Spatial Analysis of In-Season Site-Specific Nitrogen Management Effects on Groundwater Nitrate and Agronomic Performance PDF Download
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Languages : en
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Book Description
In-season, site-specific (SS) N management based on remote sensing (RS) has been suggested as a way of reducing groundwater NO3-N contamination. In-season N management seeks to match the temporal variability of crop N needs by applying appropriate amounts of N at critical crop growth stages. Site-specific N management attempts to match the spatial variability of crop N requirements by applying appropriate, spatially variable N rates within fields. We evaluated the environmental and agronomic benefits of two in-season, RS-informed N management strategies applied on a uniform field-average (FA) or SS basis. We compared these to current uniform N recommendations based on "Realistic Yield Expectations" (RYE) in a typical coastal plain cropping system. We also sought to understand the spatial and temporal dynamics of shallow groundwater NO3-N. An additional objective was to develop a statistical procedure for the analysis of spatially dense, georeferenced subsample data in randomized complete block designs, a common characteristic of precision agriculture research. The experiment was established in a 12-ha North Carolina field with a 2-yr winter wheat double-crop soybean-corn rotation. The three N management treatments were applied to 0.37 ha plots in a randomized complete block design with 10 replications. Groundwater NO3-N and water table depth were measured every two weeks at 60 well nests (two per plot) sampling 0.9- to 1.8-, 1.8- to 2.7-, and 2.7- to 3.7-m depths from 2001 to 2003. We developed a statistical procedure for selecting an appropriate covariance model in randomized complete block analyses in the presence of spatial correlation. When warranted, incorporating spatial covariance in the statistical analysis provides greater efficiency in estimating treatment effects. Elevations, soil organic matter (SOM), and water table elevations (WTE) were spatial covariates used for explaining NO3-N spatial correlation. Compared to RYE, SS achieved: (i) less groundwater.
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Languages : en
Pages :
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Book Description
In-season, site-specific (SS) N management based on remote sensing (RS) has been suggested as a way of reducing groundwater NO3-N contamination. In-season N management seeks to match the temporal variability of crop N needs by applying appropriate amounts of N at critical crop growth stages. Site-specific N management attempts to match the spatial variability of crop N requirements by applying appropriate, spatially variable N rates within fields. We evaluated the environmental and agronomic benefits of two in-season, RS-informed N management strategies applied on a uniform field-average (FA) or SS basis. We compared these to current uniform N recommendations based on "Realistic Yield Expectations" (RYE) in a typical coastal plain cropping system. We also sought to understand the spatial and temporal dynamics of shallow groundwater NO3-N. An additional objective was to develop a statistical procedure for the analysis of spatially dense, georeferenced subsample data in randomized complete block designs, a common characteristic of precision agriculture research. The experiment was established in a 12-ha North Carolina field with a 2-yr winter wheat double-crop soybean-corn rotation. The three N management treatments were applied to 0.37 ha plots in a randomized complete block design with 10 replications. Groundwater NO3-N and water table depth were measured every two weeks at 60 well nests (two per plot) sampling 0.9- to 1.8-, 1.8- to 2.7-, and 2.7- to 3.7-m depths from 2001 to 2003. We developed a statistical procedure for selecting an appropriate covariance model in randomized complete block analyses in the presence of spatial correlation. When warranted, incorporating spatial covariance in the statistical analysis provides greater efficiency in estimating treatment effects. Elevations, soil organic matter (SOM), and water table elevations (WTE) were spatial covariates used for explaining NO3-N spatial correlation. Compared to RYE, SS achieved: (i) less groundwater.
Author: Nan Hong
Publisher:
ISBN:
Category :
Languages : en
Pages : 145
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Book Description
Keywords: remote sensing, precision agriculture, groundwater nitrate, In-season site-specific N management, covariance model selection, spatial analysis.
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Category : Dissertations, Academic
Languages : en
Pages : 884
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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: Jason Cole
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Lidia Razowska-Jaworek
Publisher: CRC Press
ISBN: 148229835X
Category : Technology & Engineering
Languages : en
Pages : 312
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Book Description
The first book devoted entirely to the problem of nitrate risk and behaviour in groundwater, this volume includes twenty-seven papers selected from those presented during the Euromeeting of the International Association of Hydrogeologists "Nitrate in Groundwater in Europe" held in Wisla, Poland in 2002. The problems presented and discussed in Wisla
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:
Publisher:
ISBN:
Category : Agriculture
Languages : en
Pages : 820
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Book Description
Author: Matt Bell
Publisher: Frontiers Media SA
ISBN: 2889660559
Category : Social Science
Languages : en
Pages : 104
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Book Description
This eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contact.
Author: John V. Stafford
Publisher: Brill Wageningen Academic
ISBN: 9789086863372
Category : Precision farming
Languages : en
Pages : 0
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Book Description
Precision agriculture is a reality in agriculture and is playing a key role as the industry comes to terms with the environment, market forces, quality requirements, traceability, vehicle guidance and crop management. These proceedings contain reviewed papers presented at the 12th European Conference on Precision Agriculture. The papers reflect the wide range of disciplines that impinge on precision agriculture - technology, crop science, soil science, agronomy, information technology, decision support, remote sensing and others.
