Chemical, Mitscherlich, and Neubauer methods for determining available potassium in relation to crop response to potash fertilization
1943
Olsen, S.R. | Shaw, B.T.
A study was made of the crop response to potash onsix Ohio soils from 1939 to 1941. Corn was grown each year. A definite crop response was shown each year on the Clermont and Miami soils, a slight crop response was found on the Wooster and Mahoning soils, and none on the Muskingum and Brookston soils. The available potassium in each soil was determined by chemical, Mitscherlich, and Neubauer methods. All methods agreed in placing the soils in the same order with respect to available potassium as indicated by field response. The Mitscherlich and Neubauer methods gave a somewhat better differentiation of available potassium than the chemical test in the two soils which showed the most crop response to potash additions. The Neubauer method was used to study the amount of nonexchangeable potassium released from the silt fractions. Only three soils, the Clermont, Wooster, and Brookston, were examined. Significant amounts of potassium were removed by the rye seedlings from each fraction. As the particle size decreased, the amount of potassium removed increased. The lower the exchangeable potassium in thie soil the greater was the proportion of potassium taken up from the silt fraction.
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