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Research

Increasing Magnitudes and frequences of extreme precipitation events used for hydraulic analysis in the midwest
                by: C.E. Davis, J.M Harbour, and B. Tyner

Surface water diversion impacts on farm income and sources of irrigation water: the case of the grand prarie in Arkansas
               by: J. HIll, B. Watkins, E. Wailes, M. Popp, J. Popp, J. Smartt, and K. Young

Daily estimates of rainfall, water runoff, and soil erosion in Iowa.     

(For Full PDF Click here)
            By:  R. Cruse, D. Flanagan, J. Frankenberger, B. Gelder, D. Herzmann, D. James, W. Krajewski, M. Kraszewi, J. Laflen, J. Opsomer, and D. Todey

Manure management and nutrient loss under winter conditions- a literature review
             By : M.S. Srinivasan, R.B. Bryant, M.P. Callahan, J.L. Weld

Field evaluation of vegetative filter effectiveness and runoff quality from unstocked feedlots

             by:  K.R. Mankin, P.L. Barnes, J.P. Harner, P.K. Kalita, and J.E. Boyer

Tillage and perennial grass effects on ponded infiltration for seven semi-arid loess soils.

             by:   S.B. Wuest, J.D. Williams, and H.T. Gollany

 

Improvement in soil less estimation in usle type experiments

            by: C.A.A. Ciesiolka, B. Yu, C.W. Rose, H. Ghadiri, D. Lang, C. Rosewell

 

Organic carbon and nitrogen contents in size  fractions of virgin, pasture, and agriculture soils affected by wind erosion of semiarid argentina

           by: D.E., Buschiazzo, M.J. Mendez, L.D., Oro, J.E., Panebianco, J.C. Colazo

Longterm grass ley set aside on sandy soils: A case study
             by:  M.A. Fullen and C.A. Booth

 

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Increasing Magnitudes and frequencies of extreme precipitation events used for hydraulic analysis in the Midwest
     C.E. Davis, J.M Harbour, and B. Tyner

ABSTRACT: Precipitation depths for high magnitude, low frequency storm events are critical inputs in designing hydraulic and erosion control structures for soil and water conservation.  The common standard for precipitation magnitude and frequency data for prior to 2004 was NWB Technical Paper 40, which has been superseded by NOAA Atlas 14.  Comparison between these two reports for Midwestern sites with long climate records reveals important changes in design storm events; in some cases event magnitudes increased up to 46%.  The 24-hour 100-year recurrence interval precipitation depth increased at 89% of study locations, but there was little change in events with 2- and 10-year recurrence intervals.  These changes most likely result from increased accuracy in precipitation statistics and localized patterns of increased storm magnitude.  Because of the impact of these changes on the design of hydraulic and erosion control structures, design manuals and local ordinances should be updated to reflect the new data.

 

Keywords: Design storms, extreme precipitation, Midwest, precipitation statistics, watershed management

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Surface water diversion impacts on farm income and sources of irrigation water:  the case of the Grand Prairie in Arkansas

         J. Hill, B. Watkins, E. Wailes, M. Popp, J. Popp, J. Smartt, and K. Young

 

ABSTRACT: Alternative water conservation investment choices for the Grand Prairie Region of Eastern Arkansas have been proposed. In particular, the cost-share and river water diversion components of the Grand Prairie Area Demonstration Project (GPADP) were analyzed in this study to determine their ramifications to area farms and water use.  The cost-share alternative was deemed most effective given trade offs between ground and surface water use, income redistribution and farm income considerations.  Effects of earlier reductions in rice production on the Arkansas economy may, however, justify water diversion and thus this study suggests the importance of further review of the GPADP project. 

Key words:  Aquifer depletion, government policy, irrigation management, on-farm water Storage, rice-soybean rotation

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Daily estimates of rainfall, water runoff, and soil erosion in Iowa.

      R. Cruse, D. Flanagan, J. Frankenberger, B. Gelder, D. Herzmann, D. James, W. Krajewski, M. Kraszewi, J. Laflen, J. Opsomer, and D. Todey

ABSTRACT: The major water quality impairment in the Midwest U.S. is sediment eroded from agricultural lands.  Yet, few understand where or when erosion occurs, or the dynamics of soil erosion, the relative impact of precipitation, topography, land management and severe events over time and space.  The objectives of this project are to: 1) develop methodology for estimating near real time spatial and temporal soil erosion and water runoff losses; and 2) explore issues in applying the method to a large area by setting up and running a prototype system for the state of Iowa. To accomplish this, soil erosion and water runoff loss are estimated daily at the township level (~10 by ~10 km area) (~6.2 mi²) and a map is posted on the Internet daily showing precipitation with runoff and soil erosion estimates for every Iowa township.  We use WEPP (Water Erosion Prediction Project), a daily simulation model, to compute soil erosion and surface runoff.  WEPP uses accumulated precipitation by 15-minute periods obtained with NEXRAD radar.  Other needed weather data are obtained from an Iowa weather network.  The National Resources Inventory provides soil, topography, cropping and management information required for running WEPP.  Daily and annual spatial precipitation, runoff and erosion estimates illustrate a high level of spatial variability related to topography, precipitation characteristics, soils and management practices.

Keywords:  Radar, WEPP, NR

For a Full PDF of this article Click Here

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 Manure management and nutrient loss under winter conditions- a literature review

 

M.S. Srinivasan, R.B. Bryant, M.P. Callahan, J.L. Weld

 

ABSRACT: Excessive losses of nitrogen (N) and phosphorus (P) from agricultural fields have detrimental impacts on environmental quality.  Nutrient management guidelines, such as the P Index, are designed to minimize the risk of nutrient loss with minimal disruption to the whole farm operation.  Restricting winter spreading of manure, which is common to most management guidelines developed for cold climates, is a contentious issue in the northern-tier states of the United States and almost all provinces of Canada.  Producers have strong opinions with regard to the merits of winter spreading and arguments against the alternative practice of manure storage.  The purpose of this paper is to review the results of scientific studies relevant to the issue of winter spreading of manure, and identify needs for additional research in this area.  Collectively, these studies illustrate the complexity of N and P dynamics in response to a wide spectrum of winter conditions.  They do shed some light on the potential for nutrient loss following manure application during winter with respect to cropping system effects on runoff, manure mulching effects, manure properties, and differences due to manure placement relative to a snow pack and timing of application.  However, process-level understanding of nutrient loss following manure application during winter is still lacking, and critical variables that control hydrologic and transport processes under winter conditions are not fully identified or understood.  Extensive watershed-scale observations in combination with plot and field scale experiments that focus on specific processes should yield sufficient knowledge and data to develop empirical models, a useful first step in developing more detailed understanding of nutrient losses associated with manure spreading under winter conditions.

Keywords: Manure, nutrient loss, winter, snow, frozen soil, nitrogen, phosphorus

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Field evaluation of vegetative filter effectiveness and runoff quality from unstocked feedlots

K.R. Mankin, P.L. Barnes, J.P. Harner, P.K. Kalita, and J.E. Boyer

 

Abstract: Smaller beef cattle feedlots (< 1000 head) are often used for only a part of each year, but little is known about the pollution potential caused by feedlot residual manure when cattle are not present or about the effectiveness of vegetative filter strips (VFSs) under these conditions. This study quantified beef cattle feedlot runoff quality, particularly during unstocked conditions, evaluated reductions of fecal bacteria and nutrients in VFSs treating feedlot runoff, and assessed the relative importance of site characteristics on observed reductions. Established VFSs on four commercial feedlots located across central and eastern Kansas were instrumented with automated samplers at VFS inlets and outlets, and 22 feedlot runoff events were analyzed for reductions in fecal coliforms (FC), Escherichia coli, fecal streptococci (FS), total nitrogen (TN) and total phosphorus (TP). Events when few or no cattle were present averaged one-sixth the TN (20 mg/L), one-seventh the TP (6 mg/L), and one-fortieth the FC (2.1x10⁴ cfu/mL) of events with cattle present. Measured concentration reductions from all events and VFSs averaged 77% (FC), 83% (E. coli), 83% (FS), 66% (TN), and 66% (TP). VFSs allowed no discharges for 92 and 93% of feedlot runoff events at the sites with VFS:drainage area ratio > 0.5. Constituent reductions were positively correlated to VFS:drainage area ratio and negatively correlated to event rainfall depth. This study provides general support for the use of VFS:drainage area ratio as a design guideline.

 

Keywords: Livestock waste management, vegetative filter strips, fecal bacteria, feedlot runoff.

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Tillage and perennial grass effects on ponded infiltration for seven semi-arid loess soils.

 

S.B. Wuest, J.D. Williams, and H.T. Gollany

 

ABSTRACT: To test the benefits of no-till, we measured steady-state ponded water infiltration on a Pacific Northwest geo-climo sequence of seven semi-arid soils where no-till, conventional till, and perennial grass fields were in close proximity.  Average infiltration was 30% greater under no-till and grass compared to conventional tillage, although variability among sites and years was high.  This indicates that these practices can reduce the potential for runoff and erosion when measured over many sites, but might not at a particular site.  Infiltration correlated positively with sand content (r = 0.75), negatively with silt (r = -0.78), but was not correlated with water stable aggregates (WSA) because texture had a dominant effect.  The number of years since tillage was positively correlated with infiltration, particulate organic matter (POM), permanganate oxidizable C (active C) and organic C (r = 0.58, 0.70, 0.50, and 0.57 respectively).  Among soil properties, organic C was positively correlated with active C, POM, WSA, and silt (r = 0.92, 0.63, 0.38, and 0.41, respectively).  Despite high variability and the need for numerous subsamples, measurement of infiltration was an effective test for documenting benefits of no-till.  Additional research with correlated indicators appears warranted, but researchers should be cautious in assuming their relationship to infiltration.

 

Keywords: Aggregates, infiltration, organic carbon, perennial grass, no-tillage


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Improvement in soil less estimation in usle type experiments

 

C.A.A. Ciesiolka, B. Yu, C.W. Rose, H. Ghadiri, D. Lang, C. Rosewell

 

ABSTRACT: Soil erosion experimentation around the world commonly uses field runoff plots from which runoff and soil loss are collected. The volume of the collected water-sediment mixture is usually so great that sub-sampling techniques are required to estimate total soil loss in any erosion event. It has been shown that the commonly used method involving a collection box or tank, agitation of the water-sediment mixture and then sub-sampling can lead to serious under-estimation of total soil loss. The various possible sources of this error are investigated. For the error due to the unavoidable short time delay between completion of sediment stirring and sample collection, a simple practical method of correction based on settling theory is described and illustrated for four different soil types. Application of this correction requires measurement or estimation of the time delay, and of the soil’s settling velocity characteristics.

 

Keywords: Oden theory, runoff plots, settling velocity, soil erosion measurement, sub-sampling error, USLE.

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Organic carbon and nitrogen contents in size  fractions of virgin, pasture, and agriculture soils affected by wind erosion of semiarid argentina

 

D.E., Buschiazzo, M.J. Mendez, L.D., Oro, J.E., Panebianco, J.C. Colazo

 

ABSTRACT Wind erosion is an important soil degradation process in semiarid environments that can affect soil organic carbon (OC) and nitrogen (N) dynamics. Wind erosion can decrease the proportion of easily erodable <0.84 mm size fractions (aggregates + individual particles), and increase the non erodable. Tillage and rain can breakdown large aggregates increasing OC and N losses by wind erosion, and can decrease the proportion of aggregates to sand in coarse size fractions. Therefore the variations of OC and N in size fractions of 20 A-horizons of Haplustolls and Ustipsamments of the semiarid part of Argentina submitted to three management conditions with increasing tillage and wind erosion levels (VIRGIN < Eragrostis curvula  PASTURE <  AGRICULTURE) were analyzed. The <2, 2 to 50, 50 to 74, 74 to 100, and 100 to 2000 ?m size fractions (aggregates + individual sand particles) were separated by wet sieving, and their content of OC and N determined. The relative amount of aggregates and sand were analyzed together, in order to asses the effect of tillage on the proportion aggregates to sand within each size fraction and the selection caused by wind erosion. Results showed that AGRICULTURE decreased the 74 to 100 um and the 2 to 50 ?m sized fractions in relation to VIRGIN soils. Decreases of 74 to 100 um fractions were attributed to the breakdown by tillage of the aggregates composing this size fraction; while decreases of 2 to 50 ?m sized fractions (100% aggregates) were attributed to losses by wind erosion. PASTURES showed lower proportions of 2 to 50 ?m sized fractions than VIRGIN soils, probably as a consequence of wind erosion events occurred before the Eragrostis curvula pasture plantation. The amount of aggregates of the 100 to 2000 um size fraction did not differ between management systems probably because they suffered a rapid turnover in AGRICULTURE soils. Nevertheless, the proportion of sand in relation to aggregates was higher in comparison to VIRGIN soils in this size fraction, which indicates that a relative accumulation of sand occurred. The 2 to 50 ?m size fraction (aggregates) were positively correlated with contents of total organic matter (R² = 0.55, p< 0.001) and silt + clay [R² = 0.39, p<0.01]. A multiple regression analysis demonstrated that both variables explained 77% of the aggregate variability. Organic C and N contents tend mainly to decrease from fine to coarse aggregates within each management type. This was attributed to the formation of organo-mineral complexes with fine sized particles in finer aggregates. Organic C and N contents of coarse fractions (>50um) were higher in VIRGIN than in both PASTURE and AGRICULTURE soils, indicating that cultivation promoted C and N losses in coarser fractions. AGRICULTURE promoted larger N than OC losses in coarse fractions, indicating that nitrogenous compounds were more affected than C compounds. Organic C and N contents in < 50 sized fractions, (i.e. aggregates) did not differ between management systems, probably because of the higher stability of nitrogenous and carbon compounds accumulated in these fine fractions as organo-mineral complexes. C/N ratios remained unchanged in most cases, indicating homogeneous composition of organic matter with all management types. We concluded that VIRGIN soils converted to agriculture in the semiarid part of Argentina will decrease the proportion of coarse fractions, mainly by breakdown of their aggregates by tillage, and will increase the proportion of sand in these size fractions. The 2 to 50 um sized aggregates generated by the breakdown of coarser aggregates will be eroded by wind. The concentration of OC and N will be drastically decreased by cultivation in coarse size fractions but not in the fine ones. The Eragrostis curvula pasture is not effective in recovering soil aggregation nor increasing OC or N levels in coarse fractions of degraded soils.

 

Key words: Semiarid regions, organic carbon, nitrogen, size fractions, aggregates.

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Longterm grass ley set aside on sandy soils: A case study

 M.A. Fullen and C.A. Booth

 

ABSTRACT: Investigations assessed the potential contribution of grass-ley set-aside to soil conservation. Ten runoff plots (7 to 15^o, 12 to 27 percent gradients) at the Hilton Experimental Site, England, were put to ley in 1991, simulating one specific set-aside land-use. Runoff and erosion rates were low, despite potentially erosive rains. Mean runoff was 0.24 percent of precipitation (standard deviation 0.20), compared with a 15-year mean value of 0.13 percent (standard deviation 0.04) on permanent grassland. Erosion rates decreased to tolerable levels once approximately 30 percent vegetation cover had established and remained low. Under developed ley cover, plot erosion rates were approximately 0.1 to 0.5 t ha^-1 yr^-1 (mean of 69 plot years 0.21 t ha^-1 yr^-1). Results suggest erosion rates decrease through time, as the ley cover matures. Soil organic matter content increased consistently and significantly on the set-aside plots (mean of 1.07 percent by weight in 10 years) and soil erodibility significantly decreased. Results suggest using grass-leys for set-aside proves a valuable and viable soil conservation technique, which may contribute to carbon sequestration.

 

Keywords: Carbon sequestration, grassland, runoff plots, soil erodibility, soil conservation, soil organic matter

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