Abstract
Fused potassium silicate fertilizer was produced with steelmaking slag and additional potassium carbonate in the steelmaking process. In order to evaluate the availability of slow-release potassium, solubility and crop response were investigated using three type of fused potassium silicate fertilizers which had different solubility. In the soil column experiments, potassium contained in fused potassium silicate fertilizers was released in very slow form compared with potassium sulfate, though W-K_2O of fused potassium silicate fertilizer was relatively high. Eluviation quantity from fused potassium silicate fertilizer was much lower than from potassium sulfate. Response of crops showed fused potassium silicate fertilizer, which contained relatively high amounts of W-K_2O, in terms of the growth and the dry matter production, to be as effective as potassium sulfate. As for the amount of potassium uptake of Chinese cabbage, potassium sulfate showed the highest value; however, the dry matter production of potassium sulfate was almost same as for fused potassium silicate fertilizer. These results indicated that fused potassium silicate fertilizer could supply potassium in slow form to crops and result in effective utilization by crops.
