Cultivation of Forage Grasses as a Remedy for Excessive Salt Accumulation in Soils of Plastic Greenhouse : II. Salt Absorption by Forage Crasses from Soils and Decomposition of the Harvests in Soils

摘要

Cultivation of Forage Grasses as a Remedy for Excessive Salt Accumulation in Soils of Plastic Greenhouse. II. Salt Absorption by Forage Grasses from Soils, and Decomposition of the Harvests in Soils. Noritsugu SHIMADA, Yukio SATO, Shoichi ASHIHARA, Hisakazu OIZUMI, Yasuo TAKASAKI, Zenichi KANARI and Hiroshi NOJIMA. Faculty of Horticulture, Chiba University, Matsudo, Japan. Tech. Bull. Fac. Hort. Chiba Univ., No.26 : 15-21, 1979. Short term cultivation of forage grasses in summer with pot experiment was examined as a countermeasure to prevent salt accumulation in soils, which frequently occured in the growth under structure. Four species of forage grasses (corn, sorgo, African millet and rhodesgrass) were cultivated on the soils in which the salt concentrations were varied into four nutrient levels. The greatest absorption of salts was observed in corn. Dry matter yields of African millet was much smaller than that of corn, but the total amount of salts absorbed by a single plant of this species was next to corn and nearly equal to that of sorgo, having relatively high concentration of each elements. EC values of soil solutions were lowered down by the cultivation of the forage grasses, corresponding to the amount of salts absorbed by the crops. Model experiments on the mineralization of the harvests in soils were carried out to evaluate them as a organic material for soil improvement. During 20 days of incubation, both corn and sorgo added into soils accelerated the organization of inorganic nitrogen which was previously contained in the soils or derived from themselves in this period. Even 30 days of incubation, the amount of inorganic nitrogen in the corn-added soil was less than that in blank soil. It was recognized that potassium contained in forage grasses was rapidly dissolved into soils after incubation.