Effect Of Fertilization On GRSP And Environmental Factors In Alpine Meadows On The Qinghai-Tibetan Plateau

Glomalin-related soil protein(GRSP) is a glycoprotein produced by arbuscular mycorrhizal fungi(AMF). It plays an important role in soil organic carbon(SOC) cycle. Fertilization, as an important soil management measure, can significantly affect carbon the carbon sequestration in alpine meadow. In this study, we investigated the effects of N, P and N+P fertilization on soil GRSP content at three rates of 5, 10, and 15 g m-2 yr-1(N5, N10, N15, P5, P10, P15, N5P5, N10P10, and N15P15) compared to control and analyzed the relationship between GRSP and SOC in alpine meadows on the Qinghai-Tibetan Plateau.The results showed that:a) Fertilization decreased soil p H(except P5, N10P10 in 0-20 cm and P5 in 20-40cm); Only N10 fertilization significantly decreased the soil water content in 0-20cm;b) Fertilization had no significant effect on soil nitrogen and phosphorus; P alone, N10P10, and N15P15 fertilization significantly decreased the ratio of soil N and soil P;c) The SOC content notably decreased in the treatment of N5, P5, P10, N15P15 in 0-20 cm and P5, P10 in 20-40cm;d) N10, N15 and N5P5 fertilization significantly increased the content of TGRSP, N5 remarkably decreased the content of TGRSP, while it had no significant effect on others treatment in 0-20cm; N10, N15, P15 and N5P5 fertilization significantly increased the content of TGRSP, N10P10 and N15P15 fertilization significantly decreased the content of TGRSP, while it had no significant effect on others treatment in 20-40cm; What’s more, only N15P15 fertilization notably increased the content of EEGRSP in 0-20cm;e) N15, N10P10 and N15P15 fertilization significantly decreased plant diversity;f) Nitrogen fertilization alone(except N10) increased while P fertilization alone decreased AMF biomass, but both were not significant;g) Soil N/P, AMF biomass and SOC had a significant positive correlation with T-GRSP content; The content of GRSP is about 15% of SOC content;According to these results, we draw the following conclusions:a) Effect of N fertilization alone was greater than P fertilization alone on the content of GRSP; Middle and high rates of N fertilization increased GRSP while P fertilization and NP fertilization at 10, 15 g m-2 yr-1 had no significant effect on GRSP content; Effect of fertilization on the content of TGRSP was greater than EERSP;b) Fertilization modified plant composition, while plant community diversity was not the key factor in affecting the content of GRSP; soil N/P and AMF biomass were the main factor in influencing GRSP content; Although fertilization had no significant effect on soil N and P, fertilization remarkably decreased soil N/P in top soil; this would affect AMF biomass and GRSP content;c) Fertilization increased the ratio of GRSP and SOC. This indicated that GRSP had a significant contribution to soil organic carbon pool.