Effects of crop residue incorporation and inorganic potassium fertilization on soil potassium supply power

摘要

Crop residues can be used as an effective replacement for inorganic potassium (K) fertilizers. However, the impact of the type and quantity of crop residue on soil K supply capacity in different soil types remains poorly known. To investigate the effects of crop residue incorporation rate and inorganic K fertilization on apparent K balance and soil K supply capacity in cotton-wheat cropping system, we conducted two, six-year field experiments on two soil types in Nanjing and Dafeng, China. At both sites, crop residue incorporation ameliorated the negative K balance and improved the soil water-soluble, exchangeable, and non-exchangeable K (WSK, EK, and NEK) contents. The soil WSK, EK and NEK contents were positively correlated with the net K accumulation at both sites across two soil layers. However, the correlations between net K accumulation and quantity-intensity related parameters varied with the soil types. Treatment with wheat straw (9000 kg ha(-1)) + cotton residue (7500 kg ha(-1)) at both sites performed better than the 300 kg K2O ha(-1) treatment in terms of balancing soil K depletion and keeping adequate K fertility status. Incorporation of adequate crop residues performed similarly to inorganic potash in improving the soil K supply power.