Maintaining Companion Planting Techniques while Mechanizing in Diverse, Small-Farm Vegetable Operations

Final Report for FNC10-814

Project Type: Farmer/Rancher
Funds awarded in 2010: $6,000.00
Projected End Date: 12/31/2012
Region: North Central
State: Iowa
Project Coordinator:
Rob Faux
Genuine Faux Farm
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Project Information


This project’s purpose was to identify field planning techniques to integrate mechanization while maintaining companion planting (intercropping) practices on a small farm that raises diverse vegetable crops. The first year of the project focused on the identification of appropriate tools needed to scale up the operation and implement new spacing techniques for intercropping. A study was piloted in the first year to compare new spacings with established intercropping spacings that had exhibited benefits on the farm in prior years. The pilot provided input to adjust the spacings and the study parameters so that a treatment/control study could be performed on two cash crop pairings: beans/potatoes and brassica family/allia family.

Results Abstract

The results of this project may be divided into three portions:
1. The identification of tools to scale-up the operation and the corresponding spacings for cash crops that are intercropped in a diverse vegetable operation.
2. The development of a treatment/control study for two separate crop type pairings.
3. The implementation of the study for two separate crop type pairings.

This project implemented equipment using a smaller, category 1 tractor with standard Ford or Massey 8n tire spacing. Many operations looking to scale up may find it easiest to take the first steps with a tractor of this size, thus a 40 inch wide seed bed was identified with 60 inches from the outside of one wheel to the other. Companions typically were placed 8 inches from the edge of the 40 inch bed, providing a 24 inch gap between the companion plants within the seed bed. The distance between companions in different beds was approximately 28-30 inches.

The first year of the project was spent identifying new spacings and attempting to implement them on as many companion crop sets as was feasible. Each set was implemented in a field where the South half maintained the farms traditional spacing techniques. These served as a control for the project and have been developed and used by the farm for several years to take advantage of the smaller tools in its possession. New spacings were explored for vine crops and their companions, brassica and allia, potatoes and beans, tomatoes and basil. It was determined that the new spacings for the potatoes/beans and brassica/allia would be appropriate for a treatment/control study – with the treatment being the new spacings developed in year one versus the traditional spacings used by the farm in prior years. This study was intended to measure the companion benefits, the potential labor savings and the crop yield.

The second year of the project allowed us to test new spacing techniques with the equipment we acquired and learned to use in year one. Only minor modifications were needed from year one in order to respond to issues discovered in the process of working the fields. As a result, we were able to collect data between the control (our prior spacing methods) and the treatment (new spacing methods). As with most research projects, this one may have done a better job isolating more questions than it did answering them. However, we do feel we have made great strides in identifying some companion cash crop spacings that could be used by growers looking to scale up. We have adopted many of these spacings in our future plans with some modifications. Results were compelling enough for the farm to adopt the new spacing for potatoes and beans, but results for brassica/allia require more development.


Description of Project Purpose

Mechanization has been developed primarily in response to the labor intensive nature of farming. As a result, farming systems have become more reliant on monoculture systems in order to take full advantage of equipment that is often developed for specific crop requirements. Even equipment intended for smaller farms with diverse operations has a tendency to force isolation of one cash crop from another.

Companion planting techniques have been used by growers for generations. The potential for pest control and improved ecosystem health with a diverse planting fits organic principles well. Further, success with companion planting can significantly reduce reliance on outside inputs. But, the requirements for plant spacing make it difficult to scale up an operation for commercial implementation. This holds true even for small farms that focus on direct sales with a diverse product. The varying requirements of companions seem to place a ceiling on production amounts due to inordinate labor requirements.

The purpose of this research was to attempt to find a balance between labor and companion planting benefits by introducing mechanization with proper planning and implements.

Project Importance

Companion planting techniques are a large part of the legacy knowledge passed down through the generations. Recent research is beginning to show support for the empirical knowledge. Sunflowers have been shown to reduce thrips problems in peppers (SARE Project Number: FSOI-140). Companion crops have shown statistically significant control of cucumber beetles in cucurbits (SARE Project Number: LS01-127). We have our own (non-scientific) research and observation that tell us bean and potatoes, brassica and allium, tomato and basil, borage, zinnia and melons are all good companions for various reasons. Companion plants can be another cash crop, a trap crop, or a host crop. Benefits can take the form of pest control through masking, repellant or attractant properties. Other benefits may be through beneficial chemical sharing or the ability of one crop to be a nurse crop for another. Some benefits may be as simple as providing a natural wind block for a crop that is more susceptible to strong winds. Regardless of direct companion planting benefits, a diverse and complimentary system leads to healthier growing conditions that do not require additional inputs.

The Genuine Faux Farm is dedicated to maintaining companion planting practices but has found it difficult to continue with companion plants due to production challenges brought about by the scale of the operation. The root of the problem appears to be based on weed control issues. Companion crops often have different spacing and planting requirements. As a result, most cultivation is performed using hand tools, which can be effective if the available labor pool can complete the task within the window of opportunity for controlling weed establishment. However, weather conditions in recent years have provided limited windows for cultivation, mulch application and other weed control techniques. Once a canopy is developed by the companions, weed control is no longer a major issue. But, planting times may differ between companions, which add further complications to the cultivation plan. Failure to control weeds in companion planted fields reduces the effectiveness of the companion effect and decreases crop yields.

Rearranging already complex planting plans for new tools was difficult, but a worthwhile exercise. New plans considered companion plant benefits, rotation issues and production requirements. It was possible that any such plans would either negate benefits of companions or fail to result in any labor reduction or weed control benefits. It was important to integrate the tool(s) and the plan in stages to avoid possible crop failures due to failure to properly implement new systems. The farm did not wish to add reliance on a new tool that failed to provide improvement to the overall success of the operation.

Discussion with other growers of a similar size revealed that most have not considered companion planting. In most cases, this has more to do with a lack of information on successful companions. On the other hand, planning for and executing systems with companions is a difficult task. Growers of this size will not adopt a new practice if the perception is that it will introduce inefficiency to a system that is already difficult to maintain. It is our belief that we could convince others to include companion planting in their growing techniques if we are able to illustrate methods that can be adopted with acceptable changes in current systems. It is possible that successes in this area could reduce reliance on chemical applications for pest control.

Project Objectives:
2011 Objectives

1. Identify and Trial spacings that might work with new equipment
2. Identify crops to be tested with spacing differences
3. Identify equipment and source equipment.
4. Learn the use of the equipment and trial equipment with identified spacings.
5. Trial data collection techniques for intercropping effects.
6. Maintain qualitative records throughout 2011 season to allow for changes in 2012 season application of project.
7. Identify two sets of cash crops to study in the second year of the project. Confirm the study methods by piloting the structure in 2011.

2012 Objectives

1. Implement spacings (both treatment and control) for identified crop sets
2. Utilize equipment sourced for project
3. Collect data on intercropping effects.
4. Compare results between treatment and control sections of project
5. Collect qualitative records regarding the process and observed issues with the project.


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Materials and methods:
Research Plan

• Research Question: Can companion planting spacing and successions be modified in such a way as to add weed control mechanization without negatively impacting the benefits of the companions and reduce the labor resources required?
• Scope: In year one, this project was implemented on three planting plots in the farm’s seven year rotation and one of four plots in the four year rotation. Many of the annual vegetable crops produced by the farm and their companions were included.
• Control: Half of each plot will be planted using planting plans similar to prior year models.
• Treatment: Half of each plot had spacing changed to respond to the needs of the equipment used for cultivation and other weed control.
• Variables: The independent variable was the inclusion of mechanized cultivation by altering the planting spacing and succession plan to allow for its use. Dependent variables included labor costs, weed pressure and yield.
• Controlling External Variables: Treatments such as cultivation, mulch, irrigation, etc were undertaken on each half of a field in the same time frame. Cultivar choices were consistent in each field half A flower or other plant border provided a barrier between the halves of the field.
• Control for Learning Curve: It was expected that some of the initial spacing selections and cultivation choices would not be optimal. The first year’s results were evaluated and modified for year two in an effort to address observed problems with the new techniques.

Year 2 Study Method

Two fields were identified as being sufficient for study. Two others were identified as having potential for new spacing techniques but would require a more complex study to measure success. The bean/potato and the brassica/allia cash crop companion pairs were identified for research.

Two plots, measuring 60 feet x 200 feet, in an East/West orientation, were split in two lengthways. The North section was randomly determined to be the treatment section in each plot, leaving the South section in each to be the control. Seed beds ran the full length in each section. Crop ordering for the control section was planted in a mirror image of the treatment section. Rows in the center and outside edges were not included for data collection for yield and labor data. However, these rows were included for pest observation, though these observations were kept separate from the rest of the seed beds. Qualitative observations were maintained for all areas.

Control seed beds were the width of the walk-behind tiller. Our traditional spacing starts with potato rows approximately 65 inches apart, with double bean rows in between (the bean rows approximately 8 inches apart). The brassica (broccoli, cauliflower, etc) and allia (onion, leek) were similar, with rows of brassica approximately 65 inches apart with a double row of the allia crop in between.

Treatment seed beds were developed at 40 inches wide (the distance between the tractor’s wheels) with wheel tracks approximately 1 foot wide. A single row of each companion were planted 8 inches in from the bed edge, giving approximately 24 inches of space between the two companion rows.

All potatoes and beans were planted within a 48 hour period in both the control and treatment areas. Varietal differences within the field were placed in a mirror image of each other in the field. Green bean varieties used were Jade and Provider. Potato varieties were Purple Majesty and Rio Grande (a russet).

Brassica and Allia were more complex, with multiple successions in the field. Each succession was mirrored on each side of the field, with each being planted within the same 48 hour window. Measurements were taken for broccoli (Gypsy and Belstar) and onions (Redwing, Ailsa Craig Exhibition) for yield.

Weeding, irrigation, mulching and any other field treatment was undertaken equally between control and treatment sections of each field. In cases where it was impossible to perform a treatment within 48 hours on each half, it was noted that this was the case and comparisons for yield need to be adjusted in those cases.

Standard yield measurements for potatoes, beans and broccoli were in pounds. Yield measurements for onions were by bulb/fruit. Yield measurements were taken from the entire harvest of a given row. The rows were located in the center of each plot section to avoid edge bias. Culls were not included in weight or count measures. Yield quality was maintained only as observational data for beans and potatoes. Main head counts for broccoli give some data for size comparisons.

Labor data focused on the efforts of controlling weeds in the fields. Data was kept regarding worker hours spent for each section of the project. In particular, work was measured for the rows that were also used for yield measurements. Qualitative observations by all workers involved in the process round out the data.

Pest control attributed to the intercropped companions were measured twice during the season. In each case, the measurement was prompted by the observation of the pest in the crop. Once observed, a measurement was taken of the prevalence of the pest. A second measurement was taken two weeks later. Measurements were made by manual observation of random sections in each row.

Research results and discussion:

We first determined that a single implement would not likely leave us in a position to fully implement the project. However, we were also able to locate sources for used equipment that could be rehabilitated for use with our Ford 8n/9n tractor (category 1, 22 hp). As a result, we were able to acquire equipment within our budget.

Equipment –
• S tine cultivator (14 foot cut down to 7 foot) with row covers
o 1/2 is now an all purpose ‘plow’ for field preparation
o 1/2 is now a row cultivator to handle wheel track weeding cost = $400
• 6-foot Disk harrow (some repair needed); cost = $400
• 2-bottom plow; cost = $250
• Underminer/potato digger; cost – $50
• Chisel – single point; cost = $75
• hiller = $175
. flat bed mulch layer (with repairs) = $500
– tractor repairs/modification = $900

All costs include repairs, etc.

Budget was $1500 with $750 requested as part of the grant. Actual cost is currently $2750.

Of these tools, the S-tine in row cultivator was used exclusively in the treatment area. The flat bed mulch layer was used experimentally in the vine crops for treatment areas only (it would not work in the control areas). Once some rows were planted in the control, the disk harrow could not be used there, but it could be used in the treatment area once a bed was harvested without destroying crops in neighboring rows. The potato digger was used in both the control and treatment, but provided us with the opportunity to harvest both control and treatment within the same 48 hour window.

Intercropping – Crop Identification

The following crops were amenable to a control/treatment set up with two different spacings.

Plot 1: Brassica/Allium
Plot 2: Winter Squash/Companion Flowers AND/OR melon/companion flowers
Plot 3: Beans/Potatoes

It was determined that these plots would be sufficient to prove the concept without making the project management so unwieldy as to prevent implementation. For the second year, data was collected for the treatment/control for only two of them (plot 1 and 3).

Plot 1:
Brassica include: broccoli, kohlrabi, cauliflower, cabbage, kale, chinese cabbage, brussels sprouts
Allia include: onions, green onions, cipollini onions, leeks
Purpose of interplanting:
– reduce damage by cabbage worm and cabbage looper in brassica crops.
– reduce potential spread of onion diseases by splitting the crop.

Plot 2:
Winter squash: butternut, buttercup, acorn and specialty or Melon (open pollinated heirloom)
Companion flowers: nasturtium, marigold, borage, zinnia, bee’s friend
Purpose of interplanting:
– reduce loss to vine borers
– reduce squash bug population
– increase predator and pollinator habitat near squash plants

Plot 3:
Beans: green beans and bush dry beans
Potatoes: 5 types including a russet, 2 yellow, 1 red and 1 purple variety.
Purpose of interplanting:
– reduce loss to Colorado potato beetle (beans mask presence of potatoes)

For the purposes of data collection, we focused on broccoli (Gypsy and Belstar) and onions (Ailsa Craig and Redwing) for the brassica/allia field. We selected Jade and Provider green beans and Rio Grande and Purple Majesty potatoes for data collection in the bean/potato plot.

Our winter squash spacing was most amenable to modification since rows are 5 foot on center, with companions placed in a 5 foot row. We adjusted to this by placing companions nearer to the squash plants themselves, potentially improving companion effects in nearby rows, but perhaps reducing them elsewhere. We maintained the same 40 foot bed with similar wheel spacings. We determined that it would be more beneficial to study companion and paper mulch impacts with these crops and chose not to include them in the data collection for the 2012 study parameters.

Bean/Potato Intercropping

The treatment spacing was deemed a success by virtue of similar yields, similar pest control and increased work efficiency. In particular, work savings were identified in the weed control efforts. We anticipate that this will be extended with the inclusion of a flex tine weeder in future years.

1. Time savings in treatment section for weed control.
Primary time savings were observed in the treatment section as anticipated simply by reducing the time required to control weeds in the wheel tracks between rows. Weed control time in row was also reduced slightly as workers found it easier to weed between a bean/potato row in the treatment as opposed to the double bean rows in the control.

2. Time savings in treatment section for bean harvest.
Secondary time savings were identified with respect to harvest labor. Picking time per pound was greater in the double rows implemented in the old spacing techniques. Harvesters reported difficulty making sure they harvested all beans in the areas between the two bean rows. They reported no difficulty with beans on the side of the plants next to the potatoes in the treatment beds.

3. Slight time loss in treatment section for planting.
At this time, all planting was done manually. It is likely this time loss will decrease as familiarity with the new system increases.

4. Potato harvest equivalent between treatment and control.
Potato harvest time was similar since potatoes were harvested after all beans completed their seasons. Thus, the potato digger could be used in all rows.

5. Crop limitation – planting and harvest times less flexible due to the presence of companions.
A limitation for growers with intercropping beans and potatoes with either spacing is the need to restrict planting and harvest times. It is unreasonable to expect to plant potatoes in April and beans in the same bed four weeks later. On the other hand, we experience no problems with a later planting date for our potatoes in Iowa. And, our market for the potatoes works well with a later planting. Short of undermining all potatoes by hand with a broadfork, any mechanical approach to digging potatoes will most certainly destroy the adjacent beans. Therefore, potato harvest must wait until beans have completed their harvest cycle or beans must be terminated prior to completion of the harvest cycle. This may not be an issue for growers who do not extend the harvest of a green bean planting as long as we tend to do. However, we experience no problems with completing the bean crop in time to harvest the potatoes. If this is a problem, we find dry bush beans are a reasonable alternative.

6. Potato beetle control similar in control and treatment.
The potato beetle control afforded by bush beans in potatoes showed no difference between the treatment and the control during both seasons of the project. The only potato beetles observed were on the edges of the field or in the middle rows of the field where two potato rows were adjacent to each other. The presence of Colorado potato beetle in these areas indicates that pest pressure was possible during each season. Absence in areas with adjacent beans indicates sufficient control. Future study could identify minimum required distances for beneficial effect.

7. Statistically similar yield numbers per seed foot.
Both bean and potato yields were statistically similar, with no issues with proximity of beans and potatoes to each other in the treatment spacings. An observed difference in one of the potato varieties reflects a germination issue in the row with a lower yield. Once factored in, the data remained statistically similar. On the other hand, one of our bean varieties exhibited a positive difference per seed foot in the treatment spacing versus the traditional spacing. Since the second variety does not show a similar difference, we cannot claim a yield benefit with the treatment spacing.

8. Conclusion – we will adopt the treatment spacing for future growing years.

The reduction in labor is sufficient to recommend this approach for use on our farm. Other variables, such as yield and pest control remained the same. As a result, we feel we can maintain this intercropping technique with increased production levels. The addition of a flex tine weeder is now possible for our farm, which should increase the efficiency of weed control significantly for the in row weeds.

9. Further research recommended.

a. Determine maximum distance possible for these companion crops to effectively control Colorado Potato Beetle in the potato crops.
If crops could be separated into their own 40 inch bed and still maintain control of the pest, some of the planting and harvest limitations would be removed.

b. Identify a technique that would allow planting of one companion in a row 2-3 weeks before the other. This may increase flexibility in beneficial companions that may be selected.

c. A randomized, replicated study showing control of Colorado Potato Beetle populations in potato crops adjacent to green bean crops does not appear to exist at this time. We are convinced that this companion planting works to control this pest. However, use of this technique is not likely to be adopted without scientific study.

Yield Data Beans

Pounds Pounds/ Seed Foot Pounds/ Row Foot
Provider Treatment 193 0.97 0.97
Provider Control 235.65 0.59 1.18
Jade Treatment 169.85 0.85 0.85
Jade Control 353.5 0.88 1.77

Observation 1: Germination rates equivalent for all rows.

Observation 2: Jade produced consistently for a longer period of time. Provider gave reasonable harvests of good quality for 6 (six) weeks. Jade extended the pick period to 10 (ten) weeks.

Observation 3: One of the Jade treatment rows lost plants during a mechanical cultivation. This cultivation occurred after some harvesting had been done, so the number of row feet were not adjusted. The resulting pounds per seed foot and row foot are still considered to be reasonably representative for the purposes of this project.

Observation 4: Control spacing in our traditional 60 foot x 200 foot fields would include 11 rows of potatoes and 10 double rows of beans. If a treatment spacing were adopted for each of these fields, 14 rows of potatoes and 14 rows of beans could be placed in the field.

Results 1: Results are dependent on variety
Clearly, Provider does not appreciate having competition with itself. The double rows in the control have a statistically significant decline in production per seed foot (p<=.005). In order to be certain of this, a study of single row Provider versus double row Provider (and not potato variable) would be needed to confirm. On the other hand, Jade shows the same production per seed foot, resulting in double the production per row foot in the control.

Results 2: No specific bean yield advantage determined.
The data recorded does not indicate a specific advantage for one spacing versus another. If the control spacing were used with single row Provider, it could be inferred that the production per seed foot would likely be equivalent. The data shows production per seed foot for Jade is equivalent. The only argument against the treatment spacing for bean yield is the possibility that double row spacing will produce more pounds per row foot with Jade. However, the treatment spacing does not preclude dedicating a bed in the field to this double row spacing. And, more importantly, it still shows similar per seed foot numbers. Simply put, there is no adverse advantage to the production of the bean plants with this approach.

Yield Data Potatoes

Rio Grande Control 213.4
Rio Grande Treatment 151.2
Purple Majesty Control 173.0
Purple Majesty Treatment 182.6

Observation 1: 200 foot rows, single row planted at 12 inch spacing.

Observation 2: Issues for Rio Grande in Treatment row
A shortage of seed resulted in a short row for the treatment row of Rio Grande. It is likely potatoes were cut a bit small without sufficient eyes to guarantee germination. To adjust, the measured yield was in a 170 foot area. Also, it is possible that a crimped drip line may have reduced the delivery rate of water to the area where production dropped dramatically. This could be dramatic given the extremely dry year.

Results 1: Tuber sizes equivalent between treatment and control.
Two samples were taken randomly from each of the above. A weight was taken and a count of potatoes in that tray was made. Sizes were a bit smaller than many years due to a very dry year for our area. We are not accustomed to irrigating potatoes since too much water is usually a problem for them on our farm rather than not enough.

Results 2: Results could be different depending on varieties.
Rio Grande could not be shown to have a statistically different yield due to external variables. However, there was an observable difference in yield that may be held up with future study.

Results 3: Yield appears to hold up sufficiently well between treatment and control.
Yields appear to be similar regardless of the spacing type for potatoes. In other words, proximity to a bean row in a 40 inch bed does not appear to adversely affect production. We suspect planting in a bed any closer than 2 feet may cause difficulties.

Brassica/Allia Intercropping

The attempted intercrop spacing technique was not successful for brassica and allia. A windstorm rolled most of the larger brassica over onto the the allia, which resulted in stunted plants.

Weeding efforts were not successfully reduced with the treatment spacing. As a result, most allia were undersized at this point and unable to provide a decent crop.

Brassica in both the control and treatment did equally well. Observations seem to indicate that they may have benefitted from the interplanting. But, we are prepared to make no claims as there was minimal pressure on our farm from cabbage loopers and cabbage worms in 2012. There was significant pressure in 2011. Proximity in both spacings to living allia plants appeared to reduce the pressure. However, our data collection techniques were still under development in 2011, so data is not sufficient to draw conclusions.

Future Research:
1. Allia clearly are not a good companion with larger brassica in a 40 inch bed with a similar planting period. It is possible this spacing would work if the allia were planted 2-4 prior to the brassica.
2. Other companions, such as sage and other aromatics may work better in the bed with brassica.
3. Allia may be able to provide sufficient benefit if each bed is dedicated to one of the crops (broccoli in one bed and onion in another).
4. We suspect an even better intercropping approach would be to include an aromatic in the bed with the brassica and alternate beds with allia and brassica.
5. The addition of a flex tine cultivator may encourage us to dedicate a 40 inch bed to onions in order to manage in row weeds, since this is where the labor issue resides with these crops.

Impact of Results/Outcomes

Presentation at the Small Farms Conference 2012

Powerpoint is attached below. A video of the presentation is located on the NCR-SARE YouTube channel. It can be found by using the following link:

Practical Farmers of Iowa Conference – Poster

Attached is poster presented at 2013 Practical Farmers of Iowa Conference.

Participation Summary

Educational & Outreach Activities

Participation Summary

Education/outreach description:

See Accomplishments section.

Project Outcomes


Future Recommendations

See recommendations for future research in various sections.

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.