Long-term Arkansas soil study finds benefits from not burning post-harvest crop residue
While the common practice of burning crop residue provides short-term benefits for weed control and preparing the seedbed for planting, producers may be missing out on the long-term benefits of keeping residue on the field, according to soil scientists with the Arkansas Agricultural Experiment Station. Burning crop residue after harvest means lost nitrogen and sulfur, displaced phosphorus and potassium and less crop residue as food for bacteria and fungi that help build soil aggregates and create slow-release nutrients. Additionally, despite having some short-term benefits, conventional tillage practices commonly combined with burning crop residue can induce soil compaction, disrupt soil aggregate stability and increase soil organic matter decomposition leading to a loss of carbon as carbon dioxide in the long term.
In response, a continuous 18-year field study was conducted at the experiment station’s Pine Tree Research Station near Colt in St. Francis County and the Lon Mann Cotton Research Station in Marianna in Lee County. Data were collected for three years at the Pine Tree station and for 18 years at the Lon Mann station. The study compared the impacts of not burning crop residue combined with conservation tillage and burning crop residue with conventional tillage practices in a wheat-soybean, double-crop production system.
The study found that total soil nitrogen increased more over time in the no-burn treatment averaged over tillage, residue level and soil depth. Researchers hypothesized that greater levels of total soil nitrogen under the no-burn treatment were partially due to the cumulative effects of crop residue retention on the soil surface. When not burned, the residue slowly contributed nitrogen to the soil as it decomposed, and mineralization occurred. Conservation tillage and not burning crop residue demonstrated many benefits over the long haul, including improved water-holding capacity.
Link to full statement on website: http://landgrantimpacts.tamu.edu/impacts/show/6175