Effect of biogas slurry application on soil nutrients, phosphomonoesterase activities, and phosphorus species distribution

摘要

Purpose Biogas slurry (BS) is used for soil productivity amendment, but its effect on soil phosphorus (P) form distribution has not been thoroughly examined. The objective of this study was to determine the effect of BS on soil nutrients, phosphomonoesterase activities, and P species distribution. Materials and methods A 91-day incubation study was carried out for a silt soil which was amended with BS at a rate equivalent to 120 kg N ha(-1) and 38 kg P ha(-1) and 240 kg N ha(-1) and 76 kg P ha(-1). The soil with no BS addition was used as control. Solution P-31 nuclear magnetic resonance (P-31-NMR) spectroscopy was used to characterize soil P species. Acid phosphomonoesterase (ACP) and alkaline phosphomonoesterase (ALP) activities, pH, cation exchange capacity (CEC), NH4+-N, NO3--N, and Olsen P were also evaluated. Results and discussion The results indicated that the application of BS increased pH, CEC, NH4+-N, NO3--N, and Olsen P contents. Moreover, the addition of BS inhibited ACP activity, but it increased ALP activity. A significant positive correlation was found between ALP and orthophosphates, suggesting ALP activity may play important roles in the release of orthophosphates. The P composition was dominated by inorganic orthophosphate (59.9-76.2% extracted P) and orthophosphate monoesters (23.8-38% extracted P), with smaller concentration of pyrophosphates (1.2-3.6% extracted P), and orthophosphate diesters (less than 1.5% of the extracted P). Conclusions The P was mainly in the form of inorganic orthophosphates and organic monoesters. The present study shows that BS can be a substitute solution for the supply of essentials nutrients for plants. However, care would be entirely taken with long-term application of BS, since extreme nutrients addition may cause eutrophication of water bodies.