September/October 2005: Volume 60, Number 5
Table of Contents
Features:
Green Roofs are Sprouting up
By Deb Happe
Rangeland Field Data Techniques and Data Applications
By Ken Spaeth, G.L Peacock, J.E. Herrick, P. Shaver, and R. Dayton
Life after Methyl Bromide
By Pat Hemminger
Research
Departments
· Homefront
· Raise Your Voice
· Going Retro-Celebrating 60 Years of the JSWC
· Notebook
· Conservogram
Phosphorus indexes in four Midwestern states: An evaluation of the differences and similarities
(Full text appears in the Journal of Soil and Water Conservation, Vol. 60, No. 5)
J.L. Benning and C.S. Wortmann
ABSTRACT: Phosphorus (P) indexes have been developed to assess the potential for agricultural P loss to surface waters, to plan and regulate P application, and for education. We compared the P indexes of four states through application to field scenarios varying in soil test P,
P application, distance to surface water, and erosion rates. Importance of these factors to runoff P risk assessment scores varied considerably with P indexes. Increasing soil test P from 30 to 90 mg kg-1 (ppm) increased scores by zero percent to 300 percent. Scores increased by 0 to 64 percent for surface application as compared to injection of manure and by 0 to 29 percent by applying manure 30 m (100 ft) rather than 15 m (50 ft) from the edge of a water body. Increasing erosion loss of soil from 2.3 to 11.3 Mg ha-1 (1 to 5 t ac-1) increased scores by 30 to 244 percent. The differences and similarities were evaluated in consideration of research findings.
Keywords: Erosion, eutrophication, risk assessment, runoff, water quality
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Development of an agricultural land evaluation and site assessment (LESA) decision support tool using remote sensing and geographic information system
(Full text appears in the Journal of Soil and Water Conservation, Vol. 60, No. 5)
E.J. Dung and R. Sugumaran
ABSTRACT: The general trend in North America, which is agriculturally based, have indicated that prime agricultural lands are being constantly lost to natural hazards such as soil erosion, land degradation, and especially through human activities such as urban development. In order to control and manage these prime agricultural lands, there is a need for improved agricultural land evaluation methods. Lately, a combination of geospatial technologies (GST) such as remote sensing, geographical information systems (GIS), and the global positioning system (GPS), and land evaluation methods such as Land Evaluation and Site Assessment (LESA) have shown to be promising tools for land evaluation. Even though numerous studies have demonstrated the importance of integrating land evaluation models with GIS, few studies have combined the popular LESA model with GIS to provide a decision support tool for mangers. The goal of the study is to develop a decision support tool for agricultural land evaluation using geospatial technologies and a LESA model in Black Hawk County, Iowa. Currently, the county is using an Excel-based land evaluation and site assessment system, which lacks a spatial context even though land evaluation factors are spatial in nature. In order to develop a decision support tool, LESA criteria, and relevant data for these criteria were collected from different sources. Then, these data were analyzed using ERDAS IMAGINE and ArcGIS software. Finally, a decision support tool was developed by customizing ArcGIS software using Visual Basic Application. The results of the study found that soil productivity, development potentials, and farmland are the major factors in the LESA model in this county. The decision support tool developed in this study is easy to use, accurate, combines spatial and non-spatial data, and saves time and money for the planners in the county over traditional methods.
Keywords: ArcGIS, GIS, LESA, prime agricultural land, remote sensing, spatial decision support systems
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Profit and yield of tillage in cotton production systems
(Full text appears in the Journal of Soil and Water Conservation, Vol. 60, No. 5)
R.A. Buman, B.A. Alesii, J.F. Bradley, J.L. Hatfield, and D.L. Karlen
ABSTRACT: Adoption of conservation tillage for cotton (Gossypium hirsutum L.) increased a modest 5.5 percent from 1992 to 1998 despite the evidence of the benefits to erosion control, soil health, and associated natural resources derived from conservation tillage. The Monsanto Centers of Excellence were established to evaluate the potential benefits of conservation tillage across a range of soils and climates. Our objective is to summarize the results from field-scale studies conducted at 12 Centers of Excellence sites in seven states from 1998 through 2002. No-tillage, strip tillage, reduced tillage and conventional tillage cotton production were evaluated in this study. All sites had a no-tillage and conventional tillage system, while eight of the 12 sites had a reduced tillage system and two of the 12 sites had a strip tillage system. Differences among tillage systems within a site did not show any significant effects on soil quality indicators. The variability within a site was quite large due to the limited number of samples collected at each location and the short-period of record covered by the study. Lint yield differences between no-tillage, strip tillage, reduced tillage, and conventional tillage systems were not significant. The 5-year average profit for the no-tillage system ranged from $17 to $164 ha-1
($7 to $66 ac-1) higher than the other 3 systems. Even though these differences were not significant because of large variations in environment, soil type, and production practices between sites and years the profit was always positive for no-till systems compared to other tillage systems. We conclude that farmers, crop consultants, and others should carefully consider overall profit rather than just crop yield when evaluating alternative tillage practices.
Keywords: Conventional tillage, cotton, no-till, strip till
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Phosphorus stratification and potential for runoff loss following long term manure application
(Full text appears in the Journal of Soil and Water Conservation, Vol. 60, No. 5)
M. Mamo, D. Ginting, W.C. Zanner, D.L. McCallister, R.R. Renken, and C.A. Shapiro
ABSTRACT: Understanding phosphorus (P) accumulation and stratification in surface soil following manure application is critical for runoff P loss abatement. The objectives of this study were to predict soil P stratification and assess its effects on runoff P losses following long-term manure application. A two-step approach was developed to use field data and predict P stratification and runoff over time. First, extractable soil P in 0 to 5, 5 to 10, and 10 to 15-cm (0 to 2, 2 to 4, and 4 to 6-in) depths were measured in a 2.5 ha (6.2 ac) watershed, where cattle and swine manure were applied for four consecutive years. Second, the measured P and management practices were used to calibrate input parameters of the Groundwater Loading Effects of Agricultural Management System (GLEAMS) simulation. The calibrated parameters were used to estimate soil P stratification and runoff P losses following 25 years of simulated annual manure application. The Iowa P index rating was calculated for the same scenarios. Correlation among extractable P fractions were high (r2 > 0.88). The GLEAMS simulation predicted reasonably well the exacerbation of soil P stratification following manure application. The simulation estimated a 5.3 mg L-1 and 7.4 mg L-1 runoff P increase for each 1 mg kg-1 soil labile-P increase in the 0 to 1-cm and 1 to 5-cm depths (0.4 and 2 in), respectively. Soil Bray-P in 0 to 5-cm vs. 0 to 15-cm depth increases P-index risk towards manure application rates. Prediction of P stratification with models is useful for improving P loss risk assessment when combined with the P-index and thus provisions should be made for P stratification in comprehensive nutrient management programs.
List of abbreviations:
Bray-P P extracted in 0.025 M hydrochloric acid and 0.03 M ammonium fluoride
FeO-P iron oxide extractable P
GLEAMS Groundwater Loading Effects of Agricultural Management System
Keywords: Phosphorus stratification, runoff
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Development of survey-like assessment tools to assess agricultural best management practice performance potential
(Full text appears in the Journal of Soil and Water Conservation, Vol. 60, No. 5)
B.L. Benham, J.H. Robbins, K.M. Brannan, S. Mostaghimi, T.A. Dillaha, J.W. Pease, and E.P. Smith
ABSTRACT: Sixteen survey-like assessment tools were developed to address the need for a low cost, rapid method of quantifying the quality of agricultural best management practices (BMPs). BMPs quality is defined as the adherence to design, site selection, implementation, and maintenance criteria as specified by state and federal conservation practice standards. Quality assessments made with the tools are based upon visual observations of BMPs rather than traditional assessment methods such as water quality monitoring. Tools were developed and tested as are part of a proof of concept study. One hundred and fifty-five cost-shared and 150 non cost-shared BMPs were assessed on 128 farms in the James River Basin of Virginia. Results indicate that when using the tools developed here to assess BMPs, there is little statistical difference (p<0.05) in quality between cost-shared and non cost-shared practices sampled.
Keywords: Agriculture, best management practices, nonpoint source pollution
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Measurement and simulation of herbicide transport from the corn phase of three cropping systems
(Full text appears in the Journal of Soil and Water Conservation, Vol. 60, No. 5)
F. Ghidey, R.N. Lerch, N.R. Kitchen, E.E. Alberts, and E.J. Sadler
ABSTRACT: Soils that naturally have a significant runoff component because of low permeability, such as claypans or steep slopes, are especially susceptible to herbicide losses in runoff. For these soils, seasonal losses as impacted by management practices are not well quantified. The objectives of this study were to evaluate the effect of three cropping systems on herbicide loss in surface runoff and develop a model that calculates herbicide concentration. Cropping System 1 (CS1) was a mulch tillage corn-soybean rotation system with herbicides surface applied then incorporated. Cropping System 2 (CS2) was a no-till corn-soybean rotation system with herbicides surface applied and not incorporated. Cropping System 5 (CS5) was a no-till corn-soybean-wheat rotation system with split herbicide application in 1997 and 1999 and no incorporation. The study was conducted on 0.37 ha (0.92 ac) plots equipped with flumes and automated samplers. During each runoff event, runoff volumes were measured, and water samples were collected at equal flow increments and analyzed for atrazine [2-chloro-4-ethylamino-6-isopropylamino-s-triazine] and metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethy/acetamide]. Averaged over years, atrazine and metolachlor losses from CS2 were 2.2 and 1.6 times those from CS1, respectively. Atrazine loss to surface runoff from CS1, CS2, and CS5 accounted for 1.6, 2.5, and 5.7% of the total atrazine applied, respectively. Metolachlor loss to surface runoff accounted for 1.8, 2.0, and 2.0% of the total applied for the three cropping systems. Herbicide concentrations were extremely high in the first runoff event measured after application, particularly when it occurred within a few days after application. A generalized model was developed to account for the effects of time after application, runoff volume, and application rate on herbicide concentration in runoff. Overall, the study showed that accounting for incorporation, split application, runoff volume, and timing of runoff events relative to the day of application can increase the confidence in calculations of the amount of herbicide transported to surface runoff.
Keywords: Atrazine, metolachlor, mulch tillage, no-till, water quality
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Effects of curve number modification on runoff estimation using WSR-88D rainfall data in Texas watersheds
(Full text appears in the Journal of Soil and Water Conservation, Vol. 60, No. 5)
J.H. Jacobs and R. Srinivasan
ABSTRACT: The purpose of this study was to evaluate variations of the Natural Resources Conservation Service (NRCS) curve number method for estimating near real-time runoff for naturalized flow, using high resolution radar rainfall data in Texas watersheds. This study was undertaken in an attempt to provide more accurate runoff estimates to watershed and water resource managers for planning purposes. Stage III Weather Surveillance Radar 1988 Doppler (WSR-88D) precipitation data, obtained from the West Gulf River Forecast Center, was used as the precipitation input for runoff estimates in this study. The study areas consisted of dominant or homogenous land use and were characterized by naturalized flow. Findings indicate that the use of a dry antecedent soil moisture condition curve number value and a reduced initial abstraction coefficient (Ia) in the NRCS curve number equation produced the most statistically significant comparison between observed and estimated runoff in nine out of ten watersheds. The combined comparison for all events in these nine watersheds produced a coefficient of efficiency (COE) of 0.70, with a slope of 0.78 and an r2 of 0.77. Overall, the results of this research suggest that, although further improvements can be made for improved runoff estimation, the use of modified inputs to the NRCS curve number equation in conjunction with WSR-88D radar rainfall data could be useful in producing runoff estimates for Texas in real-time.
Keywords: Hydrologic modeling
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