Submitted to: Journal of Agronomy and Crop Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/18/2008
Publication Date: 9/23/2008
Citation: Glaz, B.S., Reed, S.T., Albano, J.P. Sugarcane Response to Nitrogen Fertilization on a Histosol with shallow Water Table and Periodic Flooding. Journal of Agronomy and Crop Science. 194:369-379 Interpretive Summary: Sugarcane growers in Florida provide about 23% of the sugar produced domestically in the U.S., and sugarcane is the major agronomic crop of Florida. About 80% of the 400,000 acres of sugarcane in Florida are grown on organic (muck) soils that, when drained, provide nitrogen (N) far in excess of what is optimum for sugarcane. This nitrogen is made available to sugarcane by aerobic microbial oxidation of these organic soils. In recent years, sugarcane in Florida has been increasingly exposed to shallow water tables and periodic floods because growers do not drain fields after heavy rains when this drainage would send unacceptable levels of phosphorus (P) to the natural Everglades. Because these shallow water tables and periodic floods reduce the N made available by aerobic microbial oxidation, a study was conducted to assess their effect on the N nutrition of sugarcane. One 19-week and one 11-week experiment tested sugarcane growing in pots exposed to a shallow water-table depth (25 cm) and 2-day floods repeated weekly with N fertilizer rates of 0, 50, 100, 150, and 200 kg per hectare. Two sugarcane cultivars were tested, CP 80-1743, a cultivar developed in Florida’s high nitrogen soils and known to be sensitive to shallow water-table depths; and LCP 85-384, a cultivar developed in Louisiana under conventional nitrogen nutrition. Periodic flooding caused reductions in leaf, stalk, and root weights. There were positive responses in plant weights, leaf chlorophyll content (SPAD), and leaf N content to N fertilizer up to about 100 kg N per hectare. However, responses were similar for both cultivars in flooded and drained treatments. These results suggest that N fertilization of sugarcane may be useful in Florida for sugarcane exposed to water-table depths of 25 cm with and without periodic flooding on organic soils in south Florida. This information will help scientists develop N fertilizer recommendations for sugarcane under these new shallow water tables in Florida which will enable growers to sustain high yields while contributing positively to Everglades restoration by reducing drainage with excessive P to the natural Everglades.
Technical Abstract: Sugarcane (Saccharum spp.) is routinely exposed to periodic floods and shallow water tables on Histosols in the Everglades Agricultural Area (EAA) of Florida. Through microbial oxidation, these soils provide excess N for sugarcane, but it is not known if supplemental N would improve yields when microbial oxidation is reduced by shallow water tables and periodic floods. The purpose of this study was to evaluate the effects of soil applied N fertilizer rates on two sugarcane cultivars exposed to a 25-cm water-table depth with and without repeated 2-day floods. Two pot studies were planted in 2001 and 2002 with sugarcane cultivars CP 80-1743 and LCP 85-384, and five equally spaced rates of N fertilizer from 0 to 200 kg ha-1, under either a constant 25 cm water-table depth measured from the soil surface, or a 25-cm water table with 2-day floods applied weekly. Leaf, stalk, and root weights were reduced by periodic flooding and the magnitude of the reduction was sometimes greater for LCP 85-384 than for CP 80-1743. Plant weights, leaf chlorophyll content (SPAD), and leaf N content had some significant quadratic responses to N rate with optimums near 100 kg N ha-1. Except for a linear decrease in SPAD due to increasing N under periodic flooding, N rate did not interact with water treatment. Nitrogen fertilization on sugarcane may be useful for sugarcane exposed to water-table depths of 25 cm with and without 2-day repeated floods on EAA Histosols.