Abstract:

To study the characteristics of soil nutrients and the ecological stoichiometric ratios of carbon (C), nitrogen (N), phosphorus (P) and potassium (K) under different land use types, the distribution of soil nutrients in the surface layer (0-20 cm) of paddy fields, drylands, grasslands and woodlands and the differences were analyzed by bibliometric methods. The results showed that the four land use types were relatively rich in total potassium and fast-acting potassium, but generally deficient in total phosphorus, with significant differences (P<0.05); soil total nitrogen was positively significantly correlated with total phosphorus (P<0.05), and negatively significantly correlated with adequate phosphorus (P<0.05), soil organic matter showed a highly significant positive correlation with total nitrogen (P<0.01), and total soil phosphorus showed a highly significant positive correlation with total potassium (P<0.01). Soil C:N values were highest in paddy fields, soil C:K, C:P and N:K values were highest in grasslands, N:P values were highest in woodlands and P:K values were highest in drylands; based on the integrated soil nutrient pool index, it could be concluded that the overall soil nutrient levels of the four different land use types showed paddy fields>grasslands>drylands>woodlands. The four land use types effectively presented the differences between soil nutrient content and ecological stoichiometric ratio of elements, which could provide theoretical support for the revegetation and soil improvement of different land-use types.

Key words: land use change, soil fertility, stoichiometry, soil nutrient assessment system