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 to 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

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:

a. 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.

b. 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.

c. 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.

d. 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.

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

Performance targets:

a. Farm businesses that adopt 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.

b. Provide regionally relevant information to growers for reduced till organic vegetable production.

c. 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.

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:

a. 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 and learning from, and broadcasting this kind of experimentation and behavior change, are important performance targets for our project.

b. 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.

c. 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

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 2012 included: cover crop biomass, fall soil nutrient sample, continuous soil temperature, moisture, 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.

Two cover crop trials were planted at WSU Puyallup Research and Extension Center and WSU Northwest Washington Research and Extension Center, Mount Vernon. Eight cover crops and two mixes were evaluated, including: ‘Strider’ barley, ‘Alba’ barley, ‘Aroostook’ rye, common rye, ‘Purple Bounty’ vetch, ‘Lana’ vetch, common vetch, hairy vetch and combinations of ‘Strider’ and ‘Purple Bounty’ and ‘Strider’ and ‘Lana’.

On-farm trials were performed at Kirsop and Let Us Farms, and an on-farm demonstration was planted at Jubilee Farm. Kirsop compared two cover crops (‘Strider’ vs. ‘Strider’ + crimson clover) and two tillage types (rototilling vs. strip tilling), with a randomized, strip block design with six replications for tillage type and two strips of ‘Strider’ + crimson clover and one strip of ‘Strider’ alone. At Let Us farm, all plots were planted to a mixture of ‘Strider’ + peas + red clover. Four replications were used to evaluate three termination type + tillage treatments: flail mower+spader, roller/crimper+strip tiller and flail mower+ strip tiller. At Jubilee, barley, pea and vetch were planted as summer cover crops, and chard and kale were fall transplanted with one replication.

Grower Field days were held at WSU Puyallup in late May and late June to demonstrate cover crops and greenhouse gas evaluation respectively. Farm walks were held at Kirsop farm in August and at Jubilee Farm in late September to show on-farm experiments and demonstrate the no-till planting aid. A total of 144 participants attended the four events.

Results of our work were presented at the 6th National Small Farms Conference, Memphis TN, and two separate presentations were delivered at the Tilth Producers of Washington Regional Conference.

The reduced systems trial will continue for two more years. The trial is being adaptively managed so that results of the cover crop trial can be used to influence choice of cover crops in the systems trial. We planted ‘Aroostook’ to precede green beans and squash and planted ‘Purple Bounty’ to precede broccoli.

Another cover crop trial planted at WSU Puyallup will evaluate six vetches (common, ‘Purple Bounty’, ‘Lana’, “Langaduk’, hairy and ‘Cahaba’), four grains (‘Aroostook’, ‘Merced’, ‘Strider’ and common rye) and combinations of ‘Purple Bounty’ and common vetch with ‘Strider’, ‘Aroostook’ and ‘Merced’. At Mount Vernon we are evaluating ‘Strider’, ‘Aroostook’, ‘Merced’, ‘Lana’, common vetch, hairy vetch’, ‘Cahaba’, ‘Langaduk’, common rye and ‘Purple Bounty’.

Two on-farm trials were planted at Kirsop and Let Us Farm and another on-farm trial is planned for summer planting at Jubilee Farm. Additionally, four on-farm demonstrations were planted around western Washington.

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. At a late May 2012 field day at WSU Puyallup, attendees were able to see 16 different cover crops and cover crop combinations and two different reduced tillage mechanisms to terminate cover crops. Fifty-six % of the field day attendees were farmers and 60 % of the farmers were certified organic. In a retrospective, post-field day evaluation (n=18), most participants (61%) considered themselves to have moderate or advanced experience with cover crops. However, only 33% considered themselves to have moderate or advanced experience with reduced tillage. Four out of six of the attendees that had incorporated reduced-tillage in their farming practices indicated that they had been influenced to do so through observations and knowledge gained at previous WSU No-Till Extension events, especially observation of field trials. Lack of specialized equipment was frequently listed as the largest impediment to more adoption.

A second field day at WSU Puyallup, with a focus on monitoring greenhouse gases in agriculture, attracted an audience of mostly agriculture professionals (53%) and graduate students (33%). In a retrospective, post-event evaluation (n=15) most attendees reported that they had a moderate (40%) or advanced (47%) understanding of organic agriculture, while only 13% self-identified as beginners to organic agriculture. When asked about their understanding of greenhouse gases in agriculture respondents were less confident, with 27% describing their knowledge as beginner, 47% moderate and only 27% advanced.

Following the field day at Jubilee Farm, post-event evaluations indicated that 92% of participants reported gaining new information, 95% of attendees found the workshop useful to them and 76% said the information presented could help solve problems with their current operation. Eighty-six percent of participants claimed they would change at least one practice, and 100% were willing to share the information with others as a result of this field day presentation.

We are continuing to prepare for the work ahead and look forward to a successful research and growing season.

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