Watershed-scale agricultural land-use impact on instream physicochemical parameters

Nonpoint source (NPS) pollution is often the result of runoff losses from agricultural or urban areas. Even though the watershed approach to controlling NPS pollution is identified as the most efficient approach, data linking watershed scale land use and specific water quality implications are very limited. The objective of this study was to quantify the impact of agricultural land use on stream physico-chemical properties. The upper reach of Flint Creek was monitored at two sampling points draining an agricultural land. At each of these points, continuous measurement of stream characteristics such as temperature, dissolved oxygen (DO) concentration, depth, pH, and conductivity were taken at three different dates. Also, water samples were collected and analyzed for nitrogen (N) and phosphorus (P) concentrations to discern the impact of agricultural land use on water quality. The results indicated that nitrate N (NO3-N) and phosphate P (PO4-P) concentrations increased as the agricultural land use increased in the watershed. Fluctuation in the DO concentration also increased with higher agricultural land use. In order to help decrease the amount of nutrients introduced to the stream, a variety of best management practices (BMPs) could be implemented in the watershe

Quantification of land-use impact on stream water quality

Accelerated eutrophication of Beaver Lake in northwest Arkansas is a major environmental concern. When developing watershed-management plans to protect lake water quality, it is important that linkages among land-use activities and water quality of tributary streams be quantified. This study assessed longitudinal base-flow and storm-flow water quality at War Eagle Creek and quantified linkages between stream water quality and land-use conditions within the War Eagle Creek sub-watershed of the Beaver Lake watershed. We collected six water samples: three from base-flow conditions and three from storm-flow conditions during Spring 2002. In general, concentrations of nitrate nitrogen (NO3-N), total N (TN), total organic carbon (TOC), conductivity, and total dissolved solids (TDS) increased as the sampling moved downstream. All stream water-quality parameters, except phosphate phosphorus (PO4-P), were significantly correlated to the ratio of agricultural-to-forest land-use (r2 = 0.90 to 0.97). These results indicate that the ratio of agricultural-to-forest land-use within the watershed can be used to evaluate stream water quality, and that increases in this ratio may result in increased TDS, NO3-N, TN, and TOC concentrations

A tool for estimating Best Management Practice effectiveness in Arkansas

Increased nutrient and sediment losses from expanding agricultural practices and urban development in Arkansas are important environmental concerns. Best Management Practices (BMPs) are being implemented to lessen the effects of these developments on existing water bodies. There is, however, insufficient scientific base as to the effectiveness of these practices. A number of studies have been conducted in recent years to determine BMP effectiveness. Data from these studies can only be reliably used for the individual site from which they were obtained. When considered collectively, these data comprise quantitative effectiveness over a wide range of conditions and can thus be used to provide reliable estimates of BMP effectiveness. This study develops a tool for estimating BMP effectiveness, based on accumulation and analyses of data reported in previous studies, with a focus on site conditions and management interventions in Arkansas. This study incorporates data from a variety of regions in the southeastern U.S., which have site conditions and management similar to those in Arkansas. Developed within Microsoft® Access© from a pre-existing BMP characterization tool, this tool will be made accessible to local and state agencies and will aid rural and urban planners in developing management solutions for nutrients and sediment control. The tool describes individual BMPs in detail and gives site-specific estimates of their long-term effectiveness in sediment and nutrient control

Effect of Spatial Variability of Rainfall on Modeling Hydrologic/Water Quality Processes

Biosystems Engineerin

Spatial Optimization of Six Conservation Practices Using Swat in Tile‐Drained Agricultural Watersheds

Targeting of agricultural conservation practices to the most effective locations in a watershed can promote wise use of conservation funds to protect surface waters from agricultural nonpoint source pollution. A spatial optimization procedure using the Soil and Water Assessment Tool was used to target six widely used conservation practices, namely no‐tillage, cereal rye cover crops (CC), filter strips (FS), grassed waterways (GW), created wetlands, and restored prairie habitats, in two west‐central Indiana watersheds. These watersheds were small, fairly flat, extensively agricultural, and heavily subsurface tile‐drained. The targeting approach was also used to evaluate the model's representation of conservation practices in cost and water quality improvement, defined as export of total nitrogen, total phosphorus, and sediment from cropped fields. FS, GW, and habitats were the most effective at improving water quality, while CC and wetlands made the greatest water quality improvement in lands with multiple existing conservation practices. Spatial optimization resulted in similar cost‐environmental benefit tradeoff curves for each watershed, with the greatest possible water quality improvement being a reduction in total pollutant loads by approximately 60%, with nitrogen reduced by 20‐30%, phosphorus by 70%, and sediment by 80‐90%.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/112253/1/jawr12338.pd

Cost and benefits of using best management practices to control non-point sources of pollution under environmental and economic uncertainty

The economy of northwest Arkansas, including the Lincoln Lake watershed (a sub-watershed of the Illinois River), relies greatly upon livestock and poultry production. The supply of production by-products is increasingly under scrutiny as one of the potential sources of water pollution in the region. In light of the recent economic crisis, methodologies that help producers to evaluate the environmental and economic impacts of several practices before implementing them may be a cost-effective means of increasing BMP adoption. This study uses stochastic dominance techniques to evaluate, environmentally and economically, ten best management practices (BMPs) combinations to lessen water pollution in the Lincoln Lake watershed. All BMP combinations analyzed were effective in reducing total phosphorous (TP) losses. However, six combinations also decreased net returns (NR) when compared to a baseline. This suggests that including BMPs in the bermudagrass production systems may lead to increased NR risk. Without additional incentives, producers will not likely implement these BMP combinations regardless of their TP reduction benefits. Although, as expected, rankings of BMP combinations in terms of TP or NR differed from each other, four scenarios established that environmental and economic goals are not necessarily conflicting; they may be complementary. Additionally, this analysis revealed that producers’ risk preferences did not matter when selecting among the top-four BMP combinations but it could be a factor for other less preferred scenarios.nonpoint pollution, watershed, best management practices, risk analysis, stochastic dominance, Environmental Economics and Policy, Risk and Uncertainty, Q25, Q53,

Adaptive Targeting: Engaging Farmers to Improve Targeting and Adoption of Agricultural Conservation Practices

Targeting of agricultural conservation practices to cost‐effective locations has long been of interest to watershed managers, yet its implementation cannot succeed without meaningful engagement of agricultural producers who are decision makers on the lands they farm. In this study, we engaged 14 west‐central Indiana producers and landowners in an adaptive targeting experiment. Interviews carried out prior to targeting provided rich spatial information on existing conservation practices as well as producers' preferences for future conservation projects. We targeted six of the most accepted conservation practices using the Soil and Water Assessment Tool and spatial optimization using a genetic algorithm approach. Fairly optimal conservation scenarios were possible with even the most limiting constraints of farmer‐accepted practices. We presented in follow‐up interviews a total of 176 conservation practice recommendations on 103 farm fields to 10 farmers whose lands were targeted for conservation. Primary findings indicated producers were interested in the project, were open to hearing recommendations about their lands, and expressed a high likelihood of adopting 35% of targeted recommendations. Farmers generally viewed the interview process and presentation of results quite favorably, and the interviews were found to build trust and make the targeting process more acceptable to them.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/112239/1/jawr12336.pd

Effectiveness of Vegetative Filter Strips in Controlling Losses of Surface-Applied Poultry Litter Constituents

Vegetative filter strips (VFS) have been shown to have high potential for reducing nonpoint source pollution from cultivated agricultural source areas, but information from uncultivated source areas amended with poultry litter is limited. Simulated rainfall was used in analyzing effects of VFS length (0, 3.1, 6.1, 9.2, 15.2, and 21.4 m) on quality of runoff from fescue (Festuca arundinacea Schreb.) plots (1.5 x 24.4 m) amended with poultry litter (5 Mg/ha). The VFS reduced mass transport of ammonia-nitrogen (NH3-N), total Kjeldahl nitrogen (TKN), ortho-phosphorus (PO4-P), total phosphorus (TP), chemical oxygen demand (COD), and total suspended solids (TSS). Mass transport of TKN, NH3-N, TP, and PO4-P were reduced by averages of 39, 47, 40, and 39%, respectively, by 3.1 m VFS and by 81, 98, 91, and 90%, respectively, by 21.4 m VFS. Effectiveness of VFS in terms of mass transport reduction was unchanged, however, beyond 3.1 m length for TSS and COD and averaged 35 and 51%, respectively. The VFS were ineffective in removing nitrate-nitrogen from the incoming runoff. Removal of litter constituents was described very well (r2 = 0.70 to 0.94) by a first-order relationship between constituent removal and VFS length