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Ranjith P Udawatta - One of the best experts on this subject based on the ideXlab platform.

  • agroforestry buffers for nonpoint source pollution reductions from Agricultural Watersheds
    Journal of Environmental Quality, 2011
    Co-Authors: Ranjith P Udawatta, H E Garrett, Robert L Kallenbach
    Abstract:

    Despite increased attention and demand for the adoption of agroforestry practices throughout the world, rigorous long-term scientific studies confirming environmental benefits from the use of agroforestry practices are limited. The objective was to examine nonpoint-source pollution (NPSP) reduction as influenced by agroforestry buffers in Watersheds under grazing and row crop management. The grazing study consists of six Watersheds in the Central Mississippi Valley wooded slopes and the row crop study site consists of three Watersheds in a paired watershed design in Central Claypan areas. Runoff water samples were analyzed for sediment, total nitrogen (TN), and total phosphorus (TP) for the 2004 to 2008 period. Results indicate that agroforestry and grass buffers on grazed and row crop management sites significantly reduce runoff, sediment, TN, and TP losses to streams. Buffers in association with grazing and row crop management reduced runoff by 49 and 19%, respectively, during the study period as compared with respective control treatments. Average sediment loss for grazing and row crop management systems was 13.8 and 17.9 kg ha yr, respectively. On average, grass and agroforestry buffers reduced sediment, TN, and TP losses by 32, 42, and 46% compared with the control treatments. Buffers were more effective in the grazing management practice than row crop management practice. These differences could in part be attributed to the differences in soils, management, and landscape features. Results from this study strongly indicate that agroforestry and grass buffers can be designed to improve water quality while minimizing the amount of land taken out of production.

  • runoff and dissolved organic carbon loss from a paired watershed study of three adjacent Agricultural Watersheds
    Agriculture Ecosystems & Environment, 2009
    Co-Authors: Kristen S Veum, Keith W Goyne, Peter P Motavalli, Ranjith P Udawatta
    Abstract:

    Organic matter plays several important roles in the biogeochemistry of terrestrial and aquatic ecosystems including the mobilization and transport of nutrients and pollutants. Cropping, tillage practices and vegetative buffer strip installation affect losses of dissolved organic carbon (DOC). While many studies show reductions in pollutant export from agroecosystems where vegetative buffers have been implemented, buffer strips may be a source of DOC and contribute to surface water pollution. Using a paired-watershed approach, the objectives of this study were to determine the effect of grass and agroforestry buffers on runoff and DOC loss, compare runoff and DOC losses between the growing and fallow seasons, and investigate crop effects on runoff and DOC losses. The study design consisted of three small Agricultural Watersheds in a no-till, maize-soybean rotation located in the claypan region of northeast Missouri, USA; one watershed was planted with grass buffer strips, one with agroforestry buffer strips, and one unaltered watershed served as the control. Runoff and DOC loss were measured during a six-year calibration period (1991–1997) prior to buffer installation and for a nine-year treatment period (1997–2006). The grass buffer strips significantly decreased runoff by 8.4% (p = 0.015) during the treatment period while the agroforestry buffer system exhibited no significant change in runoff (p = 0.207). Loss of DOC was not significantly affected by grass or agroforestry buffer installation (p = 0.535 and p = 0.246, respectively). Additionally, no significant difference in runoff or DOC loss was found between crops (maize and soybean) or between seasons (growing and fallow). Overall, this study indicates that grass buffer systems are effective at reducing runoff and that DOC contamination of surface waters is not exacerbated by either type of vegetative buffer strip.

  • nitrogen losses in runoff from three adjacent Agricultural Watersheds with claypan soils
    Agriculture Ecosystems & Environment, 2006
    Co-Authors: Ranjith P Udawatta, H E Garrett, Peter P Motavalli, John J Krstansky
    Abstract:

    Abstract Despite improvements in the use of soil conservation practices, crop rotation and managed fertilizer applications, large losses of nitrogen (N) in runoff continue to occur from row-cropped Watersheds. Increasing requirements for implementing water quality standards in the United States, has increased pressure for the development of research-based guidelines to reduce N losses from Agricultural runoff. The objectives of this study were to examine the effects of management, watershed characteristics, and precipitation on TN and nitrate-N (NO3−-N) loss over time by comparing losses on three adjacent Watersheds with claypan soils. The three adjacent north-facing, corn–soybean rotational Watersheds in northeastern Missouri were instrumented with H-flumes, water samplers, and flow-monitoring devices in 1991. Runoff samples from each individual rainfall event between 1991 and 1997 were analyzed for TN and NO3−-N concentrations. The 7-year mean annual TN losses on the three Watersheds ranged from 13 to 19 kg ha−1 with a mean of 16 kg ha−1. Nitrate-N losses ranged from 8 to 14 kg ha−1 with a mean of 11 kg ha−1. During the study, 67% of the TN was lost as NO3−-N with a range from 22% in 1997 to 76% in 1996. The mean annual TN losses for corn and soybean years during the study were 30.7 and 5.7 kg ha−1, respectively. Significantly higher loss (57%) of N from Watersheds occurred during the period between fall harvest and spring planting when crops were not present (referred to as the “fallow” period in this paper; 86.8 kg ha−1) compared to N losses during the cropping period (64.5 kg ha−1). In 1994, 96% of the annual TN loss and 98% of the annual NO3−-N loss occurred during the fallow period. In contrast, the lowest fallow period losses of TN (19%) and NO3−-N (14%) occurred in 1993. The watershed-mean TN and NO3−-N losses in 1993 alone accounted for 44 and 46% of the total losses observed over the 7-year period because during that year the study area received 142% of the normal precipitation. When the study area received 51% of the annual precipitation before planting in 1996, the TN and NO3−-N losses accounted for 34 and 38% of the 7-year loss, respectively. Nitrogen fertilizer that was applied in 1993 and 1996 may also have contributed to the observed large losses. The results of this study suggest that the maintenance of a suitable vegetative cover throughout the year could reduce runoff and lower TN and NO3−-N loss from Agricultural Watersheds under a corn–soybean rotation.

  • phosphorus loss and runoff characteristics in three adjacent Agricultural Watersheds with claypan soils
    Journal of Environmental Quality, 2004
    Co-Authors: Ranjith P Udawatta, Peter P Motavalli, H E Garrett
    Abstract:

    Effects of precipitation, runoff, and management on total phosphorus (TP) loss from three adjacent, row-cropped Watersheds in the claypan region of northeastern Missouri were examined from 1991 to 1997 to understand factors affecting P loss in Watersheds dominated by claypan soils. Runoff samples from each individual runoff event were analyzed for TP and sediment concentration. The annual TP loss ranged from 0.29 to 3.59 kg ha(-1) with a mean of 1.36 kg ha(-1) across all the Watersheds during the study period. Significantly higher loss of TP from the Watersheds was observed during the fallow period. Multiple small runoff events or several large runoff events contributed to loss of TP from the Watersheds. Total P loss in 1993, a year with above-normal precipitation, accounted for 30% of the total TP loss observed over seven years. The five largest runoff events out of a total of 66 events observed over seven years accounted for 27% of the TP loss. The five largest sediment losses were responsible for 24% of the TP loss over seven years. Runoff volume and sediment loss explained 64 to 73% and 47 to 58% of the variation in TP loss on Watersheds during the study. Flow duration and maximum flow accounted for 49 and 66% of TP loss, respectively. The results of this study suggest that management practices that reduce runoff volume, flow duration, maximum flow, and sediment loss, and that maintain a suitable vegetative cover throughout the year could lower P loss in claypan soils.

D S Fisher - One of the best experts on this subject based on the ideXlab platform.

  • most probable number methodology for quantifying dilute concentrations and fluxes of escherichia coli o157 h7 in surface waters
    Journal of Applied Microbiology, 2009
    Co-Authors: Michael B Jenkins, Dinku M Endale, D S Fisher
    Abstract:

    Aims: To better understand the transport and enumeration of dilute densities of Escherichia coli O157:H7 in Agricultural Watersheds, we developed a culturebased, five tube-multiple dilution most probable number (MPN) method. Methods and Results: The MPN method combined a filtration technique for large volumes of surface water with standard selective media, biochemical and immunological tests, and a TaqMan confirmation step. This method determined E. coli O157:H7 concentrations as low as 0AE1 MPN per litre, with a 95% confidence level of 0AE01–0AE7 MPN per litre. Escherichia coli O157:H7 densities ranged from not detectable to 9 MPN per litre for pond inflow, from not detectable to 0AE9 MPN per litre for pond outflow and from not detectable to 8AE3 MPN per litre for within pond. The MPN methodology was extended to mass flux determinations. Fluxes of E. coli O157:H7 ranged from 10 4 MPN per hour. Conclusion: This culture-based method can detect small numbers of viable ⁄ culturable E. coli O157:H7 in surface waters of Watersheds containing animal agriculture and wildlife. Significance and Impact of the Study: This MPN method will improve our understanding of the transport and fate of E. coli O157:H7 in Agricultural Watersheds, and can be the basis of collections of environmental E. coli

  • most probable number methodology for quantifying dilute concentrations and fluxes of salmonella in surface waters
    Journal of Applied Microbiology, 2008
    Co-Authors: Michael B Jenkins, Dinku M Endale, D S Fisher
    Abstract:

    Aims: To better understand and manage the fate and transport of Salmonella in Agricultural Watersheds, we developed a culture-based, five tube‐four dilution most probable number (MPN) method for enumerating dilute densities of Salmonella in environmental waters. Methods and Results: The MPN method was a combination of a filtration technique for large sample volumes of environmental water, standard selective media for Salmonella and a TaqMan confirmation step. This method has determined the density of Salmonella in 20-l samples of pond inflow and outflow streams as low as 0AE1 MPN l )1 and a low 95% confidence level 0AE015 MPN l )1 . Salmonella densities ranged from not detectable to 0AE55 MPN l )1 for pond inflow samples and from not detectable to 3AE4 MPN l )1 for pond outflow samples. Salmonella densities of pond inflow samples were associated with densities of Escherichia coli and faecal enterococci that indicated stream contamination with faeces and with nondetectable pond outflow densities of the faecal indicator bacteria. The MPN methodology was extended to flux determinations by integrating with volumetric measurements of pond inflow (mean flux of 2AE 5ls )1 ) and outflow (mean flux of 5AE 6ls )1 ). Fluxes of Salmonella ranged from 100 to greater than 10 4 MPN h )1 . Conclusions: This is a culture-based method that can detect small numbers of Salmonella in environmental waters of Watersheds containing animal husbandry and wildlife. Significance and Impact of the Study: Applying this method to environmental waters will improve our understanding of the transport and fate of Salmonella in Agricultural Watersheds, and can be the basis of valuable collections of environmental Salmonella.

  • hydrology of a zero order southern piedmont watershed through 45 years of changing Agricultural land use part 1 monthly and seasonal rainfall runoff relationships
    Journal of Hydrology, 2006
    Co-Authors: Dinku M Endale, D S Fisher, Jean L Steiner
    Abstract:

    Abstract Few studies have reported runoff from small Agricultural Watersheds over sufficiently long period so that the effect of different cover types on runoff can be examined. We analyzed 45-yrs of monthly and annual rainfall-runoff characteristics of a small (7.8 ha) zero-order typical Southern Piedmont watershed in southeastern United States. Agricultural land use varied as follows: 1. Row cropping (5-yrs); 2. Kudzu (Pueraria lobata; 5-yrs); 3. Grazed kudzu and rescuegrass (Bromus catharticus; 7-yrs); and 4. Grazed bermudagrass and winter annuals (Cynodon dactylon; 28-yrs). Land use and rainfall variability influenced runoff characteristics. Row cropping produced the largest runoff amount, percentage of the rainfall partitioned into runoff, and peak flow rates. Kudzu reduced spring runoff and almost eliminated summer runoff, as did a mixture of kudzu and rescuegrass (KR) compared to row cropping. Peak flow rates were also reduced during the kudzu and KR. Peak flow rates increased under bermudagrass but were lower than during row cropping. A simple process-based ‘tanh’ model modified to take the previous month's rainfall into account produced monthly rainfall and runoff correlations with coefficient of determination (R2) of 0.74. The model was tested on independent data collected during drought. Mean monthly runoff was 1.65 times the observed runoff. Sustained hydrologic monitoring is essential to understanding long-term rainfall-runoff relationships in Agricultural Watersheds.

David R. Lapen - One of the best experts on this subject based on the ideXlab platform.

  • Long-Term Observations of Nitrogen and Phosphorus Export in Paired-Agricultural Watersheds under Controlled and Conventional Tile Drainage
    Journal of environmental quality, 2015
    Co-Authors: Mark Sunohara, Emilia Craiovan, Edward Topp, N. Gottschall, Steven K. Frey, Graham Wilkes, Z Que, Ousmane Seidou, David R. Lapen
    Abstract:

    Controlled tile drainage (CTD) regulates water and nutrient export from tile drainage systems. Observations of the effects of CTD imposed en masse at watershed scales are needed to determine the effect on downstream receptors. A paired-watershed approach was used to evaluate the effect of field-to-field CTD at the watershed scale on fluxes and flow-weighted mean concentrations (FWMCs) of N and P during multiple growing seasons. One watershed (467-ha catchment area) was under CTD management (treatment [CTD] watershed); the other (250-ha catchment area) had freely draining or uncontrolled tile drainage (UCTD) (reference [UCTD] watershed). The paired Agricultural Watersheds are located in eastern Ontario, Canada. Analysis of covariance and paired tests were used to assess daily fluxes and FWMCs during a calibration period when CTD intervention on the treatment watershed was minimal (2005-2006, when only 4-10% of the tile-drained area was under CTD) and a treatment period when the treatment (CTD) watershed had prolific CTD intervention (2007-2011 when 82% of tile drained fields were controlled, occupying >70% of catchment area). Significant linear regression slope changes assessed using ANCOVA ( ≤ 0.1) for daily fluxes from upstream and downstream monitoring sites pooled by calibration and treatment period were -0.06 and -0.20 (stream water) (negative values represent flux declines in CTD watershed), -0.59 and -0.77 (NH-N), -0.14 and -0.15 (NO-N), -1.77 and -2.10 (dissolved reactive P), and -0.28 and 0.45 (total P). Total P results for one site comparison contrasted with other findings likely due to unknown in-stream processes affecting total P loading, not efficacy of CTD. The FWMC results were mixed and inconclusive but suggest physical abatement by CTD is the means by which nutrient fluxes are predominantly reduced at these scales. Overall, our study results indicate that CTD is an effective practice for reducing watershed scale fluxes of stream water, N, and P during the growing season.

  • investigation of an escherichia coli environmental benchmark for waterborne pathogens in Agricultural Watersheds in canada
    Journal of Environmental Quality, 2012
    Co-Authors: Thomas A Edge, David R. Lapen, A H Elshaarawi, Victor P J Gannon, Cassandra C Jokinen, Robert A Kent, Izhar U H Khan, Wendell Koning, J J Miller, Norman F Neumann
    Abstract:

    Canada's National Agri-Environmental Standards Initiative sought to develop an environmental benchmark for low-level waterborne pathogen occurrence in Agricultural Watersheds. A field study collected 902 water samples from 27 sites in four intensive Agricultural Watersheds across Canada from 2005 to 2007. Four of the sites were selected as reference sites away from livestock and human fecal pollution sources in each watershed. Water samples were analyzed for Campylobacter spp., Salmonella spp., Escherichia coli O157:H7, Cryptosporidium spp., Giardia spp., and the water quality indicator E. coli. The annual mean number of pathogen species was higher at Agricultural sites (1.54 ± 0.07 species per water sample) than at reference sites (0.75 ± 0.14 species per water sample). The annual mean concentration of E. coli was also higher at Agricultural sites (491 ± 96 colony-forming units [cfu] 100 mL(-1)) than at reference sites (53 ± 18 cfu 100 mL(-1)). The feasibility of adopting existing E. coli water quality guideline values as an environmental benchmark was assessed, but waterborne pathogens were detected at Agricultural sites in 80% of water samples with low E. coli concentrations (<100 cfu 100 mL(-1)). Instead, an approach was developed based on using the natural background occurrence of pathogens at reference sites in Agricultural Watersheds to derive provisional environmental benchmarks for pathogens at Agricultural sites. The environmental benchmarks that were derived were found to represent E. coli values lower than geometric mean values typically found in recreational water quality guidelines. Additional research is needed to investigate environmental benchmarks for waterborne pathogens within the context of the "One World, One Health" perspective for protecting human, domestic animal, and wildlife health.

H E Garrett - One of the best experts on this subject based on the ideXlab platform.

  • agroforestry buffers for nonpoint source pollution reductions from Agricultural Watersheds
    Journal of Environmental Quality, 2011
    Co-Authors: Ranjith P Udawatta, H E Garrett, Robert L Kallenbach
    Abstract:

    Despite increased attention and demand for the adoption of agroforestry practices throughout the world, rigorous long-term scientific studies confirming environmental benefits from the use of agroforestry practices are limited. The objective was to examine nonpoint-source pollution (NPSP) reduction as influenced by agroforestry buffers in Watersheds under grazing and row crop management. The grazing study consists of six Watersheds in the Central Mississippi Valley wooded slopes and the row crop study site consists of three Watersheds in a paired watershed design in Central Claypan areas. Runoff water samples were analyzed for sediment, total nitrogen (TN), and total phosphorus (TP) for the 2004 to 2008 period. Results indicate that agroforestry and grass buffers on grazed and row crop management sites significantly reduce runoff, sediment, TN, and TP losses to streams. Buffers in association with grazing and row crop management reduced runoff by 49 and 19%, respectively, during the study period as compared with respective control treatments. Average sediment loss for grazing and row crop management systems was 13.8 and 17.9 kg ha yr, respectively. On average, grass and agroforestry buffers reduced sediment, TN, and TP losses by 32, 42, and 46% compared with the control treatments. Buffers were more effective in the grazing management practice than row crop management practice. These differences could in part be attributed to the differences in soils, management, and landscape features. Results from this study strongly indicate that agroforestry and grass buffers can be designed to improve water quality while minimizing the amount of land taken out of production.

  • nitrogen losses in runoff from three adjacent Agricultural Watersheds with claypan soils
    Agriculture Ecosystems & Environment, 2006
    Co-Authors: Ranjith P Udawatta, H E Garrett, Peter P Motavalli, John J Krstansky
    Abstract:

    Abstract Despite improvements in the use of soil conservation practices, crop rotation and managed fertilizer applications, large losses of nitrogen (N) in runoff continue to occur from row-cropped Watersheds. Increasing requirements for implementing water quality standards in the United States, has increased pressure for the development of research-based guidelines to reduce N losses from Agricultural runoff. The objectives of this study were to examine the effects of management, watershed characteristics, and precipitation on TN and nitrate-N (NO3−-N) loss over time by comparing losses on three adjacent Watersheds with claypan soils. The three adjacent north-facing, corn–soybean rotational Watersheds in northeastern Missouri were instrumented with H-flumes, water samplers, and flow-monitoring devices in 1991. Runoff samples from each individual rainfall event between 1991 and 1997 were analyzed for TN and NO3−-N concentrations. The 7-year mean annual TN losses on the three Watersheds ranged from 13 to 19 kg ha−1 with a mean of 16 kg ha−1. Nitrate-N losses ranged from 8 to 14 kg ha−1 with a mean of 11 kg ha−1. During the study, 67% of the TN was lost as NO3−-N with a range from 22% in 1997 to 76% in 1996. The mean annual TN losses for corn and soybean years during the study were 30.7 and 5.7 kg ha−1, respectively. Significantly higher loss (57%) of N from Watersheds occurred during the period between fall harvest and spring planting when crops were not present (referred to as the “fallow” period in this paper; 86.8 kg ha−1) compared to N losses during the cropping period (64.5 kg ha−1). In 1994, 96% of the annual TN loss and 98% of the annual NO3−-N loss occurred during the fallow period. In contrast, the lowest fallow period losses of TN (19%) and NO3−-N (14%) occurred in 1993. The watershed-mean TN and NO3−-N losses in 1993 alone accounted for 44 and 46% of the total losses observed over the 7-year period because during that year the study area received 142% of the normal precipitation. When the study area received 51% of the annual precipitation before planting in 1996, the TN and NO3−-N losses accounted for 34 and 38% of the 7-year loss, respectively. Nitrogen fertilizer that was applied in 1993 and 1996 may also have contributed to the observed large losses. The results of this study suggest that the maintenance of a suitable vegetative cover throughout the year could reduce runoff and lower TN and NO3−-N loss from Agricultural Watersheds under a corn–soybean rotation.

  • phosphorus loss and runoff characteristics in three adjacent Agricultural Watersheds with claypan soils
    Journal of Environmental Quality, 2004
    Co-Authors: Ranjith P Udawatta, Peter P Motavalli, H E Garrett
    Abstract:

    Effects of precipitation, runoff, and management on total phosphorus (TP) loss from three adjacent, row-cropped Watersheds in the claypan region of northeastern Missouri were examined from 1991 to 1997 to understand factors affecting P loss in Watersheds dominated by claypan soils. Runoff samples from each individual runoff event were analyzed for TP and sediment concentration. The annual TP loss ranged from 0.29 to 3.59 kg ha(-1) with a mean of 1.36 kg ha(-1) across all the Watersheds during the study period. Significantly higher loss of TP from the Watersheds was observed during the fallow period. Multiple small runoff events or several large runoff events contributed to loss of TP from the Watersheds. Total P loss in 1993, a year with above-normal precipitation, accounted for 30% of the total TP loss observed over seven years. The five largest runoff events out of a total of 66 events observed over seven years accounted for 27% of the TP loss. The five largest sediment losses were responsible for 24% of the TP loss over seven years. Runoff volume and sediment loss explained 64 to 73% and 47 to 58% of the variation in TP loss on Watersheds during the study. Flow duration and maximum flow accounted for 49 and 66% of TP loss, respectively. The results of this study suggest that management practices that reduce runoff volume, flow duration, maximum flow, and sediment loss, and that maintain a suitable vegetative cover throughout the year could lower P loss in claypan soils.

K Auerswald - One of the best experts on this subject based on the ideXlab platform.

  • seasonal variation of grassed waterway effectiveness in reducing runoff and sediment delivery from Agricultural Watersheds in temperate europe
    Soil & Tillage Research, 2006
    Co-Authors: Peter Fiener, K Auerswald
    Abstract:

    Abstract Grassed waterways (GWWs) with large hydraulic roughness exhibit a great potential to reduce runoff, sediments and pollutants coming from Agricultural Watersheds. For conservation planning the knowledge of overall effectiveness and its seasonal variation is highly relevant. Our objectives were to (i) evaluate the seasonal variation in runoff reduction and sediment trapping in a GWW, (ii) identify the driving parameters and (iii) measure and analyse the seasonal variation of each of these parameters. Runoff and sediment delivery were measured between 1994 and 2001 in two paired subWatersheds, both optimised to reduce runoff and sediment delivery by an intensive soil conservation system within the fields. In one of the subWatersheds additionally a GWW (290 m long, 37 m wide) was established to further improve soil and water conservation. During the observation period it reduced runoff and sediment delivery by 87 and 93%, respectively. 70% of total outflow and 68% of total sediment output occurred between February and April, mainly controlled by watershed hydrology. Seasonal changes in GWW properties, namely soil water content and hydraulic roughness, had a minor effect. It was most notably in May and June, when available field capacity averaged 59% while inflow was dominated by single heavy rain events (15% of total inflow). In general, the results indicate the high potential of GWWs for reducing runoff and sediment delivery, especially if combined with an intensive soil and water conservation system in the draining fields. For conservation planning, the least effectiveness at the end of winter should be taken into account.

  • managing erosion and water quality in Agricultural Watersheds by small detention ponds
    Agriculture Ecosystems & Environment, 2005
    Co-Authors: Peter Fiener, K Auerswald, S Weigand
    Abstract:

    Abstract Terrace-contouring systems with on-site water detention cannot be installed in areas of complex topography, small parceling and multi-blade moldboard plow use. However, field borders at the downslope end may be raised at the deepest part where runoff overtops to create detention ponds, which can be drained by subsurface tile outlets and act similar to terrace-contouring systems. Four of such detention ponds were monitored over 8 years. Monitored effects included the prevention of linear erosion down slope, the sediment trapping from upslope, the enrichment of major nutrients in the trapped and delivered sediments, the amount of runoff retained temporarily, the amount of runoff reduced by infiltration, the decrease in peak runoff rate and the decrease in peak concentrations of agrochemicals due to the mixing of different volumes of water within the detention ponds. The detention ponds had a volume of 30–260 m 3  ha −1 and trapped 54–85% of the incoming sediment, which was insignificantly to slightly depleted (5–25%) in organic carbon, phosphorus, nitrogen and clay as compared to the eroding topsoil, while the delivered sediment was strongly enriched (+70–270%) but part of this enrichment already resulted from the enrichment of soil loss. The detention ponds temporarily stored 200–500 m 3 of runoff. A failure was never experienced. Due to the siltation of the pond bottom, the short filled time (1–5 days) and the small water covered area, infiltration and evaporation reduced runoff by less than 10% for large events. Peak runoff during heavy rains was lowered by a factor of three. Peak concentrations of agrochemicals (Terbutylazin) were lowered by a factor of two. The detention ponds created by raising the downslope field borders at the pour point efficiently reduced adverse erosion effects downslope the eroding site. They are cheap and can easily be created with on-farm machinery. Their efficiency is improved where they are combined with an on-site erosion control like mulch tillage because sediment and runoff input are reduced. Ponds had to be dredged only after the first year when on-site erosion control was not fully effective.

  • effectiveness of grassed waterways in reducing runoff and sediment delivery from Agricultural Watersheds
    Journal of Environmental Quality, 2003
    Co-Authors: Peter Fiener, K Auerswald
    Abstract:

    Grassed waterways (GWWs) drain surface runoff from fields without gullying along the drainageway. Secondary functions include reducing runoff volume and velocity and retaining sediments and harmful substances from adjacent fields. Grass cover (sward)-damaging sedimentation in the GWW is commonly reduced by frequent mowing, but in doing so the effectiveness of the waterway relative to the secondary functions is reduced. Our objectives were to (i) evaluate whether the maintenance of a GWW can be reduced if on-site erosion control is effective, (ii) measure the effectiveness of such a GWW, and (iii) analyze the underlying mechanisms. A long-term (1994-2000) landscape experiment was performed in four Watersheds, where two had GWWs for which maintenance was largely neglected. An intensive soil conservation system was established on all fields. Runoff and sediment delivery were continuously measured in the two Watersheds with GWWs and in their paired Watersheds that were similar, but without GWWs. Runoff was reduced by 90 and 10% for the two sets of paired Watersheds, respectively. The different efficiencies of the GWWs resulted from different layouts (doubled width and flat-bottomed vs. v-shaped drainageway). The GWWs reduced sediment delivery by 97 and 77%, respectively, but the sward was not damaged by sedimentation. Grain sizes > 50 microm were settled due to gravity in both GWWs. Smaller grain sizes were primarily settled due to infiltration, which increased with a more effective runoff reduction. In general, the results indicated a high potential of GWWs for reducing runoff volume and velocity, sediments, and agrochemicals coming from Agricultural Watersheds.