Quantifying the effects of alternative surface inlet protection strategies on water quality

Subsurface drainage systems with surface inlets are widely used to divert water in crop producing areas, but pose problems because they can allow unfiltered, sediment-laden water to travel quickly to other waterways. The project tested several modest, uncomplicated inlet protection practices with potential to keep nutrient and sediment flows in check

Impacts of conventional and diversified rotation systems on crop yields, profitability, soil functions and environmental quality

Comparisons were made among contrasting cropping systems within a long-term, large-scale field experiment in Boone County, Iowa. Combining crop diversity with lower herbicide inputs and non-transgenic crops was effective in reducing requirements for nitrogen fertilizer; maintaining or improving weed suppression, grain yields, and profi ts; and increasing several soil quality indicators

Theme Overview: Agriculture and Water Quality in the Cornbelt: Overview of Issues and Approaches

Resource /Energy Economics and Policy, Q25,

A Tale of Three Watersheds: Nonpoint Source Pollution and Conservation Practices across Iowa

Resource /Energy Economics and Policy, Q25,

Agricultural Conservation Planning Framework: 1. Developing Multipractice Watershed Planning Scenarios and Assessing Nutrient Reduction Potential

Spatial data on soils, land use, and topography, combined with knowledge of conservation effectiveness, can be used to identify alternatives to reduce nutrient discharge from small (hydrologic unit code [HUC]12) watersheds. Databases comprising soil attributes, agricultural land use, and light detection and ranging–derived elevation models were developed for two glaciated midwestern HUC12 watersheds: Iowa’s Beaver Creek watershed has an older dissected landscape, and Lime Creek in Illinois is young and less dissected. Subsurface drainage is common in both watersheds. We identified locations for conservation practices, including in-field practices (grassed waterways), edge-of-field practices (nutrient-removal wetlands, saturated buffers), and drainage-water management, by applying terrain analyses, geographic criteria, and cross-classifications to field- and watershed-scale geographic data. Cover crops were randomly distributed to fields without geographic prioritization. A set of alternative planning scenarios was developed to represent a variety of extents of implementation among these practices. The scenarios were assessed for nutrient reduction potential using a spreadsheet approach to calculate the average nutrient-removal efficiency required among the practices included in each scenario to achieve a 40% NO3–N reduction. Results were evaluated in the context of the Iowa Nutrient Reduction Strategy, which reviewed nutrient-removal efficiencies of practices and established the 40% NO3–N reduction as Iowa’s target for Gulf of Mexico hypoxia mitigation by agriculture. In both test watersheds, planning scenarios that could potentially achieve the targeted NO3–N reduction but remov

Science in the Supply Chain: Collaboration Opportunities for Advancing Sustainable Agriculture in the United States

Consumers and corporations are increasingly interested in understanding the sustainability of agricultural supply chains and reducing the environmental impacts of food, fiber, feed, and fuel production. This emerging need to quantify environmental impacts from agricultural production creates an opportunity for collaboration with the scientific community. Without such collaboration, sustainability efforts risk failure by adopting unrealistic goals or misguided approaches. This commentary explores the role of science in Field to Market, a nonprofit organization developing a sustainability program for US commodity crops, and highlights opportunities to address emerging science challenges. We evaluate changes over the past 35 years in key environmental impacts of crop production used to inform land managers as well as companies that are committed to improvements. Achieving improvements will only be possible if three key gaps are addressed regarding available simulation models and data, scale of implementation and uncertainty, and effectiveness of conservation practices. Filling these gaps presents an opportunity for dialogue between scientists, farmers, and private-sector stakeholders to advance scientific knowledge and promote the common objective of sustainable agriculture

Changes in lateral floodplain connectivity accompanying stream channel evolution: Implications for sediment and nutrient budgets

Floodplain storage commonly represents one of the largest sediment fluxes within sediment budgets. In watersheds responding to large scale disturbance, floodplain-channel lateral connectivity may change over time with progression of channel evolution and associated changes in channel geometry. In this study we investigated the effects of channel geometry change on floodplain inundation frequency and flux of suspended sediment (SS) and total phosphorus (TP) to floodplain storage within the 52.2 km2 Walnut Creek watershed (Iowa, USA) through a combination of 25 in-field channel cross section transects, hydraulic modeling (HEC-RAS), and stream gauging station-derived water quality and quantity data. Cross sectional area of the 25 in-field channel cross sections increased by a mean of 17% over the 16 year study period (1998–2014), and field data indicate a general trend of degradation and widening to be present along Walnut Creek\u27s main stem. Estimated stream discharge required to generate lateral overbank flow increased 15%, and floodplain inundation volume decreased by 37% over study duration. Estimated annual fluxes of SS and TP to floodplain storage decreased by 61 and 62% over study duration, respectively. The estimated reductions in flux to floodplain storage have potential to increase watershed export of SS and TP by 9 and 18%, respectively. Increased contributions to SS and TP export may continue as channel evolution progresses and floodplain storage opportunities continue to decline. In addition to loss of storage, higher discharges confined to the channel may have greater stream power, resulting in further enhancement of SS and TP export through accelerated bed and bank erosion. These increased contributions to watershed loads may mask SS and TP reductions achieved through edge of field practices, thus making it critical that stage and progression of channel evolution be taken into consideration when addressing sediment and phosphorus loading at the watershed scale

A Targeted Conservation Approach for Improving Environmental Quality: Multiple Benefits and Expanded Opportunities

Find out how targeted conservation practices can have the most impact on environmental quality while causing only a small change in overall agricultural production. Environmental benefits are discussed related to clean air and water, productive soils, diverse wildlife and plant habitat, and biological controls for crop protection.https://lib.dr.iastate.edu/extension_ag_pubs/1084/thumbnail.jp