Effect of exchangeable base in soil on mineral balance of forage crop

The content of the exchangeable base in the soil the meadow in the Fukui prefecture and the mineral element in the forage crops were investigated, and the relation was examined. Moreover, the influence and the effect on the dry matter yield and the mineral balance when the amount of the potassium fertilizer using was decreased and when the calcium fertilizer and the magnesium fertilizer used were examined by using 1/2,000 a Wagner pots as a cultivation experiment about two grass kinds of a Sudan glass and Italian rye grass. As a result, the field ratio where the tetany ratio of the forage crop is 2.2 or more was about 60 percent, and that with the potassium concentration in the forage crop is 3% or more was about halves, and the content of the exchangeable magnesium was few in the soil, and the contents of the exchangeable potassium was much. Moreover, there was a positive correlation between the tetany ratio and the potassium concentration of Italian ryegrass, and when the tetany ratio was 2.2, the potassium concentration was 3%. In addition, it was shown for the assumption of the exchangeable potassium in the soil less than 44 mg/100 g for each drying soil to suppress the tetany ratio to less than 2.2, to suppress the potassium concentration to less than 3%, and to obtain dry matter yield of about 600 kg/10 a. The tetany ratio has not been decreased easily though the amount of using of the potassium fertilizer is decreased when there is a lot of exchangeable potassium in the soil. However, when there was a lot of exchangeable potassium in the soil, it was suggested that the tetany ratio has not decreased though the amount of using of the potassium fertilizer was decreased, and that the tetany ratio decreased though the calcium fertilizer and the magnesium fertilizer were used.