|Gilbert, Robert - UNIV. OF FLORIDA|
Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 19, 2005
Publication Date: July 15, 2006
Citation: Glaz, B.S., Gilbert, 2006. R.A. Sugarcane response to water table, periodic flood, and foliar nitrogen on organic soil. Agronomy Journal 98:616-621. Interpretive Summary: Sugarcane, the primary crop on the organic soils of the Everglades Agricultural Area in Florida is increasingly exposed to undesirably high water tables and short-duration floods. One reason that growers manage these high water tables is that phosphorus export from farms to the natural Everglades is reduced by minimizing pumping from farms to public canals. This 2-year study tested yield responses of two sugarcane cultivars, CP 72-2086 and CP 80-1827, to water-table depths and periodic floods. Treatments were constant target water-table depths of 23, 37, and 51 cm and a target water-table depth of 44 cm that was exposed annually to nine flood-drain cycles of 2-days flood followed by 12 days of drainage to 44 cm. The overall 2-year mean yields of both cultivars dropped as water tables approached the soil surface. However, water-table depth did not affect yields of either cultivar in the plant-cane crop, while yield loss due to shallow water table of cultivar CP 72-2086 was greater than that of CP 80-1827 in the first-ratoon crop. Surprisingly, yields of both cultivars were generally improved by the 2-day periodic floods. This new knowledge that sugarcane can tolerate and even improve its yields after 2-day floods should expand the flexibility of Florida sugarcane growers in managing quantities and rates of water discharged from fields to public canals, which in turn will help them minimize phosphorus discharge. Less frequent pumping of flooded fields may also improve efforts to conserve the organic soils on which sugarcane is grown in Florida.
Technical Abstract: Sugarcane (Saccharum spp.) is exposed to periodic floods and high water tables in the Everglades Agricultural Area (EAA) of Florida. Learning sugarcane responses to these conditions will help sustain and improve yields. This study evaluated the effects of three constant water-table depths, periodic floods, and foliar N fertilization on cane and sugar yields of two sugarcane cultivars. In 2001 and 2002, two foliar N and four water treatments were applied to the plant- and first-ratoon crops of cultivars CP 72-2086 and CP 80-1827 in lysimeters filled with Pahokee muck soil. Constant target water-table depths were 23, 37, and 51 centimeters. A fourth treatment was flooded for 2 days in each of eight 14-day cycles per year, and otherwise drained to a target depth of 44 centimeters. No consistent effects of foliar N were identified. Over cultivars and crop years, for every centimeter increase in water-table depth, theoretical recoverable sucrose decreased by 0.13 grams per kilogram, and cane and sucrose yields increased by 0.16 and 0.02 kilograms per meter squared, respectively. However, water-table did not affect CP 80-1827 in either crop year or CP 72-2086 in the plant crop. Cane and sugar yields of CP 72-2086 increased by 0.38 and 0.04 kilograms per meter squared, respectively, with each centimeter increase in water-table depth in the first-ratoon crop. Repeated 2-day floods often increased yields of both cultivars. After heavy rains, allowing floods to remain for 2 days may improve yields and reduce phosphorus discharge to the Everglades.