Effects of the Application of Water Treatment Sludge on Growth of Lettuce (Lactuca sativa L.) and Changes in Soil Properties

概要

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The effectiveness of the application of water treatment sludge (WTS) to soils for cultivating a vegetable was examined. Initially, properties of original WTS, decomposed granite (DG) soil and volcanic ash(VA) soils were investigated, including physical properties of water content, porosity, dry density, saturated hydraulic conductivity, and texture and chemical properties of pH, EC, organic matter content, CEC, phosphate adsorption coefficient, and C, N, and H contents. Lettuce (Lactuca satuva L.) was grown in a phytotron room at a temperature of 20℃ using pots filled with DG soil and VA soil mixed with WTS at rates of 0 (N-P-K standard fertilizer application), 0, 4.5, and 9.0 Mg ha^<-1>. The yields of lettuce grown for the treatments of 4.5, and 9.0 Mg ha^<-1> sludge addition in VA soil were lower by 38% and 7% compared with the treatment of 0 Mg ha^<-1> sludge addition, respectively. However, the yield in DG soil was significantly higher by 72% (4.5 Mg ha^<-1> WTS addition) and 71% (9.0 Mg ha^<-1> WTS addition) compared with 0 Mg ha^<-1> sludge addition, respectively. These results suggest that land application of WTS may act positively to organic matter-deficient soils like DG soil, but negatively to fertile soil like VA soil.
2010-02-26