Sustainable Vegetable Production: Screening Cover Crops for Water Use Efficiency

Sustainable Vegetable Production: Screening Cover Crops for Water Use Efficiency

Summary

During the third year of this project (2010), research trials were re-established to evaluate cover crops productivity. Due to insufficient activity, a graduate student supported by this project was released from the program. While the student worked on the project for two years, the results collected, research conducted, and overall quality of the data was marginally useful. As a result, much of the data is of little value, and we need to try to salvage and redo the research assessing the water use efficiency of spring/summer planted cover crops in part of the 2010 production season. Any analysis from the 2009 growing season is suspect, and we are doing our best to salvage some of the findings. Clearly some of the objectives will never be fully addressed do to these unfortunate events.

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 and 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

Objectives 1 & 2:

Organic production systems using cover crops (CCs) for nutrient cycling require some understanding of their water use and level of biomass generation. In 2010, we explored modifications to local seeding rates as a way to increase stand establishment, cover crop density and weed suppression for spring/summer seeded grass (annual rye, millet, barley, sorghum), broadleaf (buckwheat, rape) and legume (chickling vetch, soybean, hairy vetch, lentil, adzuki bean, lab lab and lupine) cover crops. Many of these CCs that had performed well in the past showed some drought tolerance and produced reasonable amounts of biomass. Crops were seeded at the standard rate and at a 2x rate on June 21 to ensure high densities and better cover. Plots were irrigated and stand counts taken on July 7 and fresh and dry weights measured on July 28. Cover crops that show potential adaptation to the intermountain west include annual rye, barley, millet, hairy vetch, buckwheat, rape and sorghum. Less adapted CCs included soybean, adzuki bean, lentil, lab lab and chickling vetch which had weaker stands, slow growth/cover and less biomass. These types also allowed more weed growth due to lower density and more open stands. During the spring 2011 period, 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 Greg and Tim Vetere (Green River, UT), we evaluated winter wheat cover crops for weed management and soil stabilization in 2010 (Photo 3 to 7). The Vetere’s grow a range of vegetables and use fall-seeded wheat to hold sandy soils in place and provide wind protection for early planted melons. Because they have irrigation, good stands are established and plots are sprayed out in the spring, strip tilled and then planted. In 2011, we will evaluate the timing of cover removal and how density impacts melon establishment and growth.

Objective 3b):

Cooperators David Sterling (Leeds, UT) and Tim Thompson (Hurricane, UT) continue to use cover crops for weed and wind management for seeded and transplanted melons (water and cantaloupe). All the cooperators note that dry winters (limited snow or open fields) create stand losses that then provide limited biomass needed for protection in the spring. This seems to be a common problem in the dryer areas of eastern and southern Utah (Grand and Washington Counties). While these growers use plastic mulches and drip or center pivot (drop nozzles) irrigation for their crops if winter CC 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. While we continue to ask about trying to establish mixed cover crop systems (with legumes) to improve soil nutrition re-cycling, growers are not that interested in the nutrient aspects of the CC system.

Objective 3c):

In cooperation with onion grower Morgan Reeder, we continued to evaluate inter-cropping of carrot, buckwheat and phacelia with onions (Photos 1 & 2). These plants are all known to be very attractive to onion thrips. We periodically sampled the cover crops and onions in proximity to the CCs for thrips and their impact on onion productivity.

• Onion Growers Discussing Trap (Cover) Crops
• Phacelia Trap (Cover) Crop in Onions
• Greg Vetere Observing Direct Seeded Melons in Cover Crops
• Wheat Cover Crop
• Wheat Cover Crop Wind Break in Transplanted Melons
• Wind Damaged Melons
• Tim and Greg Vetere discussing Cover Crop Wind Breaks

Impacts and Contributions/Outcomes

April 5, 2010 – Graduate student gave an oral on the 2008-09 research findings to the department of Plants, Soils and Climate as part of the weekly seminar series at Utah State University.

June 30, 2010 – Summer Evening Field Tour; Norman Farms, Corinne, UT. Ten onion growers and industry persons observed how different cover crops could be used to attract onion thrips.

August 17, 2010 – Kaysville Field Day. Kaysville, UT. Fifty-six fruit and vegetable growers, industry persons and extension educators toured the USU organic vegetable trials that are using various cover crop combinations (fall & summer planted) to cycle nutrients and support vegetable growth.

Collaborators: