Release of non-exchangeable potassium from some Rhodesian soils cropped with grass

Abstract

1. Thirty Rhodesian soils were cropped with weeping love-grass (Eragrostis curvula) for up to 11 months in the glasshouse, the potassium released on cropping being compared with soil contents and that released on prolonged suspension in dilute CaCl2 or by reaction with H-exchange resin.2. Love-grass produced up to 33 tons of dry matter and removed up to 700 lb. of K2O/acre, and releases of non-exchangeable potassium ranged from 3 to 2931b. K2O/acre. With some soils potassium uptake by love-grass (and K-release) was about 60% of that reported for perennial rye-grass, showing that different crops have differing abilities to use non-exchangeable potassium reserves.