Intercropping Systems For Small Scale Vegetable Production

Final report for FNC19-1173

Project Type: Farmer/Rancher
Funds awarded in 2019: $8,867.00
Projected End Date: 02/28/2021
Grant Recipient: New City Neighbors
Region: North Central
State: Michigan
Project Coordinator:
Lance Kraai
New City Neighbors
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Project Information

Description of operation:

New City Farm is a 3-acre vegetable farm and has been in operation since 2012. We have been sustainable growers (using organic practices while not being certified) since the farm started.

Summary:

This project will research innovative practices of intercropping in order to make small scale CSA farm operations more economically and ecologically sustainable. While CSA models are socially beneficial to farmers and communities because they create a direct relationship between farmers and consumers, CSA farms often struggle with managing a large diversity of crops in a financially viable way. This problem is particularly acute for small farms that try to grow space-consuming crops like sweet potatoes, winter squash, and broccoli. Because these crops need many days to reach maturity and a lot of space, many CSA farms abandon growing these crops and focus instead on more short day small crops such as salad greens. This can reduce the value of CSA shares to consumers; research consistently shows consumers highly value hearty vegetables like sweet potatoes, squash and broccoli. This project will demonstrate that these crops can be grown profitability on a small scale if they are intercropped with short day small crops. We will research the combination of sweet potatoes with onions, winter squash with garlic, and broccoli with lettuce. Our research will provide farmers with specific information about an intercropping growing system along with the supporting economic data.

Project Objectives:
  1. Research and record the yield per acre of three intercropping systems: broccoli/lettuce, sweet potatoes/onions, and winter squash/garlic
  2. Determine return on investment for each of the intercropping pairings by recording materials and labor expenses, and comparing market value to the yield recorded for each separate pairing
  3. Produce a digital document outlining the spacing and timing of each intercropping system along with two short videos documenting project results
  4. Share project results through a field day, conference presentations, and through social media

Research

Materials and methods:

This project will be a demonstration project. Three 150ft x 150ft test plots will be established to trial the three intercropping pairings of broccoli/lettuce, winter squash/garlic, and sweet potatoes/onions.

In the broccoli pairing, broccoli and lettuce will be planted at the same time. Two rows of lettuce will be planted on the outer edges of a 30in bed top. Broccoli will be transplanted down the center row. We will plant this intercropping into bare soil and will manage weeds with scuffle hoes.

The sweet potato/onion intercropping and winter squash/garlic planting will be planted with the same spacing and put in landscape fabric. By using the same spacing, growers can reuse fabric interchangeably between each pairing during subsequent seasons. The landscape fabric was chosen in order to manage weeds on both of these vining crops. The fabric will have holes burned in it for a 30in bed top. Each bed will have three rows. The outer rows will be for the garlic or onions and the center row will be for winter squash or sweet potatoes.  

In the squash pairing, garlic will be planted in the fall ahead of the winter squash. Winter squash will be transplanted in the center row of the bed in early June. Garlic will be harvested in July, just as the squash plants begin to vine out.

In the onion/sweet potato pairing, onions will be transplanted 50 days ahead of the winter squash planting. This will allow the onions ample time to be established without competition and will ensure they receive full sunlight into the equinox. The sweet potato slips will be transplanted in early June. Onions will be harvested in late July, just as the sweet potato vines begin to take over the entirety of the space. Please see attached drawing for specific planting patterns (SARE-Intercropping-diagram).

Research results and discussion:

We learned that all of the methods we trialed can work. Of the three combinations the Winter Squash/Garlic planting had the highest return. Not factoring in long-term costs like land/infrastructure/insurance, etc. we estimated a net hourly wage of $83.95 per hour for this combination. The Broccoli/lettuce planting netted an hourly wage of $68.85, and the Sweet Potatoes/Onion combination netted an hourly wage of $40.90. See SARE Intercropping Trials for these calculations. The Winter Squash/Garlic combo had the highest sales value, the least annual costs, and required little labor. Conversely, the Sweet Potato/Onions combination had high annual costs because the Sweet Potato slips are expensive, and we start our onions from seed in the greenhouse and starting that many plants proved timely and expensive. In addition, the labor to harvest both the onions and the sweet potatoes was substantive. Still, for a CSA farm it makes sense to grow all three of these combos and we find that running a CSA is greatly helped by having these storage crops to buffer fresh greens and fruits that do not have store-ability. In particular, our winter shares greatly benefit from having Sweet Potatoes, Winter Squash, Onions and Garlic in storage. Also note that the numbers given were estimates based on going to Market. We did not actually go to market, all of this product was distributed through our CSA. Market farms would likely have issues moving this much product via a Farmer’s Market.   

Participation Summary
3 Farmers participating in research

Educational & Outreach Activities

2 On-farm demonstrations
4 Online trainings
4 Tours
2 Webinars / talks / presentations
1 Workshop field days

Participation Summary

180 Farmers
20 Ag professionals participated
Education/outreach description:

On August 19 we hosted a farm group from the Michigan State University (MSU) Student Organic Farm. We gave a tour of the farm and showed our intercropping systems. At the end of the tour we provided pizza from our wood fired pizza oven and talked about value added production and our previous SARE project. This event was advertised through the MSU Student Organic Farm as a farmer field day school. Approximately 25 farmers were in attendance.

We also presented our findings at the Michigan Family Farm Conference on February 8, 2020. Approximately 55 farmers were in attendance.

We presented at the Indiana Small Farms Conference on March 6, 2020. Approximately 100 farmers were in attendance.

We presented at the Michigan Food & Farm Conference 2021 virtually. 

We presented to 3 classes from Grand Valley State University’s Sustainability Department virtually.

We presented an online tour through the West Michigan Growers Group.

 

Learning Outcomes

100 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation
Lessons Learned:

We learned that all of the methods we trialed can work. Of the three combinations the Winter Squash/Garlic planting had the highest return. Not factoring in long-term costs like land/infrastructure/insurance, etc. we estimated a net hourly wage of $83.95 per hour for this combination. The Broccoli/lettuce planting netted an hourly wage of $68.85, and the Sweet Potatoes/Onion combination netted an hourly wage of $40.90. See SARE Intercropping Trials for these calculations. The Winter Squash/Garlic combo had the highest sales value, the least annual costs, and required little labor. Conversely, the Sweet Potato/Onions combination had high annual costs because the Sweet Potato slips are expensive, and we start our onions from seed in the greenhouse and starting that many plants proved timely and expensive. In addition, the labor to harvest both the onions and the sweet potatoes was substantive. Still, for a CSA farm it makes sense to grow all three of these combos and we find that running a CSA is greatly helped by having these storage crops to buffer fresh greens and fruits that do not have store-ability. In particular, our winter shares greatly benefit from having Sweet Potatoes, Winter Squash, Onions and Garlic in storage. Also note that the numbers given were estimates based on going to Market. We did not actually go to market, all of this product was distributed through our CSA. Market farms would likely have issues moving this much product via a Farmer’s Market.   

Here is why we chose to intercrop:

  • It creates higher yields by using all available space.
  • There are fewer weeds because all available space is always being used.
  • It may reduce insect pressure.
  • Gives shading advantages to cool crops.
  • It is beautiful. 
  • It is fun.

Here are some of the guiding principles we used:

  1. Intercropping needs really good soil. I think the soil should test at over 5% organic matter. I would argue this organic matter should come from plant based compost. At least 3 inches of plant based compost to begin, an inch each year after for three years. Amend with custom mix and fish as needed. 
  2. If your soil is right the only limitation is the sun. Try to use all available sunlight at all times.
  3. Plants grow in circles not squares! So use staggered planting patterns. (Think like a pixel printer not like an 8 bit Atari).
  4. Keep heavy feeders (Brassicas especially) in the center of inter-cropped beds and light feeders like lettuce on the outside.
  5. Place longer season crops in the center and short season crops on the outside.
  6. Experiment and have fun. Discover what combinations work for you.

Here is what we learned from the garlic/winter squash trial and the onion/sweet potatoes trial. We chose these combinations because:

  1. All four crops are difficult to manage weeds with. Onions/Garlic because they are weakly rooted. Sweet Potatoes and Winter Squash because they vine out.
  2. We wanted to use landscape fabric with vining crops, but fabric is expensive and labor intensive so we wanted a higher return on this investment.
  3. Sweet Potatoes and Winter Squash take up a lot of space.
  4. By intercropping these 4 crops we get a higher return on material and labor costs while maximizing space.

We were very successful in the garlic/winter squash planting.

What we did:

  1. We planted the garlic the previous season. It is best to plant the garlic in October so that the bulbs root, some of our garlic that got planted in November somewhat heaved. In our second season Garlic was planted in October and we had no heaving.
  2. Spacing: 32in. bed tops. 4½ ft. wide with pathway.
  3. Winter Squash spaced at 12in. apart down the center of the bed, slightly offset.
  4. Outer edges of the bed spaced at 6in. apart (see image in attached powerpoint presentation).
  5. We burned holes in the fabric with a template using a plumbing torch. Can do multiple sheets at a time. We used 15ft. wide rolls to make sheets to cover 3 beds together. The fabric should be ground cover (smooth on both sides).
  6. Use fabric staples to secure the fabric (about 6ft. apart). Reused staples are better because as they corrode and rust they grab the soil better. A staple setter (magnet on the end of a 3ft. handle) is a worthy investment.
  7. Drip irrigation should be set up under the fabric.
  8. We transplanted winter squash on June 28. The later the better so you give the garlic the time it needs. We used a 90 day Butternut variety (Waldo) to ensure that the squash would finish with a late planting.
  9. Harvest the garlic after the tops begin to brown but before the whole top browns. This lets you easily pull up the garlic at harvest, otherwise tops can tear off and the garlic is difficult to harvest because you can’t use a fork to lift the garlic because of the fabric.
  10. We hand weeded weeds that emerged through the holes two-three times. Because the fabric controls the majority of the weeds this is a fairly quick task as long as it is done early.     
  11. We had a strong harvest of both crops.

Onions/Sweet Potatoes:

This planting is very similar to the above planting. We used the exact same fabric and template spacing. Onions were planted in mid-April and the Sweet Potatoes after the risk of frost. We had a great onion crop. Onions were very large. In 2019, we missed an important second/third hand weeding though. As a result, we had a surge in tall grass that grew up and around the onions. We couldn’t weed this because we did not want to disrupt the onions, but the tall grass shaded the sweet potatoes and lowered our sweet potato yields. After we harvested the onions we cleared the field of weeds and the sweet potatoes rebounded, but our short Michigan summers require the sweet potatoes to have full access to the sun through the whole growing season. In 2020, we made sure we did a very clean hand weeding the third time. This kept our field clean the whole season and harvesting for all crops much easier and we had a sizable sweet potato harvest. Our only issue was that many of the sweet potatoes had splits. We don’t know if this was related to the intercropping, or the variety used. We observed that Beauregard had more firsts than Georgia Jet. We still weren’t that pleased and will trial Covington in 2021. Several farmers on tours affirmed this as the best variety for quality sweet potatoes in Michigan.

Challenges:

We had some staff changes mid-season so we were unable to properly account for yields, labor and return on investment in 2019. We were able to track this data in 2020. 2020 had it own sets of challenges that need not be named. We survived though and had a good growing season.

 

Project Outcomes

10 Farmers changed or adopted a practice
1 New working collaboration
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.