Agronomic effectiveness of partially acidulated phosphate rock as influenced by soil phosphorus-fixing capacity |
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Authors: | S H Chien L L Hammond |
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Institution: | (1) Agro-Economic Division, International Fertilizer Development Center (IFDC), 35662 Muscle Shoals, AL, USA |
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Abstract: | A greenhouse study compared the effect of soil P-fixing capacity on the relative argonomic effectiveness (RAE) of partially
acidulated phosphate rock (PAPR) and water-soluble P. Such information is lacking in the literature. Six soils varying widely
in P-fixing capacity (5.6%–56.1%) were used. A phosphate rock (Huila PR) from Colombia was acidulated with H2SO4 at 50% of the level necessary to achieve full conversion to single superphosphate (SSP). Rates of P applied from PAPR or
SSP were 0,05, 100, and 300 mg P kg−1. The P fertilizers were mixed with the soils, and maize was grown for 6 weeks before harvest.
The results show that the effectiveness of PAPR in increasing dry-matter yield and P uptake over yield and uptake obtained
with SSP linearly increased as the soil P-fixing capacity increased. PAPR and SSP were equally effective in increasing dry-matter
yield or P uptake at P-fixing capacities of 28% or 36%, respectively. PAPR was found to be more effective than SSP in soils
(treated with Fe-gel) with P-fixing capacity higher than these values. The internal efficiency, which is defined as the ratio
between dry-matter yield and P uptake, was the same for both PAPR and SSP in all the soils. |
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Keywords: | dry-matter yield P availability P uptake partially acidulated phosphate rock (PAPR) soil P-fixing capacity |
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