Selecting management practices and cover crops for reducing tillage, enhancing soil quality, and managing weeds in western WA

Selecting management practices and cover crops for reducing tillage, enhancing soil quality, and managing weeds in western WA

Summary

This integrated research and extension project will: 1) Identify production methods that effectively integrate cover crops and reduced tillage technologies to improve soil quality while reducing in-season weed pressure and seed bank populations on western WA organic farms; 2) Evaluate profitability and greenhouse gas impacts of reduced tillage cropping systems on these farms; 3) Facilitate adoption of reduced tillage technologies and ideas by a wide audience. In 2012 we initiated a multi-year reduced tillage cropping systems experiment and executed two on-farm experiments, one on-farm demonstration, two cover crop selection trials and four educational events for participating growers.

Objectives/Performance Targets

Objective 1: Identify production methods that effectively integrate cover crops and reduced tillage technologies to improve soil quality while reducing in-season weed pressure and seed bank populations on western WA organic farms.

Performance targets:

1. Through rigorous evaluation we will identify reduced organic no-till systems that are the most practical, economical and beneficial to soil quality for Pacific NW vegetable producers.
2.  Weeds are a challenge when tillage and cultivation – the most common weed control tools for organic farmers – are removed or reduced. An important performance target will be to find cover crop species, cover crop management techniques and cover crop termination strategies that combine to suppress weeds to the same degree as cultivation and tillage.
3. Find cover crop varieties that mature early enough to be terminated and still plant or transplant a variety of cash crops. They must also produce sufficient biomass to cover the soil with a weed-suppressive mulch.
4. Introduce leguminous cover crops into organic no-till rotation either alone or in combination with a grain cover crop to provide a nitrogen source while still serving a weed-suppressive function.

Objective 2: Evaluate profitability and greenhouse gas impacts of reduced tillage cropping systems on these farms.

Performance targets:

1.  Farm businesses that adapt new techniques must remain profitable to remain viable. To provide farmers with a broad analysis of reduced tillage cropping systems, we will compare relative profitability of these systems to their conventional counterparts. This will allow us to more fully address the viability of systems and also be extremely important in outreach.
2.  Provide regionally relevant information to growers for reduced till organic vegetable production.
3. Consumers are increasingly aware of the environmental impacts of agriculture. Another performance target for our project will be to increase our understanding of greenhouse gas impacts from potential increased carbon storage and reduced fuel use and convey this information to growers and the public.

Objective 3: Facilitate adoption of reduced tillage technologies and ideas by a wide audience and identify tools and strategies most effective at encouraging behavior change.

Performance targets:

1. Since our 2009 symposium and planning meeting we have seen increased interest in reduced tillage in organic vegetable production. One of our “light house” farmers and cooperators, who already uses cover crops extensively, experimented this year with strip tillage (imposed with a walk-behind tiller) to grow winter squash surrounded by a mat of cover crop. Enabling, enhancing, learning from and broadcasting this kind of experimentation and behavior change is an important performance target for our project.
2. We will survey farmers throughout our field days and workshops to monitor their interest in adopting and willingness to try new soil conservation strategies such as reduced tillage. We will also survey and interview farmers to see what challenges they perceive to changing behavior around soil tillage. Identifying the top three or four strategies likely to result in behavior change will be another performance target.
3. Facilitating farmers to overcome the obstacles to adopting reduced tillage will be another performance target. Equipment is likely to be one of these challenges, and working with local agencies such as conservation districts and NRCS to help acquire appropriate technologies for use by interested farmers will be another performance target.

Research objectives 1 and 2 will be addressed by project researchers and producers by evaluating reduced-till cropping systems and cover crop varieties in the maritime NW through experiment station and on-farm trials. Outreach objective 3 will be addressed through evaluations and surveys of producers that participate in research and outreach events.

Accomplishments/Milestones

Reduced-Tillage Cropping Systems. A multi-year reduced-tillage cropping systems experiment was initiated at the WSU Puyallup Research and Extension Center. The experiment includes five treatments that vary the type of cover crop termination and ground preparation: 1) roller/crimper+ no-till planting aid, 2) roller/crimper+ strip till, 3) flail mower + planting aid, 4) flail mower + strip till, and 5) flail mower + spader.

The experiment is a completely randomized block design with four replications (blocks). Blocks were arranged efficiently based on soil carbon and weed seed bank mapping using ad hoc power analysis. All plots were amended with compost and planted to Strider barley September 2011. Three cash crops were planted to each treatment; squash, broccoli and green beans. Parameters evaluated in 2013 included: cover crop biomass, fall soil nutrient sample, continuous soil temperature, moisture, and light penetration, penetrometer, bulk density, infiltration, soil nematodes, microbial biomass, in-situ respiration, weed biomass, weed counts, timed hand weeding, timed tractor activity and cash crop yield.

Cover Crop Trials. Two cover crop trials were planted at WSU Puyallup Research and Extension Center and WSU Northwest Washington Research and Extension Center, Mount Vernon. Ten cover crops and six mixes were evaluated, including: ‘Strider’ barley, ‘Aroostook’ rye, common rye, ‘Merced’ rye, ‘Purple Bounty’ vetch, ‘Lana’ vetch, common vetch, hairy vetch, ‘Cahaba’ vetch, ‘Langadok’ vetch; mixes included ‘Purple Bounty’ combined with either ‘Strider’ ‘Aroostook’ or ‘Merced’ and common vetch combined with either ‘Strider’ ‘Aroostook’ or ‘Merced’.

On-Farm Trials. Two on-farm trials were performed at Kirsop Farm and one trial was performed at Let Us Farm. The first trial at Kirsop compared squash growth under three treatments following an ‘Aroostook’ rye cover crop: flail mowing + rototilling, flail mowing + strip tilling, and rolling/crimping + strip tilling with a randomized block design with four replications. The second trial compared broccoli and kale growth under two treatments following a common vetch cover crop: flail mowing + strip tillage and flail mowing + rototilling with a randomized block design with two replications. At Let Us Farm, all plots were planted to ‘Aroostook rye’. Four replications were used to evaluate squash growth with three termination type + tillage treatments: flail mower + spader, roller/crimper + strip tiller, and flail mower + strip tiller.

Grower Field Days. One grower field day was held at WSU Puyallup in mid-August to demonstrate reduced tillage techniques. The field day attracted 39 participants with an interest in reduced tillage in organic agriculture. A farmer-collaborator assisted in presenting to producers at the field day.

Presentations and Articles.   Results of our work were presented at the Agronomy Society of America, Tampa FL and the Tilth Producers of Washington Regional Conference, Yakima, WA. An article in the Tilth Producers Quarterly focused on producers that are adopting reduced tillage organic agriculture. Another peer-reviewed article published in eOrganic described focus group research on adopting reduced tillage organic agriculture.

Future Research Station and On-Farm Trials and Demonstrations. The reduced systems trial will continue for at least one more year (summer 2014). We hope to continue the experiment for another three years beyond 2014. The trial is being adaptively managed, and results of the cover crop trial were used to influence choice of cover crops in the systems trial. Based on the cover crop trials in 2012, we planted ‘Aroostook’ to precede green beans and squash and planted ‘Purple Bounty’ to precede broccoli. This was successful in summer 2013, and we continued this rotation by planting the same cover crops in fall 2013.

One on-farm trial was planted at Kirsop Farm in fall 2013. Based on success of the 2013 trial, the 2014 trial will repeat the 2013 trial with common vetch and broccoli.

We will also continue to reach out to growers through field days that allow producers to see cover crops in the ground and reduced-tillage equipment and strategies in action.

Impacts and Contributions/Outcomes

Interest in incorporating cover crops and reducing tillage to improve soil quality is high among organic growers in Washington. During an August field day at WSU Puyallup, attendees were able to see our reduced tillage organic agriculture experiment. In a retrospective, post-field day evaluation (n=24), 54% of participants considered themselves to be at a beginning level with cover cropping and 75% considered themselves to have little to no experience with reduced tillage organic agriculture. Four producers indicated they had adopted some reduced tillage practices while another 16 producers indicated that they felt equipment, knowledge and weed control were still challenges to their ability to adopt these techniques.

Collaborators: