Cover cropping strategies for year-round weed control on mixed vegetable farms in southern New England

Cover cropping strategies for year-round weed control on mixed vegetable farms in southern New England

Summary

This project was undertaken to explore methods for improving soil health in high-intensity vegetable production systems without reducing yields or “idling” fields. We focused on tillage reduction and expanded use of cover crops as ways to increase soil organic matter. This report covers calendar year 2013, which is the end of year 3 and beginning of year 4 for this project (official start date was June 1, 2010).

In 2013 we completed the research portion of this project; results were published in a graduate thesis in August 2013 and manuscripts are in preparation. When evaluated over the entire project, none of the conservation tillage treatments out-yielded the conventional approach of spring tillage and a fall-planted covercrop, but several of the conservation tillage approaches produced yields equivalent to the conventional approach.

The conventional approach resulted in a decrease in soil health over the course of the study, and the conventional treatment plot had the lowest soil organic matter and active carbon in years 2 and 3. The zone tillage treatment was the only one that actually increased soil health over the course of the study; this was disappointing because the zone tillage treatment completely failed to produce acceptable yields. However, the other two conservation tillage treatments resulted in smaller declines in soil health than the conventional approach, while producing comparable yields. The perennial living mulch system in particular has potential as soil health held constant throughout the study. The primary difficulties encountered with the perennial living mulch system were difficulty controlling weeds at the edges of the planting rows, and difficulty laying plastic mulch.

We held our third winter workshop on February 14, 2013; 43 people attended. Talks centered on cover crops, with a presentation of the research results from this project, and invited speakers. We continued our extension focus on cover crops through the summer, trying a number of cover crop combinations from the winter workshop presentations on the research farm and highlighting cover crops at our April and August twilight meetings.

Objectives/Performance Targets

Performance Target: Twenty vegetable producers (10% of Rhode Island total) will adopt a combination of cover crops and reduced tillage to control weeds and improve soil quality on a total of 500 acres (25% of RI vegetable acreage). Quarterly twilight meetings and workshops will attract 200 growers over three years; participants will learn about new vegetable varieties and production methods they can adopt on their farms. Fifty University of Rhode Island students pursuing careers in agriculture will receive hands-on learning opportunities by assisting with cover crop trials as part of the vegetable production class or as summer interns.

Milestones

• 20-30 growers will attend each Twilight Meeting at the URI research farm. This milestone will be met repeatedly in years 1-3.

o   23 growers attended the April meeting, and 38 attended the August meeting.

• At least 50 growers will attend each winter workshop. This milestone will be met repeatedly in years 1-3.

o   The 2013 workshop was attended by 43 people from throughout southern New England. Attendance was lower than hoped for as lack of communication resulted in a cover crops conference being scheduled in Connecticut within a few weeks of our workshop.

• 15 URI undergraduate students will participate in the cover crop research each year as part of the vegetable production class.

o   This objective was not met in 2013 in large part because the field research portion of the project had been completed.

• By the end of the second year 50 growers will have contacted us for more information on cover crops/reduced tillage and individual assistance in implementing these practices on their farms.

o   We continue to encourage the growers we work with to expand their use of cover crops. Growers have not been eager to adopt the reduced tillage practices we have been experimenting with because of the practical difficulties we have encountered with weed control and raised beds in reduced tillage. Our larger growers in particular rely on raised bed systems.

• The field research will generate new information on the relative efficacy of the four cover crop + tillage treatments for improving soil quality, controlling weeds, and maintaining profits.

o   The field research has generated a large amount of information, which was published as an MS thesis in August 2013. Journal articles and extension publications derived from the research are in preparation.

Accomplishments/Milestones

Research

Final soil analyses were completed in the spring of 2013. The first half of 2013 was devoted to analyzing and interpreting the research data. The graduate student on this project, Jeff Peiper, successfully defended his thesis in July 2013. He is now employed as an extension agent in Colorado.

Extension

In the original plan effort in 2013 was supposed to focus on on-farm demonstrations of cover crops and reduced tillage, and on working with growers who were implementing integrated cover crops and tillage reduction techniques on their farms. The extension partner on the team, Kristen Castrataro, was primarily responsible for this portion of the project. Kristen left URI in December 2011, and we have struggled with the extension portion of this project ever since. We have continued to reach out to growers through twilight meetings and workshops, and have revived the RI Ag Experiment Station Bulletin as an on-line publication hosted by Digital Commons. These methods of communication are effective but limited. We do not have strong grower industry groups in RI, and growers are not accustomed to turning to URI extension for assistance. In rebuilding our ag extension program Kristen relied heavily on personal connections with growers, forged through growing up in a RI farm family and through farm visits. The downside of this is that many of those connections were lost when Kristen left. Our new extension agent, Andy Radin, has worked hard to develop new connections with growers but he is not invested in this project to the degree Kristen was. As a result we have not been able to do any on-farm demonstrations, and have had few growers ask us for assistance in implementing integrated cover crops and tillage reduction techniques on their farms.

We have developed a survey instrument to follow up with people who have attended our workshops and twilight meetings over the past four years. Hopefully this will allow us to measure the impacts of this work, and learn more about implementation. The survey will be distributed in January 2014.

Impacts and Contributions/Outcomes

This project has been very effective in training students at the undergraduate and graduate levels. We continue to focus on cover crops and soil health in vegetable production. In 2013 our farm manager, Tim Sherman, and the grad student on this project, Jeff Peiper, worked together to plant large portions of the research farm into summer cover crops, including soybeans, millet, buckwheat, cowpeas, and sudex. We also invested in a Celli spading machine, as another way to reduce the harmful effects of tillage on our soil without sacrificing yields and weed control.

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