Efficacy of different phosphate application methods in relation to phosphate sorptivity of soils
1989
Holford, I.C. (New South Wales Agriculture and Fisheries, Tamworth (Australia). Agricultural Research Centre)
The efficacy of top-dressing, shallow and deep subsurface placement, and uniform mixing of phosphate through the top 17 cm of soil was compared on 6 soils varying in sorptivity from 100 to 10 000 ml per g in a glasshouse experiment. Shallow banding at 5 cm depth was the most consistently superior method of application. Top-dressing was equally effective in the most weakly sorptive soil but inferior in the most strongly sorptive soil. Deep placement at 15 cm and top-dressing were generally the least effective methods. The almost equivalent effectiveness of phosphate-soil mixing to shallow banding, regardless of sorptivity, suggests that the important factor in maximizing fertilizer effectiveness is its positional availability in the root zone rather than restriction of chemical immobilization by fertilizer concentration in bands.
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