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Home » Journal of Soil and Water Conservation » Abstracts and Archives » Jan-Feb 2003
Jan-Feb 2003

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January - February 2003: Volume 58, Number 1

Table of Contents

Features

  • Five low-cost methods for slowing streambank erosion
    By Christina Johnson
  • New proposed National Resources Inventory protocols on nonfederal rangelands
    By Kenneth E. Spaeth, F.B. Pierson, J.E. Herrick, P.L. Shaver, D.A. Pyke, M. Pellant, D. Thompson, and R. Dayton

Research

Departments

  • Home Front
  • Viewpoint
  • Raise Your Voice
  • Notebook
  • Conservogram

Sediment and nutrient removal in an established multi-species riparian buffer
(Full text appears in the Journal of Soil and Water Conservation, Vol.58, No. 1)

K.H. Lee, T.M. Isenhart, and R.C. Schultz
ABSTRACT: Riparian buffers are widely recommended as a tool for removing nonpoint source pollutants from agricultural areas especially those carried by surface runoff. A field plot study was conducted to determine the effectiveness of an established multi-species buffer in trapping sediment, nitrogen, and phosphorus from cropland runoff during natural rainfall events. Triplicate plots were installed in a previously established buffer with a 4.1 by 22.1 m (14 x 73 ft.) cropland source area paired with either no buffer, a 7.1 m (23 ft) switchgrass (Panicum virgatum L. cv. Cave-n-Rock) buffer, or a 16.3 m (53.5 ft) switchgrass/woody buffer (7.1 m swithgrass/9.2 m woody) located at the lower end of each plot. The switchgrass buffer removed 95% of the sediment, 80% of the total-nitrogen (N), 62% of the nitrate-nitrogen (NO3-N), 78% of the total-phosphorus (P), and 58% of the phosphate-phosphorus (PO4-P). The switchgrass/woody buffer removed 97% of the sediment, 94% of the total-N, 85% of the NO3-N, 91% of the total-P, and 80% of the PO4-P in the runoff. There was a significant negative correlation between the trapping effectiveness of the buffers and the intensity and total rainfall of individual storms. While the 7 m (23 ft) switchgrass buffer was effective in removing sediment and sediment-bound nutrients, the added width of the 16.3 m (53.5 ft) switchgrass/woody buffer increased the removal efficiency of soluble nutrients by over 20%. Similar or even greater reductions might have been found if the 16.3 m (53.5 ft) buffer had been planted completely to native warm-season grasses. In this buffer, combinations of the dense, stiff, native warm-season grass and woody vegetation improved the removal effectiveness for the nonpoint source pollutants from agricultural areas.

Keywords: Erosion, grass filter, nonpoint source pollution, riparian buffers, water quality

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A case study of river temperature response to agricultural land use and environmental thermal patterns
(Full text appears in the Journal of Soil and Water Conservation, Vol.58, No. 1)

M.M. Borman and L.L. Larson
ABSTRACT: Water temperature standards, are being implemented in various states. This may impact agricultural land management. We evaluated the association between river temperature patterns, existing agricultural land uses, and the thermal equilibrium condition of the surrounding environment (e.g. air and soil temperatures). This case study was conducted on irrigated hay (meadow and wet meadow ecological sites) and pasture (sodic meadow ecological site) land in northeastern Oregon. Shading over the river channel (approximately 12 m channel width) was estimated at 1 to 5% based on site characteristics. Daily mean and maximum stream temperature increases along approximately 1.6 km (1.0 mi) reach lengths were 0 to 0.1 and 0.1 to 0.2°C, respectively, and were not different between existing land uses/ecological sites. Mean air and water temperatures were approximately 1°C apart indicating that an equilibrium condition existed during the study. As expected when temperatures approach equilibrium, weather conditions were the dominant influence on river temperature, much more than land use influences.

Keywords: Shade potential, thermal equilibrium, water quality, water temperature

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Management effects on erosion of Civil War military earthworks
(Full text appears in the Journal of Soil and Water Conservation, Vol.58, No. 1)

W.M. Aust, A. Azola, and J.E. Johnson
ABSTRACT: The U.S. National Park Service has the difficult task of preserving Civil War battlefields, including trench and fortification earthworks, while allowing public access. Soil erosion, both natural and human-induced, is a primary concern facing the preservation of the military earthworks. Vegetative cover is central to protecting military earthworks against erosion and a variety of vegetative-management regimes have evolved in the parks. This study used a modification of the Universal Soil Loss Equation (Dissmeyer and Foster, 1984) and erosion pins to estimate soil erosion that occurred for five earthwork-vegetation management practices: prescribed burning, mowing, herbaceous-trimming, woody-trimming, and forest for one year following treatment installation.

Both erosion estimation methods indicated that the prescribed burning treatment resulted in the highest erosion rates. The erosion pin data indicated that the woody-trimming treatment could potentially increase erosion. The forested military earthworks had the lowest erosion rates, while the trimmed and mowed management regimes had intermediate erosion values. Overall, this study indicates that military earthworks managed for continuous ground cover with minimum physical intervention are best protected from erosion. Treatments that minimize ground cover should be used only in areas where historic accuracy regarding vegetation or high visitor interest can justify the potential for increased erosion.

Keywords: Erosion pins, groundcover, preservation of military earthworks, soil erosion, Universal Soil Loss Equation, vegetation management

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The feasibility of restoring previously drained wetlands to reduce flood damage
(Full text appears in the Journal of Soil and Water Conservation, Vol.58, No. 1)

S.D. Shultz and J.A. Leitch
ABSTRACT: The economic feasibility of restoring previously drained wetlands to reduce flood damage was evaluated in North Dakota’s Maple River Watershed, a sub-watershed of the Red River Valley of the North. Benefit-cost ratios ranging from 0.2 to 0.7 were not significant enough to make simple wetland restoration—based on plugging existing drains, restoration with outlet control devices, or complete restoration intended to provide a full range of wetland-based environmental services—economically feasible over a 20-year future period. Peak flood stage and flood damage would need to be reduced by 3.3% to 8% in order for wetland restoration options to break-even and the inclusion of likely non-flood related wetland benefits did not improve feasibility. It is not recommended that public funds be used for extensive wetland restoration projects throughout Maple River Watershed or across large areas of the Red River Valley for the purpose of reducing flood damage.

Keywords: Flooding, Red River Valley, wetland restoration

 

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Land application of manure by animal feeding operations: Is more land needed?
(Full text appears in the Journal of Soil and Water Conservation, Vol.58, No. 1)

M. Ribaudo, N. Gollehon, and J. Agapoff
ABSTRACT: Animal manure has become a major focal point of conservation efforts. A shift in the industry over the past decade towards fewer, larger operations has resulted in concerns over the utilization and disposal of animal manure. Land application of manure, a preferred disposal method, may be difficult and costly to implement on larger operations if restrictions on land disposal increase the amount of land required for spreading. The hog sector provides an example of how restrictions on manure application rates can affect the need for land. Using data from the 1998 Hog Agricultural Resource Management Survey we found that most confined hog operations would need to increase the land receiving manure to meet the needs of a nitrogen-based (N-based) or phosphorus-based (P-based) nutrient management plan. Both are possible under proposed Clean Water Act regulations by the Environmental Protection Agency (EPA) and program goals for the U.S. Department of Agriculture. Smaller operations tended to have adequate land on the operation to meet the needs of a N-based plan in most regions. Larger operations generally had inadequate land for N-based plans. All large operations would need to find substantial amounts of additional land to meet the needs of a P-based plan.

Keywords: Animal feeding operation, assimilative capacity, manure, nitrogen, nutrient management plan, nutrients, phosphorus, phytase

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Earthworm (Lumbricidae) survey of North Dakota fields placed in the United States Conservation Reserve Program
(Full text appears in the Journal of Soil and Water Conservation, Vol.58, No. 1)

E.J. Deibert and R.A. Utter
ABSTRACT: Twenty-three field sites in North Dakota, where highly erodible soil is placed under permanent vegetation in the U.S. Conservation Reserve Program (CRP) from five to eight years, were surveyed for the presence or absence of earthworms. Soils were sampled to determine chemical and physical properties, and soil cores were collected to estimate earthworm populations. Earthworm species identified at 12 CRP sites were Aporrectodea tuberculata (Eisen), Aporrectodea trapezoids (Duges), Aporrectodea caliginosa (Savigny), Dendrobaena octaedra (Savigny), and Lumbricus rubellus (Hoffmeister). Sites with earthworms were associated with organic matter levels of greater than 2.5%. Sand content of the 11 sites without earthworms averaged 67% (±13), and the soil usually contained what appeared to be sharp shiny crystals or grains that might not be ideal for earthworm survival. Dendrobaena octaedra and Lumbricus rubellus were found at sites with the highest soil organic matter and nitrate-N levels plus low sand percent. Soil P, K, pH and EC levels were not related to the presence or absence of earthworms in these CRP sites. Total earthworm population estimates from five CRP sites averaged 6.3 million ha-1 (±4.7), with adults, juveniles, and cocoons at 0.6 (±0.4), 4.5 (±3.1), and 1.2 (±2.0) million ha-1, respectively. Earthworm populations along a 90-meter transect from the edge of the CRP field were similar when averaged over the five sites. An estimate of population at the other seven earthworm sites was not possible because environmental stress as earthworms tended to migrate only to areas in the field where taproot plant species were located. The presence of wetlands or tree habitat in these CRP fields could not be used as criteria for determining the presence of earthworms.

Keywords: Aporrectodea, Conservation Reserve Program, CRP, earthworms, Lumbricidae, soil properties

 

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Applying a GIS slope-stability model to site-specific landslide prevention in Honduras
(Full text appears in the Journal of Soil and Water Conservation, Vol.58, No. 1)

B.F. Zaitchik and H.M. van Es
ABSTRACT: Conventional output of an environmental landslide model is some form of a distributed hazard index. Viability of these models has proven to be strong in tested environments, and this has encouraged modelers to apply landslide hazard models to tropical regions that generally lack advanced information systems. For steep-land farmers in the tropics, however, information on relative landslide hazard is useful but not sufficient, as knowledge of primary causes of instability is needed to develop management practices for sustained use of landslide-prone lands. Stability Index Mapping (SINMAP) is a physical slope-stability model in which relative hazard predictions are primarily governed by local slope gradient (a) and relative wetness (W). This model was applied to an agricultural region of Honduras that suffered extensive landslide damage during Hurricane Mitch, and its stability predictions were empirically evaluated. Zones of predicted instability were subsequently categorized according to a, derived from the Digital Elevation Model, and W, based on steady-state hydrology for hurricane conditions. W and a varied in a soil-specific and site-specific manner, indicating that site-specific management strategies are required for slope stabilization in the study area. Knowledge of a*W in potentially unstable zones allows for informed stability management practices, improving the utility of the hazard model for communities that contend with landslide risk.

Keywords: Central America, Hurricane Mitch, slope failure, spatial modeling

 

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Examining the targeting of conservation tillage practices to steep vs. flat landscapes in the Minnesota River Basin
(Full text appears in the Journal of Soil and Water Conservation, Vol.58, No. 1)

P. H. Gowda, D. J. Mulla, and B. J. Dalzell
ABSTRACT: Conservation tillage practices are being prescribed as a remedy to reduce soil erosion and phosphorus losses and to increase water-holding capacity of agricultural soils. This study evaluates the targeting of conservation tillage practices to steep vs. flat landscapes in the Minnesota River Basin. Tillage practices were identified using remote sensing techniques in nine subwatersheds of the Lower Minnesota River watershed and analyzed in relation to topography. A Landsat Thematic Mapper (TM) image acquired during the 1997 planting season was used to identify conventional and conservation tillage practices at a 30 m (33 yd) resolution. Conservation tillage has been adopted on 32% to 54% of the cropland in the subwatersheds studied, while average cropland slope steepness ranges from 1.5% to 2.8%. A linear regression of percent adoption of conservation tillage vs. average slope steepness had a slope of 3.45 and an r2 of 0.07. This shows that there was no significant targeting of conservation tillage to steeper topography across subwatersheds. Within a subwatershed, however, there was a slight tendency toward greater adoption of conservation tillage on steeper landscapes, up to slope steepnesses of 5%, then a significant decline in the adoption of conservation tillage. Overall, farmers in the Lower Minnesota River watershed seem to be adopting conservation tillage for reasons unrelated to soil conservation.

Keywords: Adoption, highly erodible land, topography

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Statistical assessment of a paired-site approach for verification of C and N sequestration on Wisconsin Conservation Reserve Program land
(Full text appears in the Journal of Soil and Water Conservation, Vol.58, No. 1)
(Click here for PDF of full text)
C.J. Kucharik, J.A. Roth, and R.T. Nabielski

ABSTRACT: The threat of global climate change has provoked policy-makers to consider plausible strategies to slow the accumulation of greenhouse gases—especially carbon dioxide (CO2)—in the atmosphere. One such idea involves the sequestration of atmospheric carbon (C) in degraded agricultural soils as part of the Conservation Reserve Program (CRP). While the potential for significant C sequestration in CRP grassland ecosystems has been demonstrated, the paired-site sampling approach traditionally used to quantify soil C changes has not been evaluated with robust statistical analysis. In this study, 14 paired CRP (> 8 years old) and cropland sites in Dane County, Wisconsin, were used to assess whether a paired-site sampling design could detect statistically significant differences (ANOVA) in mean soil organic C and total nitrogen (N) storage. We compared 0 to 10 cm (0 to 3.9 in) bulk density and sampled soils (0 to 5 cm, 5 to 10 cm, and 10 to 25 cm [0 to 2 in, 2 to 3.9 in, and 3.9 to 9.8 in]) for textural differences and chemical analysis of organic matter (OM), soil organic C (SOC), total N, and pH. The CRP contributed to reducing soil bulk density by 13% (p < 0.0001) and increased SOC and OM storage (kg m-2 [lb ft-2]) by 13% to 17% in the 0 to 5 cm (2 in) layer (p = 0.1). We tested the statistical power associated with ANOVA for measured soil properties and calculated minimum detectable differences (MDD). We concluded that 40 to 65 paired sites and soil sampling in 5 cm (2 in) increments near the surface were needed to achieve an 80% confidence level (a = 0.05;

b = 0.20) in soil C and N sequestration rates. Because soil C and total N storage was highly variable among these sites (CVs > 20%), only a 23% to 29% change in existing total organic C and N pools could be reliably detected. While C and N sequestration (247 kg C ha-1 yr-1 and 17 kg N ha-1 yr-1 [220 lb C ac-1 and 15 lb N ac-1]) may be occurring and confined to the surface 5 cm (2 in) as part of the Wisconsin CRP, our sampling design did not statistically support the desired 80% confidence level. We conclude that usage of statistical power analysis is essential to insure a high level of confidence in soil C and N sequestration rates that are quantified using paired plots.

Keywords: Agricultural land management, carbon sequestration, CRP, soil organic matter, Wisconsin

 

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Copper retention from runoff by switchgrass and tall fescue filter strips
(Full text appears in the Journal of Soil and Water Conservation, Vol.58, No. 1)
J. Wu, W. Mersie, A. Atalay, and C.A. Seybold

ABSTRACT: Vegetative filter strips are recommended to reduce the load of agricultural chemicals in surface runoff. Quantitative data however, is still needed on the performance of various grass species in filter strips and their effectiveness under different runoff flow rates. A study was conducted to compare the effectiveness of switchgrass (Panicum virgatum L.) and tall fescue (Festuca arundinacea Schreb.) filter strips in removing dissolved copper pesticide from runoff flowing at 2.7 L (0.7 gallon min-1) min-1 or 6 L (1.6 gallon min-1) min-1 over 0.9 m (3 ft) soil surface area. Runoff was simulated by applying 82-L (22 gallon) solutions containing 6.9 mg L-1 (6.9 ppm) Copper (Cu) on aluminum tilted-beds set at 3% slope, filled with Bojac soil, and planted to switchgrass or tall fescue. The total infiltrated (leached plus retained) expressed as percent of applied was 21% for soil beds having no grass, 33% for switchgrass beds, and 28% for tall fescue beds at 6.0 L min-1 (1.6 gallon min-1) flow rate. At the slow flow rate (2.7 L min-1, 0.7 gallon min-1), 77%, 97% and 100% of the applied runon infiltrated in no grass, switchgrass and tall fescue beds, respectively. About 60% of the applied Cu was removed by both grasses from runoff at 6.0 L min-1 (1.6 gallon min-1) flow rate whereas at the slow flow rate, grasses helped remove all the applied Cu. Average concentration of Cu in surface runoff from all beds was 3.3 mg L-1 (3.3 ppm) whereas for leachate samples it was 0.2 mg L-1(0.2 ppm). Adsorption to soil appeared to be the primary mechanism of removal of Cu from overland flow and leachate. When runoff moved at 2.7 L min-1 (0.7 gallon min-1) in the tall fescue filter strips, greater amounts of Cu were retained in the up-slope one third of the filter strips. This indicates that a relatively small tall fescue filter strip would be adequate to remove Cu in areas where runoff is expected to move at slow flow rate. The grass filter strips reduced dissolved Cu in runoff by increasing its infiltration and its retention by soil.

Keywords: Copper, runoff, switchgrass, tall fescue, vegetative filter strips

 

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Alternate land uses for marginal soils
(Full text appears in the Journal of Soil and Water Conservation, Vol.58, No. 1)
G.R. Wells, H.A. Fribourg, S.E. Schlarbaum, J.T. Ammons, and D.G. Hodges

ABSTRACT: A long-term study (15 year) was established on 10 representative marginal soil series and attempted unsuccessfully on three others in Tennessee to evaluate productivity for forage mass or fiber. Tall fescue (Festuca arundinacea) was evaluated for production and two tree species, loblolly pine (Pinus taeda) and American sycamore (Platanus occidentalis) were planted for fiber production. Some soils had good potential for forage and fiber production, while other soils should be considered for alternate uses not involving harvesting or grazing. Tall fescue forage mass varied among soils (2.4 to over 6 Mg/ha/yr [1.1 to over 2.7 ton/acre/yr]). On most sites, because of topography and accessibility, grazing would be the preferred utilization for tall fescue. Loblolly pine generally grew better on Wolftever clay loam (Hapludult) and Philo sandy clay loam (Dystrudept) than on other soils. Response of American sycamore to Memphis silt (Hapludalf), which is not a marginal soil and was included as a control, and that of some of the more productive marginal soils in the study, suggests that this species requires soils with greater available water than loblolly pine. Alternate, non-commodity uses for droughty and severely eroded soils, such as the Ruston clay loam (Paleudult) and Lexington loam (Dystrudept), could include conservation and recreational purposes. Management directed toward increasing mast (wildlife food) and habitat to enhance game populations could provide landowners with a supplemental source of income.

Keywords: American sycamore, Festuca arundinacea, loblolly pine, Pinus taeda, Platanus occidentalis, tall fescue
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