Influence of climate warming and nitrogen deposition on soil phosphorus composition and phosphorus availability in a temperate grassland, China

Abstract

Climate warming and nitrogen (N) deposition change ecosystem processes, structure, and functioning whereas the phosphorus (P) composition and availability directly influence the ecosystem structure under conditions of N deposition. In our study, four treatments were designed, including a control, diurnal warming (DW), N deposition (ND), and combined warming and N deposition (WN). The effects of DW, ND, and WN on P composition were studied by 31P nuclear magnetic resonance (31P NMR) spectroscopy in a temperate grassland region of China. The results showed that the N deposition decreased the soil pH and total N (TN) concentration but increased the soil Olsen-P concentration. The solution-state 31P NMR analysis showed that the DW, ND and WN treatments slightly decreased the proportion of orthophosphate and increased that of the monoesters. An absence of myo-inositol phosphate in the DW, ND and WN treatments was observed compared with the control. Furthermore, the DW, ND and WN treatments significantly decreased the recovery of soil P in the NaOH-EDTA solution by 17%-20%. The principal component analysis found that the soil pH was positively correlated with the P recovery in the NaOH-EDTA solution. Therefore, the decreased soil P recovery in the DW and ND treatments might be caused by an indirect influence on the soil pH. Additionally, the soil moisture content was the key factor limiting the available P. The positive correlation of total carbon (TC) and TN with the soil P composition indicated the influence of climate warming and N deposition on the biological processes in the soil P cycling. © 2014 Science Press, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences and Springer-Verlag Berlin Heidelberg.