Phosphorus nutrition of peanut (Arachis hypogaea L.) on Cockatoo Sands of the Ord River Irrigation Area

Abstract

Yield response of field-grown Virginia Bunch peanuts to a range of soil phosphorus levels, determined using 0.5M NaHCO3 extractant, in the top 10 cm of the soil profile was evaluated on Cockatoo Sands of the Ord River Irrigation Area. Critical levels of soil phosphorus (required to attain 90% of maximum yield recorded in fertilized plots) was 7.3 ppm for pods and 7.9 ppm for kernels. Yield increases obtained with higher soil phosphorus status were due to increased pod number and kernel size. Trends in tissue phosphorus concentration in uppermost fully expanded leaves were monitored during the season, and critical concentrations for 90% of maximum pod yield were derived. The critical concentration (0.30% P, dry-weight basis) did not change with time during the vegetative phase of development, but declined in a linear fashion over time during reproductive development, from 0.27% P at 60 days after emergence to 0.12% P at 100 days after emergence.