Soil physicochemical property in public lawn in Kyoto City

Abstract

In public parks in Kyoto City, 51 lawn sites were surveyed for the status of vegetation and soil physicochemical properties. The following 18 soil properties were determined: pH (H₂O), electric conductivity, soluble potassium and nitrate (using electrodes) ; total carbon and nitrogen (using an elemental analyzer) ; available phosphate (Bray No.2) ; soluble inorganic ions (Cl^-, NO₃^-, H₂PO₄^-, SO₄^2-, NH₄⁺, Ca²⁺, Mg²⁺, K⁺ and Na⁺ by ion chromatography) ; active aluminum (allophane test) and field soil texture. Soil pH and total nitrogen were in adequate ranges that have been proposed for the substratum for general landscape planting. Available phosphate showed a great variation including many suboptimum and a few supraoptimum values according to the same criteria. Electric conductivity was determined by several ions including NO₃^- and Ca²⁺, as opposed to the case of agricultural soils where NO₃^- is usually by far the most important determinant. A principal component analysis generated the first principal component that accounted for 33% of the total variance and was interpretable as the general fertility resulting from soil texture. Other principal components had low contributions and were not clearly interpretable, probably reflecting a mosaic nature of soil material and human activity. Sites with >50% lawngrass coverage showed significantly lower concentrations of total carbon, total nitrogen as well as nitrate and significantly higher concentration of magnesium than sites with <50% lawngrass; the reason for which deserves further analysis.