“换茬如上粪”,“三年两头倒,地肥粮增产”。轮作倒茬是我国农民固有的增产经验。为什么倒茬能增产?这是因为在一块地上种植不同作物,新的茬口会对土壤的物理、化学、生物学性状带来新的影响;不同作物对氮、磷、钾和其他矿物营养的要求不同, “Change stubble as above fecal”, “Three years down, Fertilizer increase.” Crop rotation is an inherent increase in production experience of peasants in our country. Why can crop yield increase? This is because different crops are planted on a single plot. The new stubble will have a new impact on the physical, chemical and biological properties of the soil. Different crops have different requirements for nitrogen, phosphorus, potassium and other mineral nutrients ,