The Effect of Ammonium and Calcium Bearing Amendments on Soil Potassium Release and Wheat Uptake

Effects of accompanied ammonium and calcium (from CaCl2 and CaSO4 sources) with potassium fertilizer on wheat yield were investigated with six treatments in a field trial in Gorgan University of Agricultural Sciences and Natural Resources farm No.1. With a non limiting N supply, potassium is the most limiting plant growth factor in the site of the experiment. Electric diffuse double layer is expected to be truncated with a high specific surface soil in this area minimizing the soil solution diffuse double layer interface for potassium diffusion. The results showed accompanying ammonium and calcium with a high concentration ofelectrolytes increased potassium movement. The high quantity of potassium applied with the base fertilizer was still insufficient foroptimum yield production as is inferred fromincreased yield when extra potassium was applied by CaCl2 + KCl, CaSO4 + KCl and Urea + KCl treatments. Contrary to CaCl2 calcium sources, potassium uptake and yield were increased by K-accompanied calcium from CaS 4. Calcium synergistic effects on plant potassium uptake were stronger with sulfate anions as compared with chloride. Data show when potassium is applied with low quantities of accompanied ammonium, improvements in yield and potassium uptake are even greater than calcium when applied in high quantities.