Sugarcane Response to P, K, and DRIS Corrective Treatments on Florida Histosols1
- A. M. O. Elwali and
- G. J. Gascho2
Nutritional imbalances in sugarcane (a complex trispecies hybrid of Saccharum) on Florida Histosols (Medisaprists) were suggested in earlier studies. In order to eliminate possible imbalances among nutrients, the Diagnosis and Recommendation Integrated System (DRIS) was adapted to monitor the nutritional status of sugarcane in an experiment with varying P and K levels. Standard DRIS reference norms were established for nine nutrients (N, P, K, Ca, Mg, Fe, Mn, Zn, and Cu) in the top visible dewlap leaf laminae of sugarcane. Factorial P and K levels were applied with the seed cane at planting (January). Soil and leaf samples were collected during the grand growth period (July) and the DRIS indices for nutrients in the leaves were calculated. In order to correct nutritional imbalances indicated by DRIS indices at each PK-treatment, each plot was split into two subplots. One subplot did not receive additional fertilizer while the other subplot was fertilized with the required nutrients as indicated by DRIS indices for that whole plot. Leaf samples were collected again close to the end of the grand growth period (end of September). Sugarcane and sugar yields were not affected by the rates of P applied at planting but were significantly affected by the rates of K applied at planting and by the DRIS treatments. The highest rate of K (560 kg/ha) reduced both sugarcane and sugar yields compared with the other rates. Plots which received 280 kg of K/ha at planting yielded significantly more cane but no more sugar than plots with 0 Kat planting. Application of nutrients during the grand growth period (July) as indicated by DRIS indices significantly increased both cane and sugar yields over those obtained from plots which did not receive fertilizers in July. The DRIS indices for leaf nutrients during the grand growth period revealed that a shortage of P and an excess of K had been applied at planting, a fact which would have gone undetected by conventional nutrient level monitoring. The increase in cane and sugar yields from the DRIS corrective treatment rhsulted primarily from better nutrient balance as revealed by DRIS indices for leaf nutrients late in the seasonPlease view the pdf by using the Full Text (PDF) link under 'View' to the left.
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