Effect of some cations, anions, and organic residues on potassium leaching and fractionation in calcareous sandy loam soil

Abstract

Potassium (K) is one of the essential elements for plants. There has been enough research to determine pollution of nitrogen (N), phosphorus (P), and heavy metals in soil. However, by comparison research on the storage and transport of K has been neglected. Chemical fertilizer usage leads to serious environmental problems in Iran. Leaching of K can be affected by type of anions and cations present in the chemical fertilizers. Potassium leaching experiments were performed using 10 mM NH₄Cl, (NH₄)₂HPO₄, NH₄H₂PO₄, NH₄NO₃, NH₄OAC, CaCl₂, Ca(NO₃)₂, NaNO₃, and CO(NH₃)₂. The leaching experiment was lasted for 20 days (15 pore volumes). In addition, a set of experiments were conducted, where potato and wheat residues and poultry manure and sheep manure were added to soil at the rate of 5% and distilled water was used as the leaching solution to investigate impacts of organic residues on K leaching. In general, maximum K release was observed using NH₄Cl (566 kg ha⁻¹). Potato and wheat residues had maximum and minimum impacts on K leaching, respectively. Potassium fractionation was carried out after the end of the leaching experiment. The results indicated that leaching of soil in the presence of soluble salts and organic residues altered K distribution in different parts of soil.

Keywords:

• potassium leaching
• chemical fertilizers
• sheep manure
• poultry manure
• organic residues

Acknowledgments

Two anonymous reviewers made valuable comments on the manuscript. The authors gratefully express their gratitude for their thoughtful reviews.