Publications by Center Staff
(Accepted) Alvez, Juan P.; Schmitt F., A.; Erickson, J. D.; Farley, J.; Mendez, V. E. "Transition from semi-confinement to pasture-based dairy in Brazil: Farmers' view of economic and environmental performances". Journal of Agroecology and Food Systems.
Available soon. Contact Juan for more information in the meantime at email@example.com.
Berlin, L., K. Norris, J. Kolodinsky, A. Nelson. The Role of Social Cognitive Theory in Farm-to-School-Related Activities: Implications for Child Nutrition. Journal of School Health. 83(8):589-595.
Farm-to-school (FTS) programs are gaining attention for many reasons, one of which is the recognition that they could help stem the increase in childhood overweight and obesity. Most FTS programs that have been evaluated have increased students' selection or intake of fruits and vegetables following the incorporation of FTS components. However, the wide range of activities that are typically part of FTS programs make it difficult to pinpoint which components have the greatest potential to improve students' health behaviors. Within the field of nutrition education, theory-based interventions that target the key underlying factors influencing health behavior offer the most promise.
Conner, D., F. Becot, D. Hoffer, E. Kahler, S. Sawyer, L. Berlin. "Measuring current consumption of locally grown foods in Vermont: Methods for baselines and targets," Journal of Agriculture, Food Systems and Community Development.
Numerous studies have measured the economic impact of increased consumption of locally grown foods, and many advocates have set goals for increasing consumption of locally grown foods to a given percentage. In this paper, we first apply previously developed methods to the state of Vermont, to measure the quantity and value of food that would be consumed if the USDA Dietary Guidelines were followed. We also assess the potential of locally grown foods to meet these guidelines, finding that meeting dietary guidelines with a local, seasonal diet would bring economic benefit, in this case, US$148 million in income for Vermont farmers. A missing piece of information has been: what is the current percentage of locally grown food being consumed in a given city, state, or region? The Farm to Plate Strategic Plan, a 10-year plan for strengthening Vermont's food system, attempted to answer this question. To date, we know of no credible set of methods to precisely measure the percentage of food consumed that is locally grown. We collect data from a variety of sources to estimate current local consumption of food. We were able to measure and account for about US$52 million in local food expenditures, equal to about 2.5% of all food expenditures in Vermont. We then discuss limitations and suggestions for improving measurement methods moving forward..
Alvez, Juan P.; Schmitt, A.; Farley, J.; Alarcon, G.; Fantini, A.C. The Potential for Agroecosystems to Restore Ecological Corridors and Sustain Farmer Livelihoods: Evidence from Brazil. Journal of Ecological Restoration.
The Atlantic Forest is a highly diverse biome, extending from the northeast to the south of Brazil. The diversity of elevation and climate of this biome allows for extraordinary biodiversity with high levels of endemism. The original territory of the Atlantic Forest concentrates 65% of the Brazilian population, providing fundamental ecosystem goods and services such as climate regulation, water supply, erosion control, and pollination. An estimated 100 million people in Brazil depend on the water provided by the Atlantic Forest rivers and streams. In spite of its importance, the Atlantic Forest is one of the most threatened and fragmented biomes worldwide. Slightly over 11% of the original Forest remain, which are mostly remnants (83%) smaller than 50 ha and within 100 m from forest edges, revealing high levels of fragmentation. Reconnecting forest fragments became a national policy at the end of the 1990s through the Pilot Program for the Tropical Forest Protection (PP-G7), financed by the World Bank. This program has resulted in both the establishment of protected areas and some small functional corridors between them in high priority areas, particularly in the Amazon region. In addition to the PP-G7 program, Brazil’s main Forest Act of 1965 mandates permanent preservation areas (PPA or in Brazil, APP) along rivers and streams in an effort to provide natural ecological corridors for fauna and flora species outside protected areas.
Alvez, Juan P. "Livestock Management, Ecosystem Services, and Sustainable Livelihoods". Doctorate Dissertation, (275 pg.) defended Feb. 2012. University of Vermont
Agroecosystems are frequently degraded beyond their capacity to support vital ecosystem services and thus sustain farmer livelihoods over the long-run. Adopting a more sustainable diary management system is particularly important given the pressure of this dominant human land-use worldwide. This research analyzes farmers' perceptions and the effects of different dairy management methods on ecosystem services provision, milk production, farm quality of life, and environmental awareness in two contrasting studies in Santa Catarina, Brazil and Vermont, U.S. Management intensive grazing (MIG) was found to out produce traditional grazing in Santa Catarina,while contributing to improved biodiversity protection, animal welfare, and ecosystem services from greater pasture coverage and soil restoration. No production differences were found between MIG, confinement and traditional grazing in Vermont, however environmental and social variables saw similar improvements under MIG adoption. Education and access to information was critical for the adoption of better management practices and environmental awareness. Both cases inform integrated policy strategies to address production, conservation and sustainable livelihoods.
Becot, F., Nickerson, V., Conner, D. & Kolodinsky, J. 2012. Costs of Food Safety Certification on Fresh Produce Farms in Vermont. HortTechnology, 22(5) 705-714
This article addresses the economic costs of good agricultural practices (GAPs) audits of small and medium size farms in Vermont. It focuses on the costs of infrastructure, equipment, and labor required to successfully pass a U.S. Department of Agriculture (USDA) GAPs audit. In-depth interviews and surveys of produce farmers in 2011 revealed that the cost of GAPs certification ranges between $37 and $54 per acre, and an additional 7 hours were required each week during the growing season. Based on this exploratory research, certifying all the farms in Vermont would cost between $228,216 and $3,019,114. Our study explored all the criteria of the certification and measured the costs of GAPs from planning stages to daily record keeping more than one year after the certification was achieved. This study provides information to farmers who are considering GAPs certification. It also provides background information to agricultural service providers and policymakers planning for the future of the fresh produce industry.
Berlin, L., R. Schattman, J. Hamilton. Working Towards the Common Table: The Policy and Program Implications of Vermont's Unified Approach to Social Justice, Food Insecurity and Local Food. Journal of Hunger and Environmental Nutrition. 7(4): 426-435
Hunger and food insecurity are growing concerns in the United States and around the world. Recently, the US Department of Agriculture released a report indicating that 13.6% of Vermonters are food insecure (up from 9.6% in 2004–2006) and 6.2% are hungry (termed very low food security). At the same time, there is significant financial risk associated with food production and the challenges that Vermont farmers face in achieving business viabil- ity. Unconnected strategies that either enhance food access or build economic success for agriculture may work at each other’s expense. Hence, there is a growing need for efforts that simultaneously support access to high-quality, local food for low-income Vermonters while ensuring fair return to Vermont farmers.
Colby, J. A Comprehensive Assessment of Factors Affecting Success on Vermont Grass-Based Livestock Farms, University of Vermont Department of Community Development and Applied Economics, Master's Thesis
Vermont livestock farmers have used intensively-rotated grazing management systems for over 20 years but there is very limited information on their performance based on comprehensive evaluations. The purpose of this research is to examine how economic, environmental, social, and demographic factors have affected the self-reported success and satisfaction of Vermont grass-based livestock farms and identifies future opportunities and challenges for this unique group of farms.
A mail survey was distributed to 1088 Vermont grass-based livestock producers in April 2011, yielding 229 responses, a 21.6% response rate. Survey respondents had an average age of 54, and 31.8% were female. Responding farmers managed a total of 51,528 acres of combined pasture, forest, and crop land, with 26.6% containing certified organic land and 20.1% with certified organic animals. Average farm size was 177 acres including 34% of acreage in perennial pasture and 38% in hay/pasture. For livestock, 32% ofthe farms grazed dairy, 38% beef, and 30% grazed sheep. Other livestock included goats, swine, horses, and poultry. Grazing management was very diverse with 75% of dairy cows were moved to new pasture every 3 days, while less than 44% of sheep and beef received new pasture every 3 days. The responses suggest that 68% reported grazing plants shorter than recommended. Business plans were in place on 28.8% of farms. The total gross income reported by participating farmers was $20.5 million, total net income was$1.6 million, and 61.1 % reported positive net profit. Woody plant species decreased by 5% or more on 57.6% of the farms described. Part-time farmers represented half of the responders, 38.1% of whom plan to farm full time within ten years. Full-time farmers had strong correlation to net profit, but 40.5% of full time farmers plan to decrease farming activities within the next ten years. Over 45% of responders interacted with non-family school age children in 2010 and the reported rates medical conditions were lower than state averages.
. Healthy animals, profitability, engaging the next generation, business longevity, and farming lifestyle were statistically positively correlated with self-reported success. Health insurance, decrease in woody plants, total acres owned, and presence of a business plan were positively correlated with satisfaction. Binary logistical regression identified the presence of a business plan, participation in amateur arts, increasing number of tractor hours, and increasing farmer education statistically impacted the predictability of success. The results indicate that the presence of health insurance, full-time farming, presence of a business plan, and soil testing statistically impact the predictability of satisfaction.
The results from this research will be used to guide Vermont agricultural policy by providing essential baseline information about the growing grass-based livestock sector, identify where education efforts need to be focused, and identify the challenges to adoption of more conservation based grazing management practices. Results will be shared with groups including NRCS, FSA, UVM Extension, and NOFA to improve educational programming, develop further investigation into questions revealed through the research process, and serve as a baseline for future comparison of grazing program return on investment.
Roche, E., D. Conner, J. Kolodinsky, E. Buckwalter, L. Berlin, A. Powers. Social Cognitive Theory as a framework for considering farm to school programming. Childhood Obesity. 8(4):322-328
BACKGROUND: Farm to School (FTS) programs are designed, in part, to improve childhood health and nutrition and may be implemented as a strategy to prevent childhood obesity. FTS programs have largely emerged out of grassroots efforts, and theory has not explicitly guided program development or implementation. This research considers the effectiveness of social cognitive theory (SCT) as a framework for FTS programming.
METHODS: In 2010, a survey was administered to 632 elementary schoolchildren in Vermont. Six indices were developed from 46 variables that measured personal characteristics and experiences with regard to fruits and vegetables, as described in the SCT.
RESULTS: These indices were the basis for cluster analysis, which identified three distinct clusters. Bivariate analysis showed significant differences among the clusters in the children's likelihood of meeting the Dietary Guidelines for Americans (DGA). The significant differences observed among the clusters suggest that SCT is an appropriate framework within which FTS interventions may be considered.
CONCLUSIONS: The findings show that there are distinct food-related attitudes and behaviors that differ widely by the SCT informed clusters and that can be used to inform FTS programs.
Alvez, J., Matthews, A., Schmitt Filho, A., & Farley, J. Indicadores de sustentabilidade para pecuária (Sustainability indicators for cattle farms). Resumos do I Encontro Chapecó, SC, Brazil. Pan-Americano sobre Manejo Agroecológico de Pastagens, Cadernos de Agroecologia, 6(1).
Sustainability indicators are important tools for assessing agricultural practices and implement changes when necessary. We suggest that sustainability indicators tied to agroecological practices could reduce carbon footprint and increase livestock sustainability. However, indicators and variables considered in sustainability analyses should be linked to specific activities and not generalized.
Berlin, L., R. Schattman, J. Hamilton. Working towards the Common Table: How Vermont Addresses Social Justice and Food Access with Local Food and Why it Matters. Opportunities for Agriculture Working Paper Series 2(5). Food Systems Research Collaborative at the University of Vermont Center for Rural Studies.*
Hunger and food insecurity are growing concerns in the United States and around the world. Consequently, the United States Department of Agriculture (USDA) designated Global Food Security as one of the five focal areas for the National Institute for Food and Agriculture. Recently, the USDA released a report indicating that 13.6% of Vermonters are food insecure (up from 9.6% in 2004-2006) and 6.2% are hungry (“very low food security”) compared to the national averages of 13.5% food insecure and 5.2% hungry (Nord, Coleman-Jensen, Andrews, & Carlson, 2010). At the same time, farmers in Vermont are struggling. The average net income of Vermont farms according to the USDA’s 2007 Agriculture Census was $22,816/ year. This indicates the financial risk associated with agriculture and the challenges that Vermont farmers face in achieving business viability.
Unconnected strategies that either enhance food access or build economic success for agriculture may work at each other’s expense. Hence there is a growing need for efforts that simultaneously support access to high quality, local food for low-income Vermonters while ensuring fair return to Vermont farmers. Approaches driven by this dual-goal have great potential to strengthen communities and further social equity, both important tenets of sustainable agriculture.
Farley, J., Schmitt Fo. A., Alvez, Juan P. Ribeiro de Freitas, N. "Ecosystem Services, Agriculture and Economic Institutions". Mountain Sky Group Articles.*
Society must increase food production and restore ecosystem services or suffer unacceptable consequences. Unfortunately, conventional agriculture may be the single greatest threat to ecosystem function, while restoring farmlands to native ecosystems and reducing ecologically harmful agricultural inputs threatens food production. We fell into this predicament because we designed agricultural and economic systems that failed to account for ecosystem services, and the path forward requires redesigning both systems. Agroecology is a promising approach to redesigning agriculture, but perhaps the greater challenge is creating economic institutions that reward the provision of ecosystem services and hence provide the necessary incentives to scale it up to the desired level. Payments for ecosystem services (PES) are a policy mechanism designed to provide these incentives. However, the mechanism must be carefully tailored to promote agroecology among service providers and to capture adequate resources from service beneficiaries. The private sector either fails to provide the research and development required by agroecology, or else patents the resulting knowledge, decreasing its availability to those who need it. It also fails to provide fails to provide extension services, infrastructure and affordable credit. Public sector provision of these services has historically generated exceptional returns on investment. Similarly, the private sector is unlikely to voluntarily pay for most ecosystem services. Collective institutions however can restrict access to some services, like waste absorption capacity, then charge for their use. These institutions should be at the scale of the service provided. Revenue generated can then be used to fund international research centers to develop agroecology, national extension services to disseminate it, and affordable local microcredit schemes that finance adoption by farmers, but share the risk with service beneficiaries. The resulting knowledge and those ecosystem services not depleted by use should then be open access or all. The nature of the problem requires public sector solutions, while the scale of the problem requires public sector to public sector transfers. The solutions described here may not be ideal, but they are a useful starting point as we move forward.
Farley, J.; Schmitt, A.; Alvez, Juan P.; Ribeiro de Freitas, N. How Valuing Nature Can Transform Agriculture. Solutions Journal, Vol 2, No. 6. pp. 64-73
Society must increase food production and restore vital ecosystem services or suffer unacceptable consequences. Unfortunately, conventional agriculture may be the single greatest threat to ecosystem function. At the same time, reducing ecologically harmful agricultural inputs or restoring farmlands to native ecosystems threatens food production. We fell into this predicament because we designed agricultural and economic systems that failed to account for ecosystem services, and the path forward requires redesigning both systems. Agroecology—which applies ecological principles to design sustainable farming methods that can increase food production, wean us away from nonrenewable and harmful agricultural inputs, and restore ecosystem services—promises to be an appropriate redesign of agricultural systems. We focus on the example of management-intensive grazing (MIG), which mimics natural grassland-grazer dynamics. Compared to conventional systems, MIG increases pasture growth and cattle production, reduces the use of fertilizers and pesticides, and enhances biodiversity, water quality, nutrient capture, and carbon sequestration. Redesigning economic institutions to reward the provision of ecosystem services and provide the public goods required for the global-scale development and dissemination of agroecology practices still presents a serious challenge. Payments for ecosystem services (PES) are a promising mechanism through which those who benefit from ecosystem services can compensate those who provide them, for mutual gain. Numerous schemes already exist that pay landowners for land uses that sequester carbon, regulate and purify water, and enhance biodiversity, but their effectiveness is debated. We propose a form of PES in which the potential public beneficiaries of ecosystem services at the local, national, and global scales fund the research and development, extension work (i.e., farmer education, usually supported by government agencies), and affordable credit required to scale agroecology up to the level required to provide for a growing global population.
Faulkner, J.W., W. Zhang, L.D. Geohring, T.S. Steenhuis. Tracer movement through paired vegetative treatment areas receiving silage bunker runoff. Journal of Soil and Water Conservation. 66(1):18-28.
The need for less resource-intensive agricultural waste treatment alternatives has lately increased. Vegetative treatment areas (VTAs) are considered a low-cost alternative to the collection and storage of various agricultural wastewaters. As VTAs become more widespread, the need for design guidance in varying climates and landscapes increases. The purposes of this study were to investigate runoff movement and nitrate-nitrogen concentrations within two VTAs and to use the results to improve VTA design and recommendations for management. Silage bunker runoff movement through the selected VTAs following a 7.8 mm (0.31 in) rainfall event was characterized using a chloride tracer. Both surface and subsurface runoff movement was analyzed using tracer concentrations and a simple binary mixing model. Results show that concentrated surface flow paths existed within both VTAs, and surface flow in general was more prevalent in the VTA that received a higher hydraulic loading. Rapid preferential flow to shallow monitoring wells was also observed. A shallow restrictive soil layer likely exacerbated surface flow but restricted runoff water and nitrate-nitrogen from leaching to deeper groundwater. The nitrate-nitrogen did not appear to be directly linked to runoff movement, but concentrations as high as 28 mg L-1 were observed in downslope surface flow in the wetter VTA. A more comprehensive VTA design process is called for that accounts for shallow soils and antecedent moisture conditions. Regular maintenance and design measures to prevent the formation of concentrated flow paths are also critical to the prevention of surface discharge.
Faulkner, J.W., W. Zhang, L.D. Geohring, T.S. Steenhuis. 2011. Nutrient transport within three vegetative treatment areas receiving silage bunker runoff. J Env Mngmt. 92(3):587-595.
Silage bunker runoff can be a very polluting substance and is increasingly being treated by vegetative treatment areas (VTAs), but little information exists regarding nutrient removal performance of systems receiving this wastewater. Nutrient transport through the shallow subsurface of three VTAs (i.e. one VTA at Farm WNY and two VTAs at Farm CNY) in glaciated soils containing a restrictive layer (i.e., fragipan) was assessed using a mass balance approach. At Farm WNY, the mass removal of ammonium was 63%, nitrate was 0%, and soluble reactive phosphorus (SRP) was 39%. At Farm CNY, the mass removal of ammonium was 79% in the West VTA, but nitrate and SRP increased by 200% and 533%, respectively. Mass removal of ammonium was 67% in the East VTA at Farm CNY; nitrate removal was 86% and SRP removal was 88%. The East VTA received a much higher nutrient loading, which was attributed to a malfunctioning low-flow collection apparatus within the settling basin. Results demonstrate that nutrient reduction mechanisms other than vegetative uptake can be significant within VTAs. Even though increases in nitrate mass were observed, concentrations in 1.65 m deep wells indicated that groundwater impairment from leaching of nitrate was not likely. These results offer one of the first evaluations of VTAs treating silage bunker runoff, and highlight the importance of capturing concentrated low flows in VTA systems.
Pintauro, S.J., S. Regimbald, S. Burczy, A. Nickerson, P. Buzzell, L. Berlin. Evaluation of a Nutrition and Health Educational Online Computer Program for Older Adults. Journal of Nutrition and Food Sciences. 1:117
Background: Many older adults are at increased risk for nutritional deficiencies and foodborne illnesses. The objective of this study was to develop and evaluate the effectiveness of a user-friendly computer application that provides nutrition, food safety, and health information tailored to the needs of older adults. Methods: To determine the effectiveness of the program, a 12-month intervention study was conducted in which subjects were assigned to an experimental (HE-HA) group (access to the computer program) or a control (CON) group (no access to computer program). Computers were placed in each of two Vermont rural congregate meal sites. One site served as the HE-HA group site and the other as the CON site. Forty-one adults congregate meal users (HE-HA group: n=16; CON group: n=25) age ? 55, were recruited to participate in the study. The Nutrition Screening Initiative (NSI) checklist, food behavior checklist, and computer attitude surveys were completed by participants at baseline, 3, and 12 months. Focus groups were conducted between 8 and 9 months. Between and within group over time differences were statistically analyzed by Chi-square analyses and repeated measures ANOVA. Results and Conclusions: A significant positive impact of our program was noted on fruit and vegetable consumption (p less than 0.005) and attitude regarding use of computers (p less than 0.02). Focus group results indicated that all HE-HA participants claimed to have changed at least one aspect of his/her diet and that the Website contributed to this positive change. They also noted that the help of the “peer mentors” was a significant factor in their positive experience with using the Web application and with the use of computers in general. In this study, we demonstrated the successful use of a nutrition and health computer application in improving both nutrition behavior and computer skills and attitudes in older adults.
Surdi, J., Schmitt Filho, A., Farley, J., Alvez, J. P., & Satschumi, H. O fluxo de serviços ecossistêmicos na agricultura familiar da Encosta da Serra Catarinense (The flow of ecosystem services in family farming of the Encosta da Serra Catarinense). Resumos do I Encontro Pan-Americano sobre Manejo Agroecológico de Pastagens, Chapecó, SC, Brazil. Cadernos de Agroecologia, 6(2), 1-6.
Considering the predominance of family farming in the state of Santa Catarina, Brazil, a more sustainable livestock production has proved crucial. The objective of this study was to understand dairy farmers' awareness about ecosystem services. Sixty dairy farmers working under the Voisin system were randomly selected through structured interviews. Results revealed that farmers perceived that soils were more structured, moist and covered under Voisin system. In addition, the annual silage production and supplementation decreased due to the improvement of naturalized pasture. Farmers also observed an increase in carrying capacity. After the adoption of the Voisin system, farmers began to deliver water through water-tanks in the paddocks, decreasing animal access to water sources. Thus, it was observed that pasture-based milk production improved the farm environment, causing an apparent increase in the flow of services of this pastoral agroecosystems.
Farley, J., Schmitt F. A., Alvez, Juan P., Rebollar, P. M. The farmer's viewpoint: Payments for ecosystem services and agroecologic pasture based dairy production. Advances in Animal Biosciences (2010) 1: 490-491.
Ecosystems provide a variety of services essential to human survival and well-being. For example, forests provide food and fiber, regulate climate and water, generate cultural benefits such as recreation, and create habitat for biodiversity. All economic production requires both energy and raw materials provided by nature, and unavoidably produces high entropy waste. Most raw material inputs into economic production otherwise serve as the structural building blocks of ecosystems. When economic activities remove ecosystem structure and return waste, the the result is a loss of function, including ecosystem services. Perhaps the most important problem our society currently faces is how to allocate ecosystem structure between conversion to economic production and conservation to provide ecosystem servies, both of which are essential to our well-being (Farley, 2010) Different agriculture systems proivide distinct conditions for the flow of ecosystems services. Farmers are required to produce food on an increasingly degraded environment for an ever growing population. Markets compensate for goods from the provisioning functions (food, raw materials, ornamental). Provisioning functions are tangible and can be tradable, such as the case of dairy products. On the other hand, the market does not account of the value from regulating functions such as water, forest, habitat and biodiversity protection among others (Alvez, 2010). When best management practices are adopted livestock management, especially dairy farming has the potential to promote ecosystem services such as water supply and regulation, soil formation, biodiversity, carbon sequestration, food provision, as well as supporting rural livelihoods (Meurer et al., 2009). The aim of this study is to assess farmers' perception about the flow of Ecosystems Services (Farley, 2010) associated to the transition from confined dairy production to pasture based dairy system called management intensive grazing - MIG (Meurer et al., 2009).
Faulkner, J.W., Z.M. Easton, W. Zhang, L.D. Geohring, T.S. Steenhuis. 2010. Design and risk assessment tool for vegetative treatment areas receiving agricultural wastewater: Preliminary results. Journal of Environmental Management. 91(8):1794-1801.
Vegetative treatment areas (VTAs) are commonly being used as an alternative method of agricultural process wastewater treatment. However, it is also apparent that to completely prevent discharge of pollutants to the surrounding environment, settling of particulates and bound constituents from overland flow through VTAs is not sufficient. For effective remediation of dissolved agricultural pollutants, VTAs must infiltrate incoming wastewater. A simple water balance model for predicting VTA soil saturation and surface discharge in landscapes characterized by sloping terrain and a shallow restrictive layer is presented and discussed. The model accounts for the cumulative effect of successive rainfall events and wastewater input on soil moisture status and depth to water table. Nash-Sutcliffe efficiencies ranged from 0.65 to 0.81 for modeled and observed water table elevations after calibration of saturated hydraulic conductivity. Precipitation data from relatively low, average, and high annual rainfall years were used with soil, site, and contributing area data from an example VTA for simulations and comparisons. Model sensitivity to VTA width and contributing area (i.e. barnyard, feedlot, silage bunker, etc.) curve number was also investigated. Results of this analysis indicate that VTAs should be located on steeper slopes with deeper, more-permeable soils, which effectively lowers the shallow water table. In sloping landscapes (>2%), this model provides practitioners an easy-to-use VTA design and/or risk assessment tool that is more hydrological process-based than current methods.
Zhang, W, J.W. Faulkner, S.K. Giri, L.D. Geohring, T.S. Steenhuis. 2010. Effect of soil reduction on phosphorus sorption of an organic-rich silt loam. Soil Sci Soc Am J. 74(1):240-249.
Phosporus flux from agricultural landscapes to surface waters may cause eutrophication. In the northeastern United States, P transport largely depends on P sorption of soils in variable source areas or in land treatment systems. Soil redox fluctuation commonly occurs in these areas. Nevertheless, the effect of soil redox on P sorption has been variable in the literature. This study investigated P sorption of an organic-rich northeastern glaciated silt loam (Langford) under air-dried, field-wet, and reduced conditions using batch P sorption experiments. Additionally, the influence of farm wastewater on soil P sorption was studied. Major results indicated that soil reduction increased the maximum amount of P that can be sorbed (S max) and decreased the aqueous P concentration at which P sorption and desorption are equal (EPC0), both determined from a modified Langmuir isotherm model. The slightly reduced field-wet soils had no significant difference in Smax due to limited soil reduction. Using the diluted wastewater as the sorption solution matrices instead of 0.01 mol L-1 KCl solution, the soils generally exhibited greater Smax and lower EPC0 except for the EPC0 of a reduced surface soil, implying more complex P sorption in the field. Identified P sorption mechanisms include phosphate precipitation, ligand exchange with organic matter, and adsorption onto Fe hydroxides. Transformation of Fe compounds during soil reduction is primarily responsible for the changes in soil P sorption. Abbreviations: DOC, dissolved organic carbon; ICP-AES, inductively coupled plasma-atomic emission spectrometry; OM, organic matter; SRP, soluble reactive phosphorus; TC, total carbon; TN,total nitrogen; VSA, variable source area; VTA, vegetative treatment area.
(In-review). Alvez, Juan P. and Murphy, W. Irrigation, Nitrogen, and Soil Amendment Effects on Pasture Forage Yield and Quality. Journal: Renewal Agriculture and Food Systems.
Berlin, L., R. Bell, W. Lockeretz. Purchasing foods produced on organic, small, and local farms: a mixed method analysis of New England consumers. Renewable Agriculture and Food Systems 24(4):267-275
Maurer, F., Schmitt, A., Farley, J., Alvez, J., Oldra, A., DaRolt, L., & Francisco, F. (2009). Serviços Ambientais e a Produção de Leite sob Pastoreio Voisin na Agricultura Familiar: Ativos Ambientais que Devem ser Considerados. Revista Brasileira de Agroecologia, 4(2), 3830-3834.
Matthews, A., Alvez, Juan P., Cooper. C., Kestenbaum, D., Purchase N. Dairy Stewardship Alliance: Sustainability Indicators for Dairy Farms. UVM Center for Sustainable Agriculture*
Zhang, W, J.W. Faulkner, S.K. Giri, L.D. Geohring, T.S. Steenhuis. 2009. Evaluation of two Langmuir models for phosphorus sorption of P-enriched soils in New York for environmental applications. Soil Science. 174(10):523-530.
Faulkner, J.W., T.S. Steenhuis, N. van de Giessen, M. Andreini, and J.R. Liebe. 2008. Water use and productivity of two small reservoir irrigation schemes in Ghana's Upper East Region. Irrigation and Drainage. 57(2):151-163.
Kolodinsky, J., J.R. Harvey-Berino, L. Berlin, R. Johnson, T.W. Williams. Knowledge of Current Dietary Guidelines and Food Choice by College Students: Better Eaters Have Higher Knowledge of Dietary Guidance. Journal of the American Dietetic Association 107(8):1409-1413.Book Chapters
Schmitt, A.; Farley, J.; Alvez, Juan P.; Alarcon, G.; May Rebollar, P.; Integrating Agroecology with Payments for Ecosystem Services in Santa Catarina's Atlantic Forest, In: Muradian, R. & Rival, L. Governing the provision of environmental services. Springer. ISBN 978-94-007-5175-0.
* Works denoted with an asterisk (*) are not peer-reviewed.
Last modified November 26 2013 12:41 PM