analysis indicated that microbial community structures were also influenced by different amendments in decomposition products. Our study provides a reference point for acquiring high quality straw compost and improving soil biological functions by organic fertilizer.