Location: Sugarcane Research2009 Annual Report
1a. Objectives (from AD-416)
The first objective of the research is to develop new crop and soil management techniques for sugarcane production that overcome limitations in soil and nutrient resources and maximize production efficiency. These techniques will incorporate elements of precision agriculture and remote sensing. The second objective of the research is to identify methods to mitigate the current yield loss associated with post-harvest residue retention and ripener usage in sugarcane production.
1b. Approach (from AD-416)
To address the first objective, a series of experiments will be initiated to investigate the response of sugar and energy-canes to variations in macro- and micronutrients. Results from these experiments will be used to identify critical fertility components and to optimize fertility rates for both sucrose and biomass production. Initial macro-nutrient experiments will focus on nitrogen (N), a critical component of a sugarcane fertility program whose cost has risen dramatically. Initial micronutrient experiments will focus on nickel (Ni) a nutrient that is associated with increases in disease resistance and copper (Cu) which is associated with increases in both cane and sugar yields and may also influence disease resistance. In addition, experiments will be conducted on commercial farms to investigate the utility of electrical conductivity (EC) and soil pH mapping, zone sampling, and variable-rate (VR) application techniques to optimize nutrient availability. All treatments will be arranged in randomized complete block design (RCBD) with six replications. Finally, we will investigate the utility of a newly designed yield monitor and leaf reflectance measurements, from multi-band aerial imagery and from direct hyperspectral measurement as potential indicators of cane biomass levels and sucrose content and to identify crop stresses associated with improper fertility levels of sugarcane dedicated for either sugar or bioenergy. To address the second objective, studies will be initiated to investigate the carry over response of sugar- and energy-cane crops to post-harvest residue and ripener applications made in the previous crop year. The response of energy-canes and newly-released sugarcane varieties to these factors has not been tested. In addition, studies will be implemented to screen basic and commercial germplasm for tolerance to post-harvest residue retention and to screen for self-defoliating clones that may expedite the natural decomposition of leafy residue prior to harvest. Finally, a study will be initiated to investigate in crop N application rate effects under various post harvest residue management schemes to include: partial removal, complete removal by burning, and no removal.
3. Progress Report
Project receives support from the American Sugar Cane League (6410-21000-014-04T) through a Trust Fund Cooperative Agreement, ”Improving Sugarcane Production Efficiency", as well as the in-house project 6410-21000-014-00D, "Genetic Improvement of Sugarcane by Conventional and Molecular Approaches". Additional details of research can be found in the reports of the subordinate and parent projects. Agricultural Research Service (ARS) scientists at the Sugarcane Research Unit (SRU), in cooperation with Louisiana State University (LSU) AgCenter, initiated studies in commercial plant-cane sugarcane fields to determine the optimum nitrogen requirements for newly released Louisiana varieties. Varieties evaluated in the study included HoCP 96-540, Ho 00-950, L 99-226, and the energy cane variety, L 79-1002. Nitrogen was applied to all experiments at rates ranging from 0 to 160 lb/A using 32% urea ammonium nitrate (UAN) as the nitrogen source. Leaf samples will be collected for reflectance and nitrogen analysis in July and cane and sugar yields will be determined by harvesting the experiments in November and December 2009. Studies were initiated to determine the influence of nickel (Ni) and copper (Cu) fertilizers on cane and sugar yields and also on the incidence of sugarcane diseases, particularly brown rust in Louisiana varieties HoCP 96-540 and L 99-226. Foliar Ni fertilizer was applied at a rate of 0.13 lb Ni/A in March, April and May using a commercially available Ni fertilizer source. Foliar Cu was applied at rates of 0, 0.66, 1.3 and 2.0 lb Cu/A in May using copper sulfate as the fertilizer source. Rust and other disease levels are being monitored through visual ratings and by taking leaf samples and determining percent rust lesions with image analysis software. Cane and sugar yields will be determined by harvesting plots in November and December, 2009. Four studies were initiated to investigate: 1) rates of the herbicide glyphosate needed to induce early sucrose accumulation in sugarcane and treatment to harvest intervals for new varieties; 2) management of post-harvest leaf litter (residue) for energy and sugar cane; 3) nitrogen rates needed for different residue management systems, and 4) mechanical harvesting of post-harvest residue. Additionally, seed-cane was increased for subsequent experiments. Preliminary results with glyphosate indicate that late-season chemical ripening of HoCP 96-540, L 99-233, and L 99-226 was not effective at currently recommended rates and treatment-to-harvest intervals. This was probably due to the extent of natural ripening for the 2008 crop due to exceptionally dry soils and high sunlight incidence in the fall.
1. Sugarcane Yield Monitor Predicts Field Cane Yields. Louisiana sugarcane producers continue to search for ways to increase yields and profitability. One way to increase profitability would be to accurately predict and map cane yields at harvest so that transportation costs could be minimized and in-field variability could be more effectively managed. In a cooperative research effort, Sugarcane Research Unit (SRU) scientists worked with a Kansas State University Agriculture Engineer to develop and test an optical yield monitor to predict cane yields under field harvest conditions. Results demonstrated that there was a linear relation between the optical sensor response and actual cane yields. The average observed prediction error was 7.5%; however, the magnitude of the error decreased as the total harvested area increased. The yield monitor was not influenced by variety or harvester speed and appeared to require minimal maintenance. This technology will allow sugarcane producers to map within field variability, identify areas requiring additional inputs, and help to maximize transportation efficiency.
2. Removal of Sugarcane Post-harvest Residue Does Not Increase Yields on Poorly-drained Soils. The blanket of leaf litter generated during the harvest of green sugarcane often reduces yields of the following year's crop (ratoon) in Louisiana. Studies were conducted to investigate different litter management options. Options evaluated included full retention (no removal), complete removal by burning, mechanical repositioning of the litter from the row-top to the wheel furrow, and removal of the litter from the row top by baling. In conjunction with these options, disking the litter on the row sides and inter-row area into the soil with a rolling cultivator was evaluated. Complete removal by burning increased sucrose yields by 1200 lb/A relative to the average of all other treatments. Mechanical repositioning and baling did not increase sugar or cane yield relative to full retention because of drainage impediment and damage to below ground buds that produce the subsequent ratoon crop. Mixing the litter into the soil did not affect yields. For sugarcane grown on heavy-textured soils in high-rainfall, temperate climates, producers should completely remove residue from fields as soon after harvest as possible to maximize yields in the subsequent ratoon crop.