Sustainable Vegetable Production: Screening Cover Crops for Water Use Efficiency

Sustainable Vegetable Production: Screening Cover Crops for Water Use Efficiency

Summary

During the second year of the project replicated research trials were re-established in Logan by Ms. Anna Ragland to evaluate summer and winter cover crops and cover crop combinations. Ms. Ragland has been 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 2010 production season. Field plantings on grower-cooperator sites in eastern and southern Utah were established and evaluated.

Objectives/Performance Targets

1) 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 and while contributing to better farm nutrient management and soil quality;

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

3) 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);

4) 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

Objectives 1 & 2:

Organic production systems using cover crops for nutrient cycling requires some understanding of their water use and level of biomass generation. We have explored a number of spring/summer seeded grass (annual rye, oats, millet, barley), broadleaf (mustard, sunflower) and legume (birdsfoot trefoil, cowpea, several clovers, vetch, lentil, lupin and lab lab) cover crops for their drought tolerance and biomass production. We measured leaf water potentials, stomatal conductance and soil moisture content during a 30-day dry down in field planted covers in both 2008 and 2009. These screenings showed a variety of establishment characteristics, variable growth responses and differences in tolerances to changing soil water potentials.

Cover crops that show potential adaptation to the intermountain west include annual rye, birdsfoot trefoil, mammoth red clover, lana vetch, buckwheat, golden mustard and sunflower. These performed well during the forced dry downs. Lana vetch had superior ground cover and biomass. Birdsfoot trefoil and mammoth red clover had good ground cover, but above ground biomass was lower. Sunflower was drought tolerant but needs high seeding rates to reach adequate ground cover. Cover crops evaluated that were drought tolerant but did not establish well included cowpea and lab lab bean. These were sown at 1 ½ times the recommended seeding rate but still did not establish well in this field; however cowpea established better in a field during a separate study. Oats and barley died during the forced dry down and were determined to not be drought tolerant. Lentil and white lupin performed very poor in this study and failed to grow or thrive.

Because water is costly and sometimes scarce, farmers can use this information to select more drought tolerant cover crops. Drought tolerant cover crops can also provide other benefits to farmers such as nitrogen fixation, prevention of soil erosion, weed suppression and attraction of beneficial insects. During the next funding year, some additional work on cover crop establishment will be performed to further refine the selection of cover crops and to gather information on inputs and productivity aspects of the more drought tolerant types.

Objective 3a

In cooperation with Randy Ramsley, cover crops were planted in Caineville, Utah in spring 2008. Randy is using an in inter-row establishment of permanent cover crops between his cropping rows. Several grasses, legumes and various blends are being evaluated in an area with limited irrigation availability and extreme temperature conditions (excessively hot summers-cold winters). This resulted in limited seed germination during the spring and modest growth in summer, which continues to produce limited plant cover for weed control or adequate amounts of biomass nutrient cycling into his organic vegetable cropping system. We are working on a revised planting approach (timing and crops) for spring 2010 to address the establishment issues and growth limitations his cropping system.

Objective 3b

In cooperation with David Sterling (Leeds, UT) and Tim Thompson (Hurricane, UT), the revised fall seeding approach for cover crops continues to provide weed and wind management for seeded and transplanted melons (water and cantaloupe). Dry conditions over winter and limited water availability continue to plague these growers in the southern desert area of Utah (Washington Co.). While early planting results in adequate cover crop establishment, continued winter growth utilizes stored moisture which then limits cover crop canopy development essential for weed suppression. While these growers use plastic mulches and drip irrigation for the melons if winter growth is inadequate, the between row area with the cover crop does not provide sufficient wind protection for young plants in the spring. Regardless of the growth, the growers continue to say that fruit yields and quality (size, shape, etc) are improved using this system. We are continuing to explore mixed cover crop systems (with legumes) to improve soil nutrition re-cycling.

Objective 3c

In cooperation with onion grower, Morgan Reeder, we established inter-cropping of carrot, buckwheat and phaselia which are all known to be very attractive to onion thrips. We periodically sampled the cover crops and onions in proximity to the inter-crops for thrips.

Objective 4

a) Anna Ragland presented a poster on her 2008 research findings at the 12th Annual Intermountain Graduate Research Symposium held on April 1, 2009 at Utah State University. Title: “Regenerative Organic Agriculture Systems using Cover Crops” http://www.usu.edu/usugss/symposium/downloads/2009_Intermountain_Symposium.pdf (pg 25) contains the abstract for the symposium.

b) August 12, 2009: Growers were exposed to different cover crops and fall/spring cover crop rotations at the Kaysville Research Farm. Cooperative Extension agents and specialists from throughout Utah attended the field day.

c) We (Ragland and Drost) have begun drafting a fall planted cover crop fact sheet for Utah with an expected completion in early 2010.

Impacts and Contributions/Outcomes

The research 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, UT has been using covers now for three 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 verse over 30 percent when no covers are used (losses prior to planting as related by the grower).

3) Thompson Family farm in Hurricane, UT 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. Earlier production and higher quality means 20-30% increase in profits and strong demand to ship produce from Southern Utah to Northern Utah. Fuel prices have limited his market expansion in Northern Utah.

Anna Ragland will be present additional information from her research at the 13th Annual Intermountain Graduate Research Symposium held on 31March, 2010 at Utah State University. (http://www.usu.edu/usugss/symposium/). Undergraduate and graduate students as well as faculty will review this presentation.

The Western region Integrated Pest Management (IPM) coordinating committee meetings (WERA-069) will be held in Logan on May 18-19, 2010. They have requested at tour of USU organic research activities and sites, and thus will visit the cover cropping vegetable production system in Logan.

Collaborators: