Soil organic matter and nutrients(e. g. nitrogen, phosphorus and potassium) play important roles in soilfertility.
土壤有机质和养分（氮、磷和钾等）是土壤肥力重要的物质基础。
2
This could be confirmed by the organic matter and nitrogen circulation and the improvement of soilfertility.
这可以从有机物质、氮素的循环和土壤肥力因素的改善得到证明。
3
The analytical data revealed that the potential fertility of the dryland soils was rather low, such as nitrogen, phosphorus and potassium content in soil were deficient on the whole.