Effectiveness of Dicalcium Phosphate Compared with Superphosphate for Wheat Grown on Acidic Sandy Soils

Abstract

The effectiveness of dicalcium phosphate (DCP) was compared with the effectiveness of superphosphate in a greenhouse experiment using two sandy acidic soils from southwestern Australia. Fertilizer effectiveness was determined using yield of dried shoots of 46-day-old spring wheat ( Triticum aestivum L.) plants.The DCP was about one-third as effective as superphosphate for yellow sand and one-fifth as effective for red sand; thus, about three to five times the amount of phosphorus (P) as DCP was required to produce the same yield as P added as superphosphate. Per unit of applied P, the P concentration in dried shoots was larger for soil treated with superphosphate than for soil treated with DCP. Critical P, the P concentration that was related to 90% of the maximum shoot yield, was about 0.70% (dry weight basis) for both sources of P and both soils.

keywords:

• dicalcium phosphate dihydrate
• single superphosphate
• spring wheat
• relative effectiveness
• critical P concentration

Notes

^A1:5 soil:0.01 M Cacl₂ (w/v) (Rayment and Higginston, 1992).

^BSesquioxides (Hesse, 1971).

^CThe P buffer capacity of soil (Ozzanne and Shaw, 1968), which is the amount of P sorbed when the concentration of P in the final solution is raised from 0.25–0.35 mg P/L.