Overabundant nitrate in Iowa’s surface water threatens stream health, drinking water safety, and significantly contributes to hypoxic zones in the Gulf of Mexico. Researchers have quantified surface water nitrate loads historically with grab samples and, more recently, in-situ sensors. In-situ sensor networks capture changes in nitrate concentration over small time scales, providing high temporal resolution data to accurately calculate nitrate loading. However, because advanced sensors are expensive, spatial resolution is often compromised when sensors are deployed on large rivers. To collect high spatial resolution nitrate samples that complement the high temporal resolution data from in-situ sensors, we first used traditional grab samples on small, non-navigable streams in the Clear Creek and the English River watersheds. Dense grab samples across watersheds provide higher resolution data, but not at the spatial resolution achievable on navigable streams with newly developed, boat-deployed sensor technology. We constructed a boat-deployed sensor system that automatically measured nitrate concentrations, temperature, dissolved oxygen, conductivity, and pH as we navigated a boat on a given waterbody. We used the system on the Iowa and Cedar Rivers to capture spatial and temporal changes never previously observed in Iowa. Our data suggest nitrate concentrations and yields were highest in low-relief landforms dominated by row crop agriculture. Nitrate concentrations were lower in higher-relief landforms with less row crop production. We also measured water in Storm Lake, IA with the boat-deployed system. We measured little heterogeneity of nitrate concentrations in the lake, but observed significant nitrate reduction in a large wetland just upstream. The system captured fine scale spatial dynamics of nitrate reduction in the wetland and low nitrate concentrations throughout Storm Lake. Our newly developed sensor platform captured high resolution water quality data, complementing the high temporal resolution data collected with in-situ sensors. High spatial resolution data in this and similar studies provide powerful insights for decision makers to target problematic areas, reduce nitrate, and improve water quality.

Globalization, specialization, and intensification have transformed the global food system, generating material flows and impacts that span multiple scales and levels, presenting novel governance challenges. Many argue for a transition toward a sustainable food system, although the scope and specific goals are fiercely contested. Theory and method is needed to evaluate competing normative claims and build legitimacy. In this dissertation Vermont serves as a case study to investigate how environmental and economic flows impact regional governance, focusing on efforts to manage agricultural phosphorus to achieve water quality goals. A material flow account is developed to estimate phosphorus flows embedded in commodities flowing in and out of Vermont’s agricultural system from 1925-2012. The results indicate a net imbalance of phosphorus flows for the entire period, leading to the accumulation of legacy phosphorus in soils that constitutes a long-term threat to water quality. Agricultural intensification and land cover change during this period led to increased phosphorus use efficiency, livestock density, and dependency on imported feed, the largest source of phosphorus entering Vermont since the 1980s. The evidence of persistent imbalance calls into question the effectiveness of current nonpoint source pollution policy. A critical investigation of nutrient management planning policy reveals several shortcomings: pasture is frequently excluded; many phosphorus flows that cross the farm-gate are not captured; critical information on soil phosphorus levels and runoff risk is not collected in a manner that facilitates regional governance. The integration of nutrient management plans and mass-balances is proposed as an alternative approach that can increase accountability, encourage efficiency, and facilitate management and governance, albeit within constraints imposed by Vermont’s position in a globalized market for agricultural commodities. The empirical and policy analysis is complemented by a theoretical investigation that starts from the observation that a sustainability transition inevitably entails tradeoffs amongst competing normative goals. Navigating these tradeoffs is complicated by mismatch between the reach of governance institutions and the spatial and temporal dimensions of the challenges they face. This investigation contributes to understanding how legitimacy and consensus are constructed in the context of competing normative claims and multi-level governance. It considers deliberative democracy as a means for evaluating normative claims and arriving at a shared, legitimate basis for social action. An instrumental perspective on deliberation is contrasted with a deeper notion that sees deliberation as constitutive of sustainability at a local-to-global level. A conclusion grounds this analysis by drawing out the ways in which deliberation can inform Vermont’s efforts to govern its agriculture, water quality, and economic development, sowing the seeds for a sustainability transition.

This thesis aimed to model agricultural outcomes that are important to Vermont dairy farms and their surrounding communities -- runoff, erosion, nitrogen and phosphorus losses, crop yields, and timeliness of farm operations -- under a set of possible future climates. The Agricultural Policy/Environmental eXtender (APEX) model was used for this work, and the models were calibrated using data from a project that measured most of these outcomes on a set of local farms. The model setup and calibration methodology is thoroughly documented and may be a useful starting point for others who are new to agricultural modeling. Applied to two farms growing continuous corn, the future climate simulations showed that increasing temperatures by 2 C, combined with raising total precipitation or changing the seasonality of precipitation, had little effect on any outcome. Intense rainfall has increased greatly in recent decades, so a combination of higher temperatures and more intense precipitation was also simulated. This led to more runoff, more soil loss, and more nutrient losses. While median values were only modestly increased, the 95%-ile and total losses over the simulation period increased by a larger amount (as much as 53%, depending on the site). Management practices that can reduce runoff and soil/nutrient loss exist, but their effectiveness when a higher fraction of losses occur in large events is not well known. Crop yields changed by <10% in all simulations, and in some cases increased slightly. Other studies have warned of decreases in yields because of high summer temperatures and droughts. The pilot simulations in this thesis probed only a limited range of climate parameter space, so running the models for a wider range of scenarios may illuminate the circumstances in which particularly harmful and beneficial outcomes occur. Finally, APEX can in principle calculate the delays to corn planting that are expected if climate change leads to wetter conditions in the spring. However, the models consistently predicted that only harvest operations will be delayed. The reasons for this are not well understood, and it may be a useful avenue for future work. The present work is limited in a number of ways. Chief among these are somewhat mediocre model performance, and the narrow range of farming systems and climate scenarios investigated. Statistics describing the performance of the calibrated models were poorer than anticipated, and satisfactory results could not be obtained for some nutrient loss pathways. Only two farms were modeled, in just four hypothetical future climates; results for other relevant farming systems and climates may be quite different. Nonetheless, it is hoped that this thesis serves as a useful illustration of the potential and limitations of utilizing the APEX model in this context, and that it lays the groundwork for a more extensive investigation of agricultural outcomes under climate change in Vermont.

Thesis (Msc. (Agriculture)) --University of Limpopo, 2011 / The impact of agricultural chemicals on the environment has come under close scrutiny in the country of South Africa, for that reason, we are investigating alternative and appropriate methods for nutrients management. The objective of the study was to assess infield spatial variability of soil nutrients in a uniformly managed corn field, and (ii) to recommend method that can potentially help corn (Zea mays L.) producers in Limpopo Province to enhance grain yield with optimal utilization of resources. The study was conducted at Syferkuil agricultural experimental farm (23o50’ S; 29 o40’ E) of the University of Limpopo, in the northern semi-arid region of South Africa. Prior to planting of corn on this uniformly managed 7 ha portion of a 1 705 ha farm, the field was mapped with Ag132 Trimble differentially corrected global positioning system (DGPS) equipped with Field Rover II® GIS mapping software. Land suitability assessment for corn was conducted before planting and the field was classified for suitability as S1 based on FAO guidelines for irrigated agriculture and South African Binomial System of Soil classification. Soils and corn leaf sample parameters, including N were collected and measured from geo-referenced locations on a 40 x 40 m grid. Nutrient distribution spatial maps were produced with Surfer software 8.0. There was a significant variability (P≤0.05) of soil nutrients and pH across the corn field. Corn grain yield ranged from 2.7 to 6.3 Mg ha-1. For a land suitability class of S1 under linear irrigation in a semi-arid environment, these grain yields were considered lower. This lower grain yields can be linked to variability of soil nutrients, and pH because the field was classified suitable according to FAO guidelines. This field, with its significant variability of nutrients and pH that resulted in lower grain yields, is potentially a good field for precision agriculture IX methods of nutrient management such site-specific management zones for environmental quality and economic efficiency. Keywords: Maize, Small-scale farming, Soil nutrient management, and Spatial variability

Overwintering of cows is a major cost in a cow-calf production system on the prairies. Winter feeding hay and straw directly on pasture is a potentially more efficient and economical system compared to conventional drylot feeding in a yard. The objectives of the research described in this thesis were to compare winter feeding cattle directly on pasture to traditional drylot over-wintering of cattle and the associated mechanized spreading of manure on pasture. This trial compared the effects of winter feeding systems on pasture nutrient distribution, nutrient recovery in soil and forage, pasture forage response, cattle performance, and economics. <p>The experiment was conducted at Lanigan, SK, on an old russian wildrye grass pasture. Pasture nutrient levels and distribution were measured before and after winter feeding, as well as forage yield, and cattle weight and condition. Nutrient capture and cycling was assessed along with the economics of the different systems. In the pasture fed systems, cattle were fed by either bale processing or bale grazing methods over the winter of 2003-2004. Cattle concentration was 2080 cow-days ha-1, with the cattle in the field for 130 d. In the intensive system used for comparison, cattle were fed in a drylot and 67 tonnes ha-1 of raw manure or 22 tonnes ha-1 of compost was mechanically spread on the pasture in the fall of 2003.<p>Soil inorganic nitrogen (N) levels (0-15 cm) measured in the spring where the cattle were winter fed on pasture were 3 to 4 times the unfertilized, unmanured control treatment, with a mean gain of 117 kg N ha-1. Soil inorganic N was not significantly elevated where manure or compost had been spread by machine. Soil extractable potassium (K) was doubled on the winter feeding sites, with a mean gain of 1209 kg K ha-1. Soil extractable K did not increase where manure or compost had been spread mechanically. Soil distribution patterns of both nutrients were highly uneven following pasture feeding, with levels of inorganic soil N ranging from 12 to 626 kg ha-1 and extractable soil K ranging from 718 to 6326 kg ha-1. Additional nutrients in surface residue from uneaten feed, bedding, and manure were also heavy and variable following pasture feeding. Greater retention of N and K from urine added directly to the soil in the field in the bale grazing and bale processing systems compared to the drylot system is believed to be responsible for high soil available N and K levels compared to manure hauled from the drylot into the field.<p>Soil extractable phosphorus (P) levels (0-15 cm) were measured in the fall of 2005. The compost treatment had the largest increase at 2.6 times the control, an additional 46 kg ha-1. Mean soil P levels did not increase significantly where the cattle were wintered.<p> Over 18 months and 3 harvests, forage dry matter yields where the cattle were fed on pasture were 3 to 5 times the control where the cattle were fed on the pasture, and 1.4 to 1.7 times the control where raw manure or compost was mechanically spread. Also, protein content of the forage was increased to a greater extent in the in-field feeding compared to hauled raw manure or compost, reflecting a greater conservation of N.<p>The gain of N in the forage over 18 months on the winter feeding sites was 200 kg ha-1 of N, almost double what was measured in soil inorganic forms. Fourteen kg ha-1 of P was also recovered. This represented 34% of original feed N and 22% of original feed P that was imported into the field. Recovery of nutrients applied in the raw manure and compost sites was much lower, with only 7% recovery of N and 4% recovery of P in the forage. This was calculated to be 1% of original feed N and 3% of original feed P.<p>The system by which the cattle were overwintered had little influence on cattle weight and condition. All systems performed favorably in maintaining body weight and condition over the winter. Some slight advantages in cattle weight gain and condition were found on the winter feeding systems compared to the in-yard drylot that appeared to be related to slightly increased feed intake.<p>Economic calculations favored winter feeding directly on the pasture by 25% over the drylot systems when the feed value of additional pasture growth over 18 months was included and by 56% when the value of additional soil nutrients was factored in. Feed costs were similar between the systems but pasture feeding had savings in machinery use, fuel consumption and manure handling costs, and gains in pasture productivity.<p>Systems that winter fed cattle directly on pasture provided gains in nutrient cycling efficiencies, pasture growth, and economic savings compared to drylot feeding systems, while maintaining similar cattle growth and condition.

Overwintering of cows is a major cost in a cow-calf production system on the prairies. Winter feeding hay and straw directly on pasture is a potentially more efficient and economical system compared to conventional drylot feeding in a yard. The objectives of the research described in this thesis were to compare winter feeding cattle directly on pasture to traditional drylot over-wintering of cattle and the associated mechanized spreading of manure on pasture. This trial compared the effects of winter feeding systems on pasture nutrient distribution, nutrient recovery in soil and forage, pasture forage response, cattle performance, and economics. <p>The experiment was conducted at Lanigan, SK, on an old russian wildrye grass pasture. Pasture nutrient levels and distribution were measured before and after winter feeding, as well as forage yield, and cattle weight and condition. Nutrient capture and cycling was assessed along with the economics of the different systems. In the pasture fed systems, cattle were fed by either bale processing or bale grazing methods over the winter of 2003-2004. Cattle concentration was 2080 cow-days ha-1, with the cattle in the field for 130 d. In the intensive system used for comparison, cattle were fed in a drylot and 67 tonnes ha-1 of raw manure or 22 tonnes ha-1 of compost was mechanically spread on the pasture in the fall of 2003.<p>Soil inorganic nitrogen (N) levels (0-15 cm) measured in the spring where the cattle were winter fed on pasture were 3 to 4 times the unfertilized, unmanured control treatment, with a mean gain of 117 kg N ha-1. Soil inorganic N was not significantly elevated where manure or compost had been spread by machine. Soil extractable potassium (K) was doubled on the winter feeding sites, with a mean gain of 1209 kg K ha-1. Soil extractable K did not increase where manure or compost had been spread mechanically. Soil distribution patterns of both nutrients were highly uneven following pasture feeding, with levels of inorganic soil N ranging from 12 to 626 kg ha-1 and extractable soil K ranging from 718 to 6326 kg ha-1. Additional nutrients in surface residue from uneaten feed, bedding, and manure were also heavy and variable following pasture feeding. Greater retention of N and K from urine added directly to the soil in the field in the bale grazing and bale processing systems compared to the drylot system is believed to be responsible for high soil available N and K levels compared to manure hauled from the drylot into the field.<p>Soil extractable phosphorus (P) levels (0-15 cm) were measured in the fall of 2005. The compost treatment had the largest increase at 2.6 times the control, an additional 46 kg ha-1. Mean soil P levels did not increase significantly where the cattle were wintered.<p> Over 18 months and 3 harvests, forage dry matter yields where the cattle were fed on pasture were 3 to 5 times the control where the cattle were fed on the pasture, and 1.4 to 1.7 times the control where raw manure or compost was mechanically spread. Also, protein content of the forage was increased to a greater extent in the in-field feeding compared to hauled raw manure or compost, reflecting a greater conservation of N.<p>The gain of N in the forage over 18 months on the winter feeding sites was 200 kg ha-1 of N, almost double what was measured in soil inorganic forms. Fourteen kg ha-1 of P was also recovered. This represented 34% of original feed N and 22% of original feed P that was imported into the field. Recovery of nutrients applied in the raw manure and compost sites was much lower, with only 7% recovery of N and 4% recovery of P in the forage. This was calculated to be 1% of original feed N and 3% of original feed P.<p>The system by which the cattle were overwintered had little influence on cattle weight and condition. All systems performed favorably in maintaining body weight and condition over the winter. Some slight advantages in cattle weight gain and condition were found on the winter feeding systems compared to the in-yard drylot that appeared to be related to slightly increased feed intake.<p>Economic calculations favored winter feeding directly on the pasture by 25% over the drylot systems when the feed value of additional pasture growth over 18 months was included and by 56% when the value of additional soil nutrients was factored in. Feed costs were similar between the systems but pasture feeding had savings in machinery use, fuel consumption and manure handling costs, and gains in pasture productivity.<p>Systems that winter fed cattle directly on pasture provided gains in nutrient cycling efficiencies, pasture growth, and economic savings compared to drylot feeding systems, while maintaining similar cattle growth and condition.

Whole farm nutrient budgets (WFNB) enable producers to link dairy herd management with traditional field nutrient management plans. The objective of this study was to calculate WFNBs of nitrogen, phosphorus, and potassium (N, P, and K) at a commercial farm in New Brunswick and in Prince Edward Island. Reliable estimates of N fixation from alfalfa and red clover on the farms were obtained with adjustments to the Høgh-Jensen et al. (2004) dry matter conversion models. The farms had surpluses of N, P, and K. Both farms imported feed as well as nutrient inputs for crop production. Surpluses of all nutrients were typical in comparison to WFNBs of similar dairy farms; however, the nutrient use efficiencies were low. The imported manure and fertilizer used in the crop production components contributed to surpluses of N and P which could likely be reduced to improve overall farm nutrient use efficiency.

This study investigates the impact of nutrient management regulations on pig farms in Ontario, Canada. Using mathematical programming, small, medium and large farrow to finish and finishing pig farms are examined using uniform and crop requirement based manure application. The model scenarios characterize the cost of compliance when nutrient application standards are applied from the Nutrient Management Act and a previously proposed standard from the Clean Water Act. Compliance costs for scenarios with uniform manure application are ≤6.47%; while compliance costs for scenarios with crop requirement based manure application are ≤0.25%. The Nutrient Management Act has two calculations for nutrient application standards, producers must comply with the less binding calculation. Compliance costs for producers under the less binding standard following a uniform manure application strategy are ≤1.53%; while producers following a crop requirement based manure application strategy have no compliance costs. The proposed Clean Water Act standard is more restrictive than the Nutrient Management Act standards. / Ontario Pork, OMAFRA

This study examines the compliance cost of current and proposed environmental and species regulations on Ontario beef cattle farms. A mathematical programming model was used to simulate regulatory scenarios under the Ontario Nutrient Management Act (2002), the Ontario Clean Water Act (2007) and the Ontario Endangered Species Act (2007). Both the feedlot and cow-calf models are examined using a uniform manure application and optimal nutrient management strategy in each scenario. Under the Nutrient Management Act, feedlot operations using a uniform application strategy face compliance costs of up to 3.09%, but can eliminate compliance costs altogether by switching to an optimal nutrient application strategy. Compliance costs for cow-calf farmers are up to 9.57% under a land reduction scenario and 8.68% with a previously proposed land restriction. The Endangered Species Act scenario causes cow-calf farmers to face compliance costs of up to 6.60% due to restricted use of alfalfa and pasture land. / OMAFRA

AN ABSTRACT OF THESIS Jarrod Armstrong, for the Master of Science degree in Forestry, presented on December 10, 2014, at Southern Illinois University Carbondale. Title: Nitrogen Availability and Transport Following Drought in Three Agricultural Watersheds in Central Illinois Major Professor: Dr. Karl Williard The use of inorganic nitrogen (N) fertilizers has become an essential part of modern agriculture and has helped increase yields to keep pace with an ever growing population. N is the most dynamic nutrient in nature, and biological activity can transform it into several mobile forms. Nitrate (NO3-N) is the most mobile form of N and is highly susceptible to transport to ground and surface waters. The purpose of this study was to assess N dynamics in three agricultural watersheds during and following a significant drought in 2012. Specifically, the study focuses on the mobilization and transport of residual N. The research was conducted on a ninety‐seven hectare agriculture field in Macon, County Illinois. The study site (BRKA) was divided into three watersheds, with four plots per watershed, and two topographic positions per plot. Volumetric water content (VWC) was measured continuously in each of the two topographic positions. In each watershed, stream stage collected over storm hydrographs using automated water samplers was compared to volumetric water content and NO3-N concentrations over the hydrograph. Four 6.1m groundwater monitoring wells and eight vacuum lysimeters in each watershed were monitored to determine the fate and transport of N to soil water and groundwater. Soil sampling at the 15cm depth was completed on a 0.4 hectare grid over the entire field during the fall of each year of the study. Soil and groundwater samples were analyzed monthly to compare NO3-N concentrations across topographic positions. NO3-N concentrations were highest in soil water, followed by groundwater, and lastly surface runoff. Studies in Illinois and Iowa both confirmed large amounts of residual N in the soil after the growing season in the fall of 2012 (Sawyer 2013, and Nafziger 2013). Residual N was apparent at BRKA in elevated NO3-N concentrations in soil water and groundwater after the 2012 growing season. Runoff events in April 2013 also showed increased NO3-N transport. However, due to precipitation events in the late fall and winter the residual N was flushed from the soil profile rendering it unavailable for the 2013 growing season. The soil NO3-N deficit after the 2012 drought was likely the result of decreased N fixation, N mineralization, nitrification, and leaching of any residual NO3-N. Bottomland positions consistently displayed higher soil water and groundwater NO3-N concentrations compared to uplands. However, due to a lack of plant uptake during the 2012 drought this trend was reversed and caused upland positions to exhibit higher NO3-N concentrations compared to bottomlands. This study demonstrated that even during a soybean year when no N fertilizer was applied significant drought can effectively alter the normal N dynamics at the field scale. Furthermore, this change in dynamics can lead to elevated NO3-N concentrations in soil water and ground water. These findings also suggest that precipitation events following periods of drought, like those observed after the 2012 growing season, can flush excess nutrients from the rooting zone further depleting the NO3-N pool and posing a risk to water quality. Data from a June 15, 2011 storm showed that on the falling limb of the hydrograph subsurface flow flushed soil water from the top of the slope to the bottom of the slope. This is indicative of a variable source area controlled watershed where the near stream zones undergo prolonged saturation from the subsurface drainage of the upland areas. Additionally, the early peak of NO3-N during an April 18, 2013 surface runoff event could be attributed to increased mineralization and nitrification following a rewetting of the soil profile after the 2012 drought. Lastly, topography was shown to have a strong influence on soil NO3-N concentrations across the field. This finding suggests that fertilizer applications based on topography and hydrology could help to mitigate the loss of excess NO3-N from agricultural watersheds. Furthermore, fertilizer applications should be adjusted for drought conditions that extend into the following growing season to account for residual N in the soil.