WHEAT YIELDS AND CHANGE IN CATIONS AFTER LEACHING SOIL WITH WATER CONTAINING INCREASING RATES OF POTASSIUM REFINERY DUST

Leaching a silt loam soil (cation exchange capacity 23 meq/100 g) with water containing increasing rates of potassium dust (KCl) indicated that high levels adversely affected germination and yields of wheat as well as response to fertilizer. Germination was greatly reduced by the treatment with 22.4 metric tons per hectare and nearly eliminated by 44.8 tons. The 44.8-ton/ha treatment also greatly reduced the yield of grain, but straw weights were affected very little by increasing rates of potassium dust. Response to fertilizer was also reduced by 22.4 and 44.8 tons. The exchangeable Ca and Mg decreased and K increased as increasing amounts of K dust were leached through the soil. The 44.8-ton treatment decreased the exchangeable Ca from 56.0 to 24.9% and the Mg from 21.2 to 4.9%, and increased the K from 7.2 to 51.9%. It would appear that K salts can be added to the soil, without any adverse effects, until the exchangeable K is increased to about 30%. With the soil under study this took more than 11.2 tons per ha (5 short tons/acre). The application of dolomite ameliorated the effect of excess K.