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SugarcaneA gronomy J our n al • Volume 10 0 , I s sue 3 • 2 0 0 8 845 ABSTRACT Improving soil organic matter and soil fertility are important factors in the sustainability of sugarcane (Saccharum spp.) production. A 3-yr fi eld trial was established in 2004 on a sandy Alfi sol in Florida to compare the eff ect of organic and inorganic nutrient sources on sugarcane production. Th e three nutrient sources were (i) mill mud (fi lter cake, cachaza), (ii) local standard fertilizer, and (iii) soybean cropping system before sugarcane. Soybean green manure increased sucrose yield (TSH, t sucrose ha -1 ) 20% in plant cane, however when aboveground biomass was removed soybean rotation did not improve sugarcane yields. Fertilization did not increase yields if mill mud was added to plant cane. Soybean green manure did not improve sugarcane ratoon crop yields, and there were no signifi cant interactions in the ratoon crops. Th e application of mill mud resulted in a 49% TSH increase in fi rst ratoon and a 167% increase in second ratoon whereas inorganic fertilizer application increased TSH by 31 and 49% in fi rst and second ratoon, respectively. Over the 3-yr crop cycle, addition of mill mud alone led to an increase of 4.1 TSH compared with inorganic fertilizer alone, whereas soybean green manure alone produced 2.6 TSH less than fertilizer. However, combinations of nutrient sources with mill mud had additive eff ects in the ratoon crops. Our results indicate that mill mud was more eff ective than soybean green manure or local standard fertilizer practices in increasing sugarcane yields on sand. However, growers should fertilize ratoon crops when mill mud has been applied to achieve maximum sugarcane yields.

Sugarcane (Saccharum spp.) in south Florida is often subjected to flooding due to intense summer rainfall or tropical storms. While there has been considerable research on the response of sugarcane cultivars to high water tables, there is a lack of information on cultivar morphological adaptation to long-term flooding. An experiment was established in Belle Glade, FL to examine: (i) effects of a July-September flood on the morphological characters of cv. CP 80-1743 and CP 72-2086 and (ii) significant flood 3 cultivar interactions that could be used to screen sugarcane germplasm. Sugarcane leaf, stem, primary root, adventitious root, and aerenchyma development were measured in the plant cane (2003) and second ratoon crops (2005). Morphological changes in response to flooding were similar in both years, with flooding leading to a 38% reduction in leaf weight, 4 to 15 times greater adventitious root development, 108% greater aerenchyma pipe extension, and 115% greater aerenchyma pipe diameter. Both cultivars responded to flooding by producing aboveground adventitious roots at the expense of belowground primary root biomass. A significant cultivar 3 flood interaction on aerenchyma extension and diameter was noted. Under nonflooded conditions, CP 72-2086 produced constitutive aerenchyma more than halfway up the stalk, whereas CP 80-1743 produced aerenchyma only 10% up the stalk. Aerenchyma development up the stalk may be a useful screening tool to identify flood-tolerance in sugarcane cultivars.