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United States Department of Agriculture

Agricultural Research Service

Research Project: Technologies for Managing Water and Sediment Movement in Agricultural Watersheds

Location: Watershed Physical Processes Research

Title: Application of AnnAGNPS to model an agricultural watershed in East-Central Mississippi for the evaluation of an on-farm water storage (OFWS) system

Author
item Karki, Ritesh
item Tagart, Mary
item Paz, Joel
item Bingner, Ronald - Ron

Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/9/2017
Publication Date: 7/18/2017
Citation: Karki, R., Tagart, M.L., Paz, J.O., Bingner, R.L. 2017. Application of AnnAGNPS to model an agricultural watershed in East-Central Mississippi for the evaluation of an on-farm water storage (OFWS) system. Agricultural Water Management. 192:103-114.

Interpretive Summary: On-farm water storage systems can be an effective irrigation water management practice and can control nutrient and sediment loads produced from agricultural fields, but there is limited information on their effectiveness in East-Central Mississippi. This study applied the USDA-Annualized Agricultural Non-Point Source Pollutant Model to evaluate runoff, nutrients, and sediment from an agricultural watershed in East-Central Mississippi. Evaluation of current and alternative management practices showed that fall application of poultry litter fertilizer in preparation for the next growing season can cause increased downstream nutrient losses from East-Central Mississippi agricultural fields. Additionally, leaving the field in no till in the fall after harvest and moving to a spring application of poultry fertilizer can decrease sediment and nutrient loss from the agricultural fields and allow more nutrients to be available at planting. Analysis and evaluation of these systems provides critical information to conservation managers with the goal of optimizing conservation management practices to decrease nutrient and sediment losses before actual implementation.

Technical Abstract: Annualized Agricultural Non-Point Source Pollutant Model (AnnAGNPS) is a watershed-scale, continuous simulation, physical model that has been widely used to simulate runoff, nutrients, sediment, and pesticides in different watersheds. This study applied AnnAGNPS to simulate runoff, nutrients (total Nitrogen and total Phosphorus), and sediment from an agricultural watershed in East-Central Mississippi. AnnAGNPS was then used to evaluate an On-Farm Water Storage (OFWS) system as a Best Management Practice (BMP) for nutrient and sediment loading control from agricultural fields within this watershed and as a source of irrigation. An R2 of 0.85 and E of 0.82 in daily runoff estimation showed that the model can adequately simulate runoff from watersheds in East-Central Mississippi. In addition, an R2 of 0.88 and E of 0.67 for event-based sediment estimation and an R2 of 0.74 and E of 0.54 for monthly phosphorus estimation also showed that the model can satisfactorily simulate sediment and phosphorus. However, the model was not able to simulate nitrogen, with an R2 of only 0.15 and E of -0.107 because of the lack of site specific and accurate input data. After AnnAGNPS successfully simulated runoff, sediment, and phosphorus, an evaluation of the OFWS system showed that the system was able to capture 220,000 m3 of runoff from the monitored watershed that can be stored and used for irritation. AnnAGNPS estimated that the OFWS system also captured 46 tons of sediment and 558 kg of phosphorus during the monitoring period, preventing downstream nutrient and sediment pollution.

Last Modified: 09/19/2017
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