Comparison of potential potassium leaching associated with organic and inorganic potassium sources in different arable soils in China
2022
LU, Dianjun | DONG, Yanhong | Chen, Xiaoqin | WANG, Huoyan | Zhou, Jianmin
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, K₂SO₂, KH₂PO₂, 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 at 225 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, KH₂PO₂, 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, KH₂PO₂ and straw should be preferred for reducing K leaching in low-K fixation arable soils.
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