Minimal exchangeable potassium status of fifteen smectitic soils in relation to potassium uptake and plant mobilization rate of soil reserve potassium |
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| Abstract: | Abstract A greenhouse experiment was conducted to study the minimal exchangeable potassium (minimal K) status of fifteen smectite dominant soils and its relationship with K uptake and plant mobilization rate of soil reserve K. Exchangeable K reached minimal level decreasing about 35% from initial K status after 350 days of continuous cropping. Soils with high clay content and initial K status showed higher minimal exchangeable K. Cumulative K uptake by six successive crops varied from 160 mg kg‐1 to 823 mg kg‐1 and plant mobilization of soil reserve K varied from 0.151 mg kg‐1 day‐1 to 1.880 mg kg‐1 day‐1 among soils. Minimal K explained well the variation in total K uptake (r=0.85) and plant mobilization rate (r=0.83) as compared to initial exchangeable K status of soils (r=0.67 and 0.59, respectively) suggesting that the former is a better index of K supplying capacity of soils than the later. |
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