Soil total and available C:N:P stoichiometry among different parent material soil profiles in rubber plantations of Hainan Island, China

Soil stoichiometry of carbon (C), nitrogen (N), and phosphorus (P) plays an important role in driving soil nutrient cycling. Parent material is the second important factor in soil formation that determines soil nutrient status. This study was conducted to examine the unclear effect of parent material on soil C:N:P ratios in tropical commercial forests. Here, we collected 100 soil samples developed from four parent materials (i.e., basalt, granite, metamorphic rock, and marine sediment) at four soil layers from 0 to 100 cm in rubber plantations on Hainan Island, China. We used ANOVA, redundancy, and path analyses to examine the variation of soil C:N:P stoichiometry and the impact factor. We found that total and available soil C:N and N:P ratios differed significantly among parent materials, but in a different pattern. The total N:P ratio was significantly lower in basaltic soils, resulting from the negative effect of greater P content. However, the available N:P ratio was highest in basaltic soils but lowest in marine sediment soils. This was attributed to the significantly higher available N content in basaltic soils. We thus demonstrated that basaltic soil should increase the availability of P and provide more available N for marine sediment soil to balance the nutrient supply for rubber plantations on Hainan Island. This is vital for scientific fertilization and environmental sustainability. Our study validated the effect of parent material on total and available soil C:N:P stoichiometry, both of which were recommended for consideration in soil nutrient evaluation and management advice.