Comparison of potential potassium leaching associated with organic and inorganic potassium sources in different arable soils in China

Potassium (K) leaching is detrimental to the maintenance of sustainable arable soil K fertility,especially in low-K fixation soils.It is not known whether the application of inorganic fertilizers with lower K mobility or crop straw can reduce potential K leaching in low-K fixation arable soils.The potential K leaching of 14 representative arable soils with different K fixation capacities in China was evaluated with or without the addition of K under two rainfall intensities (90 and 225 mm),and then potential K leaching was assessed in relation to five K sources (KCl,K_(2)SO_(4),KH_(2)PO_(4),maize (Zea mays L.) straw,and rice (Oryza sativa L.) straw).Without K addition,K leaching mainly occurred in sandy soils at 90 mm of rainfall and in soils with greater organic matter at225 mm of rainfall.With K addition,the leaching percentage of exogenous K ranged from 0.6%to 11.6%at 90 mm of rainfall and 1.2%to 21.2%at 225 mm of rainfall.The greatest K leaching occurred in soils with fewer K-bearing minerals and lower pH at both rainfall intensities.In most cases,KH_(2)PO_(4),which has lower K mobility,markedly reduced K leaching in both high-and low-K leaching soils at the two rainfall intensities.Maize and rice straw reduced K leaching only in soils with high K leaching,regardless of rainfall amount,whereas more K was leached in soils with lower K leaching at high rainfall intensity.In conclusion,KH_(2)PO_(4) and straw should be preferred for reducing K leaching in low-K fixation arable soils.