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

Introduction

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 States.

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 nitrogen.

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

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.  
   
 

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  
919-515-9447  
919-515-2505 Fax  
nancy_creamer@ncsu.edu  
http://www.ncsu.edu/organic_farming_systems/ 
 

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  
301-504-5057  
FAX:  301-504-6491  
E-mail:  abdul-ba@ba.ars.usda.gov  
http://www.barc.usda.gov/anri/sasl/aab.html  
http://www.barc.usda.gov/anri/sasl/covercrops.html 
 
 
 

Resource:

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.  
http://www.ars.usda.gov/is/np/tomatoes.html

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 cumbersome.  
 
 

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  
662-232-2975  
Fax:  662-232-2915  
E-mail:  sdabney@ars.usda.gov  
http://www.sedlab.olemiss.edu/personal_pages/Dabney.html

Resource:

Managing Cover Crops and Green Manures  
Seth Dabney, USDA-ARS National Sedimentation Laboratory  
http://www.sedlab.olemiss.edu/uep_unit/projects/cover_crops/index.html

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  
301-504-5057  
FAX:  301-504-6491  
E-mail:  abdul-ba@ba.ars.usda.gov  
http://www.barc.usda.gov/anri/sasl/aab.html  
http://www.barc.usda.gov/anri/sasl/covercrops.html  

Dr. Ron Morse  
Department of Horticulture  
Virginia Polytechnic Institute and State University  
Blacksburg, VA  24061  
540-231-6724  
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  
912-386-3901  
Fax:  912-386-3356  
E-mail:  phatak@tifton.cpes.peachnet.edu  
http://www.uga.edu/~hort/FacSCP.html  
http://www.uga.edu/~hort/FacSCP2.html

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  
828-654-8590  
greg_hoyt@ncsu.edu  
http://fletcher.ces.state.nc.us/staff/gdhoyt/

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  
http://ifs.orst.edu/strptil.html 
 

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.

Resource:

Cultivators for No-till and Ridge-till  
Iowa State University  
http://www.ae.iastate.edu/tillage/AE-3055.txt

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 onions.

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 Supplies  
ATTRA  
http://ncatark.uark.edu/~steved/flame-weeding-RL.doc

FOREVERGREEN™ Chemical Free Weed Control  
http://www.chemfree-weedcontrol.com/  
 
 

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.  
   
 

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.
  • 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
  • Good seed-soil contact is very important
    • Drilling produces a superior stand in comparison to broadcasting seed
    • Broadcasting seed (ideally followed by harrowing or cultivating) is a common way to “overseed” a legume into a standing crop
  • Plant seed when soil moisture is optimum, or irrigate
  • 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
  • Early-market tomatoes are usually planted on the last frost-free date
  • 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
  • Thus, no-till vetch is better suited to late-planted warm-season vegetable crops
  • Early-market vegetables are better adapted to plastic mulch
  • 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  
http://www.attra.org/attra-pub/phenology.html

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  
540-231-6724  
donna@vt.edu

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  
616-396-8738  
616-396-3619 Fax  
800-757-5268  
mtc@mechanicaltransplanter.com  
http://www.mechanicaltransplanter.com

Market Farm Implements  
[Ralph Moore]  
257 Fawn Hollow Road  
Friedans, PA 15541  
814-443-1931  
http://www.marketfarm.com/

Holland Transplanter Co.  
510 E. 16th, P.O. Box 1527  
Holland, MI 49423-1527  
616-392-3579  
616-392-7996 Fax  
800-275-4482  
hldtrans@iserv.net  
http://www.transplanter.com

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
  • Spring crops planted into no-till mulch include:  vegetables, corn, soybeans
• Groff initially tried mowing rye, but found out that timing is critical:
  • When rye is mowed at heading, it will naturally die out
  • When rye is mowed prior to heading, it will re-sprout and compete like a weed
  • 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
  • Fall crops planted into no-till mulch include:  broccoli
• In addition to soil improvement and weed suppression, the mulch enhances insect and disease control
  • Colorado potato beetles are less severe in mulched fields, the result of natural biological control by beneficial insects who inhabit the mulch
  • Onset of early blight on tomatoes was delayed on no-till ground
  • The mulch prevents soil splashing and subsequent spread of disease inoculum
  • 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