The Effects of Conservation Practices on Nutrient Loss PDF Download

Author: Gary S. Johnson
Publisher:
ISBN:
Category : Fertilizers
Languages : en
Pages : 236

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Author: Stephanie Ann Nummer
Publisher:
ISBN:
Category : Agricultural conservation
Languages : en
Pages : 79

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Nitrogen and phosphorus runoff from agricultural lands and the subsequent impact on water quality has been of great concern in the United States, due to harmful algal blooms and anoxic zones in areas such as Lake Erie and the Gulf of Mexico. Conservation practices have been widely used to reduce the quantity of nutrients leaving a field, but there is a lack of research on the effectiveness of these practices using field scale data. The objective of this thesis is to quantify the effect of conservation practices on nitrogen and phosphorus runoff in farmlands. A meta-analysis was conducted using the Measured Annual Nutrient loads from AGricultural Environments (MANAGE) database created by the USDA-ARS. MANAGE is a compilation of 65 publications including data on nitrogen and phosphorus loads, runoff, land use, fertilizer application, and other field characteristics. The observational nature of the dataset makes direct comparisons from field to field impossible because of large variations in field characteristics. Thus, additional steps must be taken to estimate the effect of conservation practices on nutrient loss. To quantify this effect, I used propensity score matching and multilevel modeling, two statistical methods common for observational data. Propensity score matching shows that conservation practices have a significant reduction of 67.5% in total phosphorus, 83% in particulate phosphorus, and 67.3% in particulate nitrogen. Multilevel modeling results - calculated using two different computational methods - support these findings by showing a significant reduction of 57.7% in total phosphorus, 76.2% and 82.1% in particulate phosphorus (via the two methods), and 63.7% in particulate nitrogen. When examining different land uses and fertilizer application methods, the multilevel modeling showed that conservation practices had the most impact on row crops (e.g. corn and soybeans) and on farms fertilized via the injected or surfaced applied method. The results from this work represent the average effect of conservation practices on a national scale. At a regional scale, the effects of conservation practices may vary because of regional differences in agricultural practices and climate. To assist future research at regional and local scales, this thesis provides a Bayesian modeling framework for future quantification of these effects.

Author: Rachelle Leah Crow
Publisher:
ISBN:
Category : Nutrient pollution of water
Languages : en
Pages : 0

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Agricultural nutrient loss in the Western Lake Erie Basin (WLEB) leads to elevated nutrient levels in Lake Erie, resulting in harmful algal blooms and anoxic conditions, decreased fish populations, and reduced recreation and tourism revenues. To combat this issue, the Ohio Phosphorus Task Force set a goal to decrease the phosphorus (P) load to the WLEB by 40% from 2008 spring loads. To meet this goal, efforts are underway to minimize the amount of P transported from agricultural fields to surface water using best management practices (BMPs). While many BMPs aim to decrease P loss by optimizing agricultural nutrient usage, some fields continue to have elevated soil test phosphorus (STP) levels even when nutrients have not been applied for decades. These fields, referred to as legacy P fields, contain more P within the soil profile than agronomically necessary and have substantial nutrient runoff potential. Because these sites disproportionately contribute to nutrient runoff, it is important to determine what variables impact and how best to manage nutrient loss from legacy P fields. Rainfall depth and intensity have been identified as driving factors causing P runoff from fields within agronomic STP levels. Better knowledge of the impact of precipitation and temperature on runoff from legacy P fields will improve management to minimize nutrient loss from these unique settings. This is especially valuable information as production and water quality management adaptations are made in reaction to climate change. To determine how weather variability impacts P runoff from legacy P fields, water quality and water quantity data was collected at 11 fields with Mehlich-3 P STP > 100 mg/kg in northwest Ohio for a total of 18.5 site-years, during which time 477 storm events each with > 6.35 mm (0.25 in) of precipitation were monitored. This study found that average nutrient concentrations within tile discharge from legacy P fields were 2.4 times (total P; TP) and 4-5 times (dissolved reactive P; DRP) larger than the equivalent on fields with agronomically appropriate STP (i.e., agronomic fields). Additionally, legacy P fields behaved similarly to agronomic fields during precipitation events: rainfall amount was the primary climatic variable affecting TP and DRP loads while tile discharge and nitrate loads were both largely affected by rainfall amount and event duration. By addressing fundamental questions about interactions between elevated STP fields, climate, and nutrient transformation and transport, this study provides greater insight to the significance of legacy P fields on water quality issues and therefore informs decisions on BMP selection and design. Stacked BMPs on fields with high nutrient loss potential are hypothesized to improve quality of runoff more than non-targeted or single practices. To measure the effectiveness of stacked conservation practices on a legacy P field, this study analyzed nutrient loss from a western Ohio field for nearly two years. The targeted subsurface tile drained 4.5 ha (11.1 acres) of the field to the first BMP, a ditch-style P removal structure (PRS) filled with electric arc furnace steel slag. The effluent from the PRS then discharged into a second BMP: a constructed wetland. Discharge moving through the stacked practices was monitored with bubbler flow meters and area velocity sensors and water samples were collected using automated water samplers at the inflows and outflows of each BMP. Between the inlet and outlet of the PRS, there was a 27% reduction in TP concentration and an 18% increase in DRP concentration. The wetland produced statistically significant and consistent reductions of TP loading and DRP loading by 30% and 18%, respectively. Although the PRS did not perform as designed, the stacked PRS and wetland in series had overall load reductions of TP (36%) and DRP (18%). The analysis of these stacked practices demonstrates that although one of the two BMPs performed poorly, there is a benefit to redundant designs, which provides insight on how to best implement BMPs on agricultural lands.

Author: Douglas A. Haith
Publisher:
ISBN:
Category : Agricultural pollution
Languages : en
Pages : 486

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Author: Bradley M. Crowder
Publisher:
ISBN:
Category : Agricultural chemicals
Languages : en
Pages : 28

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Author: Maria Angeles Munoz
Publisher: Academic Press
ISBN: 0128121297
Category : Science
Languages : en
Pages : 398

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Book Description
Soil Management and Climate Change: Effects on Organic Carbon, Nitrogen Dynamics, and Greenhouse Gas Emissions provides a state of the art overview of recent findings and future research challenges regarding physical, chemical and biological processes controlling soil carbon, nitrogen dynamic and greenhouse gas emissions from soils. This book is for students and academics in soil science and environmental science, land managers, public administrators and legislators, and will increase understanding of organic matter preservation in soil and mitigation of greenhouse gas emissions. Given the central role soil plays on the global carbon (C) and nitrogen (N) cycles and its impact on greenhouse gas emissions, there is an urgent need to increase our common understanding about sources, mechanisms and processes that regulate organic matter mineralization and stabilization, and to identify those management practices and processes which mitigate greenhouse gas emissions, helping increase organic matter stabilization with suitable supplies of available N. - Provides the latest findings about soil organic matter stabilization and greenhouse gas emissions - Covers the effect of practices and management on soil organic matter stabilization - Includes information for readers to select the most suitable management practices to increase soil organic matter stabilization

Author:
Publisher:
ISBN:
Category : Agricultural conservation
Languages : en
Pages : 402

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 134

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Part A of this report describes a study initiated to compare soil & nutrient losses from three tillage practices on a clay loam soil under intensive agriculture in Essex County, south-west Ontario. The tillage practices were: fall plough, spring disk, and one mid-season cultivation (conventional tillage); ridge tillage reformed in mid-season; and no tillage other than that associated with planting and fertilizer incorporation. Samples from surface runoff and drain discharge were analyzed for suspended sediment, nutrients, and herbicides. The crop planted was corn, and yield & moisture content were determined at harvest. Part B describes a study to provide data on herbicide losses from the three types of tillage for corn culture on a poorly drained, level plane soil. Total transport losses, seasonal distribution, and source of losses were measured for the three tillage practices for atrazine, its dealkylated analogue des-ethyl atrazine, and metolachlor.

Author:
Publisher:
ISBN:
Category : Electronic government information
Languages : en
Pages : 264

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Author: National Research Council
Publisher: National Academies Press
ISBN: 0309069483
Category : Science
Languages : en
Pages : 422

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Environmental problems in coastal ecosystems can sometimes be attributed to excess nutrients flowing from upstream watersheds into estuarine settings. This nutrient over-enrichment can result in toxic algal blooms, shellfish poisoning, coral reef destruction, and other harmful outcomes. All U.S. coasts show signs of nutrient over-enrichment, and scientists predict worsening problems in the years ahead. Clean Coastal Waters explains technical aspects of nutrient over-enrichment and proposes both immediate local action by coastal managers and a longer-term national strategy incorporating policy design, classification of affected sites, law and regulation, coordination, and communication. Highlighting the Gulf of Mexico's "Dead Zone," the Pfiesteria outbreak in a tributary of Chesapeake Bay, and other cases, the book explains how nutrients work in the environment, why nitrogen is important, how enrichment turns into over-enrichment, and why some environments are especially susceptible. Economic as well as ecological impacts are examined. In addressing abatement strategies, the committee discusses the importance of monitoring sites, developing useful models of over-enrichment, and setting water quality goals. The book also reviews voluntary programs, mandatory controls, tax incentives, and other policy options for reducing the flow of nutrients from agricultural operations and other sources.