Evaluation of the potassium status of some Fijian soils used for sugarcane production
1995
Naidu, R. | Haynes, R.J. | Gawandar, J.S. (CSIRO Division of Soils, Glen Osmond (Australia))
K status of 8 Fijian soils representing those commonly used for sugarcane production was evaluated. Samples were taken from fields where continuous cane production has been practiced for 20 to 75 years and from nearby fields where cane had been grown in rotation and sites had been in a fallow state for five to eight years prior to sampling. The K status of soils, as measured by levels of exchangeable K and soil solution K, was low on the majority of sites. Five of the sites were situated on strongly weathered oxidic soils where total K content was low and K retention capacity (net soil negative charge) also tended to be low. Two less weathered soils contained significant amounts of 2:1 expansible layer silicate minerals and had a much higher total K and non-exchangeable K content than the other 5 strongly weathered soils. However, on both of the less weathered soils intensive cultivation resulted in a decrease in non-exchangeable as well as exchangeable K in comparison with fallowed sites. This indicates that net removal of K was occurring at the intensively cultivated sites. It was concluded that the K status of the study soils was low and in view of the high K requirement of sugarcane more attention needs to be paid to K fertilizer rates and practices in the study area.
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