The effects of liming on the liberation of Potassium in some Iowa soils

Abstract

<p>The effects of lime on the liberation of potassium in a number of Iowa soils were studied in a series of experiments and the results obtained are summarized as follows:</p> <p>1. Analyses of 12 high-lime soils showed that all of the soils contained relatively large amounts of total potassium, carbonates and total nitrogen.</p> <p>2. The available potassium content of 11 of the 12 high-lime soils was insufficient for maximum plant growth according to the Aspergillus niger test. This low content of available potassium was correlated with the high carbonate content.</p> <p>3. The exchange complex of an acid Tama silt loam was completely saturated by applications of 6 tons of calcium carbonate per acre in greenhouse experiments and 6 months after treatment the amounts of exchangeable and available potassium were decreased.</p> <p>4. Calcium carbonate, calcium chloride and calcium hydroxide replaced potassium and increased the available potassium in the soil exchange complex in acid Tama silt loam and to a smaller extent in basic Webster silty clay loam, calcium chloride being the most effective. Calcium sulfate had little or no effect on the exchangeable and available potassium.</p> <p>5. The availability of potassium in high-lime soils was lower in inoculated than in uninoculated soils and the decrease in availability was greater in soils treated with calcium carbonate than in the untreated soils.</p> <p>6. It is suggested that a decreased hydrolysis of primary potassium-bearing minerals and the formation of insoluble potassium complexes and possibly also a reduction in available potassium by microorganic activity may be responsible, in part at least, for the decreased availability of potassium in these soils.</p>