Advancing living mulch in plasticulture vegetables

Final Report for ONE14-221

Project Type: Partnership
Funds awarded in 2014: $15,000.00
Projected End Date: 12/31/2015
Region: Northeast
State: New York
Project Leader:
Judson Reid
Cornell Vegetable Program
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Project Information


This project continued previous efforts to examine cover crops or ‘living mulch’ between rows of plasticulture vegetables and educate farmers on the potential benefits.  In 2014 we established 4 living mulch treatments between rows of peppers on a cooperating farm in Yates County, NY and between onions on another cooperating farm in Seneca County, NY. The living mulches were rye, barley, rye+clover and clover+barley.  To measure the effect of the living mulch we collected data on yield, weed growth and crop nutrient levels.  There were significant differences in the different mulch treatments in weed suppression. Adding clover to the grasses vastly improved ground cover late in the season.  Barley+clover was not as effective at controlling weeds as rye+clover.  The vigor and persistence of the rye allowed for complete ground cover until the clover was established mid-to-late season.  In our pepper trial, clover improved gross economic return by $574.99/A for rye by providing greater groundcover after mid-season.  Neither grain in the absence of clover provided adequate weed control.  Adoption associated inputs included cover crop seed and repeat mowings (labor).  Results were shared via on-farm meetins, newsletters and winter educational events.  This approach is still considered experimental, but for growers with a strong interest we have greater confidence in our recommendation of rye+clover as an effective living mulch in plasticulture vegetables.


Replacing bare row middles with living mulch will reduce herbicides and labor while improving harvest conditions on Northeast vegetable farms. This project will evaluate and demonstrate cover crops (living mulch) between rows of plastic mulched vegetables. The project team has conducted several years of related research and seeks funding to advance the knowledge base of the promising technique involving winter grains and clover sown in spring.

Farmers need this information as herbicides and cultivation challenge sustainability. Herbicides represent an exposure hazard to farmers, consumers and the environment; particularly aquatic wildlife. As most Northeast vegetable farms are diversified, herbicides also represent a management challenge- no single herbicide solution exists across the wide range of crops. Cultivation represents additional labor and decreases organic matter.

Hosting trials on two commercial farms, we’ll evaluate living mulch in a ‘real-world’ setting and generate scientific data. One of farm will host a demonstration meeting to be attended by 50 farmers for peer-to-peer learning. Data to be collected includes weed biomass, percent living mulch ground cover, yield and nutrient levels. Farmers will provide qualitative data on management aspects of the system. Both streams of information will be synthesized into formal presentations to be shared with 300 farmers at events such as the Empire State Producers Expo and similar winter meetings. Results will also be shared via the Cornell Vegetable Program website, YouTube Channel and Twitter accounts. Two articles will be developed for the VegEdge newsletter, reaching over 850 people in 28 NY counties and 4 states.

This projected would not have been possible without the collaboration of our two host farms; Maple Lane Produce and Sunshine Acres.

Nelson Hoover is a commercial vegetable and transplant greenhouse grower at Maple Lane Produce. He and his wife Ruth farm on 4 acres in the town of Milo on fertile Lima Silt Loam. They have operated Maple Lane Produce since 2011. Ruth and Nelson market their products wholesale to other commercial farmers (vegetable transplants), the Finger Lakes Produce Auction and smaller accounts such as restaurants. 

Eli and Lina Stotlzfus operate Sunshine Acres; a 20 acre diversified produce farm on a Honeyoe Silt Loam in southern Seneca County, NY. They have been farming there for the past 7 years.  Their produce is sold through a family owned natural food store.  They provided on-farm management of the onion portion of trial including field work, plastic laying, transplanting, irrigation and plot maintenance.

Project Objectives:

To demonstrate and refine this alternative management strategy, we proposed to conduct 2 on-farm demonstration trials with cooperating farmers. The trials included replicated plots of peppers and onions grown with uniform treatment applications at each trial location.

Treatments included rye, barley; combinations these winter grains with Dutch white clover, cultivation (on an non-herbicide farm) and herbicides (only on the cooperating conventional farm). Treatment response variables measured included marketable yield as measured by fruit number and weight, fresh weight of weeds, crop disease severity, plant height (onions only), vegetable crop petiole nutrient levels, insect damage incidence, percent soil cover, and crop management information (relayed from cooperating farmers).

The cooperating farms will fit soil and lay plastic per existing farm practice. Within the field four 100 linear-foot sections of plastic-mulched row will be measured and flagged. Prior to transplanting, living mulch treatments will be hand-sown in rows perpendicular to vegetable rows at recommended rates for cover crop production, except for rows to receive herbicide or cultivation treatment. Farmers will record application date, rate and apply any chemical treatment in compliance with all applicable Worker Protection Standards and label requirements. Onions were transplanted (plugs or bare-root) in mid-April and peppers in late-May to early June. Trellis, drip irrigation and fertilization was carried-out to grower standards by cooperating farmers. Within each of the treatment areas (mulches, cultivation and herbicide) a minimum of four 10 plant blocks of peppers, or 4 ten linear-foot blocks for onions were flagged for data collection, with onion subsamples of 10 random plants. From onion block plant height in cm were be collected a minimum of 4 times per season; 10 plants per block.

Disease severity ratings for peppers were calculated using a visual ordinal scale of 0-9 for each block, a minimum of 4 times over the course of the growing season, beginning in late June. Diseases could include Bacterial Leaf Spot or Phytothphora. Weed biomass (measured by fresh weight) from 4 randomly selected 1 sq ft sections of row middle will be measured 4 times per growing season.  Yield per 10 plant block of peppers was calculated as number and total weight of marketable fruit per block at each harvest for the length of the growing season. For onions yield data will be collected as weight and grade per 10’ block. Total labor required for the cultivation treatment was tracked by farmers and team technicians. Three tissue analyses of foliage from each treatment will be performed to measure nutrient competition from the row-middles. Percent ground cover by living mulch was calculated in each treatment block at two different timings throughout the growing season.


At the conclusion of harvest, all treatment response data were tabulated, and data analysis was conducted by an analysis of variance (ANOVA) and treatment means were separated using an LSD test with a p-value Non-quantitative management data was solicited by team technicians from cooperating farmers. This input includes impacts such as mowing, improved harvest conditions, changes in tillage requirements or other field-level management data.


Time frame

Responsible parties


Contact cooperating farmers to discuss field plans for Spring of 2014

September-October 2013



Field prep: tillage, bed formation, drip tape

April-May 2014

Hoover in Yates and Stoltzfus in Seneca Counties (NY)

Reid and Hill will be in regular contact with farmers to be sure progress in on schedule.


April-May 2014

Hoover and Stoltzfus

Reid and Hill will make themselves available to assist if the farmers desire help.

Seed living mulch treatments

April-May 2014

Reid and Buck in collaboration with farmers

These dates will be dependent on field and farm conditions

Establishment of 4 blocks per treatment within 100 linear feet

May 2014

Tech TBD (onions)

N. Hoover (peppers)


Data collection: crop height, disease incidence, insect incidence, crop yield, labor input, foliar samples

June-October 2014

Tech-onion height and yield; disease and insect incidence on onion, foliar samples of both pepper and onions.


Reid- labor input, tomato disease and insect incidence.



On-farm demonstration meeting

Late July to Mid-August

Technician and cooperating farmer will present, Parr will publicize

Location will depend on which of the two sites offers the best demonstration, as well as dates that work for the farm

Updates posted to CVP Webpage, Social Media and printed in VegEdge


Reid and Parr


Data entry and statistical analysis


Reid and Tech

Depends on final harvest date.

Winter presentations

November 2014-March 2015


Empire State Fruit and Veg Expo, Finger Lakes Produce Auction and other meetings as needed

Complete final reporting requirements

Spring 2015



  • Farmer trials/demonstration sites: Two farms will host participatory on-farm trials demonstrating living mulches. These farmers will participate and observe the impact of our treatments on their cropping systems. This will be a powerful strategy for adoption diffusion. Additionally they will receive written documentation of results specific to their farm to validate their involvement in the project.
  • On-site grower field day: A minimum of 50 farmers will be targeted for engagement in peer-based learning by attending a field meeting. Data will be shared, but just as importantly; farmer experience will be highlighted. Meeting notices will be made in newsletter, in addition to direct mailings from CVP database.
  • Conference and grower meeting presentations: Quantitative and qualitative data from the two farms farms will be synthesized in presentation given at winter events such as statewide grower Expos, produce auction meetings and others. This allows the project team to interact with a large group of people and present a synthesis of findings from multiple farms. The project team is active in organizing several of these meetings including the Empire Producer’s Expo, which draws over 1000 attendees annually.
  • Extension newsletter articles: Project findings will be printed twice within the project duration in Veg Edge, a newsletter of the Cornell Vegetable Program that reaches over 850 people in 28 NY counties and 4 states. This outreach venue will be important to reaching other educators and researchers in the region.
  • Online resources: Updates of the project’s progress will be posted to the Cornell Vegetable Program’s webpage as an on demand resource, along with the team’s YouTube Channel and Twitter feed.


Click linked name(s) to expand/collapse or show everyone's info
  • Elizabeth Buck
  • Nelson Hoover
  • Eli Stoltzfus


Materials and methods:

Two on-farm demonstration trials were established with cooperating farms in Yates and Seneca Counties (NY). Replicated plots of peppers and onions were established in the Spring of 2014 with living mulch treatments of rye, barley; combinations these winter grains with Dutch white clover, cultivation (Seneca) and composted mulch (Yates). Our seeding rates were 150 lbs/ac for grains and 20 lbs/ac for the Dutch White clover. Seeding occurred immediately after plastic was laid, prior to transplant. Fertility and pest management per grower standards.

Both trials were laid out in a three replicate randomized complete block design over Lima silt loams. Onions were transplanted into four rows (6 inch square spacing) on slightly raised beds covered with matte silver mulch. Plots were 12 feet long. Peppers were transplanted into raised, black plastic mulch beds in a staggered double row with 12" in-row spacing. Plots contained twenty plants.

Marketable yield as measured by fruit number and weight, weed fresh weight, crop disease severity, plant height (onions only), vegetable crop petiole nutrient levels, insect damage incidence, and percent soil cover data were recorded throughout the season. Treatment response data was tabulated, and processed through an analysis of variance (ANOVA). Treatment means were separated using Fisher's Protected LSD at the .05 significance level. Economic data was calculated using grower-provided prices.

Research results and discussion:
Trial Data Analysis

Pepper Weed control: 

In the pepper trial rye+clover had the lowest fresh weight of weeds, and the highest percentage of ground cover; approaching 100% at July 15 (Figure 1 Results and Economics-All tables and charts are contained there). Our observations are that barley dies out too early (often from a Rust caused by the fungus Puccinnia graminis) and provides very little coverage allowing weeds to germinate in mid-summer.  Rye outlasts barley but also dies too early to compete with mid-late season weed pressure.  Barley+clover provides fair weed control, but the barley may die back too early for complete clover establishment.  To date in our trials rye+clover provided the best weed control as the rye lasts long enough for the clover to establish.

Pepper Yield:
There were no significant differences in pepper yield between any of the living mulch treatments (Table 1).  The composted mulch treatment yielded significantly more peppers without significantly increasing the total pounds of fruit produced.

Pepper Nutrient Levels:
To better determine the extent to which the composted mulch added fertility and more accurately gain an understanding of the relative performance of the living mulch treatments, two foliar nutrient data analyses occurred.  The first included the mulch treatment, which differed statistically from all living mulch treatments only on August 13 with greater foliar N levels.  Examined alone, the living mulch treatments only differed from one another on June 12, when there was significantly less N available in the barley-clover treatment.  There were no differences in foliar N in July or August.

Onions: General
Rye failed to emerge in one plot of the rye clover treatment. Therefore, the rye clover data presented throughout this report is an average of the two sound plots and was not included in any statistical analysis. The numerical, two plot average indicates that rye clover has potential to perform well in a fully replicated trial with regard to weed control, desirable ground cover, and yield. Data presented for onion rye clover is an average of two plots only.

Onions: Weed Control

Cultivated plots were hand hoed once on June 23. All plots were managed with a string trimmer for the remainder of the season. Therefore, weed fresh weight and cultivation plot percent ground cover on June 12 should be evaluated in a pre-control context. Above ground biomass weed fresh weights did not differ among treatments in July, August, or September (Tables 2 and 3).  

Weed control significantly differed among treatments. The barley died out early and allowed weeds to become the dominant ground cover by August. At the end of the season barley clover and rye were better than barley alone, while cultivation overlapped all three. While there were fewer weeds in the plots with good living mulch canopies, the escapes were large and rebounded more quickly after trimming. Conversely, the plots with poor living mulch canopies often had a flush of weeds that were younger and less established before trimming. Fresh weights and ground cover by weeds should be considered together to gain the most complete understanding of weed competition.

Winter barley and cereal rye are not well adapted to summer conditions in the vegetative state. Barley began to die back in June, and was essentially gone by mid-August. The rye decline started in late June and was less severe. Rye alone still provided 22% ground cover in early September. Adding clover to the grasses vastly improved ground cover by cover crop late in the season.

Weeds alone contributed to the total ground cover in the cultivation treatment. In an ideal system, excellent weed control in those plots would be associated with very low (5% or less) ground cover. Total ground cover varied between treatments after June. However, control varied within living mulch treatments in August and September only, when barley/clover had significantly more ground cover than rye. Barley+clover was the only treatment included in the analysis where more of that total cover was in living mulch than weeds. Though not included in the analysis, rye+clover’s two plot average indicates that it controls weeds at least as well as barley+clover.

Onions: Yield

The average weight/bulb in the cultivation treatment was statistically greater than the rye, barley and barley+clover treatments. There were no significant differences in grade distribution (boiler, small, medium, jumbo, colossal) or weight (Tables 4 and 5). Onions were classified into three market groups: “Big” (medium and up), “Tiny” (small and boilers), and “Unmarketable/Bad” (rot and general cull). There was no difference in market category and economic value ($0.50/big onion). Small onions have very little wholesale value and thus were not included in economic calculations.

Onions: Vigor and Plant Health
Wet weather and adverse growing conditions thinned the stand and slowed crop growth. The crop was small on June 12, with no differences between treatments in stand, plant height, or leaf number. The cultivated treatment was taller than the barley, rye, and barley clover treatments on August 12. Natural lodging was more advanced in cultivated and barley clover than the barley and rye plots on Sept. 4 (Table 6).

Onions: Foliar Nutrient Levels

There were no significant differences in foliar nutrient levels of N, P, K, S, Ca, or Mg in mid-July.  B, Zn, Fe, Mn levels were all similar.  Cu was significantly higher in the mown treatment.  N, P, K, Mn, and Fe all differed by August 13 (Tables 7 & 8).  Any given treatment did not consitently contain greater or fewer nutrients than another.  For example, the mown plot had greater N than the barley clover plot, but similar levels of P and K.

Research conclusions:

Stand establishment and management continue to be a challenge for the sucess of living mulch.  Inadequate moisture or poor weed control prior to seeding can reduce weed control.  Both cooperating growers express concerns with the management (mowing) of a living mulch in-season, although this labor appears to be similar or less than cultivation. 

In this project there were no signifigant differences among the yield between living mulch treatments at either site.  Thus, in choosing a living mulch, weed control becomes the deciding factor, which at this point seems to indicate rye+dutch white clover.  However, at both sites yield was greater in control plots (cultivation and compost).

Despite the issue of yield loss, grower interest in living mulch as an alternative continues.    Through this project our team has gained confidence in recommending the addition of Dutch White Clover to a winter grain for those growers interested in the benefits offered by this system: weed control without herbicides, improved harvest conditions, reduced erosion potential and increased organic matter.

Participation Summary

Education & Outreach Activities and Participation Summary

Participation Summary:

Education/outreach description:

Demonstration/Field Meetings

  • Yates County cooperating farm on August 29th
  • Seneca County on July 23
  • Cattaraugus County on August 8th

Two articles were published in the newsletter 'VegEdge' in August and October 2014.  Social media feeds on Twitter and LinkedIn promoted the project with photo updates.

A presentation to 65 farmers and service providers was made at the 2015 Mid-Atlantic Fruit and Vegetable Convention in Hershey, PA, 110 farmers at the Finger Lakes Produce Auction (Penn Yan, NY) in January 2015 and 25 farmers at the Seneca County Auction growers update (Romulus, NY).

Project Outcomes

Project outcomes:

The composted dairy digester mulch treatment yielded significantly more peppers than any of the living mulch treatements without statistically increasing the total weight of the peppers. Assigning a retail value of 33 cents each, the composted dairy mulch peppers grossed $8,673.75 more an acre than rye-clover, the highest yielding living mulch treatment.  The dairy mulch benefited the crop in ways that confounded this study by providing extra late season N and retaining moisture.  For that reason, it is a fairer assessment of the living mulch potential to evaluate economic performance amongst the four cover crop treatments.    Rye alone grossed $622.43/A better than barley and rye-clover brought in $382.37/A more than barley-clover, attributed to rye's higher tolerance of summer conditions in the vegetative state.  Clover improved the gross by $815.05/A for barley and $574.99/A for rye by providing greater groundcover after mid-season (Figure 2 in Results section).

Trial peppers were marketed through a produce auction.  A 1/2 bushel box weighs about 11 pounds and is worth $7-10/box at a typical auction.  There was no statistical difference in weight among any of the cover crop treatments.  Gross income ranged from $16,897.28 (barley, $7/box) to $26,705.05 (rye-clover, $10/box).  Adoption of the living mulches cost between $68.44 (barley) to $92.46/A for cover crop seed and labor (Figure 4 in Results section).

Any onion over 2" in diameter was worth 50 cents a bulb.  Smaller bulbs were not marketed. There were no statistical differences in number of bulbs between any of the treatments.*  Economically, the gross income ranged from $6,824.55 (barley) to 10018.80 (rye-clover). The net value was between $6,718.92 and $9,909.02/A (Figure 3 in Results section).  Input costs associated with adoption of these practices ranged from $105.63 (barley) to 140/A (cultivation. Adoption associated inputs included cover crop seed, 5 mowings, with 1 cultivation in the appropriate plots. 

*Onion rye-clover was excluded from statistical analysis because there were too few sound plots to analyze.  Data presented for onion rye clover should be treated with some skepticism, as it is an average of two plots only.

Farmer Adoption

Farmer adoption was not measured as part of this 1-year Partnership Project.

Assessment of Project Approach and Areas of Further Study:

Areas needing additional study

There are many more cover crops (living mulch) that could be researched in plasticulture settings.  However, with the yield drag we continue to experience, research that focusses on the mechanism of this yield loss could narrow the number of living much candidates.  Appropriate seeding rates are also not completely understood.

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.