Benjamin L. Legendre

The ability of farmers to burn sugarcane is a significant economic factor for the state’s sugarcane industry. Burning of sugarcane before harvest eliminates from 30 percent to 50 percent of the leafy trash (residue) that constitutes from 20 percent to 25 percent of the total weight of the plant.
 
For example, for a yield of 50 tons of sugarcane per acre, 10 to 15 tons of residue must be removed before milling. Controlled agricultural burning allows more efficient sugarcane harvesting in the field and improves sugar quality and recovery in the factory. The residue contributes very little to the production of sugar and has little or no economic value.
 
The remainder of the plant consists of stalks from which the sugar is crystallized from the extracted juice in processing. Harvesting burned sugarcane results in less soil being brought to the factory, reduces fuel consumption because less material is transported to the factory and uses less water in washing the crop before milling. Reducing transport within the field lessens soil compaction. Currently, there is no profitable or effective way to deal with this large volume of residue by mechanical means either in the field or at the factory.

Louisiana is not the only state, nor is sugar production the only industry, facing the challenges posed by burning as an agricultural management tool. Every industry that uses burning recognizes that a cost-effective mechanism for reducing or eliminating open field burning is a high priority research topic. Further, because of current low domestic sugar prices, the farmer would be hard-pressed to survive without burning to reduce production costs and improve quality of the product delivered to the factory.

Recently, agricultural burning policy recommendations were prepared by the U.S. Department of Agriculture (USDA) Agricultural Air Quality Task Force that would help farmers implement provisions of the Clean Air Act while retaining the valid use of fire as a management tool. Task force members included representation from agricultural producers, air quality researchers, agricultural industry representatives, medical researchers and state air quality and USDA staff.

The policy addresses two goals:

(1) to allow the use of fire as an accepted management practice, consistent with good science, to maintain agricultural production on agricultural land, and

(2) to protect public health and welfare by mitigating the effects of air pollution emissions on air quality and visibility.

In 2000, the Environmental Protection Agency (EPA) conducted three public meetings including one in New Iberia, La. The EPA has also solicited written comments to help in the development of policies to address the air quality effects of agricultural burning and the use of USDA’s incentive-based programs in meeting Reasonably Available Control Measures (RACM) and Best Available Control Measures (BACM) requirements.

Until proven technology allows economically efficient harvesting without burning, it is critical for cane growers and processors to do the best job possible of managing smoke and ash. Smoke and ash management can be defined as conducting a prescribed burn under recommended weather conditions using burning techniques that lessen the impact on the environment and public health and welfare.

The Louisiana sugarcane industry has been proactive in its efforts to help this situation by developing the Certified Prescribed Burn Manager Program, which is administered by the Louisiana Department of Agriculture and Forestry (LDAF). The LDAF, the American Sugar Cane League (ASCL) and the LSU AgCenter developed a training curriculum titled, “Louisiana Smoke Management Guidelines for Sugarcane Harvesting.” Although this training was voluntary, approximately 1,400 cane farmers and/or their employees have attended one of the annual sessions held at various locations in the sugarcane-growing region since the summer of 2000.  It appears that the Certified Prescribed Burn Manager Program worked exceptionally well because there have been significantly fewer complaints received by the LDAF and the ASCL since the 2000 harvest season with only two documented complaints received during the 2004-05 crop year.  Through a grant from Entergy, a burn video was produced by LSU AgCenter Communications that will be used in the recertification effort beginning during the summer of 2005 since the original certification was good for five years.

The LSU AgCenter, in cooperation with the USDA’s Agricultural Research Service, has taken a proactive attitude toward eliminating the need for or minimizing the effect of cane burning by initiating research on viable, economically feasible alternatives to agricultural burning to include value-added products from the cane crop’s residue. Even though not specifically related to air quality, an effective management program that uses the residue over the winter and spring to reduce runoff while minimizing the impact of the residue on the yield of the subsequent year’s crop would eliminate the need to burn.

Demonstrating the potential benefits of effectively managing the residue on the crop and the environment also may result in a higher percentage of the crop being harvested green by the cane combine. Other research initiatives have shown that the residue left on the field following green cane harvesting may help suppress weeds and offer some freeze protection during the winter. However, results also indicate a significant loss of sugarcane yield in the subsequent stubble (ratoon) crop, especially following cold, wet winters.

Additional studies have indicated that leaving this residue on the field can result in a higher population of overwintering sugarcane borers, the No. 1 insect pest of Louisiana sugarcane, as well as increase the chances of damage from the sugarcane beetle, further increasing the probability of loss of yield in the subsequent ratoon crop. Burning is the most cost-effective way of removing this residue following green cane harvesting; however, research is under way to determine ways to speed up the decomposition of the residue using biological agents and sugar solutions, including molasses, which could reduce the need to burn the residue.

Long-range plans are to develop new sugarcane varieties that shed their leaves before harvest; however, this does little to eliminate the problems associated with the residue following green cane harvesting. In recent years, manufacturers of sugarcane harvesters have devoted considerable resources in the development of a more efficient green cane combine system for the domestic sugar industry; however, this again does not answer the question of what to do with the residue after harvesting.