Organic Wheat Intercropping Trials and Outreach

Final Report for FW10-032

Project Type: Farmer/Rancher
Funds awarded in 2010: $15,000.00
Projected End Date: 12/31/2010
Region: Western
State: Oregon
Principal Investigator:
Sarahlee Lawrence
Rainshadow Organics
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Project Information



We addressed the issue of meeting the nutrient needs of a large-scale organic grain crop while suppressing competitive weeds. We focused on a systems approach versus the use of expensive organic-approved fertilizer input. In India, there are native legumes that resemble clover that they have traditionally grown as a permanent cover crop with their grain crops. We wanted to know if we could mimic that symbiotic relationship that the legume has with the crop here in Central Oregon. We wanted to know if we could find a legume that would not overwhelm our wheat, but still suppress the weeds, and produce a yield that was financially acceptable. We hoped that our research would bridge the organic gap for our agricultural community.

Many farmers are skeptical of organic farming because they can only relate by substituting their conventional practices with similar organic inputs. Simply substituting fertilizers with organically certified ones is cost prohibitive and does not nurture the soil. Fighting the weed wars is discouraging at best. We sought to show that our companion planting could get adequate yields that make it worthwhile to farm organically (taking the increased worth of organic products into consideration), with more people will consider switching to organic.

We used a 25-acre transitional organic field planted in soft white spring wheat, then cross-drilled five different clover varieties at two different seeding rates, replicated three times, with a total of 33 test strips including three control strips. We kept careful track of irrigation and ultimately harvested a portion of each test strip. We ran several tests, which I describe below. Along the way, we had a field day and have submitted our data to Oregon State University for their annual agricultural publication.

I cannot say that the clover showed any statistical significance in the production of the wheat, but as I have learned with organic farming, sometimes the benefits are not immediate. All of the clovers coexisted with the wheat, and the grain yield was acceptable across the board. We had very few weeds, but we did have a good stand of clovers after harvest, which was the most significant success of our research.

Project Objectives:

1. To find a cover crop that provides nitrogen for grain production without overwhelming the grain. Which cover crop works best with the grain?

2. To determine which cover crop provides the best competition for early weeds, because the cover crop will feed the weeds as well. So, the cover crop must shade the weeds. Which cover crop works best against the weeds?

3. To find the optimum seeding rates for the companion planted crops.

4. To share with our agricultural community a cost-effective, systems approach to growing adequate organic grain yields.


Materials and methods:

Crop history for the field:

Austrian Winter Peas were planted in fall 2008 and harvested for peas, then plowed, followed by summer fallow, and then a Hairy Vetch crop was planted in fall 2009. The field was then disked in spring 2010. No chemicals have been used since spring 2008. The last time any inorganic chemicals were applied was Roundup applied in fall 2007 to get a handle on quack grass before our organic transition.

In summer 2010, the wheat/legume intercropping research was performed. Three replicas were planted with eleven treatment strips, which consisted of six legumes at 1x seeding rate, five legumes at 2x seeding rate, and control strip of mono-cropped wheat for a total of 33 strips. The legumes and wheat were planted on June 1, 2010. The wheat was planted first, and then the annual legumes were planted over the top in a separate operation, all done with a John Deere double disk drill.

Four annual legumes (perisan clover, arrowleaf clover, sub clover, black medic), a biennial legume (sweet yellow clover) and crimson clover, which was seeded in the border areas, were chosen using research done by Mylen Bohle in 1992 and 1993 at the COARC Powell Butte site. In 1992 and 1993, 10 large and 10 small seeded annual legumes were tested each year. In 1993 and 1994, he tested the effect of those annual legumes on subsequent oat hay crops here in Central Oregon. The five legumes chosen were the shortest growing legumes and produced the highest subsequent oat hay yields. The wheat variety was chosen using research done by Stephen Jones at Washington State University. Alpowa wheat is known for doing particularly well under organic cultivation.

Prior to field prep in the spring three soil samples were taken collectively for the three reps.

Three half-meter quadrants of the above ground biomass of the vetch cover crop, volunteer wheat and broadleaf and grass weeds were taken to be tested for total nitrogen and other nutrients.

A weed survey was taken throughout the field to name what was present at the starting point.

Weeds present in May prior to disking included: Flixweed or Tansy Mustard, Tumble mustard, Downy brome or cheat grass, Shepherdspurse, Redstem filaree, Dandelion, Chinese lettuce, Chickweed and Wheat.

The 25-acre field was prepped and planted with Alpowa wheat at 30 seeds per square foot. The length of the field was 1,320 feet and the width was 1,000 feet, giving each test strip 30 x 1,000 feet.

Directly after the wheat was seeded, the legumes were seeded over the top, using the small box on the seed drill without the tubes so the seeds were dropped on the surface and rolled in. The strips with the double seeding rates were planted over twice to achieve the desired rates. The appropriate innoculum for each species was mixed with the seed in the drill box at planting.

The wheel line irrigation system runs perpendicular to the test strips so that all treatments experience the same fluctuations in irrigation due to wind and timing. The irrigation was performed with a rolling wheel line. Nozzle size was 9/16. There were 18 sets irrigated for eight hours each every seven days. Off-set irrigation was employed every other irrigation pass.

Half-meter quadrants were taken from each treatment on September 5, 2010. The samples were taken at milky dough to soft dough stage, because there were various stages of greenness across the field. Aboveground biomass was clipped then separated into weeds, legumes and wheat heads which were counted. Then the wheat, broadleaf weeds and grass weeds were dried and weighed. The weights were used to determine percent biomass of each. The samples were taken at this stage to determine composition of plant species. Biomass yields are presented on an oven-dry matter basis, dried at 122 degrees Fahrenheit until no change in weight.

600 square feet (5x120 feet) of each plot was harvested with a Wintersteiger small plot combine on September 20, 2010. The wheat harvested from each plot was weighed. One quart samples were collected from each treatment. The samples were tested for protein (whole grain NIRS) and test weight by the OSU Wheat Team in Corvallis, OR. Yield is presented based on 10% moisture and protein at 12% moisture. Grain nitrogen uptake was calculated (yield * protein/ 5.7). Harvest index was calculated by dividing wheat yield / wheat biomass weight.


The benefits of intercropping clover and wheat does not prove to be statistically significant in the direct yield of wheat. In fact, the control strip produced the second most bushels of wheat. In the case of weed suppression, the control strip did not have any more weeds than the strips with clover. What is important is that the clover did not overwhelm the wheat by height or competition on the ground. All the clovers grew well with the wheat, and the clovers did not suffer significantly as the wheat dried out for harvest.

The most significant result of our study was that after the wheat was harvested, the clover was established for a winter cover crop. The most beneficial aspect of the intercropping seems to be the simultaneous growth of a legume while producing a grain. The clover may not feed that stand of grain, but it is in the process of fixing nitrogen for future crops. Also, the wheat and clover can be seeded at the same time, reducing the passes across the field by equipment and the use of fuel and other inputs associated with crossing the ground with heavy equipment, like compaction or the time and energy of the farmer. It reduces tillage and results in a cover crop for winter at the end of harvest.

Intercropping allows the farmer to fix nitrogen and grow biomass for the soil, which is of concern at every opportunity. It is important to note that the Persian clover at the 1x-seeding rate and the Sub clover at the 2x-seeding rate produced the most annual legume weight over the course of the test. These two clovers did not grow tall, but did exceptionally well as an understory to the wheat. These produced over four times more biomass than other legumes, which is of statistical significance. And the Persian clover test strip also produced the most grain out of all of the treatments.

Research results and discussion:

Intercropping is an organic, sustainable method. It has the potential to enrich already organic practices. Organic farmers use it to create biodiversity in their fields, preserve water with a leguminous under story to shade the ground and to maximize opportunity for organic input. The U.S. grows somewhere around 65 million acres of wheat, which take about 120 million pounds of herbicide per year, plus 20-150 pounds of N per acre. One third of one percent of all wheat grown in the U.S. is organic. Yet the demand for organic flour, bread, pasta, cereal, etc. is multiplying every year. Conducting this research gave me the opportunity to explore my organic grain growing practices. I have now partnered with my local bakery to grow and mill grain for them. I also provide grain for my Community Supported Agriculture (CSA) members. And there are markets like this all over the nation.

Additionally, food security has become a serious issue. In my community alone, we only have three days worth of food in our grocery stores and pantries. Grain silos are filled with junk, and fields are filled with houses.Farmers need to remember how to grow food. Our nation is hungry for organic staples, and farmers desperately need this boon of demand to breathe life into perishing rural communities.

My research did not provide the easy answer for organic grain production, but it does support one form of forward investment in the stewardship of organic ground and the reduction in fuel-intensive passes over the ground.

Participation Summary

Research Outcomes

No research outcomes

Education and Outreach

Participation Summary:

Education and outreach methods and analyses:

We have email list serves, call lists and quarterly farmer meetings that connect growers interested in local, organic food. With the help of Western SARE in 2009, we have a website to better communicate with each other and our community ( Through all these means, farmers and the public alike were notified of our field day and our results.

We hosted our field day on August 15, 2010. We hosted it in conjunction to our Slow Food August Bounty Dinner that was a collaboration of local farmers and chefs at a nearby winery. I opened my farm for the whole day prior to the event with the hopes that people would visit since they were already in the area, and they did! We had several dozen people over the course of the day. This was my first outreach to the community to share the intercropping results. Giving people the opportunity to see the practice on the ground is extremely valuable for potential adoption and measuring reactions. In the spring, I presented my results at my local growers group meeting.

I am working closely with my extension agent crop specialist so that my findings will be available to the agricultural community. Our Oregon State University Extension website where I will post my findings is extremely active. Results will also be published at each of the experiment station websites. We also have a Central Oregon Ag Newsletter with a broad readership where my findings will be published in the next issue. Results will also be published in the Central Oregon Agriculture Research Center Annual Report, both online and hard copy. I have submitted to the Capital Press Ag Newspaper before and will submit an article about my project this winter. I have encouraged people to contact me to let me know their reactions and individual results if they adopt the intercropping method.

My farm is very visible, and with my extensive involvement in the farming community, I am hoping to become a center of organic systems information specific to Central Oregon, assisting other farmers in the transition.

Education and Outreach Outcomes

Recommendations for education and outreach:

Potential Contributions

Reactions from Producers

Several of my neighbors commented on how good my field looked, for “organic.” People that attended the field day found the test to be very interesting, but not everyone was a farmer or a grain farmer. My valley is completely conventional in their farming practices if they are farming at all. I did reach those people and was able to show them the practice of intercropping on the ground. I hold hope that as people venture back into farming their land that they might consider this type of practice. I have requested feedback in my publications, but I have not received any reactions yet. Part of the problem for people is that there are no outlets for organic grain. Our local grain grower’s cooperative is not an organic facility. As I create a local niche market for organic grains, other farmers may venture into organic and intercropping will be a practice they can employ.

Future Recommendations

I was very pleased with my methods of implementation. The test really worked, and I was able to clearly see the different test strips as well as harvest and analyze them. While I hoped to discover something profound, simply adding a beneficial organic method to the list has value. I really don’t think that intercropping could actually feed a simultaneous crop of wheat. It could potentially suppress weeds for a grain crop that is less competitive than wheat. It also provided pollinator habitat through the summer with the clover flowers. Most importantly, intercropping demonstrated that I could reduce the passes over my field to go into winter with a stand of cover crop. Unfortunately, I did not leave the clover for winter cover because I did not have a full stand of it and instead planted a full field of peas.

Further study could be the over-winter benefits of these clovers. Do the clovers survive the winter? Did the clover go to seed with the wheat and therefore not produce a significant stand of biomass for plow-down in the spring? Some clovers did go to seed and my field now has a bank of beneficial “weeds”, much like they do in India. The yellow sweet clover, which is a biennial, survived the winter and went to seed in my pea crop as a tall, overwhelming nuisance. I would NOT recommend planting the yellow sweet clover in future tests.

Organic systems simply need multi-year study. At what point does the nitrogen fixed by the clover get used. The next year? Later? At what point does the intercropping and limited tillage result in a natural understory that is always working to improve the soil and prevent the usual depletion that wheat causes?

I very much appreciate the support of Western SARE to conduct this research. I took it very seriously and have an intimate understanding of intercropping. As a young organic farmer, this experience is invaluable!

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.