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Author: Tracy Alanna Campbell
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Across the Midwest, farmers, researchers, policy makers and communities are confronting increasing groundwater contamination due to agricultural practices, particularly the use of synthetic nitrogen fertilizer, coupled with the challenge of employing these practices to continue growing profitable crops. Additionally, not only are the impacts of agricultural practices felt at the local level-often in the form of agricultural runoff, unsafe drinking water, soil erosion, and decreased stream and lake levels-but also nationally. As agricultural runoff travels downstream to the Gulf of Mexico, excess nutrients have resulted in dead zones. It is likely that ongoing and future climate change across the Midwest will exacerbate current struggles and may leave many fields more vulnerable to nitrate leaching. Moving forward, to ensure safe drinking water and restore and protect ecosystem services, nitrogen management strategies need to be improved and implemented. The Wisconsin Central Sands (WCS) faces many of the challenges felt by communities across the Midwest when managing agricultural land with growing water quality contamination. The WCS region serves as a case study in improving nitrogen management for groundwater quality. To better identify pathways to improved groundwater quality, we incorporated on-farm research related to drivers of water quality variability, observations of soil-plant-environment interactions, agroecosystem modeling, and farmer surveys. In chapter one, we evaluated/quantified the spatiotemporal variability of nitrate concentrations in irrigation water across the WCS region. Additionally, we analyzed the influence of well depth, well casing diameter, nitrogen application rate, year and week of sampling event on nitrate concentration in irrigation water. We found that nitrate levels varied more across space than time, that nitrogen application rate was the most significant predictor of nitrate concentration, and that on average, nitrate levels in irrigation water across the WCS are 19.0 mg/L, or nearly twice the threshold for safe drinking water set by the EPA. In chapter two, we measured leaf level photosynthesis and calculated key photosynthetic parameters for two cultivars of potato grown under four nitrogen application rates. We found that nitrogen application rate (season total N), days after emergence (DAE), and temperature were significant predictors of Vcmax (maximum rate of carboxylation). We also found that at the highest level of nitrogen application (403.5 kg N/ha), both N content (%) and Vcmax declined relative to a nitrogen application rate of 336.3 kg N/ha. In chapter three, we modeled the impact of nitrogen best management practices (BMPs) with varied N rates on irrigated corn yield and nitrate leaching. To better understand the effectiveness and tradeoffs of BMPs considering increased weather variability, we used cluster analysis to group similar weather years. We found that nitrate leaching could be reduced through the use of BMPs (20%) and reduced nitrogen application rates (40%), but there was little room for mitigation during years experiencing wetter than average growing seasons. Additionally, nitrate concentration in the groundwater never reached safe/healthy levels (below 10 mg/L) in our simulations. In chapter four, we surveyed farmers on their current use of nitrogen BMPs, levels of concern towards environmental and economic challenges, as well as barriers to implementing certain BMPs. Our findings highlight that growers feel the greatest level of concern for the cost of government regulation and ineffective government policies, and 100% of respondents felt at least a little concerned about groundwater quality. While the BMP of split application was widely adopted (69%), growers perceived lack of information as a substantial barrier to adopting the practice of crediting nitrate in irrigation water.
Author: Tracy Alanna Campbell
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Across the Midwest, farmers, researchers, policy makers and communities are confronting increasing groundwater contamination due to agricultural practices, particularly the use of synthetic nitrogen fertilizer, coupled with the challenge of employing these practices to continue growing profitable crops. Additionally, not only are the impacts of agricultural practices felt at the local level-often in the form of agricultural runoff, unsafe drinking water, soil erosion, and decreased stream and lake levels-but also nationally. As agricultural runoff travels downstream to the Gulf of Mexico, excess nutrients have resulted in dead zones. It is likely that ongoing and future climate change across the Midwest will exacerbate current struggles and may leave many fields more vulnerable to nitrate leaching. Moving forward, to ensure safe drinking water and restore and protect ecosystem services, nitrogen management strategies need to be improved and implemented. The Wisconsin Central Sands (WCS) faces many of the challenges felt by communities across the Midwest when managing agricultural land with growing water quality contamination. The WCS region serves as a case study in improving nitrogen management for groundwater quality. To better identify pathways to improved groundwater quality, we incorporated on-farm research related to drivers of water quality variability, observations of soil-plant-environment interactions, agroecosystem modeling, and farmer surveys. In chapter one, we evaluated/quantified the spatiotemporal variability of nitrate concentrations in irrigation water across the WCS region. Additionally, we analyzed the influence of well depth, well casing diameter, nitrogen application rate, year and week of sampling event on nitrate concentration in irrigation water. We found that nitrate levels varied more across space than time, that nitrogen application rate was the most significant predictor of nitrate concentration, and that on average, nitrate levels in irrigation water across the WCS are 19.0 mg/L, or nearly twice the threshold for safe drinking water set by the EPA. In chapter two, we measured leaf level photosynthesis and calculated key photosynthetic parameters for two cultivars of potato grown under four nitrogen application rates. We found that nitrogen application rate (season total N), days after emergence (DAE), and temperature were significant predictors of Vcmax (maximum rate of carboxylation). We also found that at the highest level of nitrogen application (403.5 kg N/ha), both N content (%) and Vcmax declined relative to a nitrogen application rate of 336.3 kg N/ha. In chapter three, we modeled the impact of nitrogen best management practices (BMPs) with varied N rates on irrigated corn yield and nitrate leaching. To better understand the effectiveness and tradeoffs of BMPs considering increased weather variability, we used cluster analysis to group similar weather years. We found that nitrate leaching could be reduced through the use of BMPs (20%) and reduced nitrogen application rates (40%), but there was little room for mitigation during years experiencing wetter than average growing seasons. Additionally, nitrate concentration in the groundwater never reached safe/healthy levels (below 10 mg/L) in our simulations. In chapter four, we surveyed farmers on their current use of nitrogen BMPs, levels of concern towards environmental and economic challenges, as well as barriers to implementing certain BMPs. Our findings highlight that growers feel the greatest level of concern for the cost of government regulation and ineffective government policies, and 100% of respondents felt at least a little concerned about groundwater quality. While the BMP of split application was widely adopted (69%), growers perceived lack of information as a substantial barrier to adopting the practice of crediting nitrate in irrigation water.
Author: Wisconsin Groundwater Coordinating Council
Publisher:
ISBN:
Category : Groundwater
Languages : en
Pages : 200
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Author: Ronald F Follett
Publisher: Elsevier
ISBN: 0444599398
Category : Technology & Engineering
Languages : en
Pages : 412
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Book Description
Supplying crops with adequate nitrogen is vital to ensuring food supplies. Once nitrogen is added to the soil, it is subject to chemical transformations of the nitrogen-cycle including transformation to nitrate. Excessive amounts of accumulated nitrate may then leach out of the soil and could potentially enter and contaminate drinking water supplies. The purpose of this book is to examine the subject of nitrogen management and ground water protection. The issue of maintaining ground water quality is addressed primarily from an agronomic point of view. Topics covered include: health and economic aspects of nitrate in drinking water; nitrate sources; ground water nitrate in the USA and other developed countries; transport, leaching and accounting for nitrogen; soil, nitrogen, crop and water management; and nitrate in aquifer systems. The book contains a keyword index and is organized into thirteen chapters, each with appropriate references, tables and figures. Chapter authors are among the leading experts on the subject of nitrate and ground water quality. Readers to whom the book is directed include soil scientists and agronomists, agricultural engineers (irrigation and drainage), environmental scientists, agricultural policy makers, and hydrologists.
Author: Michael J. Travis
Publisher:
ISBN:
Category : Farm manure
Languages : en
Pages : 254
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Author: Ronald F. Follett
Publisher:
ISBN: 9780891187967
Category : Electronic books
Languages : en
Pages : 0
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Author: Peter D. Arntsen
Publisher:
ISBN:
Category : Groundwater
Languages : en
Pages : 338
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Author: Craig Roesler
Publisher:
ISBN:
Category : Groundwater
Languages : en
Pages : 178
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Author: Anthony J Jakeman
Publisher: Springer
ISBN: 3319235761
Category : Science
Languages : en
Pages : 756
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Book Description
The aim of this book is to document for the first time the dimensions and requirements of effective integrated groundwater management (IGM). Groundwater management is a formidable challenge, one that remains one of humanity’s foremost priorities. It has become a largely non-renewable resource that is overexploited in many parts of the world. In the 21st century, the issue moves from how to simply obtain the water we need to how we manage it sustainably for future generations, future economies, and future ecosystems. The focus then becomes one of understanding the drivers and current state of the groundwater resource, and restoring equilibrium to at-risk aquifers. Many interrelated dimensions, however, come to bear when trying to manage groundwater effectively. An integrated approach to groundwater necessarily involves many factors beyond the aquifer itself, such as surface water, water use, water quality, and ecohydrology. Moreover, the science by itself can only define the fundamental bounds of what is possible; effective IGM must also engage the wider community of stakeholders to develop and support policy and other socioeconomic tools needed to realize effective IGM. In order to demonstrate IGM, this book covers theory and principles, embracing: 1) an overview of the dimensions and requirements of groundwater management from an international perspective; 2) the scale of groundwater issues internationally and its links with other sectors, principally energy and climate change; 3) groundwater governance with regard to principles, instruments and institutions available for IGM; 4) biophysical constraints and the capacity and role of hydroecological and hydrogeological science including water quality concerns; and 5) necessary tools including models, data infrastructures, decision support systems and the management of uncertainty. Examples of effective, and failed, IGM are given. Throughout, the importance of the socioeconomic context that connects all effective IGM is emphasized. Taken as a whole, this work relates the many facets of effective IGM, from the catchment to global perspective.
Author: Kimberly Van Meter
Publisher:
ISBN:
Category :
Languages : en
Pages : 170
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Book Description
Global population has seen a more than threefold increase over the last 100 years, accompanied by rapid changes in land use and a dramatic intensification of agriculture. Such changes have been driven by a great acceleration of the global nitrogen (N) cycle, with N fertilizer use now estimated to be 100 Tg/year globally. Excess N commonly finds its way into both groundwater and surface water, leading to long-term problems of hypoxia, aquatic toxicity and drinking water contamination. Despite ongoing efforts to improve water quality in agroecosystems, results have often been disappointing, with significant lag times between adoption of accepted best management practices (BMPs) and measurable improvements in water quality. It has been hypothesized that such time lags are a result of the buildup of legacy N within the landscape over decades of fertilizer application and agricultural intensification. The central theme of my research has been an exploration of this N legacy, including (1) an investigation of the form, locations and magnitudes of legacy N stores within intensively managed catchments; (2) development of a parsimonious, process-based modeling framework for quantifying catchment-scale time lags based on both soil nutrient accumulations (biogeochemical legacy) and groundwater travel time distributions (hydrologic legacy); and (3) use of a statistical approach to both quantifying N-related time lags at the watershed scale, and identifying the primary physical and management controls on these lags. As a result of these explorations I am able to provide the first direct, large-scale evidence of N accumulation in the root zones of agricultural soils, accumulation that may account for much of the 'missing N' identified in mass balance studies of heavily impacted watersheds. My analysis of long-term soil data (1957-2010) from 206 sites throughout the Mississippi River Basin (MRB) revealed N accumulation in cropland of 25-70 kg ha-1 y-1, a total of 3.8 ± 1.8 Mt y-1 at the watershed scale. A simple modeling framework was then used to show that the observed accumulation of soil organic N (SON) in the MRB over a 30-year period (142 Tg N) would lead to a biogeochemical lag time of 35 years for 99% of legacy SON, even with a complete cessation of fertilizer application. A parsimonious, process-based model, ELEMeNT (Exploration of Long-tErM Nutrient Trajectories), was then developed to quantify catchment-scale time lags based on both soil N accumulation (biogeochemical legacy) and groundwater travel time distributions (hydrologic legacy). The model allowed me to predict the time lags observed in a 10 km2 Iowa watershed that had undergone a 41% conversion of area from row crop to native prairie. The model results showed that concentration reduction benefits are a function of the spatial pattern of implementation of conservation measures, with preferential conversion of land parcels having the shortest catchment-scale travel times providing greater concentration reductions as well as faster response times. This modeling framework allows for the quantification of tradeoffs between costs associated with implementation of conservation measures and the time needed to see the desired concentration reductions, making it of great value to decision makers regarding optimal implementation of watershed conservation measures. To better our understanding of long-term N dynamics, I expanded the ELEMeNT modeling framework described above to accommodate long-term N input trajectories and their impact on N loading at the catchment scale. In this work, I synthesized data from a range of sources to develop a comprehensive, 214-year (1800-2104) trajectory of N inputs to the land surface of the continental United States. The ELEMeNT model was used to reconstruct historic nutrient yields at the outlets of two major U.S. watersheds, the Mississippi River and Susquehanna River Basins, which are the sources of significant nutrient contamination to the Gulf of Mexico and Chesapeake Bay, respectively. My results show significant N loading above baseline levels in both watersheds before the widespread use of commercial N fertilizers, largely due to 19th-century conversion of natural forest and grassland areas to row-crop agriculture. The model results also allowed me to quantify the magnitudes of legacy N in soil and groundwater pools, thus highlighting the dominance of soil N legacies in the MRB and groundwater legacies in the SRB. It was found that approximately 85% of the annual N load in the MRB can be linked to inputs from previous years, while only 47% of SRB N loading is associated with “older” N. In addition, it was found that the dominant sources of current N load in the MRB are fertilizer, atmospheric deposition, and biological N fixation, while manure and atmospheric deposition account for approximately 64% of the current loads in the SRB. Finally, long-term N surplus trajectories were paired with long-term flow-averaged nitrate concentration data to as means of quantifying N-related lag times across an intensively managed watershed in Southern Ontario. In this analysis, we found a significant linear relationship between current flow-averaged concentrations and current N surplus values across the study watersheds. Temporal analysis, however, showed significant nonlinearity between N inputs and outputs, with a strong hysteresis effect indicative of decadal-scale lag times between changes in N surplus values and subsequent changes in flow-averaged nitrate concentrations. Annual lag times across the study watersheds ranged from 15-33 years, with a mean lag of 24.5 years. A seasonal analysis showed a distribution of lag times across the year, with fall lags being the shortest and summer lags the longest, likely due to differences in N delivery pathways. Multiple linear regression analysis of dominant controls showed tile drainage to be a strong determinant of differences in lag times across watersheds in both fall and spring, with a watershed's fractional area under tile drainage being significantly linked to shorter lag times. In summer, tile drainage was found to be an insignificant factor in driving lag times, while a significant relationship was found between the percent soil organic matter and longer N-related lag times. By moving beyond the traditional focus on nutrient concentrations and fluxes, and instead working towards quantification of the spatio-temporal dynamics of non-point source nutrient legacies and their current and future impacts on water quality, we make a significant contribution to the science of managing human impacted landscapes. Due to the strong impacts of nutrient legacies on the time scales for recovery in at-risk landscapes, my work will enable a more accurate assessment of the outcomes of alternative management approaches in terms of both short- and long-term costs and benefits, and the evaluation of temporal uncertainties associated with different intervention strategies.
Author: Walter Dragoni
Publisher: Geological Society of London
ISBN: 9781862392359
Category : Business & Economics
Languages : en
Pages : 200
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Book Description
There is a general consensus that for the next few decades at least, the Earth will continue its warming. This will inevitably bring about serious environmental problems. For human society, the most severe will be those related to alterations of the hydrological cycle, which is already heavily influenced by human activities. Climate change will directly affect groundwater recharge, groundwater quality and the freshwater-seawater interface. The variations of groundwater storage inevitably entail a variety of geomorphological and engineering effects. In the areas where water resources are likely to diminish, groundwater will be one of the main solutions to prevent drought. In spite of its paramount importance, the issue of 'Climate Change and Groundwater' has been neglected. This volume presents some of the current understanding of the topic.
