Soil C, N, and P stoichiometry in response to different land uses in an agroforestry hillslope of Southwest China

Land use subjected to various human managements dramatically differs soil nutrient concentrations and unbalance their stoichiometric ratios. However, the magnitude and extent of these effects remain unclear. This study aimed to explore the differences on soil nutrient concentrations and stoichiometry under the undisturbed naturally managed tea plantation (NMTP), forest land (FL) and disturbed cropland (CL) and mulberry plantation (MP) in an agroforestry hillslope in southwest China. Soil samples were collected at three soil depths (i.e. 0-10, 10-20, 20-30 cm). Soil C, N, and P concentrations were higher in NMTP and FL than in CL and MP across all soil depths. Soil C:N, N:P, pH, bulk density (BD), and total porosity (TP) differed significantly in these land uses but water-holding capacity (WHC) and C:P did not. N:P ratios in CL and MP were lower than both Chinese and global averages, presenting widespread N limitation across all soil depths. NMTP and FL showed N limitation at the top layer and shifted to P limitation or N and P co-limitation with increasing soil depth. Soil nutrient concentrations and stoichiometry showed significant correlations with pH, BD, and TP. The results highlight the considerable human management effects on alterations of soil nutrient stoichiometry.