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

摘要

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 NH4C1, (NH_4)_2HP04, NH4H2PO4, NH4NO3, NH_4OAC, CaCl_2 Ca(N0_3)_2, NaN03, and CO (NH_3)_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 NH_4C1 (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.