Kenneth Gravois, Orgeron, Albert
Kenneth Gravois and Al Orgeron
Sustainability means producing sugarcane in a manner that is economically profitable while being a good neighbor to both the local community and environment. The benefit to society is feeding the world without exploiting natural and human resources.
The Louisiana sugar industry is accomplishing this today.
Research is at the forefront of the Louisiana sugar industry sustainability effort. The LSU AgCenter’s primary research effort is sugarcane variety development. Members of the sugar industry look to the sugarcane breeding program for two primary objectives — increase sugar yield and lengthen the crop cycle (the number of crops grown from a single planting).
With increasing costs, the best means of ensuring a positive economic return is to increase sugar yield and to lower planting costs by replanting a lower percentage of total farm acres. Louisiana sugarcane breeding efforts have done this. Sugar yield has doubled from 1930 to 1970 and doubled again from 1970 until today. This means greater sugar yield for the same number of inputs per unit area.
The average sugarcane crop cycle has lengthened. Sugarcane is a perennial plant, and multiple crops can be grown and harvested. The first crop is the plant cane crop, and the next series of crops is referred to as stubble crops — first stubble grown in year two, second stubble in year three, etc. In 1947, the average crop cycle was sugarcane acreage of plant cane, first stubble, and second stubble at 40%, 40% and 20% of total production area, respectively.
Today, the crop cycle consists of sugarcane acreage of plant cane, first stubble, second stubble, and third and older stubble at 25%, 25%, 25% and 25% of total production, respectively. Longer crop cycles feature less fallow land that needs to be replanted to begin the crop cycle again. The fallow year is a time when no crop is produced on that portion of the farm. Most soil erosion happens in the fallow year. Less fallow acreage leads to less soil erosion.
Another research objective is crop protection. Weeds, insects and diseases continually lurk and can rob fields of yield potential. The first line of defense is variety selection. The most popular sugarcane variety in Louisiana is L 01-299, which was grown on about 57% of the acreage in 2022. L 01-299 is resistant to brown rust disease and to the sugarcane borer, a major stalk-boring insect pest.
Farmers use less insecticide to control stalk borers in L 01-299 than in a more susceptible variety, such as L 12-201. Variety HoCP 14-885 shades the row better than a variety with a more erect canopy, providing better weed control at no cost to the farmer. Sometimes pesticides must be used to control problems. AgCenter scientists and research collaborators determine optimal pesticide use rates, scouting techniques and thresholds. The goal is to use the correct pesticide at the right time at the proper rate, ensuring the problem is solved and resistance to the pesticide is avoided. Fields are scouted and pesticides are only applied when there’s an economic advantage to do so.
Soil fertility research maximizes crop yield, conserves natural resources and minimizes environmental impact. Soil sampling guides crop consultants and sugarcane farmers to apply the correct balance of plant nutrients. Variable rate nutrient application means applying different rates of fertilizer to different parts of the field growing the same crop. Grid sampling and electrical soil conductivity techniques create management zones that can be used to improve yield at different optimal fertilizer rates. AgCenter scientists are using nitrogen-rich strips and crop sensors to apply nitrogen at different rates in the fields. Nitrogen-rich strips help calibrate sensors that determine the nitrogen status of the crop prior to fertilization. The current practice is to apply a single nitrogen rate to the entire field. Nitrogen-rich strips, followed by sensor-based application of nitrogen, puts the fertilizer at different rates in the field depending upon need.
During a mechanical combine harvest, the sugarcane plant is cut into 8- to 10-inch segments, and fans separate leafy trash from stalk pieces. Leafy trash is deposited onto the field, and stalk segments (billets) are placed in wagons or trailers and taken to the raw sugar factory. Leafy trash is burned because of associated yield loss the following year when trash blankets are left on the soil surface. Local creativity is solving the problem. A Louisiana sugarcane farmer built a hood that redirects leafy trash onto the track of the combine harvester, which then places most of the leafy trash into the wheel furrow rather than the row top. During rainy harvests, the fields are less rutted, which allows for reduced tillage in the spring. Most importantly, these fields are not burned because yield loss is avoided when leafy trash is placed in the wheel furrow rather than the row top.
Sugarcane captures carbon dioxide from the atmosphere and with the help of sunlight and water produces sucrose and fiber. When sugarcane is processed into raw sugar, very little fossil fuel is used in the raw sugar factory. After juice is extracted from sugarcane stalks, the remaining fiber (bagasse) is burned in boilers to produce steam — the energy source that drives operations inside of the factory. Harold Birkett, LSU AgCenter chemical engineer, estimates that burning bagasse as a fuel source rather than natural gas saves a great deal of money. Louisiana ground 17,094,000 tons cane during the 2022 crop. Natural gas usage was 230,000 MCF (thousand cubic feet). Had the factories not burned the bagasse they produced, gas usage would have been 100 times more, or about 22,300,000 MCF, at a cost of about $80,000,000. Sugarcane and raw sugar production in Louisiana capture more carbon from the atmosphere than is released back into the atmosphere.
Members of the Louisiana sugar industry can be proud that the sugarcane crop grown and processed into raw sugar is done in a sustainable manner. The 225-year history of the Louisiana sugar industry has been a story of growing sugarcane today for tomorrow’s farmers.
Kenneth Gravois is the state sugarcane specialist for the AgCenter. He is stationed at the AgCenter Sugar Research Station in St. Gabriel. Al Orgeron is the resident coordinator of the AgCenter's Iberia Research Station in Jeanerette and Sugar Research Station in St. Gabriel.
This article appears in the winter 2023 edition of Louisiana Agriculture.
The Lula Sugar Factory in Belle Rose, Louisiana. One of eleven such factories that take sugarcane and produce raw sugar and molasses. Louisiana sugar factories generate energy by burning bagasse — the leftover fiber after the juice is extracted from the stalks. Bagasse serves as a green fuel replacing many millions of cubic feet of natural gas. Photo by Al Maclean
A sugarcane combine harvester that has been modified to redirect leafy trash onto the combine tracks, which then places the material onto the wheel furrow. Photo by Kenneth Gravois