Characteristics of man-made soils of greenhouse fields in urban areas, Osaka Prefecture, Japan

Abstract

Fertility status of man-made greenhouse agricultural soils in Osaka prefecture, Japan, where is characterized as highly urbanized area, were investigated. From the plow layer of greenhouse fields, 31 ordinary soil samples and 36 man-made soil samples were collected and physico-chemical properties including labile organic N by chemical extraction method, nonexchangeable nutrients and water-soluble ions were measured. We clarified that the ordinary and man-made soils differed significantly in many properties; total C, total N, phosphate buffer extractable N, and P or K fertility were significantly higher in the ordinary soils than in the man-made soils. This tendency would be reflected the longer agricultural use and incorporation of organic matter and applied fertilizers in ordinary fields through paddy use before greenhouse use. In contrast, non-exchangeable K, and water-soluble Ca and SO4 were higher in the man-made soils. The PCA (principal component analysis) analysis revealed that man-made soils could be differentiated from ordinary soils, and man-made soils were characterized by low content in soluble or exchangeable magnesium, organic matter, available and hardly extractable phosphorus, and the fact that they remained the parent materials’ characteristics. Our results demonstrated that the soil properties were considerably different between the ordinary soils and the man-made soils. It is reasonable to separate man-made soils from ordinary soils for the planning the suitable agricultural soil management.