Effects of Cover crop and filter strips on sediment and nutrient loads measured at the edge of a commerical cotton field.

Authors: THAPA, ARJUN - North Carolina A&t State University; ARYAL, NIROJ - North Carolina A&t State University; Reba, Michele; TEAGUE, TINA GRAY - Arkansas State University; Payne, Geoffrey; PIERI, ANNA - University Of Arkansas

Submitted to: Journal of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/21/2023
Publication Date: 3/26/2024
Citation: Thapa, A., Aryal, N., Reba, M.L., Teague, T., Payne, G.K., Pieri, A. 2024. Effects of Cover crop and filter strips on sediment and nutrient loads measured at the edge of a commerical cotton field.. Journal of the ASABE. 67(2):475-491. https://doi.org/10.13031/ja.15676.
DOI: https://doi.org/10.13031/ja.15676

Interpretive Summary: Soil tillage, use of fertilizers, and high irrigation-water usage to increase crop production contributes to soil erosion and nutrient losses from agricultural fields. The sediment and nutrients deposited in rivers, lakes, and coastal areas make them polluted. To mitigate that problem, switchgrass was planted at the edge of a farm in northeastern Arkansas. The discharged water from the farm that passed through the switchgrass was collected and analyzed for sediment and nutrients in the laboratory. This study found that a two-meter-wide switchgrass filter strip was able to reduce runoff by 36%, peak flow by 49%, and sediment by 56%. In addition, the filter strips were able to reduce various plant nutrients. Planting switchgrass filter strips on the edge of the agricultural field can reduce water pollution to the water body and benefit aquatic organisms and humans. Generally, findings in this research help to quantify the benefit of implementing the conservation practice of a switchgrass buffer, which is useful for land managers, modelers of agricultural systems, and farmers.

Technical Abstract: Effective use of vegetative filter strips as a conservation practice in agricultural fields can reduce sediment and other pollutant loads entering waterways. In this study we evaluated the effectiveness of using filter strips on sediment and nutrient loss at the edge of paired, 7.83 ha (19.35 ac), commercial cotton fields in the Lower Mississippi River Basin (LMRB) in northeastern Arkansas. The filter strips included a grassy turn row at the field border and switchgrass transplanted around the drainage pipe at the edge of the treatment field. The field border of the control field was generally free from vegetation. A monitoring system consisting of an area-velocity sensor and automated sampler collected discharge and composite water samples from rainfall and irrigation runoff events. Water samples were analyzed for phosphate (PO4-P), total phosphorus (TP), nitrate (NO¬3-N), ammonium (NH¬4-N), total nitrogen (TN), and suspended sediment concentrations. Baseline data were collected from 2015 and 2016 when both fields had similar conservation practices. There were 55 common runoff event samples collected from the growing seasons of 2017 to 2020 when filter strip practice was applied in the treatment field and not in the control field. A comparison of common runoff events between the control and treatment fields indicated that the mean runoff, peak flow, and sediment loads were significantly reduced by 36%, 49%, and 56%, respectively, by filter strips (p<0.05). Median nutrient load reductions in the treatment were not significantly different from the control (p>0.05). However, mean PO4-P, TP, NO¬3-N, NH¬4-N, and TN loads in the treatment field were lower in the control field by 23%, 15%, 11%, 42%, and 21%, respectively. Our results demonstrated nutrient and sediment load reductions following the implementation of a filter strip at the commercial field scale.