Organic Acids Variation in Plant Residues and Soils among Agricultural Treatments

Abstract

Organic acids have important effects on several processes of many plants and soils. In this study, variation of some organic acids in plant residues and soils among three land uses was evaluated by adding two crop residues with different water conditions and C/N ratios. The results demonstrated that the average concentration of organic acids was 0.04 g kg−1 in soils and 1.83 g kg−1 in plant residues, and higher at early and intermediate stages of the decomposition. The organic acids concentrations were higher in bean [Glycine max (L.) Merr.] than in corn (Zea mays L.), and higher in fresh plant samples than in dry samples (P < 0.05). High N content in plant caused a rapid change in organic acids of plant residues, but had no significant influences on the organic acids concentrations (P > 0.05). The organic acids concentrations of plant residues in three different land uses varied: vineyard > peach garden > corn/wheat field. Based on principal component analysis, the order of variation level in plant residues organic acids with respect to three different land uses was: vineyard > peach garden > corn/wheat field. Moreover, fresh samples exhibited more variation than dry samples, and bean straws exhibited more variation than corn straws. The addition of plant residues to soils influenced oxalic acid in soils (r = 0.72*, P < 0.05) at the early stages but had no significant influence on the organic acids in the soil (undetected at the end) over the whole 1‐yr decomposition period.