Comparing Organic No till with Conventional Tillage methods when Direct Seeding Vegetables and Incorporating Cover Crops

Final Report for FW12-035

Project Type: Farmer/Rancher
Funds awarded in 2012: $14,701.00
Projected End Date: 12/31/2013
Region: Western
State: Washington
Principal Investigator:
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Project Information

Abstract:

We conducted a two-year experiment that was designed to demonstrate the potential benefits and viability of organic no-till for directly seeding market garden vegetables. In the first year, we planted a variety of salad greens and lettuce. In year two, we switched to carrots.

Our farm is located in the Pacific Northwest where extremely wet winters and springs can delay planting dates due to problems associated with wet soils. Our experiment clearly demonstrated that we could prepare the no-till beds as much as six weeks earlier than the tilled ones without harming the soil structure.

In year one, overall yields of salad greens was greater in the no-till beds due to earlier planting dates, which effectively increased the length of the growing season. In year two, the no-till carrot yields were significantly larger due to pest damage, as well as splitting of carrots in the first tilled bed.

Introduction

Soil and Climate

Growing conditions in the maritime Pacific Northwest present some unique challenges. Extremely wet winters and springs, as well as cool temperatures throughout the summer months, can promote a host of disease and pest problems, as well as having a negative impact on soil structure and fertility.

Problems with Tillage

The soil at our farm is shallow and has high clay content and an extremely hard glacial till subsoil. Most farms in our area have poor drainage that contributes to problems associated with spring tillage in wet soil, such as loss of soil aggregate, compaction, erosion, increased run-off, nutrient leaching and anaerobic conditions that promote soil born diseases. These problems contribute to reduced crop yields and increased production costs.

Increased erosion, run-off and nutrient leaching into our watersheds has become a major concern, especially in salmon spawning habitats. Government regulations regarding setbacks to streams and wetlands has started to have a serious impact on many farmers in our area.

In our site, tillage promotes the spread of quack grass, thistle and initiates the germination of many types of weeds when compared to continuous no-till.

Benefits of No-Till

Utilizing a fall-sown cover crop into a no-till system can greatly reduce run-off and nutrient leaching. Year-round cover cropping in a no-till system also reduces the need for manure and compost.

Without the use of herbicides, organic farmers tend to depend upon tillage as their main method of controlling weeds, as well as for incorporation of green manure into the soil. In a continuous organic no-till system that combines year-round cover cropping and proper crop rotation, weed pressure is reduced, as well as the need for soil amendments.

Amendment mix for salad greens and carrots cash crops

For our two-year experiment we compared the following four treatments, using Fava Bean cover crops, chicken manure and azomite mineral amendments.

  1. No-till + manure amendments
  2. Tillage + manure amendments
  3. No-till + cover crop/manure amendments
  4. Tillage + cover crop/manure amendments

The salad mix is composed of lettuce, Red Russian Kale, Arugula and a variety of Asian greens: Tokyo Bekana, Giant Red Mustard, Tatsoi, Mizuna. In our original proposal ,we planned to grow salad mix in both years in the same beds. Unfortunately we became concerned due to the large number of greens in the salad mix that are in the mustard family. In our region, club root is a major problem and affects all members of the mustard family. That is why we modified our experiment in year two and planted carrots.

Project Objectives:

1. Use no-till to build prime agricultural soil in a region that has no class 1 soils.

2. Develop innovative methods for direct seeded salad greens using a no-till system.

3. Effectively integrate cover crops/manure using a no-till system.

4. Develop planting/cover cropping schedules that allow earlier planting dates.

5. Compare soil quality and weed pressure between tilled and no-tilled plots.

6. Measure economic benefits.

7. Measure potential benefits to agriculture and soil improvement.

8. Encourage adoption of methods/educate wider public

Cooperators

Click linked name(s) to expand
  • Andy Bary
  • Dr. Doug Collins
  • Larry Korn
  • Gary Miller
  • Dr. Tom Shultz

Research

Materials and methods:

Experiment

For our experiment starting in April 2012, we used four test beds measuring 60’x30’ and four treatments (see intro). These beds had not been tilled in the previous two years so we had a good idea of how well they would perform in regards to weed pressure.

In the fall of 2011, prior to receiving the funding, we planted a mix of cover crops into these four beds. The mix consisted of crimson clover, hairy and common vetch, fava beans, winter peas and rye grain. We should also note that a volunteer cover crop of chickweed made up a portion of the total ground cover.

Year 1: Salad Mix

In early April, we direct seeded our first salad mix. Salad is a major cash crop for us that we directly sell to high-end restaurants, as well as the local food coop. Salad mix is a cool season crop that requires weekly planting and harvesting throughout the growing season.

On average we start cutting four to five weeks after seeding, when the plants are four to six inches tall. When supply exceeds demand, we let it mature and sell as a braising mix.

Fertility in Salad Mix Beds

Maintaining fertility and nitrogen levels that salad mix requires throughout the growing season can be a challenge:

  1. Health department regulations restrict the use of manure and compost within 120 days of harvest.
  2. In Organic No-till we do not turn under the winter cover crops.
  3. We avoid the use of on-farm manure and compost in direct seeded beds out of concern for weed propagation.

These instructions require us to build a high level of fertility in the preceding seasons before we directly seed. For this purpose we use cover crop residue (composted) from the previous year, as well as purchased organic chicken manure that is weed-free. We follow standard crop rotation guidelines in choosing our salad mix beds. We also plant a legume cover crop in the fall that over winters in our climate.

Removing Cover Crop in Salad Mix beds

In our 3’ wide beds we plant four rows of salad mix. Although we use hand tools to prepare the beds, a tractor with standard implements and slight modifications would work. We prepare a section of bed two weeks prior to seeding. This gives the weeds a chance to come up, which we eliminate just before seeding with a quick pass of a hula hoe.

In the no-till beds we hand pull the cover crop, with the exception of the crimson clover and chickweed. This is quick and effective, especially in the spring when the soil is moist. If the cover crop resists pulling, we can loosen the soil with a broad fork or spading fork. We use care to minimize soil disruption with this method.

After hand pulling the cover crop, we go back over the bed with an Asian-like farmers hoe (see picture) and slightly undercut the chickweed and cover to a depth of no more than one inch. This could be accomplished with a tractor and a shallow set on a sweep cultivator or a Howard’s Rotovator set to an inch and a half depth. We rake out the cover crop residue and compost it at the end of the bed. In sections of beds that have not been planted, we allow the cover crop to mature. If the cover crop stalks become a problem, we scythe it down.

Preparing Salad Mix Beds

As previously stated, we follow up the weeding with a hula hoe and a smooth raking of the bed. Once the bed has been smoothed out, we mark out four rows. For this purpose we use a 3’ wide rake with four teeth that are 8” on centre. We use a string line to guide the rake. Straight rows are a big plus when weeding prior to cash crop emergence. Once the four rows have been marked, we add our mineral amendments (azomite, fish bone meal and kelp). We quickly mix them into the soil with a hand-held single point cultivator.

We divided the 60’ experimental beds into four 15’ sections. Each section is further divided into five 3’ sections. Each 3’ section is seeded with a single variety. Planting the salad mix as individual varieties takes a bit more time but offers tremendous timesavings when harvesting and cleaning. Because the salad mix is composed of such a wide variety of plants, their maturation dates are not the same. That is why we do not plant them as a mix.

The seeds are sown in a 3” wide band. We use a wheel attached to a handle to lightly firm the seed bed. Once the seeds are covered with soil, we make another light pass with the wheel to firm contact between the soil and the seeds. Drip tape is installed, and we keep the surface moist until the mix is up.

Within four to five weeks we start harvesting. We harvest and wash one variety at a time. We find this speeds up the process. Final mixing occurs before bagging.

The start date in our no-till bed was April 9. In the tilled bed, we had to wait until mid-May before the soil had dried out enough to rototill. Once we rototilled the tilled beds, we maintained the same planting schedule for our test plots.

Year 2: Carrots

Bed preparation and sowing of carrot seeds is almost exactly the same as the salad, except that we use pelleted seeds in a single row. We do not use manure when planting carrots.

Research results and discussion:

The most dramatic result of our two-year experiment comparing tilled and no-tilled methods in direct seeding salad greens and carrots was our increased sales from the no-till beds. In salad mix this was directly due to an earlier start date of four weeks. Salad mix is a cold season crop with most production in the spring. The earlier sowing date in the no-till beds resulted in an additional high yielding cutting. When we compared the salad mix sections started on the same date, we found a small increase in the productivity of the tilled beds. We suspect this may be due to declining nutrient levels in the no-till beds that had been previously harvested.

In the second year, overall yields of carrots was slightly higher in the no-till beds, but due to severe pest damage and splitting in the earliest seeded tilled bed (planted in May), we had significantly less marketable carrots from the tilled beds.

The second tilled bed planted in mid-July had significantly less pest damage and splitting. Although tillage is often recommended as a method for reducing rust fly and wire worm damage, it is significant to note that the no-till carrot bed planted at the same time had dramatically reduced pest damage and splitting, and no effect on their marketability. We suspect that tillage reduces natural predator populations, resulting in an imbalance that favors wire worms and rust fly.

Pest Problems in Carrots

Its clear that for tilled carrots planting dates are a significant factor in regards to pest problems. It should be noted that most local organic growers use row cover to reduce rust fly damage. Unfortunately installing and maintaining row covers is time consuming and an added production cost.

Splitting in Carrots

As carrots reach full maturity, it is not uncommon to have some minor splitting. The degree to which splitting occurred in our early tilled carrot bed is extreme, however. We suspect that tillage combined with high moisture levels from spring rain may be a factor. Recently tilled soils may offer little resistance to the carrots rapid growth.

Weeding: Carrots

Weeding time was reduced by 25% in the no-till carrot beds. On average, the tilled beds required 10 hours of weeding. The no-till bed required an average of eight hours. In the first month of growth carrots require early and frequent weeding - this is essential for a successful crop. Weeding between rows can be accomplished quickly with any type of hand-held weeding tools. In the no-till beds we do not disturb the soil deeper than an inch. Unfortunately weeding within the row is time consuming and tedious. Care must be given to prevent cutting or disturbing the carrot roots.

Weeding carrots represents the largest input of labor related to this cultivation. Weeding and thinning are performed at the same time. A bed requires three weedings in the first month of growth. After that we find carrots can compete well with the weeds and require little or no further weeding.

Weeding: Salad Mix

Weeding salad mix is not a major factor due to their rapid growth and being planted in a wide band. We seldom weed salad mix, especially during the first growth. Weeds can be a factor in the second and especially the third cutting. Rather than weeding in the bed (which is ineffective once the greens are established), we end up cutting the greens and weeds at the same time. During washing we pick the weeds out of the mix. It was therefore difficult to assess the weed pressure when comparing the tilled with the no-till beds. With salad greens we do not think it was a factor.

Participation Summary

Educational & Outreach Activities

Participation Summary:

Education/outreach description:

Workshops

Education and outreach was a vital component of our project. Two workshops were held. The first in August 2012 was comprised of a presentation by Larry Korn (editor of Fukuoka’s books The One Straw Revolution and Sowing Seeds in the Desert) who discussed Fukuoka’s no-till methods for grain production utilizing mixed cover crops. Andy Bary, soil scientist at Washington Sate University, discussed the research being done by the small farms team at Puyallup in reduced tillage. This was followed by a tour of the test beds and a demonstration and discussion of our no-till methods. This workshop was attended by approx 60 people.

The second workshop took place in March 2014 as part of the San Juan Island Agricultural Summit and was attended by 50 – 60 people. Doug Collins from WSU talked more about the small farms team’s research into reduced tillage. We gave a presentation on the following topics using the experiment as a case study:

- The Science Behind No-Till

- Transitioning to No-Till

- Cover Cropping

- Bed Preparation

- Managing Weeds

- Experiment Results

The attached pdfs are copies of our Powerpoint presentation. These were also printed and given as a handout to each participant along with a number of informative articles on organic no-till. (see attachment) We also screened edited video footage of the experiment being carried out in the field.

Media

The SARE grant enabled us to establish our website. The presentation pdfs are available to download from the ‘Learn’ page: goodearthcentre.org/learn. We have kept a blog on our website with monthly updates on the experiment: goodearthcentre.org/blog. The website has received around 11,000 views. This report will also be accessible from our site.

A Facebook page was created to help with publicizing the workshops and website. We will continue to use Facebook as a networking and publicity tool.

Many hours of video footage were generated from the workshops and the different stages of the experiment out in the field. This has so far been edited into a short film (approx 30 minutes) and is available on line: You Tube and goodearthcentre.org/learn (the file to is too large to upload here). Film is proving to be a very effective outreach/educational tool. We plan to upload the entire footage of the presentations and create more demonstration/ ‘how to’ video clips onto the internet this year.

Press

An article by Doug Collins, featuring our farm and organic no-till methods, was published in Washington Tilth Producers Quarterly magazine. See attachment. The workshops were featured in the local press and were advertised in Grow Northwest Magazine and Tilth Producers Quarterly.

Other

Other direct participants in the experiment were our interns and wwoofers (approximately 20) over the two-year period. We also had several visits from local youth groups in  summer 2013 who learnt about the experiment and particpated in harvesting and weighing yeilds.

Project Outcomes

Project outcomes:

Soil tests revealed a reduction in organic matter in all four test beds.

Report findings

It is clear that two years of demanding crops without the use of green manure, compost or manure needs to be avoided. Clearly standard soil management practices apply to both organic till and no-till. Suggestions for addressing this have been made in the contributions section.

Direct seeding of carrots and salad mix in organic no-till is a viable alternative to organic till.

In farming regions with wet springs and heavy soils, no-till permits earlier planting dates, resulting in increased yields. Continuous no-till can reduce weed pressure and promotes biodiversity. Worm populations remain higher and more stable than in tilled soil. There is strong anecdotal evidence that early rust fly and wire worm damage can be significantly reduced in carrots through the no-till method.

Soil aggregate remains higher in the no-till beds, as indicated by a simple soil test placing samples into a flask with water.

Economic Analysis

In terms of overall yields, the no-till beds outperformed the tilled beds.

Total Yields

Tilled carrots = 352 lbs

No-Till carrots = 448 lbs

Tilled Salad Greens = 133 lbs

No-Till Salad Greens = 283 lbs

See attached image for more info on yields.

Recommendations:

Potential Contributions

Word of caution on direct seeding in Organic No-till

From our experience it takes three years of continuous no-till to start seeing the benefits in terms of reduced weed pressure. Without tillage the transition to organic no-till can be challenging. We strongly recommend establishing good weed control before attempting to directly seed crops like carrots and salad mix. Cash crops that can handle some weed competition like transplanted squash, tomatoes, brassicas as well as climbing beans, peas and tubers would be a good choice prior to direct seeding.

Cover Crop in Organic No-till

Year-round cover crop can be an extremely effective tool in reducing weed pressure. The use of broad leaf like daikon radish, turnips, cabbage as well as clovers and rye can be a good choice. Bare soil invites weeds. Once you have a good handle on weeds, try transplanting directly into a standing cover crop or recently terminated one with a thick residue.

Sowing a low growing cover crop after your cash crop is established is another strategy for weed control and soil improvement. Unfortunately we have not found an effective way to direct seed carrots or salad mix into a high crop residue or standing cover crop due to our narrow row spacing. It could work in a strip no-till set up where you had at least two feet on centre rows.

Cover crops for improving the soil

In addition to weed control, cover crops are our primary means of improving soil quality and fertility. This is especially true on our direct seeded beds where we avoid the use of on-farm manure and compost due to the potential for weed problems. In the direct seeded beds, we rely on fall-sown legumes and purchased weed-free chicken manure to maintain fertility.

Incorporation of Cover Crop in an organic no till system

Traditionally cover crop (green manure) is tilled into the soil. In an ongoing no-till system this is not possible. In many Organic No-till farms, cover crop are rolled or mowed down and left on the surface to act as a mulch. As previously stated, this works well with many types of transplanted vegetables, but we have not found a practical way for utilizing this method in our narrowly 8” spaced carrots and salad mix beds.

Instead we place the cut or pulled cover crop at the end of the bed and cold compost it. The following year we broadcast it as compost over the bed. This may seem ineffective when compared to turning under a green manure, but we find it has many advantages. Green manure needs time to break down prior to planting. Given our wet soils, this can delay spring planting dates beyond what is practical.

In our experience, we also find that a vigorous cover crop allowed to mature produces not only more green growth but also an extensive root system. Recent research indicates that the root system may have more benefit than the above ground growth. In our no-till beds this extensive root system is left in place to break down and feed the soil organisms. After terminating the cover crop, we wait two weeks to allow the weeds to germinate and eliminate them prior to direct seeding.

Fava Beans as a Cover Crop

On the plus side, Fava beans when allowed to mature produce tremendous biomass and are easy to pull out. They break down quickly when composted or they could be transplanted into. But their slow growth in the fall does not work for suppressing quack grass and other fall weeds. The experiment revealed that Fava Beans should be used in a mix if weed suppression is required.

Crop Rotation

Although our experiment involved two years of direct seeding in the same beds, we no not recommend this practice. Soil tests for all four treatments, tilled as well as no-till, indicated a marked reduction in organic matter and Caton Exchange. As previously explained, we do not add any compost or manure high in organic matter into our direct seeded bed. Nor do we leave cover crop residue on the beds. In the second year, due to carrots' low tolerance for manure we did not add any.

Therefore the test beds went two years with inadequate inputs of organic matter. This is especially concerning when growing an extremely demanding crop like salad mix for an entire season.

We recommend any direct seeded crop that requires complete residue removal be pre-seeded by a low demand crop that is well-manured and composted. Following a direct seeded crop we recommend a high biomass cover crop that is left in place.

Difference in Size and Shape of Tilled and No-Till Carrots

It is interesting to note that the no-till carrots (Bolero variety) were larger and less tapered in shape than the tilled ones. (see attached image).

Farmer Adoption

Participants to our second workshop were asked to fill out a questionnaire. The results (see attachment) are very encouraging. All of the participants who were currently not using no-till methods stated that they would be using no-till in the future. We are advising a number of small-scale farmers who have contacted us with questions relating to transitioning to no-till. We will contact all of the participants from both workshops in the near future with a new questionnaire to see how far along they are with transitioning and to assess any further learning tools they may need. We are planning to hold more hands-on workshops in the future.

Future Recommendations

Areas Needing Additional Study

Two years is clearly too short of a time frame to compare organic no-till and tillage. A ten-year study containing a wide range of vegetables would be a more realistic indicator. We also think the tilled beds should have a significant separation. In our garden we have witnessed a significant increase in biodiversity. We think the two tilled beds may have benefited from this. An entomology report as well as a microorganism survey would also be a valuable tool in comparing Organic No-till with Organic Tillage.

Improved pest management in organic no-till shows promise and a long-term study would be important. Proper cover cropping is of critical importance to organic no-till. Developing proper mixes and schedules would be very helpful to vegetable growers. Developing strategies and methods for planting into high residue or intercropping with a cover crop is another area needing more study.

A major hurdle to organic no-till vegetable production, especially on a small operation, is lack of affordable equipment. Affordable seed drills and seeders for high crop residue, as well as transplanting, would be a big help in promoting organic no-till.

A simple design and plan for modifying existing equipment for no-till application:

  1. shallow cultivation
  2. seeders in high residue
  3. transplanters for high residue.

Information Products

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.