May-June 2005: Volume 60, Number 3

Table of Contents

Features
SWCS: A Forty-Year Retrospective
Max Schnepf

Drainage Management
By Mari Veliz and Jane Sadler Richards

Farmland Preservation - Innovative Approaches in Ontario 
By Wayne Caldwell and Stewart Hilts

Research

Departments

• Homefront
• Viewpoint—Jerry L. Hatfield 
• Raise Your Voice
• Notebook
• Going Retro - Celebrating 60 Years of the JSWC 
• Conservogram

The effect of socioeconomic factors on the adoption of best management practices in beef cattle production
(Full text appears in the Journal of Soil and Water Conservation, Vol.60, No. 3)

S. Kim, J.M. Gillespie, and K.P. Paudel
ABSTRACT:  Factors affecting cattle producers’ adoption of best management practices (BMPs) are examined using probit analyses. Results show that in situations such as when the farm includes more enterprises, the farmer has had contact with Natural Resources Conservation Service personnel at least once within the past year, the farmer holds a college bachelor’s degree, the percentage of income from beef cattle production is higher, or the operation includes hilly land, the likelihood of BMP adoption is greater. Having a greater number of other agricultural enterprises and having a greater percentage of income from the cattle operation were significant factors in the adoption of companion practices. Results of this study suggest changes in formulating future environmental policies associated with pasture-based beef cattle production.

Keywords: Adoption, beef cattle production, best management practices, probit

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Challenges in conducting hydrologic and water quality research in drastically disturbed watersheds
(Full text appears in the Journal of Soil and Water Conservation, Vol.60, No. 3)

J.V. Bonta
ABSTRACT: A nine-year investigation was conducted on the impacts of drastic land disturbances in small watersheds due to coal mining and reclamation activities on surface and subsurface hydrology and water quality. Three small watersheds in Ohio (12 to 20 ha) were monitored before mining, during mining and reclamation, and after reclamation for hydrology and water quality, resulting in many publications. The current increased interest in coal mining may require additional watershed-scale studies on the short? and long?term effects of drastic land disturbances on watershed hydrology, water chemistry, and sedimentation. Conducting watershed-scale studies in drastically disturbed areas is expensive, long-term, high-risk, and difficult research. The challenges and experiences of conducting the 9-yr study are identified so that other investigators may efficiently plan and conduct similar watershed-scale research in mines. The experimental design of the project, actual conditions during the project, and challenges in conducting the research are discussed. Hydrological instrumentation must be dependable and operational to collect data from the short duration disturbances because these periods are not repeatable, and watersheds require many years to approach a new equilibrium. Control watersheds must be free from previous disturbances. It was not feasible to quantitatively characterize the watersheds during the rapid and transitory periods of disturbance. Undisturbed and reclaimed watersheds can be visually undisturbed, but hydrologically disturbed. Surface? and ground?water hydrology and water chemistry processes may not reach a dynamic equilibrium until many years have passed. Association of data with periods of disturbance is not precise, depends on available data, and requires scientific judgment. The "drop-box weir" works well for sediment-laden flows with large rocks expected from drastically disturbed areas. Many recommendations are presented for future watershed-scale research on drastic land disturbances. This paper addresses challenges in researching the impacts of mining and reclamation activities but is applicable to studying other land disturbances such as urbanization.

Keywords: drop-box weir, hydrology, strip mining, surface mining, urbanization, water quality

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Irrigation return flow sourcing of sediment and flow augmentation in receiving streams: A case study
(Full text appears in the Journal of Soil and Water Conservation, Vol.60, No. 3)

L.S. Browning, J.W. Bauder, K.E. Hershberger, and H.N. Sessoms
ABSTRACT: The total maximum daily load (TMDL) approach to defining and quantifying point and nonpoint sources of impairment to surface water systems provides an analytical approach to assigning acceptable levels of allowable impairment from various sources. However, in streams affected by irrigation return flows, identifying actual origins and causes of nonpoint flow and sediment production and quantifying those contributions for use in TMDL planning is a challenging task. It has been hypothesized that Muddy Creek, a tributary of the Sun River-Missouri River watershed in west central Montana, is significantly impacted by irrigation return flows. A two-year case study of Muddy Creek gathered and analyzed stream flow and sediment data in its tributaries and main channel. Flow and sediment were partitioned among possible sources, revealing that 49 to 67 percent of flow delivered to the Sun River by Muddy Creek during the irrigation season originated within irrigation district boundaries, while 58 to 72 percent of sediment entering the Sun River via Muddy Creek during the irrigation season originated downstream of the district boundaries within Muddy Creek’s 20 km (12.5 mi) lower reach. It was concluded that this added sediment load is a direct result of flow augmentation from return flows and operational spills within the irrigation district. This protocol resulted in acquisition of reliable, objective data and could be successfully applied to other watersheds. The data also demonstrate potential effects of irrigation return flow on flow volume and sediment load of receiving streams.

Keywords: Irrigation project management, irrigation return flow, sediment, total maximum daily load (TMDL), watershed management

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Variable rainfall intensity effects on carbon characteristics of eroded sediments from two coastal plain ultisols in Georgia
(Full text appears in the Journal of Soil and Water Conservation, Vol.60, No. 3)

T.C. Strickland, C.C. Truman, and B. Frauenfeld
ABSTRACT: Carbon loss and the associated potential for facilitated transport of chemicals could be better quantified if effects of storm intensity variation could be characterized during key phases of the production year. We evaluated the effects of constant and variable rainfall intensities on the transport characteristics and amount of sediment organic carbon lost from two highly weathered Coastal Plain soils in Georgia—a Tifton loamy sand (Plinthic Kandiudult) and a Greenville sandy clay loam (Rhodic Kandiudult). Soils were air?dried, sieved (19 mm) and placed in 1.5 m² stainless steel erosion pans set to match typical field slopes for each soil (Tifton=4 percent; Greenville=7 percent). Simulated rainfall was applied for 70?min as a constant (57 mm h^-1) or variable (typical spring storm) event pattern. Runoff, sediment, sediment carbon, sediment nitrogen, and dissolved carbon were measured at 5?min intervals. Regardless of simulation intensity evaluated, sediment exported from the Tifton soil was enriched (enrichment ratio 1.17 to 1.80) and the Greeneville soil depleted (0.83 to 0.93) in carbon relative to the top 2 cm of undisturbed soil. Only minor (not significant) differences were observed in the potential for total sediment carbon loss estimated by the two simulation intensities (Tifton, 5.65 – 6.67 kg ha^-1 and Greenville, 13.44 – 14.40 kg ha^-1). However, significant differences in the effect of simulation intensities on timing and amount of carbon lost via sediment transport (more during first versus second half of simulation for variable versus constant intensity patterns respectively) were observed during the simulations. Results suggest that detachment and transport thresholds differ for total sediment versus sediment carbon losses during a given event and that variable rate rainfall simulations may be an effective means to characterize threshold differences for individual soil and management combinations. It is suggested that the systematic determination of such thresholds may improve predictions of sediment transported organic contaminants.

Keywords: Carbon enrichment, erosion, rainfall simulation

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Testing a spatially distributed sediment delivery model (SEDD) in a forested basin by cesium-137 technique
(Full text appears in the Journal of Soil and Water Conservation, Vol.60, No. 3)

C.D. Stefano, V. Ferro, P. Porto, S. Rizzo 
ABSTRACT: The aim of the paper is to validate the sediment delivery distributed (SEDD) model for estimating hillslope sediment yield estimates using net soil erosion values obtained by the cesium-137 technique. The cesium-137 technique provides spatially-distributed measurements useful to verify the predictive capability of a distributed sediment yield model. The application of the cesium-137 technique requires a calibration procedure to convert measurements of ¹³⁷Cs inventories to estimates of net soil erosion rates. Rainfall and sediment yield data from 1978 to 1994 in a small Calabrian basin forested with eucalyptus trees, were initially used to calibrate, at mean annual temporal scale, the SEDD model applicable both at the morphological unit and basin scale. Then, estimates of net soil erosion were obtained using a mass balance model and the spatial distribution of cesium-137 inventories. The reliability of the mass balance model was verified by comparing the basin net soil erosion value obtained by ¹³⁷Cs measurements against the mean annual value of sediment yield measured at the basin outlet. Finally a good concordance between calculated mean annual hillslope sediment yield and the corresponding net soil erosion values was proved at the scale of both the single morphological unit and the entire basin. In conclusion, the cesium-137 technique and the mass balance model confirmed the validity of the internal functioning of SEDD model.

Keywords: Cesium-137, RUSLE, sediment delivery processes, sediment delivery ratio, SEDD mode, sediment yield, soil erosion

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