Ineffectiveness of directly applied Burkina Faso phosphate rock on rice growth(Fertilizers and soil amendments)

概要

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Phosphate rock (PR) can be directly used to correct soil phosphorus (P) deficiency. However, a number of factors affecting the effectiveness of PR have been invalidated. This pot trial was conducted to evaluate the influences of the rates of application and water conditions on the effectiveness of Burkina Faso phosphate rock (BPR) on indica rice (Oryza saliva L. cv IR74) grown on acidic Ishigaki soil compared with monocalcium phosphate (MCP). The BPR and MCP were applied at rates of 0, 21.8, and 87.3 mg P kg^<-1> soil under flooded and upland conditions with four replications. The results revealed that BPR was absolutely ineffective for rice plants compared to MCP, regardless of application rate and water condition. An increased dissolution rate of BPR calculated by extractable Bray 2-P in soil may have represented only capital P, and this P availability for plant was nil and contributed less to plant P uptake due to low solubility of BPR. Moreover, trends of increased BPR dissolution contradicted increased fertilizer P use efficiency of BPR by rice plants in water conditions, indicating that the relationship between a quantity of P dissolved from BPR and this P availability to plants as affected by water conditions should be further investigated.
一般社団法人日本土壌肥料学会の論文