Phosphorus fractions in two calcareous soils as affected by sulfuric acid application
1994
Khorsandi, F.
An attempt was made to study the effects of sulfuric acid on phosphorus (P) fractions in calcareous soils. Several greenhouse experiments were conducted with sorghum (Sorghum bicolor L.) grown in two calcareous soils. Acid application increased soil acidity, available P and crop yields. To explain the chemistry of increased P availability, a fractionation scheme was used. Soil samples were sequentially extracted to remove nonoccluded aluminum (Al)- and iron (Fe)-bound P (A-P), P weakly readsorbed by carbonates (B-P), P occluded within Fe oxides and hydrous oxides (C-P), and calcium (Ca)-bound P (D-P). Acid applications profoundly affected the levels of P in the B-P and D-P fractions in all greenhouse expenments. Significant decreases in D-P were accompanied by significant increases in B-P. Significant positive correlations between available P and B-P, and significant negative correlations between available P and D-P suggest that acid application causes the conversion of P from the low solubility D-P pool to the more soluble B-P pool.
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