2012 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.
Second–ratoon nitrogen trials were initiated and sites for repeated first- and second-ratoon trials were also located and treatments applied. Leaf samples will be collected for reflectance and nitrogen analysis in June and July and cane and sugar yields will be determined by harvesting the experiments in October and November 2012. All first- and second-ratoon nitrogen experiments from the third year were harvested in November and December 2011. Preliminary results suggest that Louisiana sugarcane growers could save money by reducing nitrogen rates in both plant and stubble crops, while maintaining crop yields.
Studies 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, were also repeated in 2012 in second-ratoon trials. 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 where applicable. Cane and sugar yields will be determined by harvesting plots in October and November 2012. All Cu and Ni studies from the third year were harvested in November and December 2011. Preliminary results showed positive yield effects with Cu in both first- and second-ratoon trials. Yield monitor data was collected on several commercial sugarcane farms in the fall of 2011 and results indicated that the system was effective at predicting and mapping cane yields on a large scale.
Data was collected from a glyphosate carryover and residue management experiment. Data from the second-ratoon crop confirm the results obtained with first-ratoon and indicate that the stresses of glyphosate carryover and full residue retention appear to be additive as indicated by reductions in cane and sucrose yields. All second-ratoon seedlings were screened for their tolerance to residue. Cane and sugar yields were obtained from a second ratoon self-defoliating study and extraneous matter removal efficiency data was collected. Preliminary data indicates that residue decomposition is not enhanced with early defoliation and cane quality was not improved. Data from a nitrogen management study that incorporated different residue management regimes was also collected. The results indicate that the effects of including additional nitrogen to mitigate the negative influence of partial and full residue retention were not consistent across contrasting seasons.
Burning of post-harvest residues insures optimal sugarcane yields. The majority of sugarcane in Louisiana is harvested “green," which deposits large amounts of leafy residues back to the field. An eight-year study was initiated in 2001 by ARS scientists at the Sugarcane Research Unit's Ardoyne research farm near Schriever, LA, to determine if there were long-term nutrient re-cycling benefits to leaving the residue on the field and if the negative impact of the residue on yield could be reduced by the addition of more nitrogen at the start of the growing season. Complete removal of the residue by burning consistently produced the highest cane and sugar yields in the ratoon crops. Added nitrogen did not offset the effects of the residue on cane or sugar yields but did decrease soil pH in the ratoon crop that it was applied. Any potential benefits from leaving the residue in the field to soil nutrient levels and possibly a reduction in the need for additional fertilizer were not observed in this study and may require a longer period of time to be realized. Burning of the post-harvest residue blanket following green-cane harvesting continues to be the best way to insure optimal ratoon crop yields in a four-year crop cycle.
Energycane increases management flexibility for the existing sugarcane production system. Production practices may change depending if sugarcane is grown primarily for sucrose (sugarcane) or as a biofuels feedstock (energycane). A study of the affects of planting date on yields of both sugarcane and energycane indicated that the optimal period for sucrose production is August, while the establishment window for biomass production is much broader from August to September. ARS scientists at the Sugarcane Research Unit’s (SRU) Ardoyne research farm completed a five-year study comparing the flood tolerance of energycane and sugarcane. Energycane tolerated the flooded conditions better than sugarcane when biomass and sucrose yields were compared between treatments. In Louisiana, where sugar production is not economical because of delayed planting or flooded conditions, utilization of energycanes for production of cellulosic biomass may be a sustainable option.
Johnson, R.M., Viator, R.P., Richard Jr, E.P. 2011. Effects of billet planting rate and position on sugarcane yields in Louisiana. Journal of the American Society of Sugar Cane Technologists. 31:79-90.
Viator, R.P., Richard Jr, E.P. 2012. Sugar and energy cane date of planting effects on cane, sucrose, and fiber yields. Biomass and Bioenergy. 40:82-85.
Viator, R.P., White Jr, P.M., Hale, A.L., Waguespack, H.L. 2012. Screening for tolerance to periodic flooding for cane grown for sucrose and bioenergy. Biomass and Bioenergy. 44:56-63. Available online: http://dx.doi.org/10.1016/j.biombioe.2012.04.007.