Effects of the application of marl with rock phosphate fertilizer upon the chemical soil properties and responses of rice grown on three series of acid sulfate soils
1993
Wijai Chaiyong
Experiments on the effectiveness of rock phosphate and marl applied to the representative soil series of three suitability classes of acid sulfate soils (Sena, Rangsit and Ongkarak) were conducted. Chemical kinetics of the soils, growth and yield of rice were studied. The residual effect of rock phosphate and marl on the second crop were also investigated. The results showed that rock phosphate apparently could bring about increasing of soil pH, extractable Ca,Mn,P and soluble Ca, Fe, Mn, and minimized extractable Fe and Al toxicity in all soils during rice growth period. Rock phosphate was found to hasten plant height, tillers, leaf number, straw and grain weights. A level of 100 mg available P2O5/kg of rock phosphate is likely optimal rate for Sena and Ongkarak soils but not for Rangsit soil. The residual effect of rock phosphate was also observed on the second crop in which rice yield obtained appeared to be in the same trend as that of the first experiment. Effect of marl, was found giving distinctive effects by increasing soil pH, extractable Ca and water soluble Ca, Fe and decreasing extractable Fe in all soils and it could alleviate Al toxicity to rice grown especially on Ongkarak and Sena soils. Addition of marl was unlikely improving rock phosphate effectiveness in all soils in both experiments. Submergence could be cosidered as a strategic measure for solving the problem due to Al toxicity in Rangsit soil.
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