The Original USDA-ARS Experimental Watersheds in Texas and Ohio: Contributions from the Past and Visions for the Future

The USDA Soil Conservation Service (USDA‐SCS) realized the importance of understanding hydrologic processes on agricultural fields and watersheds in the mid‐1930s. Based on this realization, the research program of the Hydrologic Division of SCS established three experimental watersheds across the U.S. to analyze the impact of landuse practices on soil erosion, flood events, water resources, and the agricultural economy. Two of the original watersheds remain in operation today within the USDA Agricultural Research Service (USDA‐ARS): the Blacklands Experimental Watershed (now the Grassland, Soil and Water Research Laboratory) near Riesel, Texas, and the North Appalachian Experimental Watershed near Coshocton, Ohio. These original watersheds were designed for collection of hydrologic data on small watersheds and evaluation of hydrologic and soil loss response as influenced by various agricultural land management practices. A major contribution of these experimental watersheds is the quantification of soil loss reduction under conservation management, which has led to a drastic reduction in soil loss from cultivated agriculture in the 20th century. Riesel watershed studies produced the scientific basis for several watershed models that are now used worldwide to manage water quality and also facilitated fundamental analysis of the agronomic and environmental effects of tillage, fertilizer, and pesticide alternatives. Coshocton watershed studies led to the development of no‐till and pasture management practices to control runoff, erosion, and chemical loss and were instrumental in understanding water quality and hydrologic effects of soil macropores and mining and reclamation activities. The long‐term hydrologic records at each site have also improved understanding and management of water resources in their respective geographic regions. Because of their historical and future value, the USDA‐ARS has a unique responsibility to maintain these long‐term experimental watersheds, which are vital for addressing emerging research needs to meet future water availability, environmental quality, and food and fiber demands

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

Soil erosion assessment—Mind the gap

Accurate assessment of erosion rates remains an elusive problem because soil loss is strongly nonunique with respect to the main drivers. In addressing the mechanistic causes of erosion responses, we discriminate between macroscale effects of external factors—long studied and referred to as “geomorphic external variability”, and microscale effects, introduced as “geomorphic internal variability.” The latter source of erosion variations represents the knowledge gap, an overlooked but vital element of geomorphic response, significantly impacting the low predictability skill of deterministic models at field‐catchment scales. This is corroborated with experiments using a comprehensive physical model that dynamically updates the soil mass and particle composition. As complete knowledge of microscale conditions for arbitrary location and time is infeasible, we propose that new predictive frameworks of soil erosion should embed stochastic components in deterministic assessments of external and internal types of geomorphic variability.Key PointsSoil loss response to runoff is strongly controlled by “geomorphic internal variability”: microscale factors intrinsic to geomorphic systemPredictive skill of deterministic soil loss models at event scale is likely to remain poorErosion estimates must communicate uncertainty due to geomorphic external and internal types of variabilityPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/136017/1/grl55374-sup-0001-Supplementary.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/136017/2/grl55374.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/136017/3/grl55374_am.pd

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

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

Harnessing {13}^C-labeled myo-inositol to interrogate inositol phosphate messengers by NMR

Inositol poly- and pyrophosphates (InsPs and PP-InsPs) are an important group of metabolites and mediate a wide range of processes in eukaryotic cells. To elucidate the functions of these molecules, robust techniques for the characterization of inositol phosphate metabolism are required, both at the biochemical and the cellular level. Here, a new tool-set is reported, which employs uniformly {13}^C-labeled compounds ([{13}^C_{6}] myo-inositol, ([{13}^C_{6}]InsP_{5}, ([{13}^C_{6}]InsP_{6}, and ([{13}^C_{6}]5PP-InsP_{5}), in combination with commonly accessible NMR technology. This approach permitted the detection and quantification of InsPs and PP-InsPs within complex mixtures and at physiological concentrations. Specifically, the enzymatic activity of IP6K1 could be monitored in vitro in real time. Metabolic labeling of mammalian cells with [{13}^C_{6}]myo-inositol enabled the analysis of cellular pools of InsPs and PP-InsPs, and uncovered high concentrations of 5PP-InsP_{5} in HCT116 cells, especially in response to genetic and pharmacological perturbation. The reported method greatly facilitates the analysis of this otherwise spectroscopically silent group of molecules, and holds great promise to comprehensively analyze inositol-based signaling molecules under normal and pathological conditions