|Richard Jr, Edward|
Submitted to: International Society of Sugar Cane Technologists Proceedings
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 24, 2004
Publication Date: January 30, 2005
Citation: Johnson, R.M., Richard Jr, E.P. 2005. Utilization of Yield Mapping and Variable-Rate Lime Application in Louisiana Sugarcane. Proc. International Society of Sugar Cane Technologists. 25:351-356. Interpretive Summary: Louisiana sugarcane producers, like most U.S. agricultural producers, have faced increased economic pressure in recent years. Growers must find ways to decrease costs and maximize profits. Precision Agriculture, specifically, variable rate lime and fertilizer application, may offer an important tool to accomplish this task. The first step in this study was to evaluate the variation in sugarcane yield and quality. Experiments were conducted in two locations in South Louisiana for three growing seasons. This was done to determine if sufficient natural variability existed in Louisiana sugarcane to justify a precision agricultural approach. In all years and at both locations sugarcane yield and quality were found to vary significantly with 2-5 fold changes in yield occurring within the same field. These properties were also found to vary across the field. The observed variation was not random, but was instead found to be spatially correlated. Samples that were spaced at a distance less than the range of spatial correlation were more similar than those at distances greater than this range. This data combined with the variability data indicated that there was sufficient variability present to try a precision agricultural approach. An experiment was conducted for two years in a 48-acre sugarcane field to determine if variable rate lime application could benefit the sugarcane industry. In the variable rate method, soil samples are taken in a grid pattern in the field and are used to predict how much lime is need in different areas of the field. In the traditional method, only one rate of lime (based on an average of several soil samples) is applied to all parts of the field. In both years there was a significant yield benefit to applying lime by either the variable rate or traditional method compared to no lime additions. The traditional method resulted in yields that were slightly higher the variable rate method; however, in the second year the difference between the two methods was much lower. These combined results are promising, because if similar yields can be obtained with the variable rate system, which is actually applying less inputs, then an overall increase in profitability will be observed. The results also indicate that further research on the VR application method is required to achieve maximize yields. Sugarcane growers that adopt these methods may benefit from decreased fertilizer and lime costs, while minimizing the environmental impact of their application.