Submitted to: Sugar Journal
Publication Type: Trade Journal
Publication Acceptance Date: May 18, 2011
Publication Date: June 20, 2011
Citation: White Jr, P.M. 2011. Soil health for increasing sugarcane yield and sustainability. Sugar Journal. 74(1):30-31. Technical Abstract: Soil health can be defined as the capacity of the soil to continually produce high yields of sugarcane. Soil organic matter, native fertility, adequate moisture and drainage, soil workability, and high levels of beneficial microorganisms all contribute to soil health. Sugarcane growers in Louisiana have long recognized the importance of maintaining the soil in a healthy condition. In 1888 W. W. Pugh of Assumption Parish stated, “It was the general impression that our alluvial soil was inexhaustible…[however] during the war poor cultivation and the consequent falling off in the production of the soil suggested to thinking men that the general belief in the inexhaustibility of our soil might be an erroneous idea…” Early fertilizers, including guano (bat feces) and cottonseed meal, improved yield in soil depleted of nutrients. Victor T. Forestall of St. James Parish (1854) notes that “guano cane turned out the largest and heaviest cane in the field and produced…2,500 pounds [of sugar] per arpent. On the same ground I have never before obtained more than 1,000 pounds per arpent.” And legume intercropping was once a necessity. In a 1918 report J. M. Burguieres Co. reported that with a 4-year rotation of 2 years of sugarcane and cowpeas each at the Cypremort Plantation (St. Mary Parish) they produced the same sugarcane yield on 1/2 of their land as they previously produced with a 3-year rotation of 2 years of sugarcane and 1 year of cowpeas on 2/3 of their land. These cultural practices were successful because they replenished the soil with organic matter and nutrients needed for high sugarcane yields. Today we rely on elite sugarcane varieties, chemical fertilizers, herbicides for weed control and chemical ripening, and integrated pest management to provide high yields. Last year we sampled and analyzed soil from fields continuously cropped to sugarcane and adjacent areas of those fields not in cultivation across south Louisiana. Overall, the areas where sugarcane was continuously grown had soil organic matter levels that were reduced by a third (from 3.9% to 2.6%). These areas also had 18% less nitrogen, 24% less potash, and lower micronutrients (boron, iron, copper, and zinc). Perhaps adapting some of the past practices, such as amending the soil using milling byproducts such as filter press mud (FPM), or planting a legume crop during the fallow period, can be incorporated into modern production practices to improve soil health and increase or sustain yields. Working with Alma Plantation (Point Coupee Parish) we are testing the ability of FPM to improve yields. The FPM contains 7, 8, 16, 20, and 100 lbs. of nitrogen, phosphate, potash, calcium, and organic matter per dry ton. In April of 2010, FPM was applied at 10 and 30 dry tons/acre to plant cane of variety ‘L 01-283’ on alluvial soil. As a control, the recommended rate of nitrogen (60 lbs./acre) was applied to areas not receiving FPM. During the growing season weed abundance (mostly johnsongrass) was low and comparable to areas where we did not apply FPM, indicating that the FPM had no deleterious effect on preemergence herbicide activity. Plant-cane yield for the control was 50 tons/acre, theoretically recoverable sucrose (TRS) was 230 lbs./ton, and sugar yield was 11,500 lbs./acre. For the 10 ton FPM rate, cane yield was 52 tons/acre, TRS was 241 lbs./ton, and sugar yield was 12,500 lbs./acre. For the 30 ton FPM rate, cane yields were 53 tons/acre, TRS was 235 lbs./ton, and sugar yield was 12,500 lbs./acre. The tests continue this year with an additional FPM application (10 dry tons/acre) to the first ratoon crop to compare to residual effects of last year’s application. Growers have indicated a few concerns with intercropping legumes such as winter pea, cowpea, or soybean between cane rotations. For example, decomposing legume residue might heat up seed cane – a composting effect – and reduce plant-cane yields. However, with the current high commodity prices, intercropping soybean in the fallow period between sugarcane crop cycles can generate additional farm revenue. In 2004 and 2005 Dr. Ryan P. Viator of the USDA determined the effect of glyphosate-tolerant soybean, intercropped in the fallow period, on plant-cane yield of two sugarcane varieties, ‘HoCP 96-540’ and ‘L 97-128’, a slow and fast emerging cane, respectively. Neither soybean nor variety of sugarcane affected plant-cane yield, which averaged 48 tons and 10,400 lbs. sugar/acre. The soybean yield was 40 bushels/acre, worth a net value of $200/acre. This year our fallow-field legume intercropping studies have been expanded to include Sunn hemp and cowpea. Both will be turned under the soil as a source of organic matter and nitrogen about one-month prior to the anticipated sugarcane planting date. With these studies our overall goal is to provide support for the Louisiana sugar industry by improving soil health and ideally sugarcane ratooning ability. History continues to show us that soil management is a profitable strategy for the sugarcane grower. As guano in the 19th century produced the “finest and heaviest canes in Louisiana”1, perhaps FPM or soybean will prove to be as beneficial in the 21st century.