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Effects of phosphorus and nitrogen fertilization on soil arylsulfatase activity and sulfur availability of two tropical plantations in southern China
- Wang, Senhao, Zhou, Kaijun, Mori, Taiki, Mo, Jiangming, Zhang, Wei
- Forest ecology and management 2019
- arylsulfatase, enzyme activity, fertilizer application, forest plantations, microbial biomass, microorganisms, nitrogen, nitrogen fertilizers, nutrient management, nutrients, phosphorus, phosphorus fertilizers, soil pH, sulfur, tropical forests, tropical plants, China
- Understanding how phosphorus (P) and nitrogen (N) fertilization influence the dynamics of other nutrients [particularly sulfur (S)] is essential for improving the integrated nutrient management of tropical tree plantations. This study investigated how adding P and N fertilizers would affect S dynamics in the soils of two tropical forest plantations. Specifically, we tested whether the addition of P and N alters the availability of exchangeable S and microbial biomass S (MBS) and, hence, arylsulfatase activity (AS) and ratios of AS to C- and/or N-acquiring enzyme activity in the 0–5 cm soil layer were tested. The sites contained both control plots (no fertilizer application) and plots with 6-year continuous fertilizer (P and N) application. Soil exchangeable S clearly decreased, while AS activity marginally increased in P-fertilized plots. The ratios of soil AS activity to C- and/or N-acquiring enzyme activity tended to increase, possibly because the requirements of microbes for S relative to C and N were elevated, with P fertilization exacerbating shortages in S. In comparison, N fertilization did not influence exchangeable S, soil pH, and MBS. This lack of response might be attributed to continuous deposition of high levels of background N at the study sites. Soil AS activity and the ratios of soil AS activity to C- and/or N-acquiring enzyme activity tended to be lowered by N fertilization; thus, AS activity might be more sensitive to N fertilization than to soil pH. In conclusion, P fertilization must be carefully managed in tropical forest plantations to minimize its negative impact on soil S availability.