Fatty‐Acid Profiles and Enzyme Activities in Soil Particle‐Size Fractions under Long‐Term Fertilization

Abstract

Listen

Translate article

Core Ideas Organic treatments significantly enhanced soil organic C, total N, and most enzymes activities. The highest soil organic C, total N, and enzyme activities were existed in 200‐ to 63‐μm fraction. Soil organic C, total N, C/N ratio, α‐glucosidase, sulfatase, β‐glucosidase, β‐cellobiohydrolase, and phenol oxidase activities were significantly correlated with phospholipid fatty acids. A long‐term experiment was established in 1981 to examine the influence of mineral and organic fertilizer on soil organic carbon (SOC), total nitrogen (TN), enzyme activities, and microbial community composition. In this study, we considered 33 yr of the following fertilizer treatments: no fertilizer (control, CK), fertilizer N (N), fertilizer N and P (NP), fertilizer N, P and K (NPK), manure plus fertilizer N, P and K (NPKM), and manure (M). We focused on yellow‐brown paddy soil and its particle‐size fractions of >2000 µm (large macroaggregate sized), 2000–200 µm (coarse sand sized), 200–63 µm (fine sand sized), 63–2 µm (silt sized), and 2–0.1 µm (clay sized). Nutrient concentrations and enzymes, affected by fertilizer treatment and particle fraction, were unevenly active throughout the soils which showed significantly highest concentration and activity in the fine sand fraction, except sulfatase (Sul). However, the coarse sand fraction contributed the largest SOC, TN, and enzyme pools to bulk soil, followed by silt‐sized and large macroaggregate‐sized fractions. Compared with NPK, NPKM, and M treatments significantly improved SOC, TN, phosphatase (Pho), β‐glucosidase (βG), β‐cellobiohydrolase (βCB), N‐acetyl‐glucosaminidase (NAG), β‐xylosidase (βX), phenol oxidase (PhOx), peroxidase activities, and the total phospholipid fatty acids (PLFAs) abundance of soil fractions. Manure also accelerated SOC, TN, and most enzymes accumulation in coarse sand fraction at the expense of clay fraction. Principal component analysis (PCA) of microbial community composition showed a smaller variability in particle‐size fractions than treatments which suggested a considerable effect of soil nutrient availability on microbial community composition. Redundancy analysis (RDA) also convinced SOC, TN, C/N ratio, α‐glucosidase (αG), Sul, βG, βCB, and PhOx activities significantly governed microbial community in this study. Our results conveyed long‐term application of organic fertilizers contributed to the increase of SOC, TN, and most enzyme activities in bulk soil and particle fractions, along with abundant and diverse microbial community in fine sand fraction and other organic treated soil fractions.