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J.w. Gilliam - One of the best experts on this subject based on the ideXlab platform.
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Measurement and modeling of denitrification in Poorly Drained Soils of the lower coastal plain
2006Co-Authors: F. Birgand, R. W. Skaggs, F. Giraud, G.m. Chescheir, J.w. GilliamAbstract:A nitrogen budget study was carried out on Poorly Drained Soils of the lower coastal plain of North Carolina near the town of Plymouth in summer 1994. Four experimental plots were monitored in four sites representing a panel of water regimes (high and low water table) and land use (artificially Drained agricultural fields and natural forested wetland) commonly found in the lower coastal plain. The nitrogen budget was measured on a monthly basis, layer by layer, down to 1.50 m in depth. Net mineralization, leaching and plant uptake were calculated from the nitrogen content evolution during a month of in situ soil cores receiving different treatments. Treatments were obtained by isolating undisturbed soil cores using PVC pipes driven into the soil, left in situ for a month, period after which the cores were recovered for analyses. Denitrification rates were measured in the laboratory from undisturbed soil cores using the acetylene inhibition technique. Closely monitoring nitrous oxide accumulation in the head space of the denitrification incubation chambers revealed variations rarely taken into account in publications. Consequences on denitrification rates reported and used for model calibration are discussed. Water free pore spaces (WFPS) thresholds for denitrification were estimated for each layer of the four sites varying from 0.4 to 0.85, although most are above 0.7. Thresholds seem to be lower in the surface horizons and increase with depth. WFPS threshold were estimated to be slightly lower for the agricultural sites than for the forested ones.
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Predicting effects of water table management on loss of nitrogen from Poorly Drained Soils
European Journal of Agronomy, 1995Co-Authors: R. W. Skaggs, M.a. Brve, J.w. GilliamAbstract:Abstract Agricultural drainage and related water management practices affect the quality and quantity of water leaving the field and entering ground and surface waters. The design and management of drainage systems should consider these impacts, as well as effects on agricultural production. In many instances, water quality and environmental requirements have a priority greater than that of maximizing agricultural productivity and profits. This paper describes the application of a simulation model, DRAINMOD-N, to predict the effects of design and management of subsurface drainage systems on nitrogen losses and crop yields. DRAINMOD-N uses hydrologic predictions by DRAINMOD, including daily soil water fluxes, in numerical solutions to the advective-dispersive-reactive (ADR) equation to describe movement and fate of NO3-N in shallow water table Soils. Simulations were conducted for maize production on a Portsmouth sandy loam soil (Thermic, Typic Umbraquult) in the North Carolina Coastal Plain. Agricultural production objectives could be satisfied with 1 m deep parallel drains spaced 40 m apart or less. Predicted losses of NO3-N were significantly affected by drainage design and management. Increasing drain spacing from 20 to 40 m decreased NO3-N losses by 47 per cent. Nitrate losses can be further reduced by placing a weir in the drainage outlet so as to raise the water level in the outlet and reduce subsurface drainge rates. This practice, called controlled drainage, can be applied in both the growing season and the nongrowing season, and can be varied in intensity (with season) by placing the weir closer to or further below the soil surface. Controlled drainage during both the growing season and winter months reduced NO3-N losses from an annual average of 21.8 kg ha−1 to 10.5 kg ha−1 (52 per cent) for a 30 m drain spacing, without reducing crop yields. Analysis of simulated results on a year-by-year basis showed that large losses of NO3-N via drainage water occur in years following droughts when crops remove little of the fertilizer N because of reduced yields. Losses to the environment under these circumstances can be reduced by increasing the intensity of drainage control to minimize subsurface drainage during the following year. In one year, for example, raising the weir in the drainage outlet to a 25 cm depth directly after harvest and holding it there until time for seedbed preparation (one month prior to planting) in the spring reduced predicted NO3-N losses by 77 per cent compared to conventional drainage and by 60 per cent compared to currently recommended controlled drainage practices. The effectiveness of intensive drainage control was not as great in other years, but reduced NO3-N losses by at least 20 per cent in the years analysed. Results of this study indicate simulation modelling can be used to design and guide the management of drainage systems to address both agricultural productivity and environmental objectives.
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Wet Soils in the North Carolina lower Coastal Plain
Wetlands, 1991Co-Authors: J.w. GilliamAbstract:MostSoils in the lower Coastal Plain are potentially “wet.” However, the wettest Soils are usually those that are either next to major streams and estuaries or are on the interstream divides and broad flats. The Soils next to streams are usually wet from water coming from higher elevations, and the Soils on the interstream divides are wet because both surface and subsurface drainage is restricted. The largest areas of very Poorly Drained Soils are those on the interstream divides. The degree of wetness is the main factor determining the characteristics of the Soils found at a particular location. Deep organics (Typic Medisaprists) are located on sites that have historically been the wettest. As the Soils became progressively drier, shallow organic Soils (Terric Medisaprists), mineral Soils with a Histic epipedon (organic surface) and mineral Soils are found. The location and type of soil are both important factors influencing value of the land for development purposes and for water quality preservation. The Poorly Drained Soils immediately adjacent to streams or estuaries are much more valuable for water quality purposes than those located some distance from important water bodies. Organic Soils have the greatest potential for denitrification but very low capacity for phosphorus sorption.
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MEASUREMENT AND MODELING OF NITROGEN BUDGET IN Poorly Drained Soils OF THE LOWER COASTAL PLAIN
Hydrology and Management of Forested Wetlands Proceedings of the International Conference April 8-12 2006 New Bern North Carolina, 1Co-Authors: F. Birgand, R. W. Skaggs, F. Giraud, G.m. Chescheir, M. A. Youssef, J.w. GilliamAbstract:A nitrogen budget study was carried out on Poorly Drained Soils of the lower coastal plain of North Carolina near the town of Plymouth in summer 1994. Four experimental plots were monitored in four sites representing a panel of water regimes (high and low water table) and land use (artificially Drained agricultural fields and natural forested wetland) commonly found in the lower coastal plain. The nitrogen budget was measured on a monthly basis, layer by layer, down to 1.50 m in depth. Net mineralization, leaching and plant uptake were calculated from the nitrogen content evolution during a month of in situ soil cores receiving different treatments. Treatments were obtained by isolating undisturbed soil cores using PVC pipes driven into the soil, left in situ for a month, period after which the cores were recovered for analyses. Denitrification rates were measured in the laboratory from undisturbed soil cores using the acetylene inhibition technique. Closely monitoring nitrous oxide accumulation in the head space of the denitrification incubation chambers revealed variations rarely taken into account in publications. Consequences on denitrification rates reported and used for model calibration are discussed. Water free pore spaces (WFPS) thresholds for denitrification were estimated for each layer of the four sites varying from 0.4 to 0.85, although most are above 0.7. Thresholds seem to be lower in the surface horizons and increase with depth. WFPS threshold were estimated to be slightly lower for the agricultural sites than for the forested ones.
R. W. Skaggs - One of the best experts on this subject based on the ideXlab platform.
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Measurement and modeling of denitrification in Poorly Drained Soils of the lower coastal plain
2006Co-Authors: F. Birgand, R. W. Skaggs, F. Giraud, G.m. Chescheir, J.w. GilliamAbstract:A nitrogen budget study was carried out on Poorly Drained Soils of the lower coastal plain of North Carolina near the town of Plymouth in summer 1994. Four experimental plots were monitored in four sites representing a panel of water regimes (high and low water table) and land use (artificially Drained agricultural fields and natural forested wetland) commonly found in the lower coastal plain. The nitrogen budget was measured on a monthly basis, layer by layer, down to 1.50 m in depth. Net mineralization, leaching and plant uptake were calculated from the nitrogen content evolution during a month of in situ soil cores receiving different treatments. Treatments were obtained by isolating undisturbed soil cores using PVC pipes driven into the soil, left in situ for a month, period after which the cores were recovered for analyses. Denitrification rates were measured in the laboratory from undisturbed soil cores using the acetylene inhibition technique. Closely monitoring nitrous oxide accumulation in the head space of the denitrification incubation chambers revealed variations rarely taken into account in publications. Consequences on denitrification rates reported and used for model calibration are discussed. Water free pore spaces (WFPS) thresholds for denitrification were estimated for each layer of the four sites varying from 0.4 to 0.85, although most are above 0.7. Thresholds seem to be lower in the surface horizons and increase with depth. WFPS threshold were estimated to be slightly lower for the agricultural sites than for the forested ones.
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Hydrologic Modeling of a Drained Pine Plantation on Poorly Drained Soils
2001Co-Authors: Devendra M. Amatya, R. W. SkaggsAbstract:Three experimental watersheds in eastern North Carolina have been continuously monitored since 1988 to study long-term hydrology of loblolly pine (Pinus taeda L.) forests on Poorly Drained Soils. This study was conducted to test the forestry version of an agricultural hydrology model DRAINMOD with 10 yr (1988-1997) of data collected at one of these watersheds under conventional (open ditch) drainage. The model, which is based on hourly water balance for the land between parallel drainage ditches, simulates interception, evapotranspiration (ET) as the sum of canopy transpiration and soil evaporation, drainage, and surface runoff. Results showed that model predictions of daily water table elevations and flow rates on an average annual basis were within 0.15 m and 0.61 mm, respectively, compared to the measured data. Relative errors on drainage outflow varied from -18% to 23%, with an average of 0.4%. Errors in measured flow rates during weir submergence, missing rainfall and weather data, and uncertainty in estimates of stomatal conductance contributed to the differences between model predictions and field observations. It was concluded that the model is a reliable tool for assessing hydrologic impacts of silvicultural and water management treatments, as well as climate changes, on these pine stands. FOR. SCI. 47(1):103-114.
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Predicting effects of water table management on loss of nitrogen from Poorly Drained Soils
European Journal of Agronomy, 1995Co-Authors: R. W. Skaggs, M.a. Brve, J.w. GilliamAbstract:Abstract Agricultural drainage and related water management practices affect the quality and quantity of water leaving the field and entering ground and surface waters. The design and management of drainage systems should consider these impacts, as well as effects on agricultural production. In many instances, water quality and environmental requirements have a priority greater than that of maximizing agricultural productivity and profits. This paper describes the application of a simulation model, DRAINMOD-N, to predict the effects of design and management of subsurface drainage systems on nitrogen losses and crop yields. DRAINMOD-N uses hydrologic predictions by DRAINMOD, including daily soil water fluxes, in numerical solutions to the advective-dispersive-reactive (ADR) equation to describe movement and fate of NO3-N in shallow water table Soils. Simulations were conducted for maize production on a Portsmouth sandy loam soil (Thermic, Typic Umbraquult) in the North Carolina Coastal Plain. Agricultural production objectives could be satisfied with 1 m deep parallel drains spaced 40 m apart or less. Predicted losses of NO3-N were significantly affected by drainage design and management. Increasing drain spacing from 20 to 40 m decreased NO3-N losses by 47 per cent. Nitrate losses can be further reduced by placing a weir in the drainage outlet so as to raise the water level in the outlet and reduce subsurface drainge rates. This practice, called controlled drainage, can be applied in both the growing season and the nongrowing season, and can be varied in intensity (with season) by placing the weir closer to or further below the soil surface. Controlled drainage during both the growing season and winter months reduced NO3-N losses from an annual average of 21.8 kg ha−1 to 10.5 kg ha−1 (52 per cent) for a 30 m drain spacing, without reducing crop yields. Analysis of simulated results on a year-by-year basis showed that large losses of NO3-N via drainage water occur in years following droughts when crops remove little of the fertilizer N because of reduced yields. Losses to the environment under these circumstances can be reduced by increasing the intensity of drainage control to minimize subsurface drainage during the following year. In one year, for example, raising the weir in the drainage outlet to a 25 cm depth directly after harvest and holding it there until time for seedbed preparation (one month prior to planting) in the spring reduced predicted NO3-N losses by 77 per cent compared to conventional drainage and by 60 per cent compared to currently recommended controlled drainage practices. The effectiveness of intensive drainage control was not as great in other years, but reduced NO3-N losses by at least 20 per cent in the years analysed. Results of this study indicate simulation modelling can be used to design and guide the management of drainage systems to address both agricultural productivity and environmental objectives.
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MEASUREMENT AND MODELING OF NITROGEN BUDGET IN Poorly Drained Soils OF THE LOWER COASTAL PLAIN
Hydrology and Management of Forested Wetlands Proceedings of the International Conference April 8-12 2006 New Bern North Carolina, 1Co-Authors: F. Birgand, R. W. Skaggs, F. Giraud, G.m. Chescheir, M. A. Youssef, J.w. GilliamAbstract:A nitrogen budget study was carried out on Poorly Drained Soils of the lower coastal plain of North Carolina near the town of Plymouth in summer 1994. Four experimental plots were monitored in four sites representing a panel of water regimes (high and low water table) and land use (artificially Drained agricultural fields and natural forested wetland) commonly found in the lower coastal plain. The nitrogen budget was measured on a monthly basis, layer by layer, down to 1.50 m in depth. Net mineralization, leaching and plant uptake were calculated from the nitrogen content evolution during a month of in situ soil cores receiving different treatments. Treatments were obtained by isolating undisturbed soil cores using PVC pipes driven into the soil, left in situ for a month, period after which the cores were recovered for analyses. Denitrification rates were measured in the laboratory from undisturbed soil cores using the acetylene inhibition technique. Closely monitoring nitrous oxide accumulation in the head space of the denitrification incubation chambers revealed variations rarely taken into account in publications. Consequences on denitrification rates reported and used for model calibration are discussed. Water free pore spaces (WFPS) thresholds for denitrification were estimated for each layer of the four sites varying from 0.4 to 0.85, although most are above 0.7. Thresholds seem to be lower in the surface horizons and increase with depth. WFPS threshold were estimated to be slightly lower for the agricultural sites than for the forested ones.
Nicholas M. Holden - One of the best experts on this subject based on the ideXlab platform.
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The environmental impact of dairy production on Poorly Drained Soils under future climate scenarios for Ireland
Journal of environmental management, 2018Co-Authors: Pooja Sharma, James Humphreys, Nicholas M. HoldenAbstract:Abstract The environmental impact of dairy production in Ireland has been widely studied and it is known that regional differences in management and impact are driven by climate. Climate change projections for Ireland predict increasing temperature, change in rainfall patterns and decreasing in solar radiation, varying by agroclimatic region. This study evaluated the environmental impacts of low-cost, grass-based, rotational-grazing dairy production on Poorly Drained Soils under climate change. The Dairy_sim model was used to determine the theoretical optimum dairy system management for five different locations in Ireland assuming a Poorly Drained soil resource under baseline (1981–2000) and future climate scenarios (2041–2060, high and low emissions scenarios). An optimum system was defined as having maximum grass production and grazed grass in the diet, minimum necessary silage, minimum imported feed, minimum housing days and a very small silage surplus. Life cycle assessment was then used to quantify the environmental impacts (climate change, eutrophication and acidification) for all scenarios. The dairy production systems were predicted to be more productive in the future, with climate change impacts per unit milk reduced or the same, acidification impacts reduced and eutrophication impacts reduced. The absolute emissions driving climate change and eutrophication were predicted to significantly increase for the future low emission scenario, and emissions driving acidification were predicted to slightly increase. The predictions indicate that system adaptation to mitigate absolute emissions are needed rather than just policies that focus on impacts per unit output.
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Simulation of the influence of poor soil drainage on grass‐based dairy production systems in Ireland
Grass and Forage Science, 2008Co-Authors: Joanne Fitzgerald, A. J. Brereton, Nicholas M. HoldenAbstract:A dairy cow system simulator, Dairy_sim, designed for assessing the interaction of climate and management on dairy cow production, based on rotational grass grazing, was further developed by integrating a soil water model. The soil water model was based on the concept of soil water deficits, and influenced the growth of grass herbage in the simulator when there was an excess of water over field capacity and when water content in the soil was approaching wilting point. The soil water model was tested using baseline meteorological data (1961‐1990) and then the system simulation was parameterized and tested for Poorly Drained Soils using data from a research farm in the west of Ireland. After testing, the effects of regional differences in climate on system management on well- and Poorly Drained Soils were compared. Down-scaled Global Climate Model (GCM) data for the baseline years (1961‐1990) were used for this purpose. These data resulted in slightly more favourable weather than that recorded. It was found that the simulator was capable of generating results in good agreement with published data for dairy production on Poorly Drained Soils. The regional analysis showed dairy farms on well-Drained Soils outperformed their equivalents on Poorly Drained Soils and, in general, were able to sustain higher stocking rates by 0AE6‐0AE9 cows ha )1 . Dry matter production was around 1AE5‐3 t ha )1 greater per annum on well-Drained Soils compared to Poorly Drained Soils. The simulator, Dairy_sim, also captured a large difference in the requirement for housing and forage between the well and Poorly Drained Soils. The simulation model can now be used to evaluate interactions between Soils, systems and weather, and is thus a more useful tool for developing practical advice and for evaluating the impacts of possible climate change.
James T. Green - One of the best experts on this subject based on the ideXlab platform.
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Runoff water quality from manured riparian grasslands with contrasting drainage and simulated grazing pressure
Agriculture Ecosystems & Environment, 2008Co-Authors: David M. Butler, Noah N. Ranells, Dorcas H. Franklin, Matthew H Poore, James T. GreenAbstract:Globally,management ofgrazedriparian areasiscriticallyimportanttoagriculturalsustainabilityandenvironmentalquality.However,the potential impacts of riparian grazing management on water quality are not well-documented, particularly in the southeastern USA. The objective of this work was to determine sediment and nutrient export under simulated rainfall from Poorly Drained and well-Drained riparian Soils where heavy or light grazing pressure by cattle was simulated. Plots were established on stands of existing vegetation to create grazing pressure treatments of (a) light-use (full ground cover, uncompacted), and with stands modified to establish (b) heavy-use (bare ground, compacted) treatments. Vegetation on Poorly Drained Soils consisted of several typical wetland species (e.g., Pontederia cordata L., Juncus coriaceus Mackenzie) in the southeastern USA, whereas mixed tall fescue (Festuca arundinacea Schreb.)‐dallisgrass (Paspalum dilatatum Poir.) stands were the dominant vegetation on well-Drained Soils. Runoff volumewas generally greater from heavy-use than from light-use for Poorly Drained Soils and for well-Drained Soils. Greater runoff volume was also observed from Poorly Drained Soils compared to well-Drained Soils for both light-use and for heavy-use treatments. Light-use plots were remarkably effective at minimizing export of total suspended solids (TSS)onboth Soils (
M.a. Brve - One of the best experts on this subject based on the ideXlab platform.
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Predicting effects of water table management on loss of nitrogen from Poorly Drained Soils
European Journal of Agronomy, 1995Co-Authors: R. W. Skaggs, M.a. Brve, J.w. GilliamAbstract:Abstract Agricultural drainage and related water management practices affect the quality and quantity of water leaving the field and entering ground and surface waters. The design and management of drainage systems should consider these impacts, as well as effects on agricultural production. In many instances, water quality and environmental requirements have a priority greater than that of maximizing agricultural productivity and profits. This paper describes the application of a simulation model, DRAINMOD-N, to predict the effects of design and management of subsurface drainage systems on nitrogen losses and crop yields. DRAINMOD-N uses hydrologic predictions by DRAINMOD, including daily soil water fluxes, in numerical solutions to the advective-dispersive-reactive (ADR) equation to describe movement and fate of NO3-N in shallow water table Soils. Simulations were conducted for maize production on a Portsmouth sandy loam soil (Thermic, Typic Umbraquult) in the North Carolina Coastal Plain. Agricultural production objectives could be satisfied with 1 m deep parallel drains spaced 40 m apart or less. Predicted losses of NO3-N were significantly affected by drainage design and management. Increasing drain spacing from 20 to 40 m decreased NO3-N losses by 47 per cent. Nitrate losses can be further reduced by placing a weir in the drainage outlet so as to raise the water level in the outlet and reduce subsurface drainge rates. This practice, called controlled drainage, can be applied in both the growing season and the nongrowing season, and can be varied in intensity (with season) by placing the weir closer to or further below the soil surface. Controlled drainage during both the growing season and winter months reduced NO3-N losses from an annual average of 21.8 kg ha−1 to 10.5 kg ha−1 (52 per cent) for a 30 m drain spacing, without reducing crop yields. Analysis of simulated results on a year-by-year basis showed that large losses of NO3-N via drainage water occur in years following droughts when crops remove little of the fertilizer N because of reduced yields. Losses to the environment under these circumstances can be reduced by increasing the intensity of drainage control to minimize subsurface drainage during the following year. In one year, for example, raising the weir in the drainage outlet to a 25 cm depth directly after harvest and holding it there until time for seedbed preparation (one month prior to planting) in the spring reduced predicted NO3-N losses by 77 per cent compared to conventional drainage and by 60 per cent compared to currently recommended controlled drainage practices. The effectiveness of intensive drainage control was not as great in other years, but reduced NO3-N losses by at least 20 per cent in the years analysed. Results of this study indicate simulation modelling can be used to design and guide the management of drainage systems to address both agricultural productivity and environmental objectives.