Sharing the Flow--Water shortages are increasing because of droughts all over the Nation. How does this impact conservation efforts and agriculture?

Research

• Riparian zone impact on phosphorus movement to a Coastal Plain black water stream
  J.M. Novak, P.G. Hunt, K.C. Stone, D.W. Watts and M.H. Johnson
• Utilizing spatial technology as a decision-assist tool for precision grading of salt-affected soils
  M.B. Daniels, S.L. Chapman, and W. Teague
• Simulating grass productivity on diverse range sites in Texas
  J.R. Kiniry, H. Sanchez, J. Greenwade, E. Seidensticker, J.R. Bell, F. Pringle, G. Peacock Jr., and J. Rives
• Design and management of edge-of-field water control structures for ecological benefits
  F.D. Shields, Jr., P.C. Smiley, Jr., and C.M. Cooper
• Erosion risk mapping; a methodological case study in the Colombian Eastern Plains
  A. Vrieling, G. Sterk, and N. Beaulieu
• Effect and uncertainty of digital elevation model spatial resolutions on predicting the topographical factor for soil loss estimation
  G. Gertner, G. Wang, S. Fang, and A. B. Anderson
• Comparing three geophysical tools for locating sand blows in alluvial soils of southeast Missouri
  J.A. Doolittle, S.J. Indorante, D.K. Potter, S.G. Hefner, and W.M. McCauley
• Rural landowner liability for recreational injuries: myths, perceptions and realities
  B.A. Wright, R.A. Kaiser, and S. Nicholls
  [PDF version is available on the following page.]
• Landscape, surface runoff, and groundwater quality in the district of Puán, province of Buenos Aires, Argentina
  M. González Uriarte, J.D. Paoloni, E. Navarro, C.E. Fiorentino, and M. Sequeira

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Riparian zone impact on phosphorus movement to a Coastal Plain black water stream
(Full text appears in the Journal of Soil and Water Conservation, Vol.57, No.3)

J.M. Novak, P.G. Hunt, K.C. Stone, D.W. Watts and M.H. Johnson

ABSTRACT: Riparian zones are an important conservation practice because they can decrease the entry of sediments and nutrients into sensitive aquatic ecosystems. We evaluated the effectiveness of a Coastal Plain riparian zone in decreasing the movement of phosphorus (P) into a black water stream from an overloaded swine manure spray field. Soil P concentrations (Mehlich 3 P, M3P; and total P, TP) were measured in a spray field, grass strip, mid-riparian, and stream edge continuum. Dissolved P (DP) was measured in ground water wells located in the spray field, grass strip, and stream edge and in in-stream grab samples. The spray field and grass strip areas had high soil M3P concentrations. Low M3P concentrations were detected in soils in the mid-riparian and stream edge areas, indicating effective retention of P by the grass strip area. Elevated DP concentrations were detected in the spray field and grass strip wells, while stream edge wells were low. The riparian zone contributed to decreased DP concentrations between the grass strip and stream edge wells. Furthermore, stream grab samples were consistently low in DP concentrations. We conclude that a riparian zone can effectively limit the movement of P-enriched sediments and prevent DP-enriched ground water from entering a local stream, even in a heavily loaded situation.

Keywords: Black water stream, grass buffer strip, phosphorus movement, riparian zone

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Utilizing spatial technology as a decision-assist tool for precision grading of salt-affected soils
(Full text appears in the Journal of Soil and Water Conservation, Vol.57, No.3)

M.B. Daniels, S.L. Chapman, and W. Teague

ABSTRACT: Precision land leveling can expose subsurface soil layers that have elevated levels of exchangeable sodium and can deposit this sodium-laden material on the original soil surface in other parts of the field. Results from two case studies where a geographic information system (GIS) and global positioning system (GPS) were utilized to assist with land-leveling decisions for soils containing elevated soluble salts and sodium are discussed. In both cases, the spatial distribution of Na, exchangeable sodium percentage (ESP), and electrical conductivity (EC) were overlain with maps depicting the pattern of removal and re-deposition of soil. From this analysis, an estimate of the potential sodium hazard that might result from precision grading was determined. Decisions derived from traditional, composite sampling were compared to decisions made with site-specific technology. The spatial technology approach utilized in this work provided decision makers with reasonable assurance about their precision grading decisions apriori.

Keywords: Exchangeable sodium percentage (ESP), geographical information system (GIS), global positioning systems (GPS), grid soil sampling, natric, precision grading, precision land leveling, saline, sodic, soil survey

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Simulating grass productivity on diverse range sites in Texas
(Full text appears in the Journal of Soil and Water Conservation, Vol.57, No.3)

J.R. Kiniry, H. Sanchez, J. Greenwade, E. Seidensticker, J.R. Bell, F. Pringle, G. Peacock Jr., and J. Rives

ABSTRACT: Simulation models addressing soil erosion and water quality issues on range sites should realistically simulate grass dry matter yields across a wide diversity of soils and climate regimes. This study was designed to evaluate the ability of the ALMANAC (Agricultural Land Management Alternatives with Numerical Assessment Criteria) model to simulate annual range grass biomass production under diverse climatic conditions and soils in Texas. The objective was to compare range grass production at rangeland ecological sites, as reported in the U.S. Department of Agriculture Natural Resources Conservation Service ((USDA NRCS) soil surveys, with production simulated by ALMANAC using the most common grasses for each site. The model was run with 60 years of daily weather data on 20 different soils from a diverse set of sites in Texas. The weather data was from seven sites. Model inputs included parameters for the soil series, grass species characteristics, and locally measured climate data. After allowing 10 years for the model to equilibrate, means for simulated production for the sites for the next 50 years were similar to reported means. Simulated production in high rainfall years and low rainfall years were also similar to reported values. The soils, climate, and grass parameter data sets developed here can be useful starting points for deriving data for additional range sites, giving model users examples of realistic input data. The model shows promise as a tool for realistically simulating grass production on a diverse group of soils and in diverse climatic conditions.

Keywords: Grass biomass, grass modeling, range yields

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Design and management of edge-of-field water control structures for ecological benefits
(Full text appears in the Journal of Soil and Water Conservation, Vol.57, No.3)

F.D. Shields, Jr., P.C. Smiley, Jr., and C.M. Cooper
ABSTRACT: Stream channel incision often triggers formation of tributary gullies. These gullies erode and extend into fields, generating sediments that pollute downstream waters and degrade aquatic habitats. Standard practice for gully treatment involves damming using an earthen embankment with drainage provided by an L-shaped metal pipe. To date, thousands of these structures, also known as drop pipes, have been constructed in riparian zones adjacent to agricultural areas, but environmental criteria have played no role in design. Sixteen drop pipe sites (defined as the region of temporary or permanent impoundment created by the structure) in northwestern Mississippi were sampled for fish, amphibians, reptiles, birds, and mammals; and physical habitat characteristics were assessed by sampling vegetation and surveying site topography. Speciose sites (those yielding 65 to 82 vertebrate species) were relatively large

[= 0.09 ha (.22 ac)], with a significant pool area. Depauperate sites (only 11 to 20 species captured) were smaller, with no pool area and little woody vegetation. Considerable environmental benefits could be realized by slightly modified design and management of drop pipe structures. Results of this study suggest habitat benefits are minimal for sites smaller than 0.1 ha (0.2 ac), for sites lacking woody vegetation, and for sites that do not have at least 20% of their area below the inlet weir elevation.

Keywords: Amphibians, birds, ecological impairment, erosion control, fish, gully, mammals, reptiles, riparian zone, species diversity

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Erosion risk mapping; a methodological case study in the Colombian Eastern Plains
(Full text appears in the Journal of Soil and Water Conservation, Vol.57, No.3)

A. Vrieling, G. Sterk, and N. Beaulieu

ABSTRACT: Soil erosion caused by water is an increasing global problem. Land use and soil conservation planning for large areas requires erosion risk maps, which are typically created using erosion models. These models are often developed for different regions than where they are applied. This paper describes a new qualitative methodology for mapping soil erosion risks over large areas, called Qualitative Erosion Risk Mapping (QUERIM). It is a flexible method that uses decision trees to assign ratings to the erosion-controlling factors. Constructed using expert knowledge, these decision trees reflect the important characteristics influencing erosion risk within a specific region. Ratings for erosion-controlling factors are combined at every location to obtain potential and actual erosion risk maps. QUERIM was applied to the Puerto López municipality in the Colombian Eastern Plains. The obtained erosion risk maps showed agreement with field observations of erosion risk. However, more ground data should be gathered for a better evaluation of the method. It is concluded that a simple qualitative approach such as QUERIM can be more effective in erosion risk mapping than the use of models that were not developed for the region to which they are applied.

Keywords: Colombian Eastern Plains, erosion risk mapping, Geographic Information Systems (GIS), remote sensing, water erosion

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Effect and uncertainty of digital elevation model spatial resolutions on predicting the topographical factor for soil loss estimation
(Full text appears in the Journal of Soil and Water Conservation, Vol.57, No.3)

G. Gertner, G. Wang, S. Fang, and A. B. Anderson

ABSTRACT: Soil erosion is very sensitive to the topographical factor LS (as a product of slope length L and steepness S) in the Revised Universal Soil Loss Equation (RUSLE). Improving prediction of LS by assessing uncertainty is thus very important. In this study, digital elevation models (DEMs) at different spatial resolutions obtained by interpolation were used to derive the slope and the up-slope contributing area required in a physically based LS equation and to obtain LS maps. The effect of spatial resolution in predicting LS was investigated by comparing the maps for overall differences, spatial distribution, and spatial variability of each estimated variable. Spatial error budgets were generated for LS by modeling uncertainty propagation from slope, up-slope contributing area, and model parameters with a variance partitioning method. The results showed that the uncertainty in predicting LS came mainly from slope in gentle areas and from up-slope contributing area in steep areas. The effect of spatial resolution for LS was primarily explained by uncertainty propagation from up-slope contributing area. The coarse resolutions led to extremely large predicted values and variances of up-slope contributing area, hence large uncertainty in LS. The interpolation of a DEM into finer resolution provides more spatial information without degrading elevation accuracy, resulting in a rapid decrease of variance for predicting up-slope contributing area and LS. For the case presented in this study, a DEM with a lower resolution than 5 m (16.4 ft) was considered useless for predicting LS due to large variances from up-slope contributing areas.

Keywords: Digital elevation model (DEM), error budget, Revised Universal Soil Loss Equation (RUSLE), soil loss, spatial resolution, topographical factor LS, uncertainty

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Comparing three geophysical tools for locating sand blows in alluvial soils of southeast Missouri
(Full text appears in the Journal of Soil and Water Conservation, Vol.57, No.3)

J.A. Doolittle, S.J. Indorante, D.K. Potter, S.G. Hefner, and W.M. McCauley

ABSTRACT: The level, moderately fine and fine-textured, poorly and very poorly drained alluvial soils of the southern Mississippi River Valley are well suited to rice production. However, in many areas, small inclusions of more rapidly permeable, coarse-textured soils occur as sand blows. Because of their more rapid permeability, these included soils are considered marginal for rice production. In this study, an EM38 meter, a GEM300 sensor, and a Veris 3100 soil EC mapping system were compared and used to assess clay content and to locate sand blows in southeastern Missouri. All three tools produced similar gross spatial patterns of apparent conductivity that corresponded to mapped soil delineations and changes in clay content. However, spatial patterns of apparent conductivity are more intricate than major soil patterns and indicate soil map unit inclusions. Moderate correlations (r = 0.39 to 0.71) were found between apparent conductivity and average clay content of the 0 to 25 cm layer. Correlations improved (r = 0.63 to 0.90) as the clay content was averaged over the 0 to 75 cm and the 0 to 100 cm depth intervals. As spatial patterns reflect differences in clay content, these tools can be used to help locate small, included areas of coarse-textured soils that might otherwise be overlooked.

Keywords: Apparent conductivity, electrical conductivity, electrical resistivity, electromagnetic induction, sand blows, soil mapping

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Rural landowner liability for recreational injuries: myths, perceptions and realities
(Full text appears in the Journal of Soil and Water Conservation, Vol.57, No.3 and a PDF version can be accessed below)

B.A. Wright, R.A. Kaiser, and S. Nicholls

ABSTRACT: Concern about closure of private, rural lands to outdoor recreation has been documented in the research literature for several decades. While many reasons for this phenomenon have been posited, liability for recreational injuries has been identified as a particularly worrisome problem for landowners. However, landowners’ perceptions of liability are not commensurate with the reality of legal risks. This article examines rural landowner liability risks through an analysis of the 50 state recreation-use statutes intended to protect landowners from legal exposure tied to injuries sustained on their land. Further, data from the 637 appellate court cases heard since 1965 involving recreational injuries were compiled and analyzed based on the characteristics of the landowner (public or private), recreation activity pursued at the time of injury, and actual liability exposure. Although the focus of this article is primarily on the liability risks of private landowners and organizations, public agencies also are discussed. Recreation-use statutes are increasingly used in government defense, and cases provide more depth in understanding the reality of landowner liability. Recommendations to agencies concerned with access to private lands and suggestions for future research are included.

Keywords: Private lands, landowners, liability, recreational access, recreational injuries

Landscape, surface runoff, and groundwater quality in the district of Puán, province of Buenos Aires, Argentina
(Full text appears in the Journal of Soil and Water Conservation, Vol.57, No.3)

M. González Uriarte, J.D. Paoloni, E. Navarro, C.E. Fiorentino, and M. Sequeira

ABSTRACT: The Puán district in the southwest of the province of Buenos Aires covers an area of 6,385 km2 (2,465 mi2) and has a population of about 18,000 residing in small urban centers and rural areas where farming is the main economic activity. Owing to the absence of freshwater streams and the low level of rainfall, groundwater provides the principal source of water and is used for human and animal consumption, as well as for the growing network of supplementary irrigation. This paper gives an overview of the district’s water resources by reporting on

the landscape, surface runoff, and groundwater quality within the framework of six geomorphological environments. Groundwater depth, anion-cation content and principal pollutants are measured in representative samples from each geomorphological unit. Pollutants are divided into those of natural origin (arsenic-boron-fluoride) and those induced by anthropic activity. The results obtained provide a basis for the adequate planning of water management, taking into account the consequences of groundwater exploitation and the implementation of preventive measures where necessary.

Keywords: Geomorphology; groundwater quality; Puán, Argentina

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