|Southwick Jr, Lloyd|
Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/2006
Publication Date: 11/1/2006
Citation: Kornecki, T.S., Grigg, B.C., Fouss, J.L., Southwick Jr, L.M. 2006. Effectiveness of Post-Harvest Sugarcane Residue and Polyacrylamide on Reducing Soil Deposition in Quarter-Drains. Applied Engineering in Agriculture. 22(6):857-865. Interpretive Summary: Sedimentation has been identified as a major water quality concern on sugarcane land in Southern Louisiana. Bare alluvial soil surfaces of quarter-drains and furrows are exposed to intense rainfalls that cause sediment transport from furrows through quarter drains to main ditches. Consequently, sediment diminishes the capacity of main ditches, thus require frequent cleanup with an average yearly cost of $293/ha. For decades, crop residue has been known to effectively protect topsoil from erosion caused by falling raindrops energy. Also, for many years, soil amendments such as Polyacrylamide (PAM) have been used on irrigated agriculture to reduce soil loss. Historically burning of sugarcane residue has been common management practice in southern Louisiana. However, during the burning process all benefits that residue could provide are lost, and toxic gases are discharged into the atmosphere causing a health and environmental hazard. Our experiment was designed to study effects of sugarcane residue and PAM in reducing soil loss from sugarcane land. Based on four rainfall events with a cumulative depth of 105 mm, sugarcane residue left on the field significantly reduced soil sediment by 34% in quarter-drains compared to residue removed by burning. Results also showed that, in addition to residue left on the field, applying an aqueous PAM solution to quarter drains further reduced soil loss to 42%. However, since no statistical difference was found between these treatments, data suggest that residue mainly controlled soil loss. Data indicated that leaving sugarcane residue on the field after harvest instead of burning could reduce soil loss within surface drainage system by 4.2 tons per year and decrease yearly reformation cost of surface drainage ditches by $106/ha. Direct PAM application to quarter drains might help to better stabilize conditions of surface drainage ditches under typical weather conditions; however, sugarcane residue must be left in furrows to efficiently control soil loss from furrows. Low PAM effectiveness during the experiment could be related to PAM’s degradation caused by the sun’s UV and cracks formation in the quarter drains due to unusually dry and hot weather in spring 2003.
Technical Abstract: Each spring, quarter-drains (small surface ditches, perpendicular to sugarcane rows) that transfer runoff from furrows to main surface ditches have to be re-conditioned to be effective. Exposing bare soil surfaces in quarter-drains and furrows to intense rainfalls cause soil loss in furrows and quarter drains and sediment buildup in main surface ditches. Consequently, sediment that accumulates in main ditches diminishes the capacity of these structures, thus require frequent and costly cleanup. Present practice in managing post-harvest residue is burning. However, residue burning has a negative effect on the environment and human health due to discharging toxic gases into the atmosphere. An alternative to burning is to leave sugarcane residue on the surface after harvest. This experiment was designed to study effects of sugarcane post-harvest residue and Polyacrylamide (PAM) applied directly to quarter-drains in reducing soil loss from quarter-drains in spring 2003. Treatments were: (1) residue left on the field (swept to furrows); (2)Residue burned; (3) Residue left + PAM; and (4)Residue burned + PAM. Overall, during four rainfall events with a cumulative amount of 105 mm, sugarcane residue left in furrows reduced soil deposition in quarter drains by 34% compared with residue burned. PAM application to quarter drains with residue left in furrows further reduced soil loss by 8% to 42%. The maximum reduction of soil deposition in quarter-drains was recorded after the 1st rainfall; the highest soil deposition reduction (62%) was observed with residue left + PAM treatment. Residue left reduced soil deposition in quarter-drains by 46% in comparison with no-residue burned. The lack of significant difference in soil loss between residue left and residue left + PAM treatments might indicate that residue cover left on the field was mainly responsible for reducing soil deposition in quarter-drain. Adding PAM as a water solution provided only minimal protection from soil loss in quarter drains. Data suggest that PAM effectiveness was likely inhibited by abnormally dry and hot weather in spring of 2003, and might be related to the polymer’s chemical, photo, and mechanical degradation.