SIMPLE EMPIRICAL INTENSITY AND BUFFERING CAPACITY MEASUREMENTS TO PREDICT POTASSIUM UPTAKE BY WHITE CLOVER

This experiment examined the feasibility of predicting K uptake in white clover by the use of simple and relatively rapid tests that would dispense with the need of knowing the quantity of plant available potassium. Potassium uptake was found to correlate highly (R=>0.9) in linear bivariate regressions using K concentration in the soil solution displaced by centrifuging and an empirical estimate of potassium retention. There was no advantage in determining activity ratios because in at least some of the soils used the ratio law did not apply. Exchangeable potassium alone correlated rather poorly with uptake except at very low soil potassium status. This was not because nonexchangeable potassium was an important source of this nutrient to white clover but because of the large differences in the retention of K amongst the soils used. © 1979 Martinus Nijhoff.