September - October 2004: Volume 59, Number 5
Table of Contents
Features
Budgeting in a state of uncertainty
By: D. Happe
The length we go
By: M.J. Mausbach and A.R. Dedrick
A long, long time ago...
By: E. West and G. Ruark
Research
- Evaluation of structural best management practices 20 years after installation: Black Creek Watershed, Indiana
K.S. Bracmort, B.A. Engel, and J.R. Frankenberger
- Effects of pine straw harvesting on quantity and quality of surface runoff
D.H. Pote, B.C. Grigg, C.A. Blanche, and T.C. Daniel
- Willingness to pay for green space preservation: A comparison of Soil and Water Conservation District clientele and the general public using the contingent valuation method
T.W. Blaine and F.R. Lichtkoppler
- Where should buffers go? Modeling riparian habitat connectivity in Northeast Kansas
G. Bentrup and T. Kellerman
- Hydrological and terrain variables to aid strategic locations of riparian buffers
M.R. Burkart, D.E. James, and M.D. Tomer
- Evaluation of optical remote sensing models for crop residue cover assessment
D.P. Thoma, S.C. Gupta, and M.E. Bauer
Departments
- Home Front
Viewpoint
- Raise Your Voice
- Notebook
- Conservogram
Evaluation of structural best management practices 20 years after installation: Black Creek Watershed, Indiana
(Full text appears in the Journal of Soil and Water Conservation, Vol.59, No. 5)
K.S. Bracmort, B.A. Engel, and J.R. Frankenberger
ABSTRACT: Millions of dollars have been spent on agricultural watershed projects across the nation, but little is known about the long-term impacts of watershed management and protection efforts. Information pertaining to long-term condition and water quality impact of best management practices (BMPs) is scarce. Evaluation methods that estimate the current condition of the practice based on visual inspection and comparison to selected original design dimensions were developed for grassed waterways, grade stabilization structures, field borders and parallel terraces. The evaluation tools were tested for validity using an expert panel approach and for reliability based on inter-rater correlation. The evaluation tool’s three-point scale rating system assigns a score of three to a BMP that was fully functional and still met its original design purpose and a score of one to a BMP that no longer performed as designed. The newly developed evaluation tools were applied to a subset of structural BMPs implemented in the late 1970s in a major watershed management project in an Indiana watershed. One-third of the BMPs no longer remain. Those BMPs that remain today are in fair condition and are reasonably functional. Grassed waterways and terraces were most likely to remain, while the field borders that still existed had the highest condition score. This study suggests that BMPs can in some cases continue to function past their design life, but serves as a reminder that BMP functional life is limited, a fact that needs to be explicitly considered in conservation and watershed planning.
Keywords: Best management practices, Black Creek watershed, evaluation methods
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Effects of pine straw harvesting on quantity and quality of surface runoff
(Full text appears in the Journal of Soil and Water Conservation, Vol.59, No. 5)
D.H. Pote, B.C. Grigg, C.A. Blanche, and T.C. Daniel
ABSTRACT: Pine needles (straw) are an attractive landscape mulching material that protects the soil surface against erosion, conserves soil moisture, moderates soil temperature, and inhibits weed growth; yet it retains a loose, open structure that allows air, fertilizer, and water to easily penetrate the soil surface. Such characteristics have made pine straw a valuable commodity, but the loss of those mulching benefits from pine forests has raised concerns about effects on watersheds where pine straw is harvested. For example, pine straw absorbs the impact of raindrops and slows the speed of runoff, so its removal may increase soil erosion and nutrient losses, and decrease water-holding capacity of the forest floor. To test this hypothesis, three pine-straw harvesting practices and a control treatment (no straw harvest) were compared to determine harvesting effects on water, soil, and nutrient losses in runoff. The 24 plots (six replications of each treatment) were constructed in an established (16 yrs) loblolly pine (Pinus taeda L.) stand that had tree spacing of 3.0 m by 1.5 m (10 ft by 5 ft), and basal area of 41.3 m2 ha-1 (180 ft2 ac-1). Each plot (2 m by 1 m or 6.6 ft by 3.3 ft) had four percent slope, aluminum borders, and a runoff collector. Simulated rainfall was applied [5 cm h-1 (2 in h-1)] to produce 20 minutes of runoff from each plot. Annual pine straw harvesting clearly increased runoff, soil erosion from 0.5 to 91.6 kg ha-1 (0.4 to 81.7 lb ac-1), and losses of phosphorus (P), carbon (C), and total Kjeldahl nitrogen (N) in runoff; but these losses were partially controlled by less-frequent harvesting, and declined to control levels when pine straw had accumulated for two years.
Keywords: Agroforestry, erosion, pine-straw harvesting, nutrient loss, runoff, water quality
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Willingness to pay for green space preservation: A comparison of Soil and Water Conservation District clientele and the general public using the contingent valuation method
(Full text appears in the Journal of Soil and Water Conservation, Vol.59, No. 5)
T.W. Blaine and F.R. Lichtkoppler
ABSTRACT: This paper reports results from a contingent valuation study of conservation easements in Cuyahoga County, Cleveland, Ohio. The survey sample consists of registered voters and Soil and Water District (SWCD) clientele. Results show that strong majorities of both groups support the establishment of a conservation easement program to protect soil and water resources in the community (79 percent and 82 percent respectively). Willingness to pay for the program is highly sensitive to the fee levied, household income, and perceived importance of natural resource conservation. Mean household willingness to pay was estimated at $36.48 per year for SWCD clientele and $32.28 for the voting public. Local conservation districts may find this kind of information useful in strategic planning, program planning and resource allocation. Contingent valuation is a viable tool in assessing public opinion on preservation issues in the face of continuing development pressure combined with fewer state and federal dollars allocated to preserve soil and water resources.
Keywords: Conservation easement, contingent valuation method (CVM), economics, green space, public opinion, soil and water conservation, willingness to pay (WTP)
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Where should buffers go? Modeling riparian habitat connectivity in northeast Kansas
(Full text appears in the Journal of Soil and Water Conservation, Vol.59, No. 5)
G. Bentrup and T. Kellerman
ABSTRACT: Through many funding programs, riparian buffers are being created on agricultural lands to address significant water quality problems. Society and landowners are demanding many other environmental and social services (e.g., wildlife habitat and income diversification) from this practice. Resource planners therefore need to design riparian buffer systems in the right places to provide multiple services. However, scientific guidance for this is lacking. We developed a geographic information system (GIS)-based assessment method for quickly identifying where buffers can be established to restore connectivity of riparian areas for the benefit of terrestrial wildlife. An area in northeastern Kansas was selected to evaluate this tool. Species with limited dispersal capabilities were used as indicators for riparian connectivity. To improve connectivity, results indicated that 22 percent of the perennial stream length in the study area would need riparian buffers. This coarse-filter approach appears to be appropriate for large area planning and can be used singly or in combination with other GIS-guided resource assessments to guide riparian buffer design and implementation.
Keywords: Connectivity, corridors, fragmentation, geographic information systems (GIS), riparian buffers, wildlife
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Hydrological and terrain variables to aid strategic location of riparian buffers
(Full text appears in the Journal of Soil and Water Conservation, Vol.59, No. 5)
M.R. Burkart, D.E. James, and M.D. Tomer
ABSTRACT: Methods for mapping hydrologic variables to locate vegetated riparian buffers were explored using examples from the Deep Loess Region of the Midwest. Elevation and stream-flow data were used to define wetness, baseflow, sediment transport, and discharge indices. Groundwater dominates discharge in very small streams and through riparian areas in the region. All indices showed that riparian areas along first order streams have greater potential to intercept groundwater or runoff than similar areas along larger streams. A wetness index, used to indicate saturated soils, defined a significantly (p<0.05) greater probability of saturation along smaller streams, enhancing the potential for groundwater interception. Significantly smaller values of the sediment transport index along smaller streams provide enhanced opportunities for deposition of sediment and associated contaminants. A discharge index shows that buffers along first order streams have orders of magnitude greater opportunities to intercept water passing through riparian areas than reaches of larger streams.
Keywords: Digital elevation model (DEM), geographic information systems (GIS), hydrology, land use planning, nonpoint source pollution, riparian buffers, terrain analysis, water quality
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Evaluation of optical remote sensing models for crop residue cover assessment
(Full text appears in the Journal of Soil and Water Conservation, Vol.59, No. 5)
D.P. Thoma, S.C. Gupta, and M.E. Bauer
ABSTRACT: Measurement of crop residue cover over large areas is useful for monitoring conservation tillage adoption, assessing carbon sequestration potential and erosion modeling. This study was designed to test the accuracy of crop residue estimates in current Tillage Transect Surveys, and to test the feasibility of predicting crop residue cover based on data recorded by Landsat Enhanced Thematic Mapper Plus (ETM+) satellite scenes. A total of 468 corn and/or soybean fields in 11 Minnesota counties were characterized for residue cover in the course of three sampling campaigns coinciding in time with satellite scene acquisition. Results showed that Tillage Transect Survey estimates were correct for 49 percent to 74 percent of fields when either five or two categories were used in classification respectively. Regression analysis showed a strong positive relationship between percent soybean residue cover and ETM+ bands 1, 3, and 7 (r2 =0.66) and between percent corn residue and ETM+ bands 4, 5 and 7 (r2 = 0.44). Three additional indices based on satellite digital numbers, the Soil Tillage Index, Normalized Difference Index, and Normalized Difference Tillage Index had coefficients of determination between 0.02 and 0.56 for corn and soybean residues. The Crop Residue Index Multiband model, a more physically based model, correctly predicted residue cover categories for 30 to 64 percent of fields when five or two categories were used in classification respectively. We conclude that remote-sensing techniques had accuracy as good or better than Tillage Transect Surveys estimates when residue cover classifications were decreased to two categories (0 to 30 percent, and >30 percent). Since residue cover information is primarily needed to assess the extent of two categories, conservation and conventional tillage, remote sensing with Landsat imagery provides a means of sampling every field with an efficient, economical and uniform methodology.
Keywords: Crop residue, Landsat, tillage
