Both immediate and long-term effects of liming on some soil K properties were determined. Experimental conditions closely simulated field environment but the complicating factor of differential plant removal was avoided. The soil (pH 4.5) was treated with 0, 0.8, 1.6, 3.2, 4.8 and 8 ton per acre of hydrated lime and sampled at intervals during a 6-year period.
Total K, which was high (1.42%) in relation to exchangeable K (66 ppm.), did not change after liming. Exchangeable K was significantly reduced by nearly the same extent (17%) with all liming rates above 0.8 ton per acre.
Potassium released by a water-equilibration procedure was influenced by liming, the response pattern being greatly affected by time and rate of lime. The heavier treatments effected first an increase in equilibrated K values, then a progressive decrease over succeeding years to a 50% depression at the end of the experiment. With the lighter rates (0.8 and 1.6 ton per acre) substantial depressions occurred initially, becoming progressively greater with time.
Water-equilibrated K was shown to be closely related to plant content (total %), in a short-term plant growth experiment.