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									No-Till Vegetable Production: Non-Chemical Methods of Cover Crop Suppression
                               and Weed Control
                                  by Steve Diver
            Appropriate Technology Transfer for Rural Areas — ATTRA
                              Fayetteville, Arkansas
                            Last Updated April, 2002

No-till systems are gaining increased attention as a practical way to raise vegetables and
improve soil quality at the same time. Growing and managing cover crops to provide
killed mulches and living mulches is an important component of these production
systems. The combination of organic mulches on the soil surface and reduction of tillage
have numerous benefits to soil biology, soil structure, and soil health.

In conventional no-till vegetable production, herbicides are commonly used to kill cover
crops and create a no-till mulch, and for follow-up post-emergent weed control.
Herbicides do a good job of controlling vegetation and they are a major reason no-till
agriculture has been so successful.

However, sustainable agriculture has a goal of reducing chemical inputs, instead relying
on cultural practices, biological processes, and naturally-derived products. Secondly,
herbicides are simply not allowed in certified organic vegetable production. So the
question arises, how can farmers get into no-till production without herbicides?

The purpose of this document is to provide resources on no-till vegetable production in
general, and secondly, to address non-chemical options for cover crop suppression and
weed control. A companion ATTRA publication, Pursuing Conservation Tillage Systems
for Organic Crop Production, may be referred to for a more detailed review of the cover
crop and tillage techniques described in this publication. It also features a selection of
research abstracts that summarize efforts underway in different regions of the United

                                 Conservation Tillage

No-till vegetable production is a form of conservation tillage. Conservation tillage is the
generic term that describes reduced-tillage cropping systems like no-till, strip-till, mulch-
till and ridge-till. In agronomic crop production, for example corn, soybeans, cotton, and
peanuts, crop residue management to control soil erosion is the primary goal of
conservation tillage. For example, technical specifications for conservation tillage state
that crop residues should remain on 30% of the soil surface. These residues protect the
soil from erosion and by wind and water.

Conservation tillage also reduces the number of equipment passes (e.g., plow, disc,
harrow) required to prepare a seedbed and thus saves fuel and reduces soil disturbance
and compaction. The operating principle of conservation tillage is simply to minimize
disturbance of the soil.
Maintenance of crop residues, especially killed mulches from cover crops, is key to
proper management of these systems. Some benefits of a no-till organic mulch include
moisture conservation, weed suppression, erosion control, increased soil organic matter,
food and habitat for soil organisms, and, in the case of a legume, biologically fixed

Conservation agriculture is another term used to describe a systems approach to
agriculture that focuses on minimal soil disturbance, cover crops, and crop residues.

 Conservation agriculture refers to several practices which permit the management of
 the soil for agrarian uses, altering its composition, structure and natural biodiversity
 as little as possible and defending it from degradation processes (e.g. soil erosion and
 compaction). Direct sowing (non-tillage), reduced tillage (minimum tillage), non- or
 surface-incorporation of crop residues and establishment of cover crops in perennial
 woody crops (of spontaneous vegetation or by sowing appropriate species) or in
 between successive annual crops, are some of the techniques which constitute
 conservation agriculture. Generally, conservation agriculture includes any practice
 which reduces, changes or eliminates soil tillage and avoids residue burning to
 maintain enough surface residue throughout the year.

 Conservation Agriculture: For a Better Environment
 European Conservation Agriculture Federation

For background information on the value and importance of conservation tillage on soil
health, one book in particular may be viewed as essential reading, Stubble Over the Soil
by Carlos Crovetto Lamarca (1). Focusing on the vital role of reduced tillage and plant
residues to improve soil quality, Lamarca provides an interesting and practical review of
this revolutionary shift in agriculture. His 245-page book is filled with color photos and
educational illustrations of no-till agriculture, agricultural implements, cover crops,
mulches, crop residues, and soil quality improvements. Larmarca is an agronomist with
Chequen farm in Chile, a famous site of no-till agriculture in South America. He has
played an instrumental role in no-till agriculture in Venezuela, Columbia, Argentina,
Brazil, Uruguay, Bolivia, Mexico, the United Kingdom, and the U.S.

                  Managing Cover Crops and Weeds Through
                          Mechanical Suppression

Cover crops are an integral component of conservation tillage cropping systems. A
typical system is fall establishment of a winter cover crop, followed by herbicide kill
prior to spring planting. The killed residue that results is essentially an organic mulch
grown in place.
While herbicides are commonly used to manage cover crops, non-chemical alternatives
do exist, though they are less widely known. In keeping with ATTRA‟s mandate to
transfer technology on low-chemical-input farming methods, and to support the
information needs of farmers who want to reduce their use of herbicides or raise certified
organic crops, emphasis is placed on non-chemical options to suppress cover crops.

In addition, while the organic mulch that results from cover crops—whether killed by
chemical or mechanical means—can provide fairly good weed suppression for the first
30-45 days after kill-down, there will always be additional weeds that sprout through the
mulch; therefore, follow-up weed control methods are important.

Non-chemical methods of cover crop suppression that can be integrated with no-till
vegetable production include: strip tillage, mowing, rolling and crimping (also known as
roll chopping), undercutting, and thermal weed control (flame, steam, infra-red). Based
on extensive research and field experience, growers looking into no-till vegetable
production can proceed with a high degree of confidence that strip tillage, mowing, roll
chopping, and undercutting are solid performers. However, further work is needed to
define the commercial viability and affordability of the thermal control techniques in
terms of knock-down cover crop suppression.

To handle follow-up weed control for weeds emerging through the killed mulch,
supplemental weed control options include: high-residue cultivators, weeder geese,
chicken tractors, hand hoeing, and spot-spray steam weed control.

High-residue cultivators are widely used in agronomic no-till crop production, and would
be an affordable option on larger-scale no-till vegetable farms raising sweet corn, green
beans, and related row crops. Weeder geese, chicken tractors, and hand hoeing also have
a proven track record, but are geared to smaller-scale market farming. [See Farmer
Profiles] Spot-spray steam weed control is a technique the author feels has good
potential as an appropriate technology in association with organic no-till mulch. While
commercial steam equipment is available to control vegetation it is extremely expensive
and targeted to other market segments (e.g., Aqua Heat for large-scale orchards, Waipuna
for municipal parks and non-croplands). Thus, steam needs an infusion of on-farm
technology development. Infra-red thermal weeding equipment, on the other hand, looks
affordable and practical. Trials in association with organic no-till mulches are needed to
ascertain how well it actually works. A companion ATTRA publication, Flame Weeding
for Vegetables, provides essential details and equipment suppliers for flame and infra-red
weeding systems.

Where is no-till vegetable production taking place, and who are some of the innovative
farmers and researchers implementing this technology? What are some examples of non-
chemical cover crop suppression? These are the focus of the remaining sections.
                                Focus on Cover Crops

      A cover crop is any crop grown to provide soil cover, regardless of whether
      it is later incorporated. In no-till farming, cover crops need to match the
      growing cycle of the cash crop, be susceptible to chemical or mechanical
      killing techniques, and provide a reasonably thick mulch.

      Common plants raised as cover crops:

      Cereal grains: rye, wheat, barley, oats
      Grasses: sorghum sudan, millet, annual ryegrass
      Forage legumes: clover, vetch, medics
      Grain legumes: cow pea, soybean, field peas
      Broadleaves: buckwheat, rapeseed, mustard

      Resources on Cover Crops:

      Managing Cover Crops Profitably, 2nd Edition.
      SAN Handbook No. 3

      Overview of Cover Crops and Green Manures

             Converting the Cover Crop Into an Organic Mulch

Three methods have emerged as non-chemical approaches to knocking down and killing
cover crops to create a no-till mulch: mowing, rolling , and undercutting.

Flail mowers are viewed as ideal mow-down equipment, but small-scale farmers are
known to employ rotary mowers (commonly known as a "brush hog") and even string
weeders (commonly known as a "weed eater") to chop down cover crops. Obviously, the
number of acres in production makes a big difference in terms of which piece of
equipment is most affordable. For example, the cost of a 4-6 foot wide rotary mower
starts at $400-600 while a flail mower starts at about $2,000.

The primary advantage of a high-speeed flail mower is that it can chop cover crops down
to about an inch above the ground, shredding the material and leaving the mulch in
place. Rotary mowers clip higher and tend to throw the vegetative residue over a wider
area. However, a market gardener in Georgia had a local machine shop weld metal strips
onto the back end of his rotary mower so that it catches and distributes the cover crop
mulch on top of his production beds. Thus, growers are known to make do with what
they have and adapt.
Timing is important; hairy vetch should be mowed when it has already begun flowering;
mowing of rye should also be delayed until flowering (when the anthers are shedding
pollen). When annual cover crops are mowed at the optimum time, the root system
senesces and dies. Emphasis is placed on optimum timing because cover crops mowed
too early will re-sprout and start to compete with the vegetable crop like a weed. Vetch,
for example, is notorious for re-sprouting when it is mowed too early.

Mechanical roller-crimpers and rolling stalk-choppers have evolved as a means to roll
down and crimp cover crops -- a technique known as rolling or roll chopping. These are
heavy-duty drum rollers with horizontal-welded blunt-steel strips. When they are pulled
through the field they crush and crimp the cover crop, which leaves residue lying flat on
the soil surface and discourages regrowth.

The rolling stalk chopper is an implement used in field corn production, modified and
adapted to no-till vegetable production. Steve Groff, a no-till vegetable farmer in
Lancaster County, Pennsylvania, is probably the best known example of a no-till
vegetable farmer using a rolling stalk chopper to manage cover crops like rye-vetch.

Mechanical roller crimpers, on the other hand, were specially developed for cover crop
management in no-till production. Millions of acres of conservation agriculture in Brazil
and Paraguay are managed with these mechanical roller crimpers. Researchers in
Alabama showed that rolling down cereal grains like winter rye, wheat, and black oats
was most effective during the early milk stage, which occurs after flowering (anthesis)
and prior to the soft dough stage (grain formation) (2). Mowing at this stage killed cover
crops just as well as herbicides.

The undercutter-roller is a specialized implement developed at Ohio State University,
designed to slice through the soil and sever cover crop roots underground. It consists of a
V-plow sweep blade mounted on a toolbar, followed by a rolling harrow to crimp and roll
the cover crop residue at it falls on the ground.

Undercutting suppressed weeds in trials better than either a flail mower or sicklebar
mower (3-4). Whereas mowing cuts the cover crop residue into little pieces and
promotes faster breakdown, the undercut mulch is thicker and better able to prevent light
penetration to the soil surface, which results in fewer weeds. The residue also remains on
the soil surface longer. Materials to build one of these units costs around $800. An
schematic diagram of the undercutter toolbar was published in American Journal of
Alternative Agriculture (4), and it provides sufficient details to reproduce one of these
setups in a local machine shop.

Dr. Nancy Creamer, who led team that developed the undercutter system at Ohio State, is
now located at North Carolina State University. Dr. Creamer continues to work on tillage
systems integrated with cover crops in association with vegetable production, and can
provide details on modifications since made to the undercutter implement.
Contact: Dr. Nancy Creamer
Organic Farming Systems
Campus Box 7609
North Carolina State University
Raleigh, NC 27695-7609
919-515-2505 Fax

The USDA Mow-Kill System of No-Till Vegetable Production

USDA researchers in Beltsville, MD demonstrated that no-till tomatoes transplanted into
a hairy vetch mulch produce excellent yields (5-6). Since hairy vetch is a winter annual
legume, it was planted in the fall on pre-formed beds. A Brillion™ seeder was used to
establish the cover crop, ensuring good seed-to-soil contact, germination, and
establishment. In the spring the vetch was flail-mowed to about an inch high. Tomatoes
were transplanted into the mow-killed mulch immediately following the mowing
operation. Transplanting was done with minimal disturbance to the soil.

The researchers compared vetch mulch plots with plastic mulch, paper mulch, and bare
ground. Yields from plants grown under the vetch mulch averaged more than 45 tons per
acre, trailed by 35 tons for plastic mulch and 34 tons for paper mulch. Control plots
managed as bare ground averaged 19 tons per acre.

An important benefit of the vetch mulch was weed control achieved early in the growing
season. No pre-plant herbicides were necessary. Weeds emerging later in the growing
season were controlled by application of a contact herbicide.

The results of this USDA research are summarized in the USDA Farmers' Bulletin
Sustainable Production of Fresh-Market Tomatoes with Organic Mulches. For further
information or technical assistance, contact:

Dr. Aref A. Abdul-Baki
USDA-ARS Sustainable Agricultural Systems Laboratory
BLDG 010A, Room 213, BARC-West
Beltsville, MD 20705
FAX: 301-504-6491
E-mail: abdul-ba@ba.ars.usda.gov

Sustainable Production of Fresh-Market Tomatoes with Organic Mulches. 1997.
By Aref Abdul-Baki and John R. Teasdale. USDA Farmers' Bulletin No. 2279. 23 p.

Farmer Profiles: Doug Walton and Alex Hitt

In Oklahoma, Doug Walton manages a 1-acre organic market garden and sells fresh
produce at the Muskogee Farmers' Market. Walton plants cover crops on top of raised
production beds, and uses a string weeder with a plastic head attachment to cut down the
cover crops and create a no-till mulch. Hand raking and speading of mulches after weed
eating is a necessary chore, but this type of intensive hand labor is a common feature of
biointensive market farming and it fits his scale of production. In conjunction with
USDA-ARS and Oklahoma State University, Walton is also conducting research on
summer cover crops and biculture cover crop mixes, funded through the SARE farmer
research grant program.

In North Carolina, Alex Hitt is a well-known organic market gardener who sells fresh
produce at the Raleigh Farmers' Market. Following the mow-kill guidelines established
by USDA, Hitt uses a flail mower to mechanically kill a rye-vetch cover crop mix and
create a no-till mulch for tomatoes. Weeds that emerge through the mulch are simply
hand weeded. The mulch does a good job of weed suppression, and the tomatoes grow a
thick canopy of leaves that helps shade out weeds, so hand weeding is not too

            More on the Rolling Technique: Mechanical Kill of Cover Crop

Prior to the advent of the mechanical roller crimper, USDA researchers in Mississippi set
disc coulters at an angle to mechanically kill hairy vetch, referring to this technique as
rolling. They learned that the most effective time to do this was in the seed formation
growth phase for the legume (mid- to late-April in Mississippi), or when stem lengths
along the ground exceeded 15 inches (7). More recently, they have also modified an
implement used in Mississippi Delta cotton production known as a "do all." To obtain
articles and updates, contact:

Dr. Seth Dabney
USDA-ARS National Sedimentation Laboratory
P.O. Box 1157
Oxford, MS 38655
Fax: 662-232-2915
E-mail: sdabney@ars.usda.gov

Managing Cover Crops and Green Manures
Seth Dabney, USDA-ARS National Sedimentation Laboratory

Researchers with USDA and Virginia Polytechnic Institute demonstrated the feasibility
of planting vegetables (broccoli and cabbage) into a soybean cover crop that is cut or
“rolled” down to provide a no-till mulch. „Devine‟, a forage soybean variety, was bred as
a hay crop and therefore produces lush growth. More biomass is desirable because it
translates to higher nitrogen fixation and a thicker mulch. The thick thatch that results
helps keep down weeds, holds moisture, protects the soil from fall rains, and enriches the
soil with organic matter. In addition, as the soybean mulch decays, it releases nitrogen
which feeds the vegetable crop.

In research trials, yields from no-till plots were comparable to those from conventional
plots where vegetables were planted into bare soil. To ensure uniform plant stand
establishment, the researchers started with vegetable transplants and set them out with a
multi-row no-till transplanter.

Soybeans take about 60 days to grow and start flowering, a period which coincides with
optimum plowdown as a cover crop. Thus, spring-planted (April 15-May 15) “hay
beans” would be available as a summer mulch (June 15-July 15). Summer-planted (July
1-August 1) “hay beans” would be available as a fall mulch (September 1-October 1).

More recently, Dr. Aref A. Abdul-Baki has grown fond of “Iron and Clay” cowpeas as a
summer cover crop. In the 1997 growing season, which featured one of the worst
droughts Maryland experienced in years, „Iron and Clay‟ cowpeas withstood drouthy
conditions better than „Devine‟ soybeans.

For further information and details, contact:

Dr. Aref A. Abdul-Baki
USDA-ARS Sustainable Agricultural Systems Laboratory
BLDG 010A, Room 213, BARC-West
Beltsville, MD 20705
FAX: 301-504-6491
E-mail: abdul-ba@ba.ars.usda.gov

Dr. Ron Morse
Department of Horticulture
Virginia Polytechnic Institute and State University
Blacksburg, VA 24061
Fax: 540-231-3083
E-mail: morser@vt.edu

                                        Strip Tillage

Strip tillage is a specialized form of conservation tillage that is particularly well suited to
vegetable crops. A common method is to establish a winter cover crop in the fall; in the
following spring these cover crops are “strip tilled” with a multi-row tillage implement
such as a multi-vator or a multiple-head roto-tiller.

The result is a field with narrow strips of exposed soil that vegetables are planted into,
and broader strips of cover crop vegetation that remain as a living mulch between the
rows. Depending on the specific cropping system, the cover crops in the alleyway are
eventually killed (usually with herbicides) to avoid competition, or left undisturbed as a
living mulch. However, living mulch left in the field may require additional vegetative
suppression to avoid competition with the main vegetable crop. For example, partial
tillage has been shown to work well with white clover.

Dr. Sharad Phatak, a researcher at the University of Georgia, has pioneered innovative
methods of strip-tillage vegetable production in association with cover crops in the
southeastern United States. To obtain articles and updates, contact:

Dr. Sharad Phatak
University of Georgia, Coastal Plain Experiment Station
100 Horticulture Building
Tifton, Georgia 31793-0748
Fax: 912-386-3356
E-mail: phatak@tifton.cpes.peachnet.edu
Dr. Greg Hoyt, a researcher at North Carolina State University, has worked with cover
crops and strip tillage systems appropriate for vegetables and tobacco in the Appalachian
mountain region. To obtain articles and updates, contact:
Dr. Greg Hoyt
North Carolina State University
Mountain Horticultural Crops Research & Extension Center
2016 Fanning Bridge Rd.
Fletcher, NC 28732
Dr. John Luna, project leader of the Integrated Farming Systems group at Oregon State
University, has helped develop strip tillage systems appropriate for the Pacific
Northwest. The strip tillage reports on their web page at Oregon State provides details on
cover cropping systems, equipment, and related cultural practices. This is an excellent
website on strip-tillage vegetable production, including field trials with cover crops. See:
Strip Tillage Vegetable Production Systems

                              High Residue Cultivators

The aim of conservation tillage is to maintain sufficient crop residues to cover at least
30% of the soil surface after planting. Since the action of post-plant cultivation
incorporates crop residues and reduces surface protection, herbicides are preferred over
mechanical cultivation to obtain adequate weed control. In the instance where
mechanical cultivation is still desirable as a form of weed control—such as in reduced or
zero-use herbicide cropping systems, or under dry conditions when herbicides are not
effective—high-residue cultivators are an option.

Conservation tillage cultivators look much like conventional cultivators. However,
instead of three to five shovels per row, high-residue cultivators usually bear a single
shank that supports a wide sweep or horizontal disk. A coulter is mounted in front of the
shank to cut through residue. Whereas regular cultivators cut weeds and “throw” soil and
crop residues, a conservation tillage sweep is designed to cut weeds and allow soil and
residues to “float” over the sweep as it passes through the soil.

In vegetable production, high-residue cultivation may be appropriate for direct-seeded
row crops like sweet corn, green beans, and potatoes.


Cultivators for No-till and Ridge-till
Iowa State University

            Thermal Vegetation Control: Flame, Steam, Infra-Red

Several sources have reported that flamers—especially hooded flamers— are used in
Europe as a method to kill and suppress cover crops prior to planting.

Since there is little experience with flamers in the U.S. as a means of cover crop
suppression, it should be viewed as a potentially useful but experimental method. Ron
Jones of Thermal Weed Control Systems, Inc. in Neillsville, WI, a manufacturer of
hooded flamers, reports they are being used by vegetable growers in the U.S. to fry
lettuce residues between sequential crops, thereby reducing incidence of disease.

Flamers are a common non-chemical weed control technique in organic vegetable
production, mainly as a stale seedbed technique to control the first flush of weeds in the
spring (i.e., beds are flamed prior to planting the vegetables). Flaming can also be used
as a post-emergence treatment in certain vegetable crops like sweet corn, potatoes, and

Thus, while flaming equipment is available and experience supports its use to control pre-
and post-emerge weeds, trials are necessary to determine how well a flaming treatment
will, for example, suppress cover crops in a vegetative stage of growth. It is quite
possible that flaming will suppress certain cover crops and not others.

Flaming the dried residues of a killed winter cover crop mulch may result in a fire
hazard. Thus, flaming is suggested as a means to kill cover crops, but not as a method for
post-emergent weed control in association with no-till organic mulches.

Steam is an old form of thermal weed control that is regaining popularity after several
decades of little use. Steam is very effective as a non-chemical means of vegetation
control, and can be used to kill live stands of cover crops and turfgrass sod. Aqua Heat
and Waipuna are the two main companies supplying steam weeding equipment, and both
offer patented technology that improves steam's performance.

However, steam equipment is expensive and bulky and has not been developed with row
crop farming mind. The Aqua Heat equipment is geared to large-scale orchards and
vineyards, and the Waipuna equipment is geared to municipal and institutional use in
non-cropland areas such as pavements and fence rows. Innovative farmers may find a
way to devise a portable steamer. Such a device seems an ideal match to no-till organic
vegetable production, and could be used as a knock-down treatment to create a no-till
mulch or as a spot-spray treatment for post-emergent weeds.

Infra-red weeders have been used in Europe for several years, and in 2001 a North
American distributor started carrying this equipment. An infra-red weeder consists of a
propane flamer that heats a ceramic tile; these are mounted on a frame with wheels,
similar to a wheel hoe; radiant heat from the ceramic tile, rather than flame itself, sears
the weeds. Thus, an infra-red weeder could be an ideal tool to enable post-emergent
weed control in organic no-till. Field trials are needed. Two resources on thermal weed
control are provided below.

Flame Weeding Resource List: Literature, Web Links, Videos, Equipment and

FOREVERGREEN™ Chemical Free Weed Control
            Matching Cover Crops to No-Till Vegetable Production

Timing is a critical factor in vegetable production. Vegetable farmers like to plant as
soon as possible in the Spring with an aim to harvest early and sell into market windows
that yield a premium price. In addition, farmers that live in hot, dry regions plant early to
take advantage of spring rains and cooler temperatures.

On the other hand, no-till production relies on cover crop maturation to occur prior to
mechanical disturbance by mowing or roll chopping. Therefore, matching a cover crop
to the growing cycle of the vegetable crop is very important. For example, in the Mid-
South (Arkansas-Oklahoma region where the author lives) the flowering cycle of crimson
clover corresponds fairly reliably to the average frost-free date, which is April 15th.
Thus, crimson clover would be a good selection for warm-season transplant crops like
tomatoes, peppers, and summer squash, or it could be direct-seeded to sweet corn, green
beans, or watermelon. On the other hand, hairy vetch blooms 30 days later than crimson
clover. Thus, vetch is better suited to hot-loving crops like eggplant and okra, as well as
second-round plantings of tomatoes and peppers. Bigflower vetch is a desirable species
because it flowers about two weeks earlier than hairy vetch.

       Winter Annual Cover Crops + Warm-Season Vegetables:
       *Crimson clover, Hairy vetch, Winter wheat, Rye
       *Establish cover crops in September-October
       *Rapid cover crop growth in April-May, flowering begins
       *Mow or crimp cover crops in April-May
       *Plant tomatoes, peppers, summer squash, green beans into no-till mulch in

       Summer Annual Cover Crops + Cool-Season Vegetables:
       *Forage soybeans, Forage cowpeas, millet, buckwheat
       *Establish cover crops in June-July
       *Rapid cover crop growth in August-September, flowering begins
       *Mow or crimp cover crops in August-September
       *Plant broccoli, cauliflower, cabbage into no-till mulch in August,

             General Observations about Vetch as a No-Till Mulch

The United States is a large country with lots of different growing climates and soil
types. These differences in climatic growing conditions affect the way cover crops
perform in different regions. In light of these differences, it may be helpful to mention a
few universal points about hairy vetch as a no-till mulch.

First, to obtain a no-till legume mulch for spring-planted vegetables, vetch is treated as a
winter annual legume, meaning it is planted in the fall and matures in the following
spring. Thus, successful stand establishment—seeding method, legume inoculation, and
sufficient soil moisture—in the preceding autumn is rather important.

Secondly, viable options for killing the vetch, whether chemical or non-chemical, need to
be identified and implemented.

Factors to consider when planting warm-season vegetables (tomatoes, cucurbits,
eggplant, peppers) into a no-till hairy vetch mulch:

      Good stand establishment of the cover crop is critical.
           o Plant vetch seed early in the fall for optimum growth
                    Universal Rule: Legumes, forages, and cover crops that are
                      planted early in the fall produce more spring growth (biomass)
                      than those planted late in the fall
           o Good seed-soil contact is very important
                    Drilling produces a superior stand in comparison to broadcasting
                    Broadcasting seed (ideally followed by harrowing or cultivating) is
                      a common way to “overseed” a legume into a standing crop
           o Plant seed when soil moisture is optimum, or irrigate
           o Inoculate legume seed to increase nitrogen fixation
      In the Mid-South (Arkansas, Oklahoma, Texas, Louisiana, Mississippi, Tennesse)
       vetch flowers about 30 to 45 days after the last frost-free date in the spring
           o Early-market tomatoes are usually planted on the last frost-free date
           o Hairy vetch matures in late spring
                    As vetch grows longer, it produces more nitrogen
                    As vetch grows longer, it produces more biomass
                    As vetch grows longer, the resulting mulch will be denser
                    As vetch grows longer, it is easier to kill by mowing
           o Thus, no-till vetch is better suited to late-planted warm-season vegetable
           o Early-market vegetables are better adapted to plastic mulch
           o One way to bring these two events—vetch flowering and optimum tomato
               planting dates—in closer proximity to one another is the use of an early
               maturing type of vetch
                    As an example, bigflower vetch is known to flower 1 to 2 weeks
                      earlier than hairy vetch. However, the seed of bigflower vetch is
                      more expensive and less commonly available

To assist growers with background information on "when" plants bloom, sequence of
bloom, and related ecological features of phenology, ATTRA compiled a resource list at
the following website. It would be nice to have a guide that shows blooming periods for
different cover crops in each region of the country, but nothing like this has yet been
developed. See:
Phenology Web Links: Sequence of Bloom, Floral Calendars, What's in Bloom
                                No-Till Transplanters

Dr. Ron Morse, a horticulture specialist at Virginia Polytechnic Institute, developed a no-
till transplanter for cabbage production in the mountains of southwest Virginia. For
information and plans, contact:

Dr. Ron Morse
Department of Horticulture
306-C Saunders Hall
Virginia Polytechnic Institute & State University
Blacksburg, VA 24061-0327
Several transplanters used in commercial vegetable production can also be adapted to no-
till transplantation. The following dealers can provide assistance. Contact:
Mechanical Transplanters Co.
1150 S. Central Ave.
Holland, MI 49422-1708
616-396-3619 Fax

Market Farm Implements
[Ralph Moore]
257 Fawn Hollow Road
Friedans, PA 15541

Holland Transplanter Co.
510 E. 16th, P.O. Box 1527
Holland, MI 49423-1527
616-392-7996 Fax

           Farmer Profile: Steve Groff, No-Till Vegetable Farmer

Steve Groff is a no-till vegetable farmer from Pennsylvania who raises about 175 acres of
mixed vegetables (tomatoes, pumpkins, & others) and field crops (corn, soybeans, small
grains, alfalfa) on hilly land in Lancaster County. Groff says that no-till farming, cover
crops, effective crop rotations, and reduced herbicides and pesticides are the foundation
of what he calls “new generation cropping systems.”

In the early 1980s Groff brought no-till vegetable production to his farm, drawing on the
technical expertise of people like Dr. Ron Morse at VPI and Dr. Aref Abdul-Baki at
USDA. Groff uses specialized equipment, including a rolling stalk chopper to knock
down and crimp the cover crops, thus allowing him to plant vegetables into a killed cover
crop mulch. This cropping system requires post-emergent herbicides, but at greatly
reduced rates over conventional production systems. After many years of no-till
production the soils are very mellow and easy to plant into.

The following notes from seminars and conversations with Groff provide a brief
introduction to his no-till vegetable farming practices:

      Winter cover crops: rye, hairy vetch, and clover
           o Spring crops planted into no-till mulch include: vegetables, corn,
      Groff initially tried mowing rye, but found out that timing is critical:
           o When rye is mowed at heading, it will naturally die out
           o When rye is mowed prior to heading, it will re-sprout and compete like a
           o In addition, mowing chews up the cover crop residue which promotes
               faster breakdown of the mulch thatch
      Rolling is an alternative to mowing
      Groff uses a Buffalo stalk chopper to roll down and crimp the rye-vetch mix
      The no-till mulch controls weeds fairly well, but herbicides are still needed as an
       adjunct to mulch-based weed control
      Summer cover crops: German millet and forage soybeans
           o Fall crops planted into no-till mulch include: broccoli
      In addition to soil improvement and weed suppression, the mulch enhances insect
       and disease control
           o Colorado potato beetles are less severe in mulched fields, the result of
               natural biological control by beneficial insects who inhabit the mulch
           o Onset of early blight on tomatoes was delayed on no-till ground
           o The mulch prevents soil splashing and subsequent spread of disease
           o The savings in fungicide sprays can be significant. When Groff made his
               first application, Penn State had already forecasted seven fungicide sprays
               for prevention of early blight on tomatoes

"No-Till Vegetables" is a 30-minute video explaining Groff‟s new-generation cropping
system. The price is $21.95 + $3.00 shipping. Made by a professional production
company in association with Mr. Goff and university consultants, the video provides an
excellent introduction to no-till vegetable production, and like the book Stubble Over the
Soil, I highly recommend Groff's video. Contact:
Cedar Meadow Farm
679 Hilldale Road
Holtwood, PA 17532

                  Permanent Mulching Systems: The Other No-Till

Organic mulches — for example straw, hay, and leaves — have a long history of use in
organic vegetable production. A common method is to till and prepare the soil as usual,
followed by direct seeding and transplanting to establish vegetables, with post-plant top-
dressing of organic mulches to control weeds and conserve moisture.

A different approach to mulching, however, is the use of permanent, deep mulches in
association with no-till. Ruth Stout, who wrote articles for Organic Gardening magazine
from 1953 to 1971, and published the classic book, The Ruth Stout No-Work Garden
Book, is perhaps the best known advocate of permanent mulching systems for home

In the 1990s, permanent mulches as a no-till approach to commercial-scale vegetable
production received increased attention through the work of Emilia Hazelip, a
permaculture teacher and market farmer in southern France. Inspired by the work of
Masanobu Fukuoka, the Japanese farmer who advocated a natural system of no-till
production using undersown clovers and straw, Ms. Hazelip's "synergistic gardening"
method features the use of raised beds, plant residues, and companion planting (8).

Mark Cain, a market gardener in Arkansas who attended a workshop by Hazelip in 1995,
organized his farm around the synergistic gardening concept and manages about 3 acres
of production beds with permanent deep mulches using mostly local hay bales obtained at
low cost. After trying the no-till, deep mulch system for about 6 years, Cain noted that
weed populations tend to increase in the mulch after several growing seasons and
consequently labor becomes prohibitive; thus, his current strategy is to completely
renovate the beds through tillage every 3-5 years, then start over with a permanent mulch
scheme. He also came to the conclusion that wheat straw, though more expensive
because it has to be shipped in from some distance, is far superior to local hay bales
because hay mulch is loaded with weed seeds. Cain said it takes about 150 square bales
of wheat straw mulch to cover one acre of raised beds. A web article, below, provides a
description of his production system.

Synthetic weed barriers, also known as geotextile mulches, are fairly new to no-till
vegetable production. Unlike plastic mulches, which breakdown in sunlight and require
disposal after one or two growing seasons, weed barriers are very durable and may last 10
years or longer exposed to full sun conditions. A prominent example is the Sunbelt-
HydroSource Dryland Production Bed advocated by the late Dan Wofford of Western
Polyacrylamide, Inc. (9). The DeWitt Sunbelt Weed Barrier was designed for use as a
weed control ground cloth in container nurseries, greenhouses, and retail garden centers.
However, Wofford advocated the use of large sections of the Sunbelt Weed Barrier in
small-scale vegetable production as a no-till production method. Wofford's invention
was an innovate adaptation of an existing technology, and for small-scale producers, it
provides a super low-maintenance approach to long term weed control. Wofford helped
over 130 market farmers in the Missouri - Kansas - Oklahoma region set up 4,500 square-
foot no-till production beds using rolls of weed barrier that come in 15 x 300 ft. lengths.
Several web resources on this method are provided below.


In summary, no-till and reduced-tillage vegetable production has potential for wider
adaptation by commercial growers. As cover crops are an important link in no-till
production, a first step is selection of cover crops adapted to the specific region and to the
specific cropping system. For example, the use of hairy vetch as a no-till mulch for
tomatoes has performed very nicely in Beltsville, Maryland. Adapting the USDA Mow-
Kill+Vetch System to other climatic regions of the country will require some trial and

Non-chemical weed control options do exist to manage cover crops, but success is often
dependent on specialized equipment, cultural practices, good timing , and also some
tinkering on the part of the farmer. In addition, the biological growing conditions that
effect cover crop establishment, biomass production, nitrogen fixation, and mechanical
kill varies from place to place and season to season. A common experience among early
adopters of no-till is the development of partnerships with the Extension Service to obtain
technical assistance, especially with specialized equipment.

Organic mulches and synthetic weed barriers are available to implement no-till at the
market garden scale, and experience demonstrates they are an effective form of weed
control that do not rely on cover crop establishment and vegetation management.

The ability to implement a conservation tillage vegetable production system is highly
dependent on factors that impact the individual farmer: cost of equipment, technical
assistance, time, labor, crop rotation, soil type, slope, weed populations, and weather.


1) Lamarca, Carlos Crovetto. 1996. Stubble Over the Soil: The Vital Role of Plant
Residue in Soil Management to Improve Soil Quality. American Society of Agronomy,
Madison, WI. 245 p.

2) Ashford, D.L., D.W. Reaves, M.G. Patterson, G.R. Wehtje, and M.S. Miller-
Goodman. 2000. Roller vs. herbicides: An alternative kill method for cover crops. p.
64-69. Proceedings: 23rd Annual Southern Conservation Tillage Conference for
Sustainable Agriculture. June 19-21, Monroe, Louisiana.

3) Regnier, Emilie. 1990. Controlling weeds with winter cover crops. Sustainable
Agriculture News. The Ohio State University. Winter-Spring. p. 4-5.

4) Creamer,N.G., B. Plassman, M.A. Bennett, R.K. Wood, B.R. Stinner, and J.
Cardina. 1995. A method for mechanically killing cover crops to optimize weed
suppression. American Journal of Alternative Agriculture. Volume 10 Number 4.

5) Stanley, Doris. 1991. More for less: A new way to grow tomatoes. Agricultural
Research. October. p. 14.

6) Abdul-Baki, Aref A., J.R. Teasdale, R. Korcak, D. Chitwood, and R. Huettle.
1995. Yield, earliness, and fruit weight of fresh-market tomatoes grown in synthetic and
organic mulches. HortScience. Vol. 30, No. 4. p. 806.

7) Dabney, S., N. W. Buehring, and D. B. Reginelli. 1991. Mechanical control of
legume cover crops. p. 146-147. In: Hargrove, W. L. (ed.) Cover Crops for Clean
Water. Soil and Water Conservation Society, Ankeny, IA.

8) Emilia Hazelip video

9) AVG article

Web Resources:

Smart Cover Cropping
Steve Groff feature, Sustainable Farming Connection website
Accessed at:

Transplanter and Stalk-Chopper Modifications
Steve Groff feature, Sustainable Farming Connection website
Accessed at:

Rolf Derpsch - GTZ

No-Tillage, Sustainable Agriculture in the New Millenium
Rolf Derpsch - GTZ

A no-tillage agriculture website by the famous no-till agronomist, Rolf Derpsch. It reviews the
benefits of no-till, including a paradigm comparison between tillage and no-tillage agriculture, as
well as topics relating to sustainability; organic matter; soil quality; etc.

Affordable Small-Scale Equipment for Production of Transplanted Vegetables in
High-Residue, No-Till Farming Systems
Ronald Morse, Department of Horticulture, Virginia Tech
The classic paper by Ron Morse on the use of tranplant equipment in association high-residue,
no-till vegetable production.

Managing Cover Crops and Green Manures
Seth Dabney, USDA-ARS National Sedimentation Laboratory
The classic on-line slide show by Seth Dabney, USDA agronomist, on cover crops in no-till
vegetable production. It combines text and photos to provide a quick educational summary of
cover crops and green manures in association with conservation tillage. An excellent introduction
to this topic!

Cultural Weed Management Methods for High-Residue/No-Till
Production of Transplanted Broccoli (Brassica oleracea L. GP. Italica)
R. Morse
ISHS Acta Horticulturae 504
These data illustrate that no-till broccoli can be successfully produced without using herbicides,
when appropriate high-residue cover crops are effectively killed by flail mowing or rolling and
broccoli transplants are properly established and maintained in these evenly distributed in situ
cover crop mulches.

Effects of Different Fertilizers and Continuous No-Till Production on Diseases,
Growth, and Yield of Staked Tomato
UT Vegetable Initiative Progress Report
The University of Tennessee
Marketable yields were significantly higher with no-till than with conventional tillage and also with
sulfate of potash instead of muriate of potash (Table 3).

Reasons for the improved yields with no-till are uncertain but may be due to improved soil
drainage, earlier nitrogen application, or improved weed control - all of which were different in
1999 than in the first two years of the study.

No-Till Production of Irish Potato on Raised Beds
Ronald Morse, Virginia Cooperative Extension
Commercial Horticulture Newsletter, November-December 1998
No-Till Broccoli Production without Herbicides
Ronald Morse, Virginia Cooperative Extension
Commercial Horticulture Newsletter, March - April 1997

Vegetable Growers, Try No-Till Transplanting
Pocono Northeast Resource Conservation & Development

Features the Subsurface Tiller Transplanter (SST-T) developed at Virginia Tech.
Cover Crop Use in Crop Production Systems

        Cover Crops Seeded Late Season in Soybeans
        Cover Crops Seeded Early Season in Soybeans
        Winter Rye Seeded Late Season for Continuous Corn
        Winter Rye - Hairy Vetch Planted for Seed Production in Irrigation Corn
        Cover Crops Seeded Late Season after Dry Edible Bean Harvest
        Cover Crops Spring Seeded to Provide Protection for Sugarbeets and Selected
         Vegetable Crops

No Till / Zone Till of Pumpkins into Cover Crops
Ohio State University Extension

A No-Tillage Tomato Production System Using Hairy Vetch and Subterranean
Clover Mulches
Aref A. Abdul-Baki and John R. Teasdale. HortScience 28(2):106-108. 1993.
Reviewed in: Sustainable Agriculture newletter, UC-SAREP, Winter 1995 (v7n1)

Nutrient Quantity or Nutrient Access?: A New Understanding of How to Maintain
Soil Fertility in the Tropics
Roland Bunch paper

A paper by Roland Bunch, author of "Two Ears of Corn: A Guide to
People-Centered Agricultural Development," featuring the Five Principles of Agriculture for the
Humid Tropics:

1.   Maximize Organic Matter Production
2.   Keep the Soil Covered
3.   Use Zero Tillage
4.   Maximize Biodiversity
5.   Feed the Crops Largely Through the Mulch
Just Say No to Till: No-Till Improves Profits, Soil Quality, and
Feature article on Steve Groff, Cedar Meadow Farm
The Vegetable Grower News

Invest in Sustainability with Cover Crop Systems: Old-Fashioned Practice has
Modern-Day Benefits
Colleen Scherer, The Grower magazine online

Cover Crops for No-Till Systems
Ontario Ministry of Agriculture, Food, and Rural Affairs

Cover Crop Types
Ontario Ministry of Agriculture, Food, and Rural Affairs

Adaptation and Use of Cover Crops
Ontario Ministry of Agriculture, Food, and Rural Affairs

Choosing a Cover Crop
Ontario Ministry of Agriculture, Food, and Rural Affairs

Managing Weeds in Conservation Tillage
Ontario Ministry of Agriculture, Food, and Rural Affairs

Soil Management: The Key to Sustainability
Aref Abdul-Baki, USDA-ARS Vegetable Laboratory

Alternative Tillage Methods for Cucurbit Crops
Michelle Infante, Rutgers Cooperative Extentsion

Conservation Tillage Methods
Dr. Mary Peet, North Carolina State University
Sustainable Practices for Vegetable Production in the South

No-Till Vegetable Production for the Sands Hill Region of North Carolina
Greg D. Hoyt
Veg-I-New, January 1999

Comparing Weed Suppression in No-Till and Conventionally Tilled Pumpkin
Systems that Utilize Stale Seedbed Techniques and Transplants
2000 New York Vegetable and Cultural Practices Results
Cornell University Commercial Vegetable Production

Permanent Mulching, Organic Mulches, Synergistic Gardening
No-Till, Mulch-Based Market Gardening
Mark Cain, Huntsville, AR

Ruth Stout and Permanent Hay Mulch
Mother Earth News, February 1999

The Synergistic Garden
Emilia Hazelip
Reproduced from Prodder, translated from French by Linda Hull

Fabric Weed Barriers in Field Production of Vegetables, Herbs, & Flowers
HydroSource Polymer & Research Library

A collection of articles by Dan Wofford on the DeWitt Sunbelt Weed Barrier to create a low-
maintenance production bed for market garden-scale vegetable production.

IPM-Based Landscape Design: Landscape Fabric and Mulch
IPM Access, IPM Practitioners Association

This website is geared to woody landscape plantings, but the background information on
geotextile mulches and how they function as a weed barrier is relevant and useful. Note: In
vegetable production the weed barrier is left *uncovered*; bark mulches are used in landscape
plantings for an aesthetic effect only, they do not increase weed control.

Growing Broccoli the Eco-Friendly Way
Agricultural Research, March 1997
Evaluation of Cover Crop Mulches in No-Till Processing Tomato Production
Final Report - January 1999, UC-SAREP

Cover Crops and Conservation Tillage for Soil Erosion Control on Cropland
Section 9: The Agronomy Guide, Pennsylvania State University

Conservation Technology Information Center

Southern Conservation Tillage Conferences for Sustainable Agriculture

Annual Conferences on conservation tillage and sustainable agriculture for the Southeastern U.S.
cropping systems have been held each year since 1978. On-line conference programs and
proceedings are available for 1998-2001. A few papers deal specifically with no-till vegetable
production. In addition, some of the agronomic papers contain helpful data on cover crop
phenology and biomass production.

24rd Annual Conservation Tillage Conference for Sustainable Agriculture
July 9-11, 2001, Oklahoma City, Oklahoma
HTML Source:

Notable Paper:

       No-Herbicide, No-Till Summer Broccoli — Quantity of Rye and Hairy Vetch on Weed
        Suppression and Crop Yield
        Ron Morse. pages: 83-92. Request reprint from the author: morser@vt.edu

23rd Annual Conservation Tillage Conference for Sustainable Agriculture
June 19-21, 2000, Monroe, Louisiana
HTML Source with Access to PDF Articles:

Notable Papers:

       Roller Vs. Herbicides: An Alternative Kill Method for Cover Crops
       No-Till Production of Tomatoes
       High-Residue, No-Till Systems for Production of Organic Broccoli

22nd Annual Conservation Tillage Conference for Sustainable Agriculture
July 6-8, 1999, Tifton, Georgia
HTML Source:
PDF Download for 222-page Proceedings:

Notable Papers:

       Opportunities for Conservation Tillage in Vegetable Production
       Impact of Compost and Tillage on Sweet Corn Yield, Soil Properties and Nematodes
       Crimson Clover-Cotton Relay Cropping with Conservation Tillage Systems
       Tomato Yield and Soil Quality as Influenced by Tillage, Cover Cropping, and Nitrogen

21st Annual Conservation Tillage Conference for Sustainable Agriculture
July 15-17, 1998, North Little Rock, Arkansas
Meeting the Challenges -- 21st Annual Southern Conservation Tillage
Conference for Sustainable Agriculture (Univ. of Arkansas Special Report 186)
HTML Source:
PDF Download to 98-page Proceedings:

Notable Paper:

       Keys to Successful Production of Transplanted Crops in High-Residue, No-Till Farming
        Ron Morse. pages: 79-82.

ATTRA is operated by the National Center for Appropriate Technology under a grant from the U.S. Fish
and Wildlife Service, Dept. of the Interior. These organizations do not recommend or endorse products,
companies, or individuals.

Compiled by:

Steve Diver
NCAT Agricultural Specialist
Updated April, 2002

Also see the ATTRA web page:


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