Nutrient management on organic vegetable farms: A research and education program for sustainable soil fertility management in southern New England

Nutrient management on organic vegetable farms: A research and education program for sustainable soil fertility management in southern New England

Summary

In the first three years of the project, we focused on our goal to create a routine soil test procedure for managing soil fertility on organic farms. We have identified a need for soil tests that are specifically targeted to the needs of organic vegetable growers. One test that shows much promise for organic farmers is the Illinois Soil N Test (ISNT). The ISNT analyses soil for amino-sugar N, a fraction of soil N that is easily mineralizable and that may become available for the crop during the growing season (Khan et al., 2001). The test has been calibrated for conventionally-grown corn in Illinois (Khan et al., 2001), New York (Klapwyk and Ketterings, 2006), and Connecticut (unpublished data). It has also been shown to predict N responsive sites where liquid or composted dairy manure is applied to corn agroecosystems (Klapwyk et al., 2006). Because of its ability to predict readily mineralizable N, it may have great utility for organic fields which have received compost or manure for several years to decades. Recently, we assessed soils from 22 regional organic farms and found significant positive linear relationships between N mineralization and organic matter content and autumn NO3 values. This preliminary data suggests that further research would offer critical insights into managing soil fertility on organic farms throughout the region.

The research team has collected soil samples in 2010 and 2011 from seventeen organic farms in New Hampshire (6), Massachusetts (7), and Connecticut (4). Members of the research team have met with farmers to discuss the project plans and to identify 3-5 fields appropriate for sampling. Data has been collected from three sampling dates (early, mid-, and late season) and is now being analyzed. Research team members discussed results from the 2010 growing season with farmers in early spring 2011, so that their nutrient management approach would reflect current soil conditions. Data from 2011 field research was distributed to the participants in early Spring 2012 to inform their soil fertility decisions. Research team members will meet again with the participating farmers in winter 2012/2013, along with Beth Hooker (Mount Holyoke College/Hampshire College) and Sandra Bell (University of Connecticut), to assess learning outcomes associated with participatory research.

Objectives/Performance Targets

• Performance target: From the 225 organic vegetable farmers who participate in the project, 50 farmers will use individual field records, nutrient management tools, soil testing procedures, and, where applicable, stalk tests to reduce N applications by 30 pounds per acre and P2O5 applications by 30 pounds per acre to achieve optimal levels on 540 acres. These practices will lead to more efficient use of soil amendments linked to crop needs and existing soil fertility, which in turn will reduce the amount of nitrate in groundwater, reduce phosphorus loading to freshwater systems, and decrease the cost of production by $12 per acre for N and $12 per acre for P2O5. Our work in 2012 was in support of this performance target; however, as anticipated, we have not achieved the performance target in this third year of the project.

• Milestone 1: A group of 25 organic vegetable growers will use two new nutrient management planning tools to assess their fertility needs: (1) an NRCS-compliant tool which utilizes a combination of spreadsheets for vegetable farmers to develop nutrient management plans; (2) a web-based program for predicting soil organic matter and P changes from applications of manure and compost. Participating farmers will gain critical insights about their soil fertility and employ modified nutrient management strategies as a result. Data from 2010 and 2011 was shared with the participating farmers. In winter 2012/2013, we are planning a series of meetings to analyze the site-specific data. We decided on this approach in order to maximize use of data and to engage farmers more fully in the data analysis.
• Milestone 2: Among the group of 25 organic vegetable farmers, 5 farmers will participate in an on-farm research trail to test the responsiveness of sweet corn to N additions. We will assess the efficacy of the ISNT, PSNT, and the cornstalk nitrate test for their ability to distinguish between N responsive and non-responsive sweet corn sites. Farmers will gain an appreciation for research design and data collection and will be active participants in the research. Established field trials, using winter squash instead of sweet corn. The change in crop better reflects farmers’ crop choices (sweet corn is a minor crop for the organic vegetable growers in this study). Established field trials on 4 farmers’ fields. Analyzed data will be shared and critiqued as part of the farmer workshop in Winter 2013.
• Milestone 3: Before the second growing season, the group of 25 organic vegetable growers will use data from the previous year in the nutrient management tools. Farmers will adjust their nutrient management approach to reflect current conditions of their soils. The group of 17 organic farmers received their data from the previous year. Members of the research team met with and answered questions about the data with farmers in New Hampshire, Connecticut and Massachusetts.

The following milestones are being planned (but have not yet happened). Here, the dates have been updated to reflect the shifted time frame.
• Milestone 4: During the second year of on-farm research trials, the continuing group of 5 organic growers will participate in the data analysis. After collecting 2 years of data on the efficacy of the ISNT, PSNT, and the cornstalk nitrate test for their ability to distinguish between N responsive and non-responsive sweet corn sites, we will work together to interpret the data. April ‘12-June ‘13. Peer educators will lead discussion of data from field trials as part of farmer workshops in 2013.

• Milestone 5: The first regional nutrient management workshops will be offered in January of year 3 for 200 farmers who use organic inputs. Two workshops will be offered in each state for a total of six workshops. Approximately 30-35 farmers will participants in each workshop. From among the core group of 25 farmers who participated in the on-farm research, 12 will serve as peer educators in the first regional workshops, with two farmer educators per workshop. The core group of 12 farmer educators, in conjunction with other project investigators, will help participants identify critical information and resources they need for nutrient management. July’12 –October ‘13. Plans include having one workshop in March 2013, and a second regional workshop in Fall 2013, based around farmer availability (difficult to hold workshops during the growning season)
• Milestone 6: The second regional nutrient management workshops will be offered to the 200 farmers who participated in the first workshops, in the manner described under Milestone 5. The second workshops will build upon the first. Participants will be involved in interpreting the results of the on-farm research projects and trials from years 1 and 2 and in developing a customized soil nutrient management plan. October 2013.
• Milestone 7: Based on the on-farm research and collaborations with Dr. Mallory in Maine, a set of peer-reviewed articles regarding soil fertility with biologically-based nutrient inputs will be submitted. We will also create a set of New England Regional Fact Sheets on Nutrient Management for Farms using Biologically-based Nutrient Inputs. These regional fact sheets will be used by 100 farmers using biologically-based nutrient inputs. Jan ’12-July ‘13.
• Milestone 8: A follow-up survey of all project participants will be conducted in year 4 to assess current soil management practices and utilization of soil testing resources. From the 25 on-farm participants, we will determine the extent of behavior change and profitability using baseline data from our soil testing database, and the follow-up survey in year 4. Reduction in environmental impacts will be assessed using literature values for N and P loading, on a farm-by-farm basis. Mar ’13-Oct ’13

Accomplishments/Milestones

Work in the third year of the project was focused on analyzing the data collected from over 65 individual fields on organic farms in Connecticut, Massachusetts, and New Hampshire. We collected soil samples in early, mid- and late-growing season. In addition to the standard soil test values (e.g., pH, OM, P, K, N), we assessed soils using the Illinois Soil Nitrogen Test (ISNT). We conducted N mineralization experiments, in order to calibrate the ISNT for soils which receive organic inputs. Much of the sample analysis was completed at the University of Maine analytical laboratory. Because of the variety of soils, management histories, and organic matter content collected from our locations, the UMaine laboratory completed additional analyses using our soils to inform the creation of a new soil carbon dioxide (CO2) analysis that can be used to quantify soil microbial activity (Haney et al., 2008). We are working with Bruce Hoskins at the University of Maine to create a publication of the results.

With Sandra Bell of the University of Connecticut, conducted work in support of educational goals for the project. In 2013, we will conduct two peer-led workshops, which will highlight our findings, as well as allow farmer-educators to explore the data to make recommendations regarding soil fertility management.

Impacts and Contributions/Outcomes

We collected soils in the 2010 and 2011 growing season and have completed analytical analyses in order to complete the following activities. We are continuing to analyze the data from both years, and are in the process of writing a paper. We aim to:
• to submit a journal article, detailing our work, within the context of other current research; main aspects of the paper will be:
o to assess the ISNT for organic farms by surveying a wide variety of organic farms
o to illustrate the utility of the in-season NO3-N test for determining whether soil N availability is adequate for crop production, especially in the case of the common practice of double-cropping on diversified organic farms;
o to assess P levels across a wide number of sites with varying compost or manure addition history to determine the relationship between nutrient management practices and P levels;
o to determine the N mineralization potential of organic soils and explore relationships between N mineralization and the ISNT, NO3-N levels over the growing season, or P levels.

In 2013, we will conduct two peer-led workshops, which will highlight our findings, as well as allow farmer-educators to explore the data to make recommendations regarding soil fertility management.

We are also working with the University of Maine, where they have used our samples in their research trial. This trial is in support of a new CO2 analysis that can be used to quantity soil microbial activity (Haney et al., 2008). Results from this collaboration will be analyzed to determine the applicability of this new analytical method to biologically-managed agroecosystems, with the aim to produce a peer-reviewed journal article.

References:
Khan, S.A., R.L. Mulvaney, and R.G. Goeft. 2001. A simple soil test for detecting sites that are nonresponsive to nitrogen fertilization. Soil Sci. Soc. Am. J. 65:1751-1760.
Klapwyk, J.H., Q.M. Ketterings, G.S. Godwin, and D. Wang. 2006. Response of the Illinois soil nitrogen test to liquid and composted dairy manure applications in a corn agroecosystem. Canadian J. Soil Science 86 (4): 655-663.
Klapwyk, JH and QM Ketterings. 2006. Soil tests for predicting corn response to nitrogen fertilizer in New York. Agronomy Journal. 98:675-681.
R. L. Haney, W. H. Brinton, and Eric Evans. 2008. Estimating Soil Carbon, Nitrogen, and Phosphorus Mineralization from Short-Term Carbon Dioxide Respiration. Comm.Soil Sci. and Plant Analy., 39: 2706–2720.

Collaborators: