Riparian buffer systems for Oklahoma

The Oklahoma Cooperative Extension Service periodically issues revisions to its publications. The most current edition is made available. For access to an earlier edition, if available for this title, please contact the Oklahoma State University Library Archives by email at [email protected] or by phone at 405-744-6311.Biosystems and Agricultural Engineerin

Expansion of the MANAGE Database with Forest and Drainage Studies

The “Measured Annual Nutrient loads from AGricultural Environments” (MANAGE) database was published in 2006 to expand an early 1980s compilation of nutrient export (load) data from cultivated and pasture/range land at the field or farm scale. Then in 2008, MANAGE was updated with 15 additional studies, and nitrogen (N) and phosphorus (P) concentrations in runoff were added. Since then, MANAGE has undergone significant expansion adding N and P water quality along with relevant management and site characteristic data from: (1) 30 runoff studies from forested land uses, (2) 91 drainage water quality studies from drained land, and (3) 12 additional runoff studies from cultivated and pasture/range land uses. In this expansion, an application timing category was added to the existing fertilizer data categories (rate, placement, formulation) to facilitate analysis of 4R Nutrient Stewardship, which emphasizes right fertilizer source, rate, time, and place. In addition, crop yield and N and P uptake data were added, although this information was only available for 21 and 7% of studies, respectively. Inclusion of these additional data from cultivated, pasture/range, and forest land uses as well as artificially drained agricultural land should facilitate expanded spatial analyses and improved understanding of regional differences, management practice effectiveness, and impacts of land use conversions and management techniques

The role of field-scale management on soil and surface runoff C/N/P stoichiometry

Agricultural runoff is an important contributor to water quality impairment. This study was conducted to evaluate the potential role of field-scale management on carbon (C), nitrogen (N), and phosphorus (P) stoichiometry in soils and runoff from agricultural fields. Cultivated and pasture fields at the Riesel watersheds in central Texas were used for this analysis, and nutrients were transformed to evaluate relative to the Redfield ratio (106 C/16 N/1 P). Using the Redfield ratio, all soil samples were P depleted relative to C and N. The majority of stormflow and baseflow runoff samples contained 9 to 19% Redfield N relative to C and P. Shifting from inorganic fertilizer application to poultry litter as a fertilizer source resulted in increased absolute C, N, and P concentrations in stormflow and baseflow runoff. Increasing rates of poultry litter application increased the Redfield P relative to Redfield C, whereas Redfield N remained relatively constant at roughly 9 to 11% in stormflow runoff from cultivated fields. This study shows how land use and management can affect C/N/P stoichiometry in stormflow and baseflow runoff

Bacteria growth, persistence, and source assessment in rural Texas landscapes and streams

Bacteria water quality impairments are the most common water quality issue in Texas and are a considerable source of impairments nationally. Fecal indicator bacteria such as Escherichia coli (E. coli) and enterococci derived from birds and mammals are used as a measure of a waterbody’s ability to support contact recreation. Relationships between monitored levels of E. coli and enterococcus have been established with human contraction of a gastrointestinal illness from pathogenic organisms and serve as the basis for water quality standards that protect contact recreation. Stakeholder processes are often undertaken to improve the quality of impaired waters, define pollutant sources, and develop strategies to reduce bacteria loading to streams. Questions are often asked during these processes regarding the fate and transport of these bacteria in various environmental settings, the distribution of E. coli sources across watersheds, and how they respond to changes in water quality. Past research conducted has worked to address these questions; however, additional work is warranted. Re-created stream mesocosms were used to develop an improved understanding of E. coli fate and transport in the environment under controlled treatment conditions. Nutrient amendments that mimic increases in nutrient concentrations seen from nonpoint source pollutant loadings and wastewater effluent loadings were applied to determine if E. coli concentrations would change as a result of the amendments and alter growth or decay relative to a control mesocosm. No E. coli growth response was observed in any trial, and no significant differences in decay rates were observed either. This suggests that a single nutrient addition to a stream environment is not sufficient to produce a growth response in the ambient E. coli community. Soil and runoff samples collected from three controlled land uses were processed to enumerate E. coli and allow individual colonies to be isolated and fingerprinted for bacteria source tracking (BST). E. coli source contributions to native prairie, managed hay pasture, and cultivated cropland sites were determined using 7-way source identification splits. In all cases, wildlife were found to be the primary E. coli contributor. Unexpectedly, cattle and humans were identified as sources of E. coli in runoff and soils from some of the sites. Cattle are not actively stocked nor have they been stocked at any of these sites for at least three years, and no known sources of human fecal deposition have occurred in these watersheds. This demonstrates the complex diversity of E. coli in unimpacted environments and the potential for bacteria to be translocated by transmission vectors.Funding support for this project was provided through a State Nonpoint Source Grant from the Texas State Soil and Water Conservation Boar

Evaluation Of WEPP For Runoff And Sediment Yield Prediction On Natural Gas Well Sites

This article discusses the evaluation of Water Erosion Prediction Project (WEPP) for runoff and sediment yield prediction on natural gas well sites, instead of focusing only on the effects on fields, rangelands, and forests

Riparian area: Management handbook

The Oklahoma Cooperative Extension Service periodically issues revisions to its publications. The most current edition is made available. For access to an earlier edition, if available for this title, please contact the Oklahoma State University Library Archives by email at [email protected] or by phone at 405-744-6311

Initial Field Evaluation of the Agro-Economic Effects of Determining Nitrogen

ABSTRACT Although agriculture is not the only contributor of excess nutrients to US waters, agriculture is an important contributor and should do its part to reduce nutrient loading. One important step in reducing agricultural contribution is to accurately account for all sources of plant available nutrients so that only needed nutrients are applied. In this study, three fertilizer rate treatments were evaluated: no fertilizer (control), traditional rate, and reduced rate based on a recently-developed enhanced soil test methodology. For each of nine sites in Texas, fertilizer data (formulation, rate, cost, and application date) and crop data (yield, price, and harvest date) were recorded, and economic throughput (profit) was determined. In this four year study, fertilizer rates were reduced 30% -50% (and fertilizer costs reduced 23% -39%) based on enhanced soil test methodology recommendations for wheat, corn, oats, and grain sorghum, but yields were not significantly reduced (0% -6%) and oat yields actually increased 5%. Profit decreased <1% for corn and increased 7% -18% for wheat, oats, and grain sorghum with reduced fertilizer rates. Although these changes were not statistically significant, they do represent benefit through increased profit potential and decreased input cost and production risk. In only 6% of the time was the traditional fertilizer rate the most profitable, compared to 51% for the unfertilized treatment and 43% for the enhanced soil test treatment. These results do not indicate that fertilizer application should be avoided but that fertilizer rates should be carefully chosen considering all sources of plant available nutrients (e.g., mineralization, irrigation water, nutrients deeper in the soil profile) to ensure that fertilizer is applied at the optimal rate

Review of Filter Strip Performance and Function for Improving Water Quality from Agricultural Lands

Filter strips (FSs) are edge-of-field conservation practices commonly implemented to reduce flux of sediment, nutrients, and other constituents from agricultural fields. While various aspects of FS effectiveness have been reviewed, this study provides a comprehensive summary of FS efficiency data for sediment, nutrients, pesticides, and pathogens as part of a special collection focused on agricultural conservation practices. This analysis also fills an important gap by assessing performance-based FS costs and cost-effectiveness. Data from 74 U.S. and international studies with 294 different treatments and 3,050 replications were compiled and analyzed. Results showed that runoff reduction tended to increase with increasing FS width up to about 15 m and that sediment reduction was significantly related to the ratio of FS area to drainage area and to FS width, with reduction tending to increase with increasing width up to about 20 m. Total P reduction was significantly related to FS soil saturated hydraulic conductivity, and total N reduction was significantly related to both saturated hydraulic conductivity and width. Total P and total N reductions both tended to increase with increasing FS width up to about 20 m and with increasing FS slope up to about 10%. Annualized FS costs were estimated to range from $314 to$865 ha-1 year-1 for different FS implementations. A major component of the cost is the opportunity cost of taking land out of production. Costs per unit of sediment retained by FS systems ranged from $10.3 to$18.6 Mg-1. A comprehensive assessment of FS cost-effectiveness (cost:benefit) is needed. Monitoring equipment, approaches, and recommendations are discussed, acknowledging the challenges of implementing field-scale FS studies. This information is critical to guide on-farm and programmatic FS decisions and to increase the scientific understanding of this commonly used agricultural conservation practice.This article is published as Douglas-Mankin, Kyle R., Matthew J. Helmers, and R. Daren Harmel. "Review of filter strip performance and function for improving water quality from agricultural lands." Transactions of the ASABE 64, no. 2 (2021): 659-674. DOI: 10.13031/trans.14169. Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted

Bacteria growth, persistence, and source assessment in rural Texas landscapes and streams

Bacteria water quality impairments are the most common water quality issue in Texas and are a considerable source of impairments nationally. Fecal indicator bacteria such as Escherichia coli (E. coli) and enterococci derived from birds and mammals are used as a measure of a waterbody’s ability to support contact recreation. Relationships between monitored levels of E. coli and enterococcus have been established with human contraction of a gastrointestinal illness from pathogenic organisms and serve as the basis for water quality standards that protect contact recreation. Stakeholder processes are often undertaken to improve the quality of impaired waters, define pollutant sources, and develop strategies to reduce bacteria loading to streams. Questions are often asked during these processes regarding the fate and transport of these bacteria in various environmental settings, the distribution of E. coli sources across watersheds, and how they respond to changes in water quality. Past research conducted has worked to address these questions; however, additional work is warranted. Re-created stream mesocosms were used to develop an improved understanding of E. coli fate and transport in the environment under controlled treatment conditions. Nutrient amendments that mimic increases in nutrient concentrations seen from nonpoint source pollutant loadings and wastewater effluent loadings were applied to determine if E. coli concentrations would change as a result of the amendments and alter growth or decay relative to a control mesocosm. No E. coli growth response was observed in any trial, and no significant differences in decay rates were observed either. This suggests that a single nutrient addition to a stream environment is not sufficient to produce a growth response in the ambient E. coli community. Soil and runoff samples collected from three controlled land uses were processed to enumerate E. coli and allow individual colonies to be isolated and fingerprinted for bacteria source tracking (BST). E. coli source contributions to native prairie, managed hay pasture, and cultivated cropland sites were determined using 7-way source identification splits. In all cases, wildlife were found to be the primary E. coli contributor. Unexpectedly, cattle and humans were identified as sources of E. coli in runoff and soils from some of the sites. Cattle are not actively stocked nor have they been stocked at any of these sites for at least three years, and no known sources of human fecal deposition have occurred in these watersheds. This demonstrates the complex diversity of E. coli in unimpacted environments and the potential for bacteria to be translocated by transmission vectors.Funding support for this project was provided through a State Nonpoint Source Grant from the Texas State Soil and Water Conservation Boar