Sugarcane Cultivar Response to High Summer Water Tables in the Everglades

difficult to maintain desired water tables after normal rainfalls. Sugarcane (interspecific hybrids of Saccharum spp.) in the EverA second factor that has complicated EAA drainage glades Agricultural Area (EAA) in Florida is frequently subjected to periods of higher-than-desired water levels. This study was conis the need to decrease P discharge to the Everglades. ducted to evaluate yields of nine sugarcane cultivars subjected to two Best management practices to lower P discharge from higher-than-conventional water tables in the EAA during the summer the EAA often include strategies to reduce quantities rainy season from the plant cane through the second-ratoon annual and rates of pumping excess water from agricultural crop cycles. Field experiments were planted in February 1997 and fields (Izuno and Capone, 1995). Decreasing microbial January 1998. During the summers from 1997 through 1999, we sought oxidation rates in the Histosols of the EAA may also to maintain water 15 cm below the soil surface (BSS) in the wetter decrease P in EAA discharge water. Morris (1975) estifield and from 15 to 38 cm BSS in the drier field. Water tables for mated that soil oxidation accounted for 87 kg P ha 1 sugarcane in the EAA fluctuate from 40 to 95 cm BSS. Targeted yr 1, or 400% of the mean rate of fertilizer P applied water levels were achieved for 40 d in 1997, 104 d in 1998, and 96 d to sugarcane (Sanchez, 1990). Water levels necessary to in 1999 in the wetter field and for 35 d in 1997, 96 d in 1998, and 82 d in 1999 in the drier field. The mean sugar per hectare in the wetter sufficiently reduce pumping, and hence achieve reducfield was 91.7% that of the drier field. Yields of ‘Canal Point (CP) tions in P export, are often higher than growers consider 72-2086’ and ‘CP 82-1172’ were not affected by water table. Cultivar optimum for sugarcane growth. CP 85-1308 had higher yields in the wetter field in two of five harvests. Another factor that complicates maintenance of optiSugar per hectare of ‘CP 80-1743’ was reduced by 25.1% in the wetter mum sugarcane water levels is the desire to grow crops field. The variability among commercial cultivars to maintain yields such as flooded rice (Oryza sativa L.) near fields of at high water tables suggests that routine screening of promising sugarcane. In some such areas, it is necessary to maintain sugarcane genotypes under high water tables would help identify more higher-than-desired water levels on sugarcane fields. cultivars that maintain high yields in wetter conditions in the EAA. Several workers in Florida have studied sugarcane genotype response to water tables. In a field study on Pahokee muck soil (Euic hyperthermic Lithic MedisaT Everglades Agricultural Area (EAA) is a prist), Kang et al. (1986) found that sugarcane genotypes 280 000-ha basin of Histosols that lay on limestone at an intermediate stage in a selection program, grown rock in the northern region of the historic Everglades at a water table 30 cm BSS, yielded 16.7% more sugar in Florida. Sugarcane is grown on about 144 000 ha concentration and 26.4% more cane than at a water in the EAA (Glaz, 1999). Before construction of an table 56 cm BSS. Gascho and Shih (1979) tested five extensive public–private drainage system of canals sugarcane cultivars at water tables of 32, 61, and 84 cm through the northern Everglades, the EAA was flooded BSS of a Pahokee muck soil in lysimeters. Overall, the most of the time (Snyder and Davidson, 1994). With this highest yields occurred at the 61-cm water table. Two drainage system, farmers normally are able to maintain of the six cultivars, however, had equal cane yields at all water levels appropriate for their crops. For sugarcane, three water levels. Although not significantly different desired water levels fluctuate from 40 to 95 cm below from the yields at the two deeper water tables, both the soil surface (BSS) (Omary and Izuno, 1995). cultivars had their highest cane yields at the 32-cm waSeveral factors have gradually made it more difficult ter table. for EAA farmers to consistently maintain desired water LeCroy and Orsenigo (1964) measured cane tonnages levels for some crop species. One factor has been the and sugar concentrations of four sugarcane cultivars at subsidence of the Histosols in the EAA, now occurring six water table depths, ranging from 37 to 88 cm BSS. at a rate of 1.4 cm yr 1 (Shih et al., 1998). As subsidence All four cultivars yielded well at the 37-cm water table, continues, the depths of EAA soil profiles is reduced. but the researchers reported variable cultivar responses This gradual soil loss has resulted in less space in the to water table depth. Andreis (1976) reported that the soil profile to store water, thus making it increasingly yields of a plant cane through third-ratoon crop cycle at a 48-cm water table equaled those at a 94-cm water B. Glaz and J.D. Miller, USDA-ARS Sugarcane Field Stn., 12990 table. A preliminary study by Deren et al. (1991) found U.S. Hwy. 441, Canal Point, FL 33438; S.J. Edme and S.B. Milligan, that variability among sugarcane genotypes was suffiUnited States Sugar Corp., P.O. Drawer 1207, Clewiston, FL 33440; cient to warrant a long-term project to breed and select and D.G. Holder (retired), United States Sugar Corp., P.O. Drawer 1207, Clewiston, FL 33440. S.J. Edme, current address: USDA-ARS for flood-tolerant sugarcane. Florida researchers have Sugarcane Field Stn., 12990 U.S. Highway 441, Canal Point, FL 33438. *Corresponding author ([email protected]). Abbreviations: BSS, below soil surface; CP, Canal Point; EAA, Everglades Agricultural Area; TRS, theoretical recoverable sugar. Published in Agron. J. 94:624–629 (2002).