SCC083: Quantifying the Linkages Among Soil Health, Organic Farming, and Food
- October 01, 2010 to September 30, 2015
- Administrative Advisor(s):
- NIFA Reps:
Statement of Issue(s) and Justification:Organic farming is a vibrant and growing sector of the U.S. farm economy. The USDA Economic Research Service reported that U.S. sales of organic foods and beverages grew from $3.6 billion in 1997 to $21 billion in 2008. Growth in the organic food market has slowed recently because of domestic and global economic crises, but trend data suggest that market expansion will continue. Consumer marketing analysts at Packaged Facts predict at least strong single-digit growth in organic food and beverage markets through 2013.
Scientific research directed at providing solutions to the problems encountered when growing crops organically is needed so that market demand can be met. Organic farmers articulated research needs to scientists during several sessions of the Scientific Congress on Organic Agricultural Research between 2000 and 2002. A summary of those sessions was provided in the National Organic Farming Research Agenda, a publication released by the Organic Farming Research Foundation in 2007. The report revealed that organic growers believe a healthy soil is essential for the sustainability of an organic farm. The farmers considered high soil organic matter (SOM) levels, lush crop canopies, reduced soil erosion, and earthworm presence to be among the indicators of healthy soils. Specific recommendations were generated from these surveys, including the need for research that would elucidate the relationship between crop nutrient content and soil health, and determine how organic farming systems can conserve SOM, enhance soil quality, protect soil from erosion, and sequester carbon to help mitigate global climate change. It is important to conduct the research across a diverse range of environmental conditions to extend the inference domain of the management tactics being investigated.
Organic amendments, crop rotations, and cover crops are used to improve soil health in organic farming systems, but the intensive tillage relied on for weed control in typical organic farming systems can compromise these gains. Conservation-tillage, organic farming systems are being explored, but the coordination of this research across a range of climates and farming systems is a key need to improve the environmental and economic sustainability of organic farming.
While comparisons of food quality between organic and conventional farming systems have been emphasized in response to consumer perceptions, specific factors contributing to enhancement of food quality within organic systems have not been examined thoroughly. In particular, little is known concerning the fundamental impact of soil biodiversity and biological activity on nutritional quality attributes and the health-promoting phytochemicals of food crops. This information is needed to determine the causal linkages between alternative organic farming practices and food quality.
Previous and ongoing research has quantified, or is quantifying, the impact of organic farming on soil health. These independent research efforts have made important contributions to our understanding of some of the linkages between soil health and organic farming at the local level. However, a more coordinated approach is needed to enhance our understanding of the relationship between soil health and specific practices used by organic farmers. This effort should include agricultural scientists with organic farming research experience representing an array of agricultural disciplines and agroecoregions. This project is designed to foster collaboration among organic farming scientists already involved, or planning to become involved, in research quantifying the soil health impacts of different organic farming practices. The project also will provide a mechanism for the engagement of food scientists in new organic farming research projects exploring relationships between food quality, soil health, and organic farming methods. In addition, the project will stimulate networking between new and experienced scientists engaged in understanding how organic farming practices affect soil health, and food quality.
This information will have broad and immediate application on most, if not all, organic farms since a common goal is to enhance the quality of the soil that is managed and the food that is produced. Project outcomes will address several SAAESD Priority Areas, including developing AN AGRICULTURAL SYSTEM THAT IS HIGHLY COMPETITIVE IN THE GLOBAL ECONOMY (Goal 1, A. Integrated and sustainable agricultural production systems), contributing to A HEALTHY AND WELL NOURISHED POPULATION (Goal 3, A. Nutritional quality of plant and animal food products), and creating GREATER HARMONY BETWEEN AGRICULTURE AND THE ENVIRONMENT (Goal 3, A. Air, soil, and water resources conservation and enhancement; B. Natural resource and ecosystem management; D. Environmentally benign agricultural operations; E. Nutrient management in agricultural systems; and F. Integrated pest management systems, including biologically-based tactics).
Related, Current, and Previous Work:
Organic farms are integrated, complex, and biologically diverse systems, capable of internal self-regulation of ecosystem processes, including optimized nutrient and carbon (C) cycling to maximize productivity and minimize environmental contamination (Stinner and Blair 1990; Reganold et al., 2001). Core elements of organic management are: 1) organic sources of nutrient inputs; 2) rotations of soil-building with soil-depleting crops, including cover crops, 3) non-chemical methods of weed control, and 4) reliance on biological control of arthropod pests and diseases (Lampkin, 1998). Nutrient Management
Soil fertility in organic systems is controlled through organic amendments, primarily composted animal manure, and forage/legume- based crop rotations (Gaskell et al., 2000). Nitrogen fertility is maintained through synchronization across space and time of N mineralization from soil organic N pools and plant uptake of inorganic N. Management of SOM to enhance soil quality and supply nutrients is a key determinant of successful organic farming. This involves balancing two ecological processes: mineralization of C and N in SOM for short-term crop uptake, and sequestering C and N in SOM pools for long-term maintenance of soil quality, including structure and fertility. The latter has important implications for regional and global C and N budgets, including water quality (Drinkwater et al., 1998; Kramer et al., 2006) and C storage in soils (Lal and Bruce, 1999; Robertson et al., 2000; Johnson et al., 2007). Organic management, especially longer crop rotations that include forage legumes and green manures, has been shown to improve soil physical properties (Reganold et al., 1993; Lal et al., 1994; Gerhart, 1997), decrease erosion (Lockeretz et al., 1978; Gantzer et al., 1991), reduce N leaching potential (Poudel et al., 2002; Kramer et al., 2006), improve SOM (Lockeretz et al., 1981; Reganold et al., 1993; Clark et al., 1998; Drinkwater et al., 1998; Liebig and Doran, 1999; Pulleman et al., 2000; Pimentel et al., 2005; Marriot and Wander, 2006a) and facilitate the production of competitive crop yields (Delate and Cambardella, 2004; Drinkwater et al., 1998; Teasdale et al., 2007). Cover crops
Cover crops planted in conventional farming systems have the potential to reduce herbicide reliance and minimize tillage while improving soil fertility (Decker et al., 1994), reducing soil erosion (Langdale et al., 1991), sequestering soil C (Sainju et al., 2002), increasing soil water infiltration and storage (Munawar et al., 1990) and suppressing weeds (Teasdale and Daughtry, 1993). Conventional no-till farmers use cover crops to suppress weeds, conserve moisture, and build soil tilth (Heer et al., 2006; Carerra et. al., 2004; McGuire, 2003; Pester, 1998). Cereal rye (Secale cereale L.) and hairy vetch (Vicia villosa Roth) are commonly used because of their winter hardiness and high biomass production (Hoffman et al., 1993; Wilkins and Belinder, 1996). Additionally, cereal rye is selected because of its residue persistence and flexible establishment date (Ruffo and Bollero, 2003), and hairy vetch for its capacity to fix large amounts of N (Abdul-Baki et al., 1997).
In an organic farming system, cover crops offer the greatest potential for weed management and enhancement of soil quality (Clark et al., 1998; Snapp et al., 2005). Effective cover crops for organic systems have included combinations of barley, rye, wheat, hairy vetch, and crimson clover, due to their quick establishment, competitiveness and ease of mechanical termination (Creamer et al., 1996; Nelson et al., 1991). Termination of cover crops through the use of traditional organic methods, such as plowing, disking or cultivating, constitutes a major challenge for organic growers as they attempt to build soil nutrient reserves with cover crops while using tillage to control weeds (Teasdale, 2007). Numerous tillage operations, implemented for weed control and seedbed preparation, stimulate SOM decomposition and can deplete biologically-active SOM pools that are critical for fertility in these systems. However, recent research comparing nine years of no-till management with organic management (including cover crops) suggests that organic farming systems can provide greater long-term soil improvement than conventional no-till systems, despite the use of tillage in organic systems (Teasdale et al., 2007).
In the absence of herbicides, cereal rye cover crops typically are terminated with tillage or with mowing when no-till is desired. In conservation tillage systems, mowing has several drawbacks including the risk of regrowth, accelerated residue decomposition, and patchy distribution of the surface residue (Wilkins and Bellinder, 1996; Creamer and Dabney, 2002). Uniformity of coverage of surface soil from cover crop residue is critical for optimizing weed suppression (Teasdale and Mohler, 2000). A roller/crimper represents a viable alternative to mowing and tillage. With this implement, the residue is deposited uniformly on the soil surface. In contrast to mowing, the resulting layer of rye residue persists for a longer period enhancing weed suppression, moisture retention, and soil conservation (Creamer and Dabney, 2002; Morse, 2001). However, recent research identified challenges that must be overcome before roller/crimper technology is adopted by many organic farmers. For example, cover crops are not killed consistently by rolling and crimping, unless the field operation is delayed until the cover crops reach a fairly advanced growth stage (Mirsky et al., 2009; Mischler et al., 2009).
The benefits of conservation tillage (e.g. no-till) on surface soil physical and chemical (Elliott et al., 1987; Ismail et al., 1994; Karlen et al., 1994; Uri, 2000; Green et al., 2005), along with biological (Frey et al., 1999; Kennedy and Schillinger, 2006) properties have been well documented in the literature with the majority of studies from conventional systems using herbicide inputs prohibited in organic production. While no-till promotes C storage in the surface soil, incorporation of crop residues using conventional tillage (e.g., moldboard plow) can increase soil organic C content at or near the bottom of the plow layer (Angers et al., 1997). Tillage appears to affect the depth distribution more than net accumulation of soil organic C. Since the behavior of many indicators of soil quality (e.g., total N, particulate organic matter, microbial biomass) are biochemically and structurally linked to soil organic C, it is likely that tillage impacts on these soil properties will be similar to those observed for soil organic C.
Organic Farming and Soil Health
Organic practices have been reported to increase biologically available forms of SOM (Wander et al., 1994; Marriot and Wander, 2006b; Flie²bach et al., 2007), and increase the activities of beneficial soil microbes (Elmholt, 1996; Gunpala and Scow, 1998; Flie²bach and Mäder, 2000) and invertebrates (Werner and Dindal, 1990; Neher, 1999; Hansen et al., 2001). Organic systems have been shown to have more microbial biomass C, greater microbial community diversity, and higher microbial activity than conventional systems for a variety of grain, vegetable, and fruit production systems (Schjönning et al., 2002; Mäder et al., 2002; Diepeningen et al., 2006; Melaro et al., 2006; Monokrousos et al., 2006; Tu et al., 2006; Widmer et al., 2006; Esperschütz et al., 2007). The more highly diverse microbial communities have been shown to transform C from organic residues (Flie²bach and Mäder, 2000) into biomass at a lower energy cost (Fliebach et al., 2000), thus resulting in higher microbial biomass within the organic systems.
Organic Farming and Food Quality
Organic management strategies can improve soil physical, chemical, and biological properties and processes (Liu et al., 2007; Mäder et al., 2002; van Diepeningen et al., 2006). It seems reasonable to assume that the quality of the soil used to produce food crops influences the quality of that food. If so, then research indicating that organic farming practices can enhance soil quality (e.g., Liebig and Doran, 1999) suggests that food quality can also be improved following adoption of organic systems. Comparisons of nutritional quality between organic food and its conventional counterpart have produced inconclusive findings due to the lack of well-designed studies and the intrinsic complexity of farming systems (Bourn and Prescott, 2002; Magkos et al., 2003). Nevertheless, recently emerging evidence suggests that organically grown fruit and vegetables might contain higher levels of health-promoting phytochemicals (Mitchell et al., 2007; Olsson et al., 2006; Sousa et al., 2008). The essential role of phytochemicals in disease prevention has been well identified (Meskin et al., 2004). Phenolics are generally recognized as the largest group of phytochemicals with potent antioxidant activity (Manach et al., 2004). It has been estimated that organic vegetables may contain 10-50% higher defense-related secondary metabolites than conventionally grown vegetables (Brandt and Mølgaard, 2001).
Within the framework of organics, there are many production conditions, and they can significantly vary both within and among farms and regions. Without an understanding of the key components of organic farming systems with regard to their effect on food quality, it is impossible to make recommendations of the organic farming practices enhance phytochemical contents. The importance of determining if organic farming can improve food quality over conventional production is perhaps less critical than the need to identify specific contributing factors that can be manipulated in production systems to enhance food quality (Zhao et.al. 2006). Interdisciplinary efforts should take place to elucidate the interconnectedness of crop and soil health, along with food quality. It will be crucial to establish the best management practices for organic farming systems towards an integrated goal of improving crop productivity, food quality, profitability, and environmental stewardship.
Several research projects exist in the CRIS database related to this project. A CRIS search in March 2009 using the keyword phrases organic farming and soil quality identified 93 different projects. Twenty of these projects still were active and considered relevant to this project. Karlen et al. (Project no. 3625-12000-012-00D) are using the soil management assessment framework (Andrews et al., 2004) to identify how different practices affect soil quality in organic and conventional systems. Ankumah et al. (Project no. ALX-SWQ) are quantifying the impact of organic and conventional systems on soil quality, with the focus on microbial community dynamics. Erich (Project no. ME08814-08H), Cogger et al. (Project no. WNPO7725), and several others (Gliessman et al. [Project no. CALW-2004-05136]; Harrington [Project no. MICL03480]; Hue and Valenzuela [Project no. HAW00875-06G]; Reeve [Project no. UTA00308]; and Zibilske et al. [Project no. 6204-12660-001-00D]) are quantifying the impact that soil amendments and nutrient levels have on soil quality in organic systems. Cogger et al. also are evaluating the impact that cover crops and reduced tillage have on soil quality, as well as incorporating pasture into a rotation with vegetable crops. Similarly, Hooks and Brust (Project no. MD-ENTO-0814) are determining the effect that cover crops have on soil quality in organic vegetable production, as is Mankolo et al. (Project no. ALAX-011-107), while Snapp et al. (Project no. MICL02132) are focusing on field crops. Mohler et al. (Project no. NYC-125569) are quantifying the interaction between soil quality and pests. Others investigating soil quality and pest management include Cardina et al. (Project no. OHO00991-SS), Kotcon et al. (Project no. WVA00447), and Williams (Project no. KY011031). Drinkwater and Wolf (Project no. NYC-145305) are quantifying the impact that cropping system selection has on soil quality, with particular focus on C sequestration. Green (Project no. ARK02156) is comparing the impact of organic and conventional farming systems, including some dedicated to biofuel production, on soil quality, while Delate et al. (Project no. IOW03801) and Posner (Project no. WIS04378) are comparing conventional and organic farming systems for their impact on soil quality in two long-term studies.
Considerable resources have and continue to be directed at quantifying the relationship between organic farming and soil health. This work is necessary and should be encouraged. Still, there is a growing need to coordinate these activities across multiple environments and regions so that information exchange is improved, resource allocation is optimized, and fundamental principles relating to soil health enhancement in organic systems can be identified and demonstrated, along with an understanding of how environment affects the mechanisms involved. This project is a response to that need and provides the vehicle for multi-disciplinary teams of scientists from north central, northeastern, southern, and western U.S. regions to work jointly on defining the linkages between production practice, soil and food quality, and environment when farming organically.
- Coordinate activities and information exchange among researchers involved in active projects designed to quantify the impact of conservation-tillage, cover crop, crop rotation, and soil amendment practices on soil health and food quality in organic farming systems.
- Provide opportunities for experienced and new organic farming researchers to establish collaborative projects designed to identify linkages between organic farming practices, soil health, and food quality.
- Conduct outreach activities that provide unbiased scientific information on the impact organic farming can have on soil health and food quality at local, regional, national, and international scales.
- Interact with the multi-state research coordinating committee and information exchange team NCERA059 and other regional committees dedicated to enhancing the soil resource base in organic farming systems.
Procedures and Activities1. Coordinate activities and information exchange among researchers involved in active projects designed to quantify the impact of conservation-tillage, cover crop, crop rotation, and/or soil amendment practices on soil health and food quality in organic farming systems.
This project will provide meeting opportunities to scientists involved in ongoing research that investigates the soil health impacts of organic farming, such as the Neely-Kinyon Long-Term Agroecological Research (LTAR) site in Iowa (Delate et al., 2003), or the USDA-ARS Beltsville Farming Systems Project (FSP) site at Beltsville, MD (Cavigelli et al., 2008). The focus of these meetings will be to discuss the various activities associated with the different studies, including data collection and analyses. Most of this discussion will occur during the annual meeting of this multi-regional project. An important outcome of this discussion will be the development of a coordinated plan for future activities by meeting participants that includes, but is not limited to, the collection of a core set of soil health data collected across all the studies. This planning generally will occur at the subcommittee level, which will be organized by the specific farming practice(s) being investigated (e.g., conservation-tillage) for its impact on soil health and/or food quality. The annual meeting likely will stimulate follow-up communication and information exchange between members of the various sub-committees as coordinated activities are refined, agreed upon, and executed. Interest in this approach was expressed during a meeting between development committee members, the administrative advisor, and prominent organic farming scientists and educators that was held in conjunction with the Tri-Societies (i.e., Agronomy, Crops and Soils) in Pittsburg, PA, on 01 November, 2009.
2. Provide opportunities for experienced and new organic farming researchers to establish collaborative projects designed to identify linkages between organic farming practices, soil health, and food quality. Project activities described under objective 1 will generate interest in developing new studies that define linkages between organic farming practices and soil health beyond those already being explored in active research. These studies will involve experienced as well as new scientists working in collaborative, inter-disciplinary teams. Involvement of food scientists in these scientist teams, including one on the development committee, will allow the learning domain to be expanded to include the linkages between organic farming methods, soil health, and food quality. The planning of research activities, including collecting of a core data set at all locations, will occur at the study conceptualization stage of the studies, allowing outreach activities to be coordinated across all studies and locations. Preliminary discussion and planning of the new studies will occur at the subcommittee level (e.g., conservation-tillage) during the annual meeting of this project, as was the case with studies discussed under objective 1. Subsequent planning and coordination of research activities will occur, as needed.
3. Conduct outreach activities that provide unbiased scientific information on the linkages between organic farming systems, soil health, and food quality at local, regional, national, and international scales.
Outreach activities will involve dissemination of project results using traditional events (e.g., field days), and by organizing special events (e.g., research symposia). Symposia and other special events typically will be collaborative and involve project participants and scientists in other professional groups (e.g., members of the Organic Management Systems division within the American Society of Agronomy during the Tri-Society annual meeting, or at regional society meetings). Project results will be presented in one or more papers presented during the symposia. Project results also will be distributed using both hard-print and electronic media. 4. Interact with the multi-state research coordinating committee and information exchange team NCERA059 and other regional committees dedicated to enhancing the soil resource base in organic farming systems.
Multistate research coordinating committee and information exchange group NCERA059 was formed around the issues of soil organic matter formation, function, and management. This group is not focused on organic farming methods per se, but organic farming systems research is not excluded from activities. Several participants in NCERA059 are prominent scientists who have or are conducting organic farming research, and have contributed to the literature. All have expertise in the soil quality area.
The current project focuses not only on soil organic matter or even soil health, but also on organic farming practices and food quality, so participants include not only soil scientists but scientists in agronomy, food science, and other disciplines. The strengthening and standardization of food-quality research within organic systems is a unique and important aspect of this effort. Few studies evaluating organic effects have documented soil characteristics in concert with plant quality assays. Several soil scientists already involved in NCERA059 have expressed an interest in participating in the proposed project. The objectives of both multi-state research groups are not identical but complementary, since the quantity and quality of soil organic matter (i.e., the focus of NCERA059) is a primary determinant of soil health which, in turn, is affected by organic farming management and impacts food quality (i.e., the focus of the present multistate project).
Writing committee members of this proposal have been in dialogue with NCERA059 group members, some of whom served as reviewers of earlier versions of the current project proposal. Invaluable advice was offered and incorporated into the current proposal. The information exchange begun between members of this project and those of NCERA059 will be continued, since this interaction enhances the potential for scientific collaboration and coordination of research activities between members of both groups.
Expected Outcomes and Impacts:
- Generation, analyses, and interpretation of data indicating the impact that cover-crop intensive, conservation tillage practices have on carbon sequestration, soil moisture conservation and use, weed suppression, augmentation of biological controls, and other ecosystem services in certified organic systems. Knowledge will be gained of the contributions provided by conservation tillage, cover-crop, crop rotation, and soil amendment practices among soil health extension service educators, natural resource managers (e.g., USDA-NRCS personnel), and farmers considering the transition to organic production methods in all participating states.
- Generation, analyses, and interpretation of data that elucidate the link(s) between organic farming practices, soil quality, and food quality along with storage life. Nutritionists and others interested in food science in each participating state will be provided with new quantitative information of how food quality and storage life are affected by different organic management practices, and on linkages between soil quality, crop heath, and food quality.
- Technology transfer tools including field days, conference and classroom presentations, presentations at professional society meetings, and refereed along with non-refereed publications where knowledge gained from the project is presented. Greater use of cover crops and, specifically, suitable species identified in this project, will occur on organic and conventional farms in each participating state.
- Creation and maintenance of website pages summarizing impacts of adopting cover-crop intensive, conservation-tillage practices on organic farms at each institutions website, and on the eOrganic website. Website pages created or modified as a result of this project will provide a forum for shared learning about cover-crop intensive, conservation-tillage practices among at least 200 organic farmers, researchers, and others annually from within and outside of the U.S.
Project Participation:Include a completed Appendix E form
There are two intended audiences of this project and its activities, and both require different outreach plans. The first intended audience are agriculturists; this group includes farmers (i.e., organic and conventional), natural resource managers (e.g., NRCS) and educators (e.g., extension service personnel). Traditional outreach activities will include field days in participating states where project objectives, activities, and results will be presented. A primary goal of these events will be to give local farmers the opportunity to see emerging organic farming practices (e.g., conservation-tillage systems) and technology in the field, and discuss how these methods and technologies can enhance soil health and, by extension, food quality. These events also will allow information exchange between scientists, farmers, natural resource managers, and educators on how to improve the efficacy of these practices under local conditions. Other goals will be specific to the field day locations, including sharing information on soil quality, food quality, cover cropping strategies, nutrient management, integration of livestock into organic crop production systems, and weed management. Field days will occur at university research plots and, where appropriate, on farms. Project participants will work with survey designers to develop field day participant surveys customized to each event, and then interpret the collected data to assess the impact, strengths and weaknesses of the activity. These survey data then will be shared among the collaborators to improve the quality of the field day activities as the project progresses. We anticipate a minimum of 30 attendees at each field day but most are expected to have much higher attendance (i.e., >100/event). These field day events will be complemented by conference and classroom presentations. These presentations typically will be made at organic conferences in each participating state where participants are located (e.g., the summer and/or winter conference of the Northern Plains Sustainable Agriculture Society in North Dakota). Classroom presentations of project activities will occur in states where participants are associated with universities that offer organic farming coursework (e.g., the Organic Agriculture: Theory and Practice class [AGRON 484X] at Iowa State University). Additionally, Information will be integrated into existing Extension curricula such as the Cultivating Success series focused on small-acreage farmers in Washington and Idaho. Results of the project will be presented to scientific peers at professional meetings.
The other intended audience will be organic farming and conventional farming researchers not participating in the project. Outreach strategies include presentation of project results at scientific meetings, including symposia organized by project participants, and the publication of project results in the refereed literature. A special effort will be made to disseminate project results to the extension community through eXtension.
Publications will constitute an important method for disseminating project results. The publications will be designed to help interested farmers transition to organic, and current organic farmers to improve their management, by introducing or refining organic farming practices that enhance soil health and food quality. The goal of the publications is to provide in-depth, engaging soil management training and resources to interested farmers and agricultural professionals around the world, helping them gain from our experience and improve their chances for success. The publications will be available for distribution at field days, conferences, and classes, as well as on the New Farm and eOrganic websites, to outreach project information to broader agricultural audiences, policy makers and other interested members of the public.
We anticipate a minimum of five refereed manuscripts, in addition to numerous contributions to non-refereed technical reports, including proceedings and popular-press articles, will be generated describing project activities. Journals we will target include Agronomy Journal, Crop Science, HortScience, the Journal of Renewable Agriculture and Food Systems, and the Journal of Sustainable Agriculture. At least one extension bulletin summarizing results of the project and including recommendations for managing cover crops for weed suppression on organic farms will be generated by this project. This bulletin will be available electronically on each institutions website and with the eOrganic community of practice with eXtension. Hard copies also will be printed to assure maximum accessibility.
The project will be planned and executed by a Technical Committee that consists of one representative from each participating state Experiment Station, one representative from each participating USDA-ARS facility, and one representative from each participating non-land grant university. The representatives will be appointed by the appropriate administrative head or director; each representative will be a voting member on the committee. A regional administrative Advisor and CSREES representative will be included on the Technical Committee with veto power, although they will be non-voting members.
The Technical Committee will meet annually to discuss progress on meeting project objectives. Summaries of work completed since the previous meeting and activities planned for the upcoming reporting period will be presented and discussed. It is anticipated that debate will occur regarding analyses and interpretation of data collected by participants and how progress is being made on meeting project objectives. Some participants may wish to alter their contributions to the project. Any changes to the project will be considered by the Technical Committee at the annual meeting and, if approved, will result in the participating entity preparing an addendum to the methods section of the project outlining the proposed work. The addendum must be signed by the appropriate administrator at the participating institution and the regional Administrative Advisor. The addendum and appropriate forms then will be forwarded for approval to CSREES. The addendum will be made a part of the project outline if approved by CSREES.
An Executive Committee will oversee efforts of the Technical Committee. The Executive Committee will consist of a chairperson, vice-chairperson, and secretary. The Executive Committee will preside at the annual meeting of the Technical Committee. Vice-chairperson and secretary positions will be elected at the annual meeting, with the vice-chairperson assuming the chairperson position the following year. Responsibilities of the chairperson include selecting a site for the Technical Committee meeting and associated logistics, and presiding over the Executive and Technical Committees. The chairperson also is responsible for preparing or overseeing the development of the annual report of the Technical Committee. The secretary will record and distribute the minutes of the annual meeting. The vice-chairperson will perform tasks assigned by the Technical Committee that are not done by either the chair-person or secretary.
Subcommittees will be organized around each project objective. Chairpersons of the subcommittees will be appointed by the Executive Committee chair and will be responsible for overseeing and reporting activities relating to the assigned objective to the full Technical Committee.
Literature Cited:Abdul-Baki, A.A., J.R. Teasdale, and R.F. Korcak. 1997. Nitrogen requirements of fresh-market tomatoes on hairy vetch and black polyethylene mulch. Hortscience 32:217-221.
Angers, D. A., M. A. Bolinder, M. R. Carter, E. G. Gregorich, C. F. Drury, B. C. Kiang, R. P. Voroney, R. R. Simard, R. G. Donald, R. P. Beyaert, and J. Martel. 1997. Impact of tillage practices on organic carbon and nitrogen in cool, humid soils of eastern Canada. Soil Tillage Res. 41:191-201.
Bourn, D. and J. Prescott. 2002. A comparison of the nutritional value, sensory qualities, and food safety of organically and conventionally produced foods. Crit. Rev. Food Sci. Nutr. 42:1-34.
Brandt, K. and J.P. Mølgaard. 2001. Organic agriculture: Does it enhance or reduce the nutritional value of plant foods? J. Sci. Food Agr. 81:924-931. Carrera, L.M., A.A. Abdul-Baki, and J.R. Teasdale. 2004. Cover crop management and weed suppression in no-tillage sweet corn production. HortScience 39(6): 1262-1266.
Cavigelli, M.A., J.R. Teasdale, and A.E. Conklin. 2008. Long-Term Agronomic Performance of Organic and Conventional Field Crops in the Mid-Atlantic Region. Agron. J. 100:785-794. Clark, M. S., W. R. Horwath, C. Shennan, and K. Scow. 1998 Changes in soil chemical properties resulting from organic and low-input farming practices. Agron. J. 90:662-671.
Creamer, N.G. and S.M. Dabney. 2002. Killing cover crops mechanically: Review of recent literature and assessment of new research results. Am. J. Altern. Agric. 17:32-40. Creamer, N.G., M.A. Bennett, B.R. Stinner, J. Cardina, and E.E. Regnier. 1996. Mechanisms of weed suppression in cover crop-based production systems. Hortscience 31:410-413.
Decker, A.M., A.J. Clark, J.J. Meisinger, F.R. Mulford, and M.S. MCinthosh. 1994. Legume cover crop contributions to no-tillage corn production. Agron. J. 86:126-135.
Delate, K. and C. Cambardella. 2004. Agroecosystem performance during transition to certified organic grain production. Agron. J. 96: 1288 1298.
Delate, K.M., M. Duffy, and C. Chase. 2003. An economic comparison of organic and conventional grain crops. Am. J. Altern. Agric. 35:1 11.
Diepeningen, A.D., O.J.de Vos, G. W. Korthals, A. H. C. van Brugeen. 2006.
Effects of organic versus conventional management on chemical and biological parameters in agricultural soils. Applied Soil Ecology 31:120-135.
Drinkwater, L. E., P. Wagoner and M. Sarrantonio. 1998. Legume-based cropping systems have reduced carbon and nitrogen losses. Nature 396: 262-265.
Elliott, L.F., R.I. Papendick, and D.F. Bezdicek. 1987. Cropping practices using legumes with conservation tillage and soil benefits. p. 1-89. In: J.F. Power (ed.). The role of legumes in conservation tillage systems. Soil Conserv. Soc. Am., Ankeny, IA.
Elmholt. S. 1996. Microbial activity, fungal abundance and distribution of Penicillium and Fusarium as bioindicators of a temporal development of organically cultivated soils. Bio. Agric. Hort. 13(2):123-140.
Fliebach, A.. and Mäder, P. 2000. Microbial biomass and size-density fractions differ between soils of organic and conventional agricultural sytems. Soil Biol. Biochem. 32:757-768.
Fliebach, A., P. Mäder, and U. Niggli. 2000. Mineralization and microbial assimilation of 14C-labeled straw in soils of organic and conventional agricultural systems. Soil Biol. Biochem. 32: 1131-1139.
Flie²bach, A., H.-R. Oberholzer, L. Gunst, and P. Mäder. 2007. Soil organic matter and biological soil quality indicators after 21 years of organic and conventional farming. Agric. Ecosys. Environ. 118:273-284.
Frey, S.D., E.T. Elliott, and K. Paustian. 1999. Bacterial and fungal abundance and biomass in conventional and no-tillage agroecosystems along two climatic gradients. Soil Biol. Biochem. 31:573-586.
Gantzer, C. J., S. H. Anderson, A.L. Thompson and J.R. Brown 1991. Evaluation of soil loss after 100 years of soil and crop management. Agron. J. 83: 74-77.
Gaskell, M., B. Fouche, S. Koike, T. Lanini, J. Mitchel, and R. Smith. 2000. Organic vegetable production in California science and practice. HortTechnology 10:699-713.
Gerhardt, R. A. 1997. A comparative analysis of the effects of organic and conventional farming systems on soil structure. Biol. Agric. Hort. 14(2):139-157.
Green, V.S., M.A. Cavigelli, T.H. Dao, and D.C. Flanagan. 2005. Soil physical properties and aggregate associated C, N, and P distributions in organic and conventional cropping systems. Soil Science 170(10):822-831.
Gunapala, N. and K. Scow. 1998. Dynamics of soil microbial biomass and activity in conventional and organic farming systems. Soil Biol. Biochem. 30(6):805-816. Hansen, B. H., F. Alroe, and E. S. Kristensen. 2001. Approaches to assess the environmental impact of organic farming with particular regard to Denmark. Agric. Ecosys. & Environ, 83:11-26.
Hoffman, M.L., E.E. Regnier, and J. Cardina. 1993. Weed and corn (Zea mays) Responses to a hairy vetch (Vicia villosa) cover crop. Weed Technol. 7:594-599. Ismail, I., R.L. Blevins, and W.W. Frye. 1994. Long-term no-tillage effects on soil properties and continuous corn yields. Soil Sci. Soc. Am. J. 58:193-198.
Johnson, J. M.-F., A. J. Franzluebbers, S. Lachnicht Weyers, and D. C. Reicosky. 2007. Agricultural opportunities to mitigate greenhouse gas emissions. Environmental Pollution 150: 107-124.
Karlen, D.L., N.C. Wollenhaupt, D.C. Erbach, E.C. Berry, J.B. Swan, N.S. Eash, and J.L. Jordahl. 1994. Long-term tillage effects on soil quality. Soil Tillage Res. 32:313-327.
Kennedy, A.C., and W.F. Schillinger. 2006. Soil quality and water intake in traditional till vs. no-till paired farms in Washington Palouse region. Soil Sci. Soc. Am. J. 70(3):940-949.
Kramer, S. B., J. P. Reganold, J. D. Glover, B. J. M. Bohannan, and H. A. Mooney. 2006. Reduced nitrate leaching and enhanced denitrifier activity and efficiency in organically fertilized soils. PNAS. 103:4522-4527.
Lampkin, N. H. 1998. Organic Farming. Farming Press. Ipswich. 715pp. Lal, R., A. A. Mahboubi and N.R. Fausey. 1994. Long-term tillage and rotation effects on properties of a central Ohio soil. Soil Sci. Soc. Am. J. 58(2): 517-552.
Lal, R. and J. P. Bruce. 1999. The potential of world cropland soils to sequester C and mitigate the greenhouse effect. Environ. Sci. Policy 2:77-185. Langdale, G.W., R.L. Blevins, D.L. Karlen, D.K. McCool, M.A. Nearing, E.L. Skidmore, A.W. Thomas, D.D. Tyler, and J.R. Williams. 1991. Cover crop effects on soil erosion by wind and water. In W.L. Hargrove (ed.) Cover Crops for Clean Water. Soil and Water Conservation Society Ankeny, IA. p.15-22.
Liebig, M.A. and J. W. Doran. 1999. Impact of organic production practices on soil quality indicators. J. Environ. Qual. 28:1601-1609.
Liu, B., C. Tu, S. Hu, M. Gumpertz, and J.B. Ristaino. 2007. Effect of organic, sustainable, and conventional management strategies in grower fields on soil physical, chemical, and biological factors and the incidence of Southern blight. Applied Soil Ecol. 37:202-214.
Lockeretz, W., Shearer, G., Klepper, R., and Sweeney, S. 1978. Field crop production on organic farms in the Midwest. J. Soil Water Conserv. 33:130 134.
Lockeretz, W., Shearer, G. and Kohl, D. 1981. Organic farming in the Corn Belt. Science 211:540 547.
Mäder, P. A. Flie²bach, A.. Dubois, L. Gunst, P. Fried, and U. Niggli. 2002. Soil fertility and biodiversity in organic farming. Science: 296:1694-1697.
Magkos, F., F. Arvaniti, and A. Zampelas. 2003. Organic food: nutritious food or food for thought? A review of the evidence. Intl. J. Food Sci. Nutr. 54:357-371.
Manach, C., A. Scalbert, C. Morand, C. Rémésy, and L. Jiménez. 2004. Polyphenols: food sources and bioavailability. Amer. J. Clinical Nutr. 79:727-747.
Marriot, E.M. and M.M. Wander. 2006a. Total and labile soil organic matter in organic and conventional farming systems. Soil Sci. Soc. Am. J. 70:950-959.
Marriot, E. M. and M. M. Wander. 2006b. Qualitative and quantitative differences in particulate organic matter fractions in organic and conventional farming systems. Soil Biol. Biochem. 38:1527-1536.
McGuire, A.M. 2003. Mustard green manures replace fumigant and improve infiltration in potato cropping system. Plant Management Network. Available on-line at: http://www.plantmangementnetwork.org/pub/cm/research/2003/mustard/. Melaro, S., J. C. R. Porras, J. F. Herencia, and E. Madejon. 2006. Chemical and biological properties in a silty loam soil under conventional and organic management. Soil Tillage Res. 90:162-170.
Meskin, M.S., W.R. Bidlack, A.J. Davies, D.S. Lewis, and R.K. Randolph. 2004. Phytochemicals: Mechanisms of action. CRC Press, Boca Raton, Fla.
Mirsky, S.B., W.S. Curran, D.A. Mortensen, M.R. Ryan, and D.L. Shumway. 2009. Control of cereal rye with a roller/crimper as influenced by cover crop phenology. Agron. J. 01:1589-1596.
Mischler, R., S.W. Duiker, W.S. Curran, and D. Wilson. 2009. Hairy vetch management for no-till organic corn production. Agron. J. 102:355-362. Mitchell, A.E., Y.J. Hong, E. Koh, D.M. Barrett, D.E. Bryant, R.F. Denison, and S. Kaffka. 2007. Ten-year comparison of the influence of organic and conventional crop management practices on the content of flavonoids in tomatoes. J. Agric. Food Chem. 55:6154-6159.
Monokrousos, N., E. M. Paptheodorou, J. D. Diamanthopoulos, and G. P. Stanou. 2006. Soil quality variables in organically and conventionally cultivated field sites. Soil Biol. Biochem. 38:1282-1289.
Morse, R.D. 2001. No-herbicide, no-till summer broccoli-quantity of rye and hairy vetch mulch on weed suppression and crop yield. p. 85-94 In J.H. Stiegler, (ed.) Proc. 24th Annual Southern Conservation Tillage Conference for Sustainable Agriculture, Oklahoma City, OK.
Munawar, A., R.L. Blevins, W.W. Frye, and M.R. Saul. 1990. Tillage and cover crop management for soil water conservation. Agron. J. 82:773-777.
Neher, D. A. 1999. Nematode communities in organically and conventionally managed agricultural soils. J. Nematol. 31, 142-154. Nelson, W.A., B.A. Kahn, and B.W. Roberts. 1991. Screening cover crops for conservation tillage systems for vegetables following spring plowing. HortScience 6:860-862.
Olsson, M.E., C.S. Andersson, S. Oredsson, R.H. Berglund, and K.E. Gustavsson. 2006. Antioxidant levels and inhibition of cancer cell proliferation in vitro by extracts from organically and conventionally cultivated strawberries. J. Agric. Food Chem. 54:1248-1255.
Pester, T. 1998. Allelopathic effects of rye (Secale cereale L.) and their implications for weed management a review. Available on-line at: http://www.colostate.edu/Depts/Entomology/courses/en570/papers_1998/pester.htm. Pimentel, D., P. Hepperly, J. Hanson, D. Douds, and R. Seidel. 2005.
Environmental, energetic, and economic comparisons of organic and conventional farming systems. BioScience. 55:573-582. Pulleman, M.M, J. Bourma E. A. van Esssen, E. W. Meijles. 2000. Soil organic matter content as a function of different land use history. Soil Sci. Soc. Am, J. 64(2):689-693.
Reganold, J. P., A, S. Palmer, J. C. Lockhart and A. N. Macgregor. 1993. Soil quality and financial performance of biodynamic and conventional farms in New Zealand. Science 260:344-349.
Reganold, J. P., J. D. Glover, P. K. Andrews and H. R. Hinman. 2001, Sustainability of three apple production systems. Nature 410:926-930.
Robertson, G.P., E.A. Paul, and R.R. Harwood. 2000. Greenhouse gases in intensive agriculture: Contributions of individual gases to the radioactive forcing of the atmosphere. Science 289:1922-1925.
Ruffo, M.L. and G.A. Bollero. 2003. Modeling rye and hairy vetch residue decomposition as a function of degree-days and decomposition-days. Agron. J. 95:900-907.
Sainju, U.M., B.P. Singh, and W.F. Whitehead. 2002. Long-term effects of tillage, cover crops, and nitrogen fertilization on organic carbon and nitrogen concentrations in sandy loam soils in Georgia, USA. Soil Tillage Res. 63:167-179.
Schjønning, P., S. Elmholt, L. J. Munkholm, K. Debosz. 2002. Soil quality aspects of humid sandy loams as influenced by organic and conventional long-term management. Agric. Ecosys. Environ. 88:195-214.
Snapp, S., S.M. Swinton, R. Labarta, D. Mutch, J.R. Black, R. Leep, J. Nyiraneza, and K. O Neil. 2005. Evaluating cover crops for benefits, costs, and performance within cropping system niches. Agron. J. 97:322-332.
Sousa, C., D.M. Pereira, J.A. Pereira, A. Bento, M.A. Rodrigues, S. Dopico-Garcia, P. Valentao, G. Lopes, F. Ferreres, R.M. Seabra, and P.B. Andrade. 2008. Multivariate analysis of tronchuda cabbage (Brassica oleracea L. var. costata DC) phenolics: influence of fertilizers. J. Agric. Food Chem. 56:2231-2239.
Stinner B. R. and J. M. Blair. 1990. Ecological and agronomic characteristics of innovative cropping systems. In Sustainable agricultural systems. C. A. Edwards, R. LaL, P. Madden, R. H. Miller and G. House. Soil and Water Conservation Society. Ankeny, IA. p. 123-140.
Teasdale, J. R. 2007. Strategies for soil conservation in no-tillage and organic farming systems. J Soil Water Conserv. 62:144A-147A.
Teasdale, J.R. and C.S.T. Daughtry. 1993. Weed suppression by live and desiccated hairy vetch. Weed Sci. 41:207-212.
Teasdale J.R. and C.L. Mohler. 2000. The quantitative relationship between weed emergence and the physical properties of mulches. Weed Sci. 48:385-392. Teasdale, J. R, C. B. Coffman, and R. W. Mangum. 2007. Potential long-term benefits of no-tillage and organic cropping systems for grain production and soil improvement. Agron. J. 99:1297-1305.
Tu, C., F. J. Louws, N. G. Creamer, J. P. Mueller, C. Brownie, K. Fager, M. Bell, S. Hu. 2006. Responses of soil microbial biomass and N availability to transition strategies from conventional to organic farming systems. Agric. Ecosys. Environ. 113:206-215.
Uri, N.D. 2000. Perceptions on use of no-till farming in production agriculture in the United States. Agric. Ecosys. Environ. 77(3):263-266.
Wander, M.M., S.J. Traina, B.R. Stinner and S.E. Peters. 1994. Organic and conventional management effects on biologically active soil organic matter pools. Soil Sci. Soc. Am. J. 58:1130-1139. Werner, M. R. and D. L. Dindal. 1990. Effects of conversion to organic agricultural practices on soil biota. Am. J. Alt. Ag. 5(1):24-32.
Wilkins, E.D. and R.R. Bellinder. 1996. Mow-kill regulation of winter cereals for spring no-till crop production. Weed Technol. 10:247-252.
Zhao, X., E.E. Carey, W. Wang, and C.B. Rajashekar. 2006. Does organic production enhance phytochemical content of fruit and vegetables? Current knowledge and prospects for research. HortTechnology 16:449-456.
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