Challenges of post-harvest residue management in the Louisiana sugarcane industry

From a global perspective, Louisiana’s nine-month sugarcane growing season is extremely short. Post-harvest residues can decrease cane yield by 4.5–13.5 t/ha. Studies were implemented in the fall of 1998 to identify the reasons for this yield loss and to assess cultural practices that might mitigate against this loss. Soil moisture and temperature were monitored in a replicated study designed to compare the effects of residue removal through burning or mechanical means, versus a non-removal control. Four commercially popular Louisiana sugarcane cultivars were grown with and without residue to determine differences in tolerance to the residue layer. Date and methods of residue removal were also investigated to determine optimal management practices. During winter months, soil temperatures ranged from 8.4 to 26.0°C (mean = 16.8°C) for the non-removal treatment and from 7.6 to 27.3°C (17.5 average) when residues were removed. Soil moisture ranged from 2.0 to 33.3 kPa (mean = 8.0 kPa) for the nonremoval treatment compared to 3.4 to 45.0 kPa (mean = 12.4 kPa) when residues were removed. Most varieties responded similarly to residue conditions. Under the non-removal treatment, sugar yields declined by 0.7 t/ha compared to treatments with a January residue removal event. The effects of mechanical removal proved similar to burning in terms of yield. Sugar yields declined by 1.2 t/ha when residues were burned after January. To avoid yield losses, producers should remove residues in January through either burning or mechanical means. If residues are removed after January, mechanical methods should be used instead of burning. Increased soil moisture and lower soil temperatures associated with a residue cover appear to be related to sugarcane yield losses in Louisiana where excessive, rather than inadequate, moisture is a limiting factor for growth. Residue removal is particularly critical during cold and wet conditions since these environmental factors typically delay the re-emergence of the ratoon crop, which is problematic, given the short Louisiana growing season.