Location: Sugarcane ResearchTitle: How much fertilizer nitrogen does sugarcane need?
|VIATOR, HOWARD - LSU Agcenter|
|TUBANA, BRENDA - LSU Agcenter|
Submitted to: Sugar Bulletin
Publication Type: Trade Journal
Publication Acceptance Date: 8/1/2013
Publication Date: 8/1/2013
Citation: Viator, H.P., Johnson, R.M., Tubana, B.S. 2013. How much fertilizer nitrogen does sugarcane need? Sugar Bulletin. 91(11):19-21.
Technical Abstract: Millable stalks of a forty-ton sugarcane crop contain up to 75 pounds of N. Total above and below ground biomass to achieve that yield level, of course, requires appreciably more N. Knowing the crop requirements for N, however, is not the same as knowing how much fertilizer N to apply. Nitrogen fertilizer management is complicated by the inability to accurately determine the potential contribution of N from the soil. Reliable pre-fertilization soil or plant tests for N are not available for sugarcane in our production environment. Currently, recommendations for N application for sugarcane take into account crop age (plant cane or stubble) and soil texture (light or heavy). Recommended rates in the 1950s ranged from 40 pounds N/A for plant cane on light-textured soil to 100 pounds of N/A for stubble cane on heavy-textured soil and increased over the next three decades to a range of 80 pounds N/A for plant cane on light-textured soil to 160 pounds of N/A for stubble cane on heavy-textured soil. The predominant N source also changed over the years from ammonium nitrate to anhydrous ammonia to urea-ammonium nitrate (UAN). These changes in source were driven by availability, cost and efficiency. In 2007, researchers at the USDA-ARS Sugarcane Research Unit in Houma, LA and LSU AgCenter embarked on an ambitious program to re-evaluate the N requirements for both the leading and newly released sugarcane varieties. Over 75 individual N fertilizer rate tests have been performed to produce information to re-formulate recommended N application rates to sugarcane growers. Separate application trials were conducted for plant-cane and first- and second-stubble crops of the production cycle. Nitrogen rates compared to the non-fertilized control were 40, 80, 120, and 160 pounds of N per acre with UAN as the N source. The net result of the re-examination of N rates was that N rates can be reduced using 32% UAN without compromising yield. Results from the trials allowed for reductions of 20 pounds of N per acre for plant-cane and 40 pounds of N per acre for stubble crops. Revised recommendations provide both economic and environmental benefits. Full adoption of the revised rates could save the sugar industry over $5 million annually in fertilizer input costs. Additional economic value from enhanced sucrose recovery should also be realized. By increasing sugar yield per ton of sugarcane, it is probable that transportation costs would decrease because it would take fewer tons of cane to achieve the same sugar yield per acre.