Distribution of soil nutrients and enzyme activities in different aggregates under two sieving methods

Abstract

AbstractSoil aggregates are the basic units of soil structure. Dry and wet sieving are two conventional methods used for isolating aggregates. However, different methods can cause variation in the distribution of enzymes and nutrients. For better understanding the influence of water on soil aggregate stability and building the relationship between soil nutrients and the enzyme activity of aggregates, three soil samples with different organic matter (OM) content were selected: Qiyang, Hunan (HN); Hailun, Heilongjiang (HLJ); and Changshu, Jiangsu (JS). In this study, we measured the enzyme activity of invertase (INV), urease (URE), phosphatase (PHO), and arylsulfatase (ARY) together the OM, total N (TN), available N (AN), available P, and available K of dry and wet sieved aggregates. The results showed that wet sieving caused 34.0, 66.8, and 35.1% decreases in the soil mean weight diameter for HN, HLJ, and JS, respectively. The TN content of wet sieved aggregates decreased to various degrees (19.9–47.7%) compared with dry sieving. The activity of INV, PHO, and ARY decreased sharply after wet sieving especially for microaggregates (reached 70% in <0.1‐mm particles of JS). Enzyme activities were mainly located in microaggregates under dry isolation but changed to macroaggregates after wet sieving. The geometric mean (GMean) index of <0.1‐mm particles were 1.54, 1.01 and 1.36 times higher than that of >2‐mm aggregates under dry sieving. Furthermore, the GMean index showed a significant positive relationship with soil OM, TN, and AN under both dry and wet sieving methods.