Potassium Uptake and Recovery by an Upland Rice-Soybean Rotation on an Oxisol
- D. W. Gill and
- E. J. Kamprath
A major limitation to improved crop growth on many acid Oxisols is low K availability. A field experiment was conducted in West Sumatra to study the effects of K fertilization of an oxisol under three levels of lime (0.375, 2.25 an 5 t ha−1) on K accumulation of a yearly upland rice (Otyza sativa L.)-soybean (Glycine max L. Merr.) rotation where all above-ground residue was removed. Six K treatments supplied 0 to 240 kg K ha−1 to each crop and lime treatment. Potassium fertilization increased grain yields of rice and soybean and K content of grain and stover of both crops. With both crops a large proportion of the K was present in the stover. Liming had no effect on K accumulation Of rice grain; an inconsistent effect on K accumulation in rice straw; and significantly increased the K content of soybean grain and stover. Upland rice was very efficient in utilizing K applied to that crop as well as residual soil K from previous fertilization. When K rate was greater than 100 kg ha−1 per crop appreciable amounts of K could not be accounted for indicating that the K was lost by leaching. Increases in exchangeable K with K fertilization only occurred in the 0- to 30-cm depth.
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