A meta-analysis of carbon, nitrogen and phosphorus change in response to conversion of grassland to agricultural land

The conversion of grassland to agricultural land is an important land use change that affects soil stocks and concentrations of C, N and P, as well as their stoichiometric ratios. However, the response mechanism of soil C, N and P change to grassland conversion remains unclear. Here, we conducted a meta-analysis of 92 studies and showed that the C and N stocks mainly depended on soil depth, conversion duration and precipitation, while the P response was insensitive to these factors. Moreover, C, N and P losses were also correlated with soil physical-chemical properties (pH, sand, silt, clay). Changes in the response ratios of C:N, C:P and N:P indicated that soil C and N were more sensitive than P to grassland conversion. These results suggest that land use management policies should protect natural grasslands, especially in the arid and semi-arid regions, to minimize soil C, N and P loss.