Reduction-oxidation effects on soil potassium and plant uptake
2003
Schindler, F.V. | Woodard, H.J. | Doolittle, J.J.
Potassium ions (K(+)) may become "fixed" between adjacent phyllosilicate layers under waterlogged conditions, rendering K less available to plant uptake. This phenomenon was investigated under greenhouse conditions to determine if K fixation due to biogeochemical reduction contributed to the K deficiency in corn (Zea mays L.) in the northern Great Plains (South Dakota). The objective of this study was to evaluate the effects of a single reduction-oxidation (redox) event on soil K fractions and plant K uptake in montmorillonitic soils. Surface soil (Udolls, 0-15 cm) was collected from various sites across east-central South Dakota and used in a completely randomized greenhouse pot study (2 x 4 factorial). Reduced (Re) and reduced/reoxidized (Re/Ox) treatments were established, and corn was grown to the V5 stage of growth in a two cropping sequence. Potassium levels among soil K fractions did not significantly change upon the redox event. Dry matter (DM) yields were not significantly affected by the redox event. Cumulative K-uptake ranged from 25.7 to 33.2 mg K (kg soil(-1)), and there were no significant differences between treatments. No increase in K fixation was observed as the result of a single reduction-oxidation event. A single redox event does not cause K fixation in four montmorillonitic soils studied under greenhouse conditions.
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