| Summary: | 碩士 === 國立中興大學 === 土壤環境科學系 === 90 === High pH and the presence of CaCO3 usually result in low availability of phosphorus (P) in calcareous soils of Taiwan. Lowing soil pH by acidifying materials to the suitable range is an important practice to reclaim calcareous soils. The researches on the reclamation of calcareous soils and the behaviors of phosphorus (P) during the reclamation of calcareous soils are limit, and needed to be study and evaluated. The objective of this study was to (1) evaluate the lowing the calcareous soil pH capacities by addition sulfur and aluminum sulfate, and the relationship between the calcareous soil pH buffer capacity and soil properties, (2)evaluate the effect of acidifying materials addition on the behaviors of P in calcareous soil. Five different calcareous soil with varying CaCO3 amount were selected in this study. Different amounts of sulfur (S0) and aluminum sulfate [Al2(SO4)3‧14H2O] were added into the soil to adjust soil pH to 4 levels and incubated at 25℃ -33Kpa water content then the amounts added and soil pH were related. The P availability index (solution P, Resin-P and Olsen-P) and the forms of phosphate were also determined. In addition, two rates of KH2PO3 (0, 250 mg kg-1) were added into soil before and after lowing pH and incubated for same time, then the P availability index and the forms of phosphate were determined. Results showed that soil pH decreasing with increasing amount of S0 and Al2(SO4)3‧14H2O applied. The time required to low soil pH to same pH with S0 application longer then that of Al2(SO4)3‧14H2O applied, but the amount needed was less. General speaking, the contents of solution P, Resin-P, Olsen-P, Fe,Al-P and Ca-P increased with increasing amount of S0 addition, however, except Fe,Al-P content, the contents of solution P, Resin-P and Olsen-P decreased with addition of Al2(SO4)3‧14H2O. Results also indication the addition sequence of acidifying materials and P did affect the availability of P and the relative changes of P compounds in calcareous soils. In general, higher contents of solution P, Resin-P and Olsen-P found in the treatments of S0 or Al2(SO4)3‧14H2O addedfirst, followed by P added than that of addition with S0 or Al2(SO4)3‧14H2O and P in reverse order. In addition, regardless of addition sequence Al2(SO4)3‧14H2O application usually resulted in lower P availability than that of S0 application.
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