Progress 10/01/08 to 09/30/09
Outputs
OUTPUTS: Activities: The content of this CRIS report will include highlights from my on-going projects with an emphasis on those that are not already documented within the CRIS database. NSF-CHN project- 1) The final year of field research was conducted in the Mississippi River Basis this summer. We continued our study clusters of farms in order to interview farmers representing the full continuum of management variation in the region and collected legume cover crop and forage samples from as many fields as possible. 2) A15N tracer experiment was conducted in Illinois comparing three different corn varieties in terms of N fertilizer uptake and allocation. We will also compare cover cropped versus bare fallow plots. 3) The farmer survey was conducted in March of 2009 and we are in the process of analyzing the responses we received. 4) Northeast SARE- The second field season for the regional project entitled Learning from Farmer Innovation in Nitrogen Fixation for Improving Nutrient Management on Organic Farms was carried out. We collected additional legume cover crop samples from 10 farmer fields in order to estimate on farm biological N fixation. 5) A second experiment was conducted to evaluate the 5 warm season legume species that were the best performers in last year's screening trial. Data are being analyzed this winter. Dissemination: Findings from my research group have been presented at numerous conferences before researchers, extension educators and farmers including the New York Fruit and Vegetable Expo, Cornell Organic Working Group meetings, and the Natural Systems Agriculture workshops at the Land Institute as well as the annual meetings of the Ecological Society of America, American Society of Agronomy and Soil Science Society of America. Presentations that were accompanied by a published abstract are listed under the publications section. Some key invited presentations from 2009 are listed below. Drinkwater, L. E. M. B. David, R. E. Galt, J. B. Gardner, S. Hufnagl-Eichiner, L. Marshall, S.S. Snapp, C. Tonitto, J. V. Westra, S. A. Wolf. 2009. Hypoxia and the Mississippi River Basin as a model system: What can we learn about social-ecological interfaces Ecological Society of America Annual Meetings. Albuquerque, NM August 2009. Gardner, J.B., Drinkwater, L.E. and R.E. Galt. 2009. What barriers prevent the application of soil ecology to agricultural systems Invited symposium talk at the Ecological Society of America Annual Meeting in Albuquerque, NM (August 2009). Drinkwater, L.E. 2009. Nutrient cycling processes in legume-based systems. 16th International Congress on Nitrogen Fixation, Big Sky, Montana, June 2009. PARTICIPANTS: Laurie Drinkwater is the principal investigator for this project. Meagan Schipanski completed her PhD in 2009. Jennifer Gardner is a PhD student working on the NSF-CHN project. She has published her first paper. Burtie Van Zyl is a MS student who joined the lab group this past year. He is conducting the research on green manure management in organic vegetable farms and will finish in 2009. Christina Tonitto is a Research Associate and works 25% FTE on modeling diversified agricultural systems for the NSF-CHN project. Sean Berthong is a post-doctoral researcher who joined the lab this year. He will be working on microbial community structure and N cycling. Ann Piombino is a Research Technician in the Drinkwater lab. Our lab group is engaged in research, extension and education in collaboration with many other researchers at several institutions as well as other stakeholders including farmers, NGO staff and extension educators. Professional development Graduate students in the lab group receive training in how to design and implement interdisciplinary agroecological research. Those working with the NSF-CHN project have developed research skills in obtaining large data sets, incorporating them into databases, and creating GIS views of the data. We hold weekly lab meetings where students and visitors lead discussions of research projects or review relevant journal articles. There are usually 2-3 undergraduates involved in the research. These students have the opportunity to gain valuable research experience through their work in the field assisting with sample collection and in the laboratory where they help with a variety of analytical procedures. This past year one of my students who is very interested in extension developed a workshop for farmers about how to do on-farm experimentation. TARGET AUDIENCES: Most of the work withing this project is funded by programs that expect new knowledge to be generated and disseminated to other scientists through publication in peer-reviewed journals and at professional meetings. As a result, the target audience for most of this work is the scientific community, however significant efforts are directed toward communicating our findings to those engaged in farmer education as well as farmers themselves. Examples of specific target audiences include: 1) certified organic producers 2) conventional producers who are planning to transition to organic production or who are interested in restoring soil quality and reducing environmental impacts 3) farmer educators interested in sustainable soil management. Since our work contributes to supporting environmentally sound, regional agriculture people in the Northeast who want to purchase certified organic produce and rural communities in state of New York are also beneficiaries. We have given presentations based our work to several regional extension-oriented conferences. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Changes in knowledge-The work of my research group continues to demonstrate multiple benefits that can be achieved though use of ecologically based approaches to soil fertility management. 1) This past year I was invited to write a chapter on research design for organic agricultural systems 2) The NSF project hosted a workshop on Ecosystem Services in Agroecosystems in Washington DC. The workshop was well attended by scientists from regulatory and research agencies including the USDA, EPA, NRCS and many natural resource management non-profits. 3) The nutrient budgeting tool is being tested by other extension groups in Pennsylvania and Vermont. We will incorporation the feedback from these groups into further development of the software.
Publications
- Maul, J. and L.E. Drinkwater. 2009. Short-term plant species impact on microbial community structure in soils with long-term agricultural history. Plant and Soil. Published on line Dec 2009.
- Drinkwater, L.E. C. Francis, M. Entz, E.A. Clark, K.M. Delate, J. Heckman, M. Liebman, R.R. Janke, P.Allen, and N.G. Creamer. 2009. Ecology in organic farming: New book from American Society of Agronomy. Abstract. Agronomy Society of America, Annual Meetings. Pittsburgh, PA. November 5-9, 2009.
- Schipanski, M.E. L. E. Drinkwater, S. J. Vanek, S. Waterman. 2009. Nutrient mass balances and agroecosystem management in New York State. Abstract. Agronomy Society of America, Annual Meetings. Pittsburgh, PA. November 5-9, 2009.
- Drinkwater, L.E., 2009. Ecological knowledge: Foundation for sustainable organic agriculture. IN: Francis, C. F., ed. 'Organic Farming: The Ecological System. Pp. 19-50.
- Gardner, JB and L.E. Drinkwater. 2009. The fate of nitrogen in grain cropping systems: a meta-analysis of N-15 field experiments. Ecological Applications, 19: 2167-2184.
- Vitousek, PM, R. Nylor, R; T. Crews, M. B. David, L. E. Drinkwater, E. Holland, P. J. Johnes, J. Katzenberger, L. A. Martinelli, P. A. Matson, G. Nziguheba, D. Ojima, C. A. Palm, G. P. Robertson, P. A. Sanchez, A. R. Townsend, F. S. Zhang. 2009. Nutrient imbalances in agricultural development. Science, 324: 1519-1520.
- Schipanski M.E., L. E. Drinkwater and M.P. Russelle. 2009. Understanding the variability in soybean nitrogen fixation across agroecosystems. Plant and Soil. Published on line Sept 2009.
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Progress 10/01/07 to 09/30/08
Outputs
OUTPUTS: Activities: The content of this CRIS report will include highlights from my on-going projects with an emphasis on those that are not already documented within the CRIS database. NSF-CHN project- 1) A second year of field research was conducted in the Mississippi River Basis this summer. We continued our study clusters of farms in order to interview farmers representing the full continuum of management variation in the region. Two additional study sites were selected for fieldwork based on the presence of significant numbers of organic farmers: one in southern Minnesota, the other in Wisconsin. 2) The 15N meta-analysis was completed the results were summarized in a paper submitted to Ecological Applications. The manuscript has been accepted pending revisions. (This paper serves as the MS Thesis for J.M. Gardner). 3) Northeast SARE- The first field season for the regional project entitled Learning from Farmer Innovation in Nitrogen Fixation for Improving Nutrient Management on Organic Farms was carried out. We collected legume cover crop samples from 12 farmer fields in order to estimate on farm biological N fixation. An additional set of farms in the Hudson Valley area were visited in the summer and interviewed about their cover crop management practices. In the second year we hope to sample at least 20 fields to expand our measurements of N fixation. 4) Research to identify warm season cover crops that suppress summer weeds and fix nitrogen moved forward. We conducted a screening trial with 8 different warm season legume species grown as monocultures and in mixed culture with non-N-fixing cover crops. Dissemination: Findings from my research group have been presented at numerous conferences before researchers, extension educators and farmers including the New York Organic Farming Conference, New York Certified Organic meetings, Cornell Organic Working Group meetings, and the Natural Systems Agriculture workshops at the Land Institute as well as the annual meetings of the Ecological Society of America, American Society of Agronomy and Soil Science Society of America. Presentations that were accompanied by a published abstract are listed under the publications section. Some key presentations from 2008 are listed below. Drinkwater, L. E. 2008. Understanding complex farming systems. Workshop on 21st Century Systems Agriculture. The National Academies, Board on Agriculture and Natural Resources and National Research Council. Washingtion, DC. August 2008. Drinkwater, L. E. 2008. Is it time for an ecosystem based approach to nutrient management? Presented to the International Workshop on Sustainable Nutrient Management., Shijiazhuang, Hebei, China. May, 2008. Drinkwater, L. E. 2008. Understanding linkages between biogeochemical and social processes in agricultural landscapes: Solving the nitrogen problem in the Mississippi River Basin, USA. College of Resources and Environmental Sciences, China Agricultural University, Beijing, China. June 2008. PARTICIPANTS: Laurie Drinkwater is the principal investigator for this project. Meagan Schipanski is a PhD student and has been carrying out the on-farm research on biological N fixation. Jennifer Gardner is a PhD student working on the NSF-CHN project. She just completed her master's research this past year and is currently writing her first manuscript. Burtie Van Zyl is a MS student who joined the lab group this past year. He is conducting the research on green manure management in organic vegetable farms. Christina Tonitto is a Research Associate and works 25% FTE on modeling diversified agricultural systems for the NSF-CHN project. Julie Grossman is a Research Associate who works half time in the lab on the biological N fixation projects. In May 2008 she accepted a tenure-track faculty position at North Carolina State. Ann Piombino is a Research Technician in the Drinkwater lab. Our lab group is engaged in research, extension and education in collaboration with many other researchers at several institutions as well as other stakeholders including farmers, NGO staff and extension educators. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Changes in knowledge-The work of my research group continues to demonstrate multiple benefits that can be achieved though use of ecologically based approaches to soil fertility management. 1) This past year I was invited to write a chapter on ecological nutrient management for an international agroecology text book. 2) In our Mississippi River Basis project, we expanded our modeling approach to include Monte Carlo modeling of observations synthesized from the literature. We framed our empirical modeling work as a comparison point to the simulation outcomes for quantifying N2O flux from agroecosystems. Our empirical model outcomes overlap with mean values from the inter model comparison. Extreme N2O flux is predicted with extremely low probability using empirical modeling techniques, a result that conflicts with multi year elevated N2O flux predictions from simulation model application. 3) At the end of our second cycle of the Sustainable Agriculture Scholars program, we collected student feedback through a post-program focus-group style interview with a third party and added a pre-program interview and a student comparison group in year two. Students reported learning about linkages between agriculture research and practice within all three environments, with farm visits being the primary site of this learning, specifically through observations of sustainable agricultural practices related to their lab work and interactions with farmers. Though students described ways in which farm visits made lab work seem more relevant, there were few instances describing how the lab work was relevant to the farming community. Four out of the six students reported increased interest in agricultural careers as a result of participating in the Program; three reported increased desire to pursue agricultural research. Service project discussions demonstrated students' sense of ownership and satisfaction about contributing to their community. Our evaluation demonstrates the potential for this and other similar programs to foster interest in sustainable agriculture and agriculture research for undergraduates.
Publications
- Tonitto, C., M.B. David, L.E. Drinkwater. (2008) Modeling N2O flux from an Illinois agroecosystem using Monte Carlo sampling of field observations. Biogeochemistry
- Drinkwater, L.E., M. Schipanski, S.S. Snapp and L.E. Jackson. (2008) Ecologically based nutrient management. IN: Snapp, S.S. and B. Pounds, eds. Agricultural Systems: Agroecology and Rural Innovation. Pp. 159-209.
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Progress 10/01/06 to 09/30/07
Outputs
OUTPUTS: Activities: The content of this CRIS report will include highlights from my on-going projects with an emphasis on those that are not already documented within the CRIS database. NSF-CHN project- a) Field research was initiated in the Mississippi River Basis this summer. We plan to study clusters of farms and the institutional environment in which they are embedded to address questions about how processes occurring at larger scales within the socioeconomic system influence farm-scale nitrogen management practices and N balances. Two study sites were selected for fieldwork: west central Ohio (Big Darby Creek and surrounding watersheds) and north central Iowa (the Des Moines lobe). The interview team consisted of a political ecologist, an organization sociologist and an agroecologist. Additional work was initiated in Louisiana and Iowa at the state level to investigate the relationship between proximity to the hypoxic zone how institutions and regulatory agencies view the N
pollution problem. b) Over the past year we have conducted a thorough review of primary literature for studies that used 15N methodology to track the fate of N in agroecosystems. 15N experiments permit the fate of 15N added to a system to be quantified in various source pools; for example, using stable isotopes, the amount of added N stored in the soil can be determined against the large background of soil N. This research will synthesize results from decades of experimental work in N management to contribute to an increased understanding of how different management practices impact the biogeochemical cycling of N. We are in the process of using the database to conduct a series of meta-analyses on the impact of environment and management practices on the fate of N. Results from the meta-analyses will be published as the first manuscript of a PhD dissertation (J.M. Gardner). Northeast SARE- A regional project entitled Learning from Farmer Innovation in Nitrogen Fixation for Improving
Nutrient Management on Organic Farms was initiated. This work will complement the research already underway in the IORE project on N fixation and includes plans for a survey of NE organic vegetable farms and significant on-farm research to assess current cover crop practices. Dissemination: Findings from my research group have been presented at numerous conferences before researchers, extension educators and farmers including the New York Organic Farming Conference, New York Certified Organic meetings, Cornell Organic Working Group meetings, and the Natural Systems Agriculture workshops at the Land Institute as well as the annual meetings of the Ecological Society of America, American Society of Agronomy and Soil Science Society of America. Presentations that were accompanied by a published abstract are listed under the publications section. Presentations to scientific, extension, student and farmer audiences that do not have a published abstract are listed within the CRIS reports for
particular projects. Several manuscripts from the NRI and NSF projects are in preparation and will be submitted in early 2008.
PARTICIPANTS: Laurie Drinkwater is the principal investigator for this project. Meagan Schipanski is a PhD student and has been carrying out the on-farm research on biological N fixation. Jude Maul is a PhD student who is conducting research on plant-microbial interactions and their impact on C,N cycling. He completed his PhD this year and was just hired as an ARS Research Scientist. Jennifer Gardner is a PhD student working on the NSF-CHN project. She just completed her master's research this past year and is currently writing her first manuscript. Burtie Van Zyl is a MS student who joined the lab group this past year. He will be conducting the research on green manure management in organic vegetable farms. Kevin Charles began as a PhD student and then switched to a MS program after deciding to follow his interests in paleoethnobotany elsewhere. He will complete his MS in early 2008. Christina Tonitto is a Research Associate and works 25% FTE on modeling diversified agricultural
systems for the NSF-CHN project. Julie Grossman is a Research Associate who works half time in the lab on the biological N fixation projects. Ann Piombino is a Research Technician in the Drinkwater lab. Our lab group is engaged in research, extension and education in collaboration with many other researchers at several institutions as well as other stakeholders including farmers, NGO staff and extension educators. Training and professional development Graduate students in the lab group receive training in how to design and implement interdisciplinary agroecological research. Those working with the NSF-CHN project have developed research skills in obtaining large data sets, incorporating them into databases, and creating GIS views of the data. We hold weekly lab meetings where students and visitors lead discussions of research projects or review relevant journal articles. There are usually 2-3 undergraduates involved in the research. These students have the opportunity to gain valuable
research experience through their work in the field assisting with sample collection and in the laboratory where they help with a variety of analytical procedures. This year we initiated an innovative undergraduate training program which was funded by the IORE grant. Three Cornell undergraduates were recruited in a competitive process to be Scholars in summer of 2007. These students were directly involved in on-farm field and lab work within the project boundaries and participated in weekly structured meetings to critically discuss and learn about the research process and the larger context of sustainable agriculture. They also carried out a service-learning project 1 day each week with an agriculturally-focused host of their choice. A focus group evaluation was organized and facilitated by our collaborators in the Education department in preparation for a published manuscript on the Sustainable Agriculture Scholars program so that others can replicate our program.
TARGET AUDIENCES: Most of the work withing this project is funded by programs that expect new knowledge to be generated and disseminated to other scientists through publication in peer-reviewed journals and at professional meetings. As a result, the target audience for most of this work is the scientific community, however significant efforts are directed toward communicating our findings to those engaged in farmer education as well as farmers themselves. Examples of specific target audiences include: 1) certified organic producers 2) conventional producers who are planning to transition to organic production or who are interested in restoring soil quality and reducing environmental impacts 3) farmer educators interested in sustainable soil management. Since our work contributes to supporting environmentally sound, regional agriculture people in the Northeast who want to purchase certified organic produce and rural communities in state of New York are also beneficiaries. We have
given presentations based our work to several regional extension-oriented conferences.
Impacts
1) Our quantitative analyses of the existing literature on N cycling in agroecosystems are contributing to the paradigm shift occurring within the nutrient management community. The first meta-analysis synthesized research aimed at evaluating cover cropping in terms of impacts on cash crop yields and nitrate leaching (Tonitto et al. 2007). In this paper we showed that use of winter annual cover crops in rotation with summer annual cash crops (mainly corn and soybeans) sequestered nearly 40 kg ha-1 and reduced nitrate leaching by an average of 70%. This finding is supported by the current meta-analysis which is based on studies using 15N to track the fate of newly added N and is in preparation (Gardener and Drinkwater 2008). Taken together these two synthesis papers support the idea that N retention can be significantly improved through the use of management practices that are ecologically-based and aim to modify multiple processes that regulate N cycling. 2) Quite a
bit of the NSF-CNH work has focused on DNDC model development and integration with long-term data sets. The DNDC model is widely applied to assess the environmental impact of the agricultural landscape has previously been applied at the national scale without calibration and validation data. Our work demonstrates that the DNDC model requires extensive calibration and validation in order to accurately simulate ecosystem fluxes in agricultural landscapes and demonstrates the need to fund long-term agroecosystem measurements. Our modelling work also shows that moving the agricultural landscape from conventional corn-soybean rotations, with extensive periods of bare fallow, to diversified grain rotations, including winter cover crops, would drastically reduce nitrate export from agricultural lands to freshwater and ultimately to estuarine systems. 3) The outcomes of the Sustainable Ag. Scholars Program spanned a range of changes in knowledge and actions. The three students in the program
gained knowledge not only about laboratory and field research methods and data analysis, but also about the larger context of real world sustainable agriculture issues. The impact of our program went beyond the three students involved, however, as many other lab groups with summer employees have shown interest in developing similar programs to help increase student excitement about their day-to-day laboratory activities, and increase awareness of the applied nature of agricultural research. 4) The studies conducted in commercial farm fields have provided new information and insights about how N use efficiency could be increased in grain systems. Fields that had been under legume-based management regime for > 10 years had small average annual surpluses (5-18 kg/ha) and greater soil N pools which corresponded to decreased N fixation rates, suggesting that higher rates of N retention as soil organic N can feedback to legume N fixation and serve as an internal mechanism for regulation of
N additions.
Publications
- Tonitto C., M.B. David, C. Li, L.E. Drinkwater. 2007. Application of the DNDC model to tile-drained Illinois agroecosystems: model comparison of conventional and diversified rotations, Nutrient Cycling in Agroecosystems. 78:65-81.
- Drinkwater, L.E. 2007. The rhizosphere in agricultural ecosystems. IN: The Rhizosphere- an Ecological Perspective. Eds. Z. G. Cardon and J. L. Whitbeck. Academic Press.
- Schipanski, M. and L.E. Drinkwater. 2007 Managing legume nitrogen fixation: The effects of soil fertility and species selections, from Organic Cropping Systems Project Web site: http://www.organic.cornell.edu/ocs/tutorial/legume_n/index.html
- Schipanski, M. and L.E. Drinkwater. 2007. Managing legume nitrogen fixation: On-farm research, from Organic Cropping Systems Project Web site: http://www.organic.cornell.edu/ocs/tutorial/legume_n_research/index.h tml
- Drinkwater, L.E. 2007. Sustainable Nutrient Management in Organic Agriculture. Symposium presentation. ASA-CSA-SSSA Joint Meetings, New Orleans, LA. November 4-9.
- Schipanski, M. and L.E. Drinkwater. 2007. Managing biological nitrogen fixation: Plant species and soil fertility interactions. Ecology Society of America Conference, San Jose, CA. August 5-10.
- Drinkwater, L.E. and S. Snapp. 2007. Nutrients in agriculture: Rethinking the management paradigm. Advances in Agronomy. 92:163-186.
- Tonitto C., M.B. David, L.E. Drinkwater, C. Li. 2007. Application of the DNDC model to tile-drained Illinois agroecosystems: model calibration, validation, and uncertainty analysis, Nutrient Cycling in Agroecosystems. 78:51-63.
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Progress 01/01/06 to 12/31/06
Outputs
We continued to make progress on the NSF-funded project that addresses biogeochemical and socio-economic processes governing nitrogen management and nitrogen use efficiency of agricultural landscapes. Our experimental design has been developed and research is progressing on several fronts. We were successful in our request for renewal funding from the NRI Managed Ecosystems Program. We will continue using commercial farms we have characterized in our initial project as a platform for conducting a series of field-based and laboratory experiments. These farms range from corn monocultures receiving N fertilizer to diversified grain-production systems relying on biological N fixation. We have demonstrated that these cropping systems vary in terms of the degree of N-saturation and biological N fixation rates, storage and composition of soil organic C and N pools and short-term inorganic N transformations. The continuation of this project involves two new collaborators. We
also launched a new project focusing on biological N fixation in organically managed cropping systems. We received funding from the USDA CSREES-IORE Program to begin intensive work in this area. The main goal of our project is to discover how the unique changes in the soil environment brought about by organic management impact N-fixation and apply this knowledge to improve management of leguminous green manure. We will investigate the complex interactions between soil environment, legume species and soil N-fixing microorganisms and develop management tools that can be used by organic farmers. In the course of this research we also develop a model system for using on-farm experiential learning as a technique for training undergraduates. The final experiment evaluating cover crop species effects on C cycling was conducted this summer. Two contrasting species were evaluated for their effects on litter decomposition. The experiment address questions about how three major factors 1) litter
quality, 2) litter location (surface vs incorporated) and 3) microbial community and soil environment impact decomposition rate. We completed two papers using the DNDC model to evaluate the relationship between management practices and N losses. This two papers are in press and will be published in 2007. The organic vegetable cropping systems experiment continued for its third year. We conducted intensive soil sampling in the experiment this year to document temporal changes in inorganic N pools and N mineralization potential. We also established microplots that will allow us to quantify biological N fixation in the leguminous cover crops.
Impacts
The main outcome of my integrated research program continues to be the generation of new knowledge that will support the development of practices that optimize management of the specific pools of SOM that can most effectively increase carbon (C) sequestration in agricultural soils. Optimized management of soil C will also impact availability and retention of the major nutrients such as nitrogen (N) and phosphorus (P) that cycle with carbon. Thus, this work will provide producers with the means to integrate management of C, N and P and improve nutrient use efficiency and soil quality in intensively managed agricultural systems concurrently. Expected outcomes include 1) reduced soil degradation and restoration of soil quality, 2) reductions in excessive applications of nitrogen and phosphorus fertilizers, 3) reduced losses of nitrogen and phosphorous from farms adopting these practices, 4) reduced soil erosion, 5) improvements in water quality and 6) increased
efficiency of soil fertility management in certified organic production systems.
Publications
- Gardner, J.B. and L.E. Drinkwater. 2006. Understanding human impacts on the nitrogen cycle. using a mass balance approach. Abstract. Presented SWCS conference, Managing Agricultural Landscapes for Environmental Quality, Strengthening the Science Base., Kansas City, Missouri, October 11 - 13.
- Schipanski, M., L.E. Drinkwater and S.Vanek. 2006. Legume nitrogen fixation as an internal regulator of nitrogen cycling in agroecosystems. Abstract. Presented at ASA-SSSA-CSS annual meetings, Indianapolis, IN. November 11-15.
- Tonitto C., David M., Li C., and Drinkwater L.E. 2006. Denitrification in Illinois Grain System: Assessment using the DNDC model. Abstract. Presented at Denitrification modeling across terrestrial, freshwater, and marine systems: Workshop. Institute for Ecosystem Studies October.
- Tonitto, C., M. David & L.E. Drinkwater. 2006. Replacing bare fallows with cover crops in fertilizer-intensive cropping systems: A meta-analysis of crop yield and N dynamics. Agriculture, Ecosystems and Environment. 112:58-72.
- Drinkwater, L.E. 2006. Agricultural systems research: From multiple origins to a unified theory. Abstract. Presented at ASA-SSSA-CSS annual meetings, Indianapolis, IN. November 11-15.
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Progress 01/01/05 to 12/31/05
Outputs
Progress was made in several externally-funded projects that are aimed at re-coupling C and N cycling and improving soil organic matter management to yields and reduce environmental impacts. A new project that will integrate research on the biogeochemical and socio-economic processes governing nitrogen management and nitrogen use efficiency of agricultural landscapes was initiated with funding from the NSF-BE Program. This project will build on work we have been engaged in at the local level and extend our research to intensive grain systems in the Mississippi River Basin. Results from the NRI-funded project support our hypothesis that re-coupling C and N cycles can improve agroecosystem scale N use efficiency in working farms. Using field-scale mass balances for nitrogen, we found that cash grain systems with diverse rotations that were based on legumes as the main nitrogen source were able to operate with lower levels of nitrogen additions. This suggests that these
systems may be subject to reduced nitrogen losses. We also found that nitrogen and carbon dynamics differed in soils from legume-based rotations compared to those receiving mainly fertilizer nitrogen additions. Legume-based systems had larger soil organic matter pools with greater amounts of occluded particulate organic matter and also had some differences in microbially mediated nitrogen transformations. We will be following-up on these preliminary results. We completed our meta-analysis of the cover crop literature and found that: 1) Yields under non-legume cover crop management were not significantly different from those in the conventional, bare fallow systems, while leaching was reduced by 70 percent on average. 2) Relative to yields following N-fertilizer, the legume-fertilized crops averaged 10 percent lower yields. However, yields under green manure fertilization were not significantly different relative to conventional systems when legume biomass provided greater than 110 kg
N ha-1. 3) On average, nitrate leaching was reduced by 40 percent in legume-based systems relative to fertilizer-based systems. These results will be forthcoming in a journal publication. Work progressed in the area of characterizing the impact of different cover crop species on belowground processes. Species differences in glomalin production, rhizosphere community composition and N dynamics have been observed. Several publications are currently in progress. The organic vegetable cropping systems experiment continued for its second year. This study is too young to produce results.
Impacts
The main outcome of my integrated research program continues to be the generation of new knowledge that will support the development of practices that optimize management of the specific pools of SOM that can most effectively increase carbon (C) sequestration in agricultural soils. Optimized management of soil C will also impact availability and retention of the major nutrients such as nitrogen (N) and phosphorus (P) that cycle with carbon. Thus, this work will provide producers with the means to integrate management of C, N and P and improve nutrient use efficiency and soil quality in intensively managed agricultural systems concurrently. Expected outcomes include 1) reduced soil degradation and restoration of soil quality, 2) reductions in excessive applications of nitrogen and phosphorus fertilizers, 3) reduced losses of nitrogen and phosphorous from farms adopting these practices, 4) reduced soil erosion, 5) improvements in water quality and 6) increased
efficiency of soil fertility management in certified organic production systems.
Publications
- Drinkwater, L.E. M. Cocke, C. Tonitto and S. Vanek. 2005. Effect of management history and SOM pool composition on microbially mediated N transformations. Poster presentation. INTECOL/ Ecology Society of America Conference, Montreal, Quebec. August 6-12.
- Maul, J. and L.E. Drinkwater. 2005. Glomalin: an Arbuscular Mycorrhizal Fungi (AMF) protein that has direct effects on ecosystem cycling of C, N, P & S. Ecological Society of America Annual Meeting, Montreal, Canada, August 2005.
- Tonitto, C., M.B. David and L.E Drinkwater. 2005. Nitrogen Management in Agroecosystems: Applying Models and Data in Policy Development. Ecological Society of America Annual Meeting, Montreal, Canada, August 2005.
- Tonitto, C., M.B. David and L.E Drinkwater. 2005. Diversified Agricultural Systems: Balancing Ecosystem Services with Economic Viability. U.S. Society for Ecological Economics Biennial Meeting, Tacoma, WA, July 2005.
- Cocke, M. and L.E. Drinkwater. 2005. Shifts in soybean nitrogen fixation across a management-induced soil fertility gradient. Poster presentation. INTECOL/ Ecology Society of America Conference, Montreal, Quebec. August 6-12.
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Progress 01/01/04 to 12/31/04
Outputs
We continue to use a variety of research approaches to achieve our objectives, including long-term and short-term field experiments on commercial farms and experiment stations, manipulative mesocosm experiments and microcosm studies. 1. The large microplot experiment that was established last year was sampled in summer 2004. We are in the process of analyzing these samples for root biomass and surface area, particulate organic matter and microbial community characteristics. 2. A pot study was conducted to investigate the role of plant species in determining microbial community composition. After plants had grown in soils for only six weeks, significant differences in the genotypic composition of microbial communities was evident. 3. The nutrient budgeting project completed its final growing season of sample collection. The long-term goal of this project was to develop tools that can be used by farmers to construct nutrient budgets for nitrogen, phosphorus and
potassium in organic cash grain and vegetable production systems. A series of databases were developed that can be used support nutrient management decisions. We also developed a prototype nutrient budgeting tool which would utilize these databases to construct multi-year budgets at the field and farm scale. This prototype budgeting tool currently exists in Excel spreadsheet format and is provided in electronic form. The sample budgets that we have developed for our study sites suggest that most organic vegetable production systems are adding significant surpluses of the major nutrients, as much as 180-200 kg P and N ha-1 yr-1 in excess. While these surpluses have been viewed as necessary during the transition to organic management, they will clearly lead to environmental problems if they are continued on a long-term basis. We have also found a number of both grain and vegetable farms are achieving profitable yields without large surpluses of P and N supporting the idea that organic
systems have the potential to operate with very high nutrient use efficiency. 4. In the 2004 growing season, research was initiated to quantify the shifts in N fixation rates of perennial and annual legumes across an in situ fertility gradient across farm sites. Two varieties of soybean (Glycine max) were grown during 2004 with a non-nodulating reference variety in replicated plots across 14 fields. Nitrogen fixation is being quantified using the 15N natural abundance method. In addition to biomass sampling, nodule counts and biomass were conducted in all plots as another indicator of reliance on N-fixation. 5. We conducted our first small-scale, 15N pool dilution experiment. We are in the process of analyzing these samples and have some data from this preliminary experiment. Our goal was to develop a feasible methodology for these agricultural soils. We have some evidence to support our ideas about how increased C abundance may influence microbial N transformations.
Impacts
This project will develop practices that optimize management of the specific pools of SOM that can most effectively increase carbon (C) sequestration in agricultural soils. Optimized management of soil C will also impact availability and retention of the major nutrients such as nitrogen (N) and phosphorus (P) that cycle with carbon. Thus, this work will provide producers with the means to integrate management of C, N and P and improve nutrient use efficiency and soil quality in intensively managed agricultural systems concurrently. Expected outcomes include 1) reduced soil degradation and restoration of soil quality, 2) reductions in excessive applications of nitrogen and phosphorus fertilizers, 3) reduced losses of nitrogen and phosphorous from farms adopting these practices, 4) reduced soil erosion, 5) improvements in water quality and 6) increased efficiency of soil fertility management in certified organic production systems.
Publications
- Carter, M.R., S. Andrews and a L.E. Drinkwater. 2004. System Approaches for Improving Soil Quality. IN: Managing Soil Quality-Challenges in Modern Agriculture. Schjonning, P., B.T. Christensen and S. Elmholt, eds. CAB International, Oxford, U.K. pp 261-281.
- Drinkwater, L.E., Tonitto, C, David, M.B. 2004. Effect of diversified rotations on yield and nitrate leaching: A meta-analysis. Ecological Society of America Annual Meeting. Portland, OR.
- Maul, J. and L.E. Drinkwater. 2004. Plant legacy effects on rhizosphere microbial community structure. Ecological Society of America Annual Meeting. Portland, OR.
- Tonitto, C, David, M.B., Drinkwater, L.E. 2004. Response of crop yields and soil N to diversified rotations: a meta-analysis. Soil Science Society of America Annual Meeting. Seattle, WA.
- Tonitto, C, Li, C, David, M.B., Drinkwater, L.E. 2004. Simulation of yield and N dynamics in corn-soy and alternative corn-soy-wheat-red clover rotations using the DNDC model. Soil Science Society of America Annual Meeting. Seattle, WA.
- Cocke, M. and L.E. Drinkwater. 2004. Shifts in biological nitrogen fixation of perennial and annual legumes across a fertility gradient.19th North American Symbiotic Nitrogen Fixation Conference. Bozeman, MT. June 27-July 1, 2004.
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Progress 01/01/03 to 12/31/03
Outputs
We continue to use a variety of research approaches to achieve our objectives, including long-term and short-term field experiments on commercial farms and experiment stations, manipulative mesocosm experiments and microcosm studies. Studies are being conducted at the Aurora Research Farm comparing the fate of root-derived C from a wide variety of plant species, including N-fixers and non N-fixers, that are either currently used in rotations as cover crops or could be used as cover crops in the future. Our findings from both experiments still indicate that while there are significant differences in the fate of C from different plat species, we have not observed consistent trends within functional groups. This suggests that we may need to evaluate potential cover crops on a species by species basis in order to predict their impact on soil organic matter retention. Currently, a manuscript is in preparation for submission to SSSAJ this spring. A larger experiment
comparing a wider range of plant species was established at Aurora in 2003. This experiment will build on the work completed in the two smaller studies conducted in 2001 and 2002. We made significant progress in the on-farm studies of how management practices effect C and major nutrient flows. Data collection continued during 2003 and sample budgets are being constructed for organic grain and vegetable farms. We are in the process of analyzing the 2003 samples for C, N, P, and K. We are in the process of identifying farm sites to use in our study of management effects on internal N cycling processes. We will be setting up an 15N experiment to study the fate of N in systems receiving organic N sources in 2004.
Impacts
This project will develop practices that optimize management of the specific pools of SOM that can most effectively increase carbon (C) sequestration in agricultural soils. Optimized management of soil C will also impact availability and retention of the major nutrients such as nitrogen (N) and phosphorus (P) that cycle with carbon. Thus, this work will provide producers with the means to integrate management of C, N and P and improve nutrient use efficiency and soil quality in intensively managed agricultural systems concurrently. Expected outcomes include 1) reduced soil degradation and restoration of soil quality, 2) reductions in excessive applications of nitrogen and phosphorus fertilizers, 3) reduced losses of nitrogen and phosphorous from farms adopting these practices, 4) reduced soil erosion, 5) improvements in water quality and 6) increased efficiency of soil fertility management in certified organic production systems.
Publications
- Drinkwater, L. E. 2003. Managing biodiversity to restore ecosystem function in intensive agricultural systems. Ecological Society of America, 88th Annual Meeting Abstracts, pg. 372.
- Drinkwater, L. E. 2003. Research Approaches in Organic Agriculture: How best to study organic production systems? Proceedings of 2003 Agronomy Society of America Meetings.
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Progress 01/01/02 to 12/31/02
Outputs
This project has just completed it first year. A variety of research approaches are being used to achieve our objectives, including long-term and short-term field experiments on commercial farms and experiment stations, manipulative mesocosm experiments and microcosm studies. Studies are being conducted at the Aurora Research Farm comparing the fate of root-derived C from a wide variety of plant species, including N-fixers and non N-fixers, that are either currently used in rotations as cover crops or could be used as cover crops in the future. The second experiment was conducted during the 2002 growing season. We still have significant sample and data analysis to complete for this project. So far, our preliminary findings suggest that there are significant differences in the fate of C from different plat species however we have not observed any trends within functional groups. This suggests that we may need to evaluate potential cover crops on a species by species
basis in order to predict their impact on soil organic matter retention. We made significant progress in the on-farm studies of how management practices effect C and major nutrient flows. An enormous amount of data and samples were collected from 14 organic farms including documentation of management practices, samples of soil amendments, green manures and harvested crops. We are in the process of analyzing these samples for C, N, P, and K. We expect to be able to construct some sample nutrient budgets this coming year. We received funding from the USDA/NRI-CRP to conducted detailed studies of the effects of SOM composition on mineralization/retention of C and N and soil microbial community structure on a sub-set of these sites. Finally, we have collected quite a bit of data on rotations and management strategies used in vegetable systems and will continue to gather this information. This spring, we are designing an experiment to be conducted at the Thompson Vegetable Research Farm
that will focus on the use of cover crops combined with reduced tillage to improve soil organic matter and nutrient management. This study will be conducted largely with funds from a second, collaborative Hatch proposal. The additional funds have allowed us to expand the scope of the experiment to include weed management and assessments of vegetable quality.
Impacts
This project will develop practices that optimize management of the specific pools of SOM that can most effectively increase carbon (C) sequestration in agricultural soils. Optimized management of soil C will also impact availability and retention of the major nutrients such as nitrogen (N) and phosphorus (P) that cycle with carbon. Thus, this work will provide producers with the means to integrate management of C, N and P and improve nutrient use efficiency and soil quality in intensively managed agricultural systems concurrently. Expected outcomes include 1) reduced soil degradation and restoration of soil quality, 2) reductions in excessive applications of nitrogen and phosphorus fertilizers, 3) reduced losses of nitrogen and phosphorous from farms adopting these practices, 4) reduced soil erosion, 5) improvements in water quality and 6) increased efficiency of soil fertility management in certified organic production systems.
Publications
- Drinkwater, L.E. 2002. Plant species and rhizosphere community effects on soil carbon cycling processes. Ecological Society of America, 86th Annual Meeting Abstracts, p. 343.
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Progress 01/01/01 to 12/31/01
Outputs
In vegetable production systems, the combination of intense tillage and minimal residues returned to the soil has resulted in soil organic carbon (C) levels that are frequently below 1%. This project aims to understand how agricultural management practices interact with the soil biological and abiotic processes that govern soil organic matter dynamics and nutrient cycling. A greater understanding of fundamental soil ecological processes will allow intensive horticultural systems to be managed in a way that will improve ecosystem health and nutrient use efficiency, reduce environmental impacts and maintain crop productivity. During this first year I concentrated on 2 areas: 1. Fate of root-derived C from different cover crop species. The experiments established here at Cornell address questions about how different plant species effect C cycling with an emphasis on comparing leguminous and non-leguminous plants used as cover crops in the Northeast. In addition to
increasing our understanding about how plant species shape ecosystem function, this work will also improve our ability to identify which cover crops are most appropriate for solving different types of soil problems encountered in intensive vegetable production systems. Two experiments are being conducted using 13C natural abundance signatures to track the fate of carbon inputs. Last spring, the first experiment using summer annuals was established. Species being compared include legumes and non_legumes: cowpea, soybean (forage and grain), mustard, perennial ryegrass, and buckwheat. Soil samples were collected in September and are in the process of being analyzed for labile pool composition. Preliminary results from the mass spec analysis indicate that we are able to detect the influx of C from these C3 plants into SOC pools. Sample extractions and mass spec analysis will be completed by March 2002. The second experiment was established this past fall with winter annual cover crop
species (hairy vetch, birdsfoot trefoil, red clover, winter rye, wheat, tricale, rape, Austrian Pea). This experiment will be sampled in late spring and SOC fractions will be extracted and analyzed in the same manner as the first experiment. 2. Nutrient budgets for organic vegetable production systems. This work is focused on addressing nutrient management problems associated with the use of organic nutrient sources such as composts and manures in organic vegetable production systems. Work currently underway will allow us to construct simple budgets for organic production systems and compile a database of the information necessary for developing nutrient management tools for organically-managed production systems.
Impacts
One expected outcome is to develop tools that will help farmers optimize soil fertility management in organic cropping systems. A second goal is to collect preliminary data and establish farm sites that can serve as a platform for more fundamental agroecosystem scale research aimed at understanding the relationship between management practices that control the quantity and quality of C inputs, labile soil organic matter pools, microbial community function and nitrogen (N) retention.
Publications
- Drinkwater, L.E. and P. Puget. 2001. Fate of root-derived carbon in annual cropping systems. Poster presentation at the Ecological Society of America Annual Meetings, Madison, WI, August, 2001.
- Puget, P., L.E. Drinkwater and R. Koch. 2001. Short-term carbon dynamics of maize residue in organically and conventionally-managed agroecosystems. 10th International Nitrogen Workshop Proceedings. Reims, France.
- Puget, P. and L.E. Drinkwater, 2001. Short-term dynamics of root and shoot-derived carbon from a leguminous green manure. Soil Sci. Soc. Am. J. 65:771-779.
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