Potassium Supplying Power of Iowa Soils at Their “Minimal” Levels of Exchangeable Potassium1
- M. A. Tabatabai and
- J. J. Hanway2
The plant removal of native K from seven surface soils and seven subsoils from Iowa was studied at their “minimal” levels of exchangeable K. The “minimal” levels of exchangeable K were directly related to the percentages of <2 μ clay present in the surface soil samples. Plant uptake of nonexchangeable K was a linear function of time of cropping for all the soils and was highly correlated with the “minimal” level of exchangeable K. In the 758-day cropping period, an average of about 24 times as much K was removed by the plants as was present as exchangeable K in the soils at their “minimal” exchangeable K levels. Long-term K supplying powers of the soils used were highly correlated with their “minimal” levels of exchangeable K.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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