Sustainable Vegetable Production: Screening Cover Crops for Water Use Efficiency

Sustainable Vegetable Production: Screening Cover Crops for Water Use Efficiency

Summary

During the first year of the project, replicated research trials were established to evaluate summer and winter cover crops, cover crop combinations and vegetable crop production systems. A graduate student was hired and is supported by this project, and she is working on the assessment of water use efficiency of summer cover crops and is planning additional research scheduled for the 2009 production season. Presentations and field days communicated results of the project to over 100 individuals from around Northern Utah and many western states. Field plantings on grower-cooperator sites in Eastern and Southern Utah were established and evaluated.

Objectives/Performance Targets

To identify and evaluate winter cover crops that can help improve early plant establishment (reducing wind erosion effects and soil crusting) while minimizing interference with plant growth and soil water storage while contributing to better farm nutrient management and soil quality;

To identify and evaluate summer cover crops that can help improve nutrient cycling and late season weed management while minimizing water establishment requirements;

To conduct these studies in a variety of different climatic conditions (regional within Utah), with different vegetable crops (cucurbits, tomatoes, corn, other crops) and cropping systems (organic and non-organic);

To disseminate this information to Utah’s farmers, service agencies, and other potential user groups at farm field days, through print and electronic media and at state, regional and national meetings.

Accomplishments/Milestones

Organic production systems using cover crops for nutrient cycling requires some understanding of their water use and level of biomass generation. Spring seeded grass, broadleaf and legume cover crops (oats, millet, barley, sunflower, buckwheat, mustard, birdsfoot trefoil, cowpea, several clovers, lentil, lupin, and lab lab) were grown and evaluated for biomass production and drought tolerance in 2008. Initial screenings showed a variety of germination ability, growth differences, and response to changing soil water potentials. Small seeded cover crops like clovers and mustards were not very competitive against weeds due to poor germination and slow initial growth. Most grass cover crops germinated well, grow vigorously and effectively competed against weeds. Larger seeded legumes performed variably. Some difficulty with poor germination and stand establishment was attributed to seed placement and our inability to sow them properly. Crops varied greatly in leaf water potential when exposed to a 3 week soil drying cycle. Initial findings suggest that there are big differences in mid-day water potential and diurnal changes in water potential suggesting more drought tolerance. During the next funding year, work will continue to further refine each of these systems and to gather information on inputs and productivity.

In a second trial on cover crops and vegetable production, combinations of winter and summer planted cover crops were tested to see if they could provide sufficient nutrients to support summer vegetable production. Fall and summer planted cover crops included broadleaf (mustard & buckwheat), grasses (winter wheat & pearl millet) and legumes (hairy vetch & cowpea). Fall seed cover crops were planted at right angles to the summer cover crops such that fall/summer combinations included fall grass/summer grass to fall legume/summer legume combinations. In the spring of 2008, broccoli, sweet corn and snap beans were planted into the different cover crop combinations and growth, productivity and quality assessed. All vegetables grew best in the combinations of winter broadleaf/summer legume or winter legume/summer broadleaf. Cover treatments consisting of winter grass/summer grass and winter grass/summer broadleaf did not support vegetable growth adequately. Weed control was fair to good in most treatments, insect pests were minimal, and productivity of the different vegetable crops was poor to average.

Objective 3a) In cooperation with Randy Ramsley, cover crops were planted in Caineville, Utah in the spring of 2008. Randy is interested in inter-row establishment of permanent cover crops between his cropping row. Seeds of several grasses, legumes and various grass-legume blends were planted and evaluated throughout 2008. Excessively dry weather for the two months after seeding and a lack of irrigation water availability resulted in limited seed germination during the spring. Some seeds did germinate during the summer but plant cover was deemed insufficient to provide weed control or adequate biomass for his cropping system. He will be working to developing alternative establishment approaches for the cropping systems during the next funding year. 3b) In cooperation with David Sterling (Leeds, UT) and Tim Thompson (Hurricane, UT), we devised a fall seeded cover cropping system to provide weed and wind management for seeded and transplanted watermelons. Early planting to get establishment and strip tillage prior to vigorous spring re-growth of the cover crops is essential to ensure weeds are suppressed and stored soil moisture needed in the spring is not depleted by the cover crops. Growers then use plastic mulches and drip irrigation for the melons but leave the between row area un-irrigated thus creating much needed wind protection for young plants in the spring. Yield records by the growers show fruit size, shape and quality is improved using this system. Growers are now interested in mixed cover crop systems (with legumes) to improve soil nutrition.

A series of field days and presentations have been given to address objective 4. a) Dr. Dr. Dan Drost was an invited speaker at Utah Resource Conservation and Development Council annual meetings held in St. George, UT on 7 November, 2007. Presentation outlined cover cropping options and initial production information to 50 land use managers from around Utah. b) On 29 July, 2008 sixty-five Experiment Station Managers from across the United States toured the Kaysville Research station. The farm managers were exposed to our organic cover crops trials, various cover cropping systems, and vegetable production approaches. c) Dr. Drost organized and hosted a cover crop identification and use workshop on 13 August, 2008 in conjunction with Kaysville Farm field day. Growers were show the different cover crops, learned about fall/spring cover crop rotations and their influence on vegetable crop production systems in an organic setting. Over 100 fruit and vegetable growers, numerous Cooperative Extension agents and specialists from throughout Utah attended the field day.

Impacts and Contributions/Outcomes

The presentations, workshops and field days related to this project have disseminated information on cover crops and crop production strategies to over 200 participants. While audience size does not necessarily equate with adoption of cover cropping, we are aware of several instances where commercial farms are adopting this technology.

1) Organic farmer-cooperator Randy Ramsley is continuing to work with us on figuring out production approaches for his farm in central Utah.

2) Sterling Farm (diverse fruit and vegetable operation) in Leeds, Utah, has been using covers now for 2 years to help with wind erosion/damage control in his melon acreage. At present he is growing over 120 acres of watermelon, cantaloupe and specialty melons for sale throughout Utah and Arizona. Field losses due to stand reduction are estimated at 2-3 percent when cover crops are used versus over 30 percent when no covers are used (losses prior to planting as related by the grower).

3) Thompson Family farm in Hurricane, Utah has been using covers now for several years after observing the effects associated with our efforts on Sterling farm. They grow 15 acres of specialty melons, tomatoes, and sweet corn for sale at local vegetable stands in St. George and at the Park City Farmers Market.

4) Anna Ragland will be presenting a poster on her 2008 research findings at the 12th Annual Intermountain Graduate Research Symposium held on 1 April, 2009 at Utah State University. (http://www.usu.edu/usugss/symposium/) Her poster title is “Assessing Cover Crops for Drought Tolerance”. Undergraduate and graduate students as well as faculty will potentially review this presentation.

5) We are beginning to write our first extension fact sheet titled “Winter Cover Crop Management” which should be submitted for publication in time for use in the fall of 2009.

Collaborators: