Relationship Between the Potassium Removed by Millet and Red Clover and the Potassium Extracted by 4 Chemical Methods from 6 Kentucky Soils
Sutton, Paul | Seay, W. A.
Six soils were cropped in the greenhouse with millet and Kenland red clover to determine the potassium-supplying power of the soils and the degree of correlation between the potassium removed by the crops and that extracted by four chemical methods. Potassium fertilizer was applied to determine the effect this would have on the potassium-supplying power. Potassium was extracted from moist and air-dry soil samples with 0.15N H₂SO₄, 1.38N H₂SO₄, 1N NH₄Ac and 1N HNO₃. The potassium extracted from moist soil samples correlated better than did air-dry soil samples with the amount of potassium removed from the soils by millet. The potassium extracted by 1N NH₄Ac and 1.38N H₂SO₄ from moist soil samples correlated better than did air-dry soil samples with the amount of potassium removed from the soils by clover. The differences in potassium extracted from moist and dry samples were small for the 0.15N H₂SO₄ and 1N NH₄Ac methods. The potassium extracted by 0.15N H₂SO₄ and 1N NH₄Ac from air-dry soil samples and the potassium extracted by 1.38N H₂SO₄ from moist soils gave the best indexes for evaluating the potassium-supplying power of these soils.Show more [+] Less [-]