Pw. Moody et al., SOIL-PHOSPHORUS TESTS AND GRAIN-YIELD RESPONSIVENESS OF MAIZE (ZEA-MAYS) ON FERROSOLS, Australian Journal of Soil Research, 35(3), 1997, pp. 609-613
The grain yield response of maize (Zea mays) to various rates of appli
ed phosphorus (P) was measured at each of 17 sites in the South Burnet
t region of south-eastern Queensland. The soils at all sites were Ferr
osols. Relative grain yield of the nil applied P treatment [100x (yiel
d at nil applied P/maximum yield)] was related to Colwell (0.5 M NaHCO
3) extractable P (P-B), CaCl2-extractable P, and equilibrium P concent
ration and P buffer capacity calculated from P sorption curves. Of the
se P measurements, P-B was most highly correlated with relative grain
yield (R-2 = 0.94 for a linear response and plateau fit, R-2 = 0.92 fo
r a Mitscherlich fit), and the P-B values at 90% maximum grain yield w
ere 20 mg/kg for the linear response and plateau model and 32 mg/kg fo
r the Mitscherlich equation.