Submitted to: Journal of Plant Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/17/2004
Publication Date: 9/16/2005
Citation: Morris, D.R., Glaz, B.S., Powell, G., Deren, C.W., Snyder, G.H., Perdomo, R., Ulloa, M.F. 2005. Leaf phosphorus diagnosis of sugarcane in organic soils. Journal of Plant Nutrition. 2005. 28:1511-1523. Interpretive Summary: Sugarcane is grown mostly on organic soils in south Florida. Phosphorus is an essential plant nutrient for high sugarcane yields, but producers are required to reduce P levels in water ways. One way to monitor P uptake in sugarcane is through leaf diagnosis. The objective of this study was to determine the best time to leaf sample during the summer months and to relate optimum leaf P tissue content and yield. A 3-year field study was conducted on four organic soil locations in south Florida. An 8 by 3 factorial experimental design with four replications was used at each location with eight sugarcane (interspecific hybrids of Saccharum sp.) genotypes in combination with three fertilizer P rates (0, 24, and 48 kg P ha-1). Upper-most fully expanded leaves were sampled in early, mid, and late summer prior to three harvests (plant cane, first ratoon, and second ratoon). Even though sugarcane yields increased with increased P fertilizer rates at three location, there was no consistent pattern relating leaf P tissue content with yields.
Technical Abstract: Most of the sugarcane production in Florida is on organic soils. Supplemental P fertilizer is often required for optimum yields, but producers are required to reduce P levels in water ways. The objectives of this study were to relate optimum leaf P tissue content with yield, and to determine optimum leaf sampling dates during the summer. An eight (sugarcane genotypes) by three (0, 24, and 48 kg fertilizer P ha-1) factorial field experiment was conducted for 3 yr at four organic soil locations. Leaves directly below the upper-most fully expanded leaves were sampled in early, mid, and late summer. There was no response to P fertilizer at one location, two locations had optimum cane yield with supplemental P at 24 kg P ha-1, and the fourth location had the highest cane yields at 48 kg P ha-1. Correlation analyses of yield vs. leaf P content across all treatments in early and mid summer were statistically significant (P < 0.05), but coefficients were very low r = 0.14 and 0.26, respectively). No consistent relationship across locations described the effect of leaf P tissue content on yield. Leaf samples should be taken in early season.