Cultivating Questions: Heat Loving Crops in Reduced Tillage Systems – Cultivating Questions
Cultivating Questions
Concerning the Bioextensive Market Garden
by Anne and Eric Nordell of Trout Run, PA
HEAT LOVING CROPS IN REDUCED TILLAGE SYSTEMS
Dear Anne and Eric,
I am a relative newcomer to the SFJ and have found your columns to be particularly useful for me and my farm.
I am very interested in improving my soils in a sustainable manner, and your methods are quickly being incorporated into our vegetable production business. Please find enclosed $30 for your video and booklets.
I have used traditional production methods in the past like plastic mulch and drip irrigation, but wish to switch over to more sustainable methods. I think your tillage-cover cropping schemes can help me move away from throw-away drip-tape, but what practices do you use, if any, to help heat loving crops reach maturity in short-season cool climates such as yours and mine? I have been impressed with the effects of black plastic on tomatoes, eggplants, peppers and squash. These are high value cash crops for us and we love the jump to maturity!
We are slowly bringing draft horse power into the market garden and having great fun! We look forward to seeing SFJ and CQ in the mailbox!
I am a convert to Sustainable Agriculture. As we move away from Conventional Ag methods, your articles are priceless for us as there seems to be a deficit of good info on this. Keep up the great work!
Dave Petrovick
Barre, MA
The short answer is we do not use plastic mulch. Period. However, our conviction to completely avoid single-use plasti-culture for hastening the maturity of heat loving crops has not required much of a financial sacrifice because our market niche is cool season crops, like leafy greens, root crops and aliums.
We should also confess that we are not anti-plastic purists. We make exceptions for agricultural plastics that can be reused over several growing seasons. For instance, our first and last plantings of field grown lettuce go under floating row cover. We also use this soil warming ploywoven material to keep cucumber beetles off of heat loving zucchini and squash. For the small quantities of early tomatoes, basil and eggplant we need to round out our market display, we use the polycovered portable hoophouses described in past issues. With a little care, we can usually get at least four to five seasons of use from both the row cover and UV-inhibited greenhouse plastic.
The long answer is that Dave Petrovick’s question really begs a fuller explanation of the tradeoffs between moisture preservation and soil warming in our reduced tillage/cover crop system. To address precisely this issue, we conclude this CQ installment with the results of the 2003 NEON tillage trial in Field 6. This research report documents the differences in soil temperature and moisture between our ridge-till and no-till cooking onions.
In order to provide a down-to-earth context for this research, we devote the middle of this column to the history and economics of Field 6. We hope that the accompanying photos and whole field analysis might also serve as a sequel to “The Diary of a Minimum-Till Horse Farmer” (in the Summer 2003 issue) which described how we used reduced tillage to plant Field 6 during a short break in the wet weather in the middle of April.
Before we get carried away with the details of ridge planting the cool season crops in Field 6, we feel we owe Dave Petrovick a more satisfactory answer to his question about sustainable alternatives to black plastic when growing heat-loving crops under moisture conserving cover crop management. Possibly the following overview of the changing relationship between no-till vegetable production and plasticulture will provide a helpful perspective on this challenging question – and hint at a possible solution for warming the soil in a high residue cropping system.
At the 1997 NOFA-NY Conference, we had the opportunity to hear a keynote address by Dr. Aref Abdul-Baki of Beltsville, Maryland. His pioneering work at the USDA-ARS research station planting tomatoes directly into a cover crop mulch of dead hairy vetch inspired researchers and growers across the U.S. to experiment with no-till vegetable production.
Dr. Abdul-Baki began his keynote by listing the reasons he was convicted to develop the no-till/cover crop system. Reducing soil erosion and chemical usage were high priorities. Improving both crop and soil quality were also objectives. But his primary incentive for no-tilling vegetables into a natural mulch of cover crop residues was to eliminate the rampant use of black plastic in both conventional and organic agriculture.
From his perspective, the thousands upon thousands of acres of plasticulture he has seen traveling this country is a far greater detriment to the environment than chemical fertilizers and pesticides. Due to the pollution problems associated with producing and disposing of plastic, he challenged the organic growers in attendance to consider plastic mulch an unsustainable practice.
In recent years, Dr. Abdul-Baki has been researching ways to make his notill strategy more sustainable by developing mechanical methods to kill the cover crop mulches rather than using chemicals. He has also been trialling new cover crop mixes which promise to provide complete weed control without relying on herbicides or mechanical cultivation.
For more information on Abdul- Baki and other pioneers of reduced tillage vegetables, contact ATTRA (Appropriate Technology Transfer for Rural Areas, Fayetteville, AR) and ask for the following free materials: “Pursuing Conservation Tillage Techniques for Organic Crop Production” by George Kuepper (inadvertently, the reference to this excellent publication was separated from a quote by the author in our Summer 2003 column), “No- Till Vegetable Production: Non- Chemical Methods of Cover Crop Suppression and Weed Control” by Steve Diver, and “Conservation Tillage” by Preston Sullivan.
Not surprisingly, almost all of the research on low-till vegetable production has been conducted in warmer parts of the country where low soil temperatures are generally not much of a problem. To the contrary, the shading effect of a natural cover crop mulch can be a benefit in hotter climates by moderating soil temperatures during the heat of the summer.
You can imagine that we sat up and took notice when we came across a project focused specifically on reduced tillage for vegetable production in cool climates among a list of 2003 SARE research grants. We contacted the research director, Dr. Anu Rangarajan of Cornell University, to learn more about this comprehensive, multi-faceted project, ranging from on-farm zonetillage demonstrations in Upstate New York and Maine to University research on mechanical weed control for ridge-till vegetables. When we asked her about the challenges of growing heat loving crops in these high residue systems, she referred us to one of the project’s cooperating farmers, Steve Groff of Holtwood, Pennsylvania.
Steve Groff has been at the forefront of no-till vegetable production, planting both fresh market and processing crops into a variety of cover crop mulches. He claims that permanent no-till has eliminated erosion on his steep-lying farm, significantly reduced the amount of chemical fertilizers, herbicides and insecticides that he uses, and dramatically improved soil organic matter levels, aggregate stability and rainfall infiltration.
Always looking for ways to improve his Permanent Cover Cropping System, Steve has been experimenting with methods to warm up the soil for early plantings of sweet corn and tomatoes to take advantage of early market prices. A zone-till planter, for example, allows him to get early sweet corn off to a faster start than no-tilling directly into an undisturbed cover crop mulch.
Three wavy coulters are mounted ahead of each planting unit, tilling a strip of soil about 8” wide and 2” deep. The zone-till planter is also equipped with row cleaners which move the cover crop residues to either size of the zone-tilled planting rows. The beauty of the zone-till system is that the clean-tilled planting rows warm up and dry out quickly for good germination while maintaining 75% of the land in a protective mulch of cover crop residues.
Steve Groff has taken early zone-till planting one step further by modifying an imported plastic mulch layer to cover the sweet corn rows with a clear film of photodegradable plastic. The Irish Mulch-laying machine is specifically designed to handle this saran-wrap-thin plastic without tearing. Steve modified the implement to set and secure the plastic right in the untilled cover crop mulch, covering two rows of zone-tilled sweet corn with one width of clear plastic.
The combination of zone-tilled and clear plastic mulch really speeds up the germination and early growth of the cold-sensitive sweet corn. In 2003, Steve planted 11 acres of sweet corn with this method on March 28, and despite receiving two snowfalls and a lot of unseasonably cold, wet weather, he was rewarded with a 90% stand and a crop that was harvested ten days earlier than usual.
Although the “no-till” photodegradable mulch layer is a one-of-a-kind tool, maybe the following four steps that Steve now uses for growing early sweet corn will suggest some possibilities for managing other heat loving crops in high residues:
- Plant a cover crop of oats in the fall. The oats will dieback over winter creating a soil protecting and moisture conserving mulch of dead residues by the time spring rolls around.
- Zone-till plant sweet corn into the dead mulch of oats as early as possible.
- Cover the zone-tilled sweet corn with photodegradable clear plastic.
- To help the sweet corn break through the saran-wrap-thin plastic, slit the film down the middle with a coulter once the crop is well established. As the sweet corn takes off, the photodegradable material literally melts into the soil.
Steve has also experimented with laying black plastic over a zone-tilled seedbed before transplanting early tomatoes. He says the system works and shows potential for other heat loving crops, although now he grows all his early tomatoes in a one-acre Haygrove tunnel.
Taking Groff’s zone-till plasticulture solution for heat loving crops the next step toward sustainability might mean replacing the plastic with a biodegradable alternative. That possibility may be practical in the not-toodistant- future as more manufacturers try to tackle the challenge of making biodegradable materials.
In fact, Dr. Anu Rangarajan is trialling two types of biodegradable mulch used successfully in Europe – one made from corn and the other from potatoes. According to one of the project’s cooperating farmers, Jody Bolluyt of Kinderhook, New York, the biodegradable mulches showed a lot of potential for soil warming and weed control. However, neither material turned out to be a good fit for the cropping system that she and her partner, Jean-Paul Courtens, have developed for growing heat loving crops like tomatoes and melons.
Jody and Jean-Paul usually lay black plastic on tilled soil early in the spring and then seed the aisles between the plastic mulch with White Dutch clover. The idea is to get the living mulch well established before transplanting the tomatoes and melons. Using both types of mulches together provides full season weed and erosion control. The downside of this double-mulch system, in their eyes, is the environmental consequences of using black plastic plus the time consuming and unpleasant job of removing the mulch from the field at the end of the growing season.
Biodegradable mulch would solve both of these problems. However, one of the plant-based materials they trialled decomposed before it was time to set out the frost sensitive tomatoes and melons. The other showed no signs of breaking down by the end of the year. Jody remains optimistic that they will be able to adapt their double-mulch cropping system to the life expectancy of the biodegradable mulch, now that they are familiar with the decomposition rate of each material.
If a change in customer demand shifted our crop mix toward the heat loving plants, we might be tempted to try out the biodegradable mulches on our no-till ridge system. We would simply stretch the solar absorbing biodegradable material over the dead cover crop mulch on the ridge, securing it with the heavy layer of wheat straw we normally use to hold moisture in the pathways. In this fantasy triple-mulch system, we imagine the ridges covered and winterkilled cover crop residues and biodegradable film would warm up even faster than black plastic laid on flat ground. At the same time, the straw mulch in the valleys should conserve enough moisture to minimize the need for drip irrigation.
We can’t help wondering if this triple-mulch fantasy could turn into a real solution to Dave Petrovick’s question about growing heat-loving crops without using drip-tape or black plastic. Sounds so promising we might have to try it, assuming we can get our hands on one of the more promising brands of biodegradable mulch on the market.
In the meantime, we intend to experiment with reusable floating row cover suspended over the no-till ridges on wire hoops. Could be just the sustainable answer for hastening the maturity of our cool season staples as well as a few rows of heat loving tomatoes, peppers and squash.
