Sediment and nutrient loading from sugarcane fields in south Louisiana: Effect of residue management

Abstract

Sugarcane (Saccharum spp.) residue management, such as burning or sweeping (repositioning residue into the furrow), poses several challenges for producers and affects soil and water conservation practices. In this study, we evaluate the effect of postharvest residue management (mulch, burn, and sweep) on the yield of sugarcane at three different locations in south Louisiana during 2012 through 2016. Runoff and total solids loading, as well as total losses of ammonia (NH₃), nitrate (NO₃⁻), and dissolved phosphorus (P), were quantified during 2013 and 2014 growing seasons. Additionally, regression analyses between the runoff from mulch, burn, and sweep fields and the associated sediment and nutrient loading were carried out. The average measured cane yield (66.7 Mg ha⁻¹) and sugar (7.97 Mg ha⁻¹) did not differ among the different residue treatments, with p-values of 0.78 and 0.99, respectively. The runoff coefficient (in a range of 0.1 to 0.4) is found to be in ascending order as mulch fields < burn fields < sweep fields, and it proportionally enlarged by the increase of rainfall intensity. There were no significant differences in total solids loading and NH₃ losses among the three residue management treatments. However, NO₃⁻ and dissolved P losses from the burn (0.54 and 0.02 kg ha⁻¹, respectively) and sweep (1.04 and 0.29 kg ha⁻¹, respectively) treatments exhibited significant differences during 2014. Based on these findings, mulching or sweeping the residue from the top of cane row is an acceptable management alternative to burning crop residue.