Tuesday, November 3, 2009
Convention Center, Exhibit Hall BC, Second Floor
The development of a more effective nitrogen (N) decision tool using remote sensor is an important step in establishing a more profitable and environmentally-sound sugarcane industry in
. The use of remote sensor-based nitrogen decision tools in wheat and corn production has resulted in improved fertilizer N use efficiency. To develop a similar tool for sugarcane, the first and major step is to determine the feasibility of using early- to mid-season canopy reflectance to predict sugarcane yield potential and responsiveness to N fertilization. Collection of normalized difference vegetation index (NDVI) readings using the GreenSeekerTM handheld sensor from multiple soil fertility trials located at the LSU AgCenter Sugar Research Station, Louisiana was initiated in 2008. A total of 12 sensing dates were conducted from mid-April to first week of July from sugarcane plots planted with different varieties (LCP85-384, HoCP96-540, Ho95-988, L97-128, L99-233, and L99-226) of different crop age. Regression analysis was performed to determine the relationships of NDVI with cane and sugar yield, and the association between the NDVI-estimated N response index and the actual sugarcane response to spring N fertilization. The NDVI readings collected in early May showed the highest association with actual cane (r2=0.46) and sugar (r2 = 0.50) yields. Early season estimates of sugarcane response to N fertilization using NDVI were also correlated with increases in cane (r2 = 0.74) and sugar (r2 = 0.62) yield attributed to spring N fertilization. The initial findings of this study showed that optimum sensing dates fell within the timeframe where spring N fertilization is commonly done, and the use of NDVI readings that were collected early in the season to predict in-season cane and sugar yield potential, and the actual sugarcane response to N fertilization is feasible.
St. Gabriel, LA