No-till broccoli. You can see how weeds start to sprout as the crimped residue breaks down.
Credit: Andrew Mefferd
How un-tilled is no-till? What exactly is no-till, and does it matter? Many of the growers I met with have their own definitions.
Any reduction in tillage is headed in the right direction. One thing all the growers I talked with agreed upon is that not inverting the soil layers was an important part of no-till.
If there is any skepticism about the scale on which no-till can be useful, one place where the transformative potential for no-till is on display is in conventional row cropping. For proof of this look to the two most widely planted crops in the US: corn and soybeans. Consider that over the last forty years no-till has gone from nonexistent to making up nearly half of the acreage of these two major conventional crops.
There is one very big difference between conventional row-crop no-till and the organic methods detailed in this book: the conventional methods depend on both herbicides and genetically modified crops, and will never be available to organic vegetable and flower growers.
As in other areas of agriculture, row-crop farmers have traditionally relied on tillage to remove the residue from one crop, prepare the soil, and suppress weeds for the next one. Traditionally, the area of land you could plant to corn or soy was limited by how much ground you could plow or otherwise prepare before planting time.
The trend in much of corn and soy has been to skip plowing altogether. There are three technologies that have made this possible: no-till planters (often called no-till drills), herbicides, and crops that have been genetically modified to survive the herbicides. No-till planters have made it possible to plant into a rough field that has not been loosened and smoothed by cultivation, and still has residue from the previous crop in it. So the drill gets around the problem of not having the slate wiped clean from the previous crop.
There’s still the problem of weeds to deal with, which is where the herbicides and genetic modification come in. Before the advent of herbicides, dealing with weeds mechanically was also a limiting factor in the amount of land that could be planted.
Herbicides of course made it possible to kill weeds by spraying them, but then there is the problem that they will kill the crop, too. The solution that has come to dominate conventional row-crop production is using a genetically modified crop that can survive the herbicides that kill the weeds. With 88 percent of corn and 93 percent of soy genetically modified, it’s hard to imagine a more complete takeover of the most widely grown crops.
This works because when the crop and the weeds germinate, herbicide is sprayed over top of both, leaving only the crop standing. I learned about this firsthand growing vegetables in Pennsylvania. Our farm was surrounded by conventional dairy. I saw my neighbor go out and no-till drill his soybeans in the spring. A few weeks later the soybeans were up — and more weeds than beans. A couple weeks later, the weeds had overgrown the beans, and the soy was barely visible through the weeds. In my naiveté, I thought, “he’s going to lose his soybean crop to weeds.”
Silly me. Shortly thereafter, he came through and sprayed herbicide, and the weeds died and the soy survived due to genetic modification. Now, I think that this solution is problematic for a lot of reasons, and I don’t think that vegetable and flower growers should aspire for the same type of solution. But it is proof of the concept that no-till can be adopted very quickly over a wide area when it is advantageous.
It is unfortunate that in conventional no-till, the increased efficiency comes along with an increase in herbicide usage, since the system only works if you are able to spray herbicides everywhere, including all over your crop. Estimates are that glyphosate production increased ten-fold during the period when genetically modified crops and conventional no-till were being rapidly adopted — from 15 million pounds in 1996 to 159 million in 2012.14
The other effect of the increase in herbicides has been the development of herbicide-resistant “superweeds.” Just as overuse of antibiotics has produced drug-resistant bacteria, relying on herbicides so heavily has bred weeds that survive them. Unfortunately something that is ostensibly good (increasing efficiency, reducing the need for tillage) on the conventional side comes with all the benefits of an arms race and drug addiction at the same time: as weeds become more resistant, farmers have to use more and stronger chemicals to get the same effect. Ultimately, only chemical companies benefit, with revenues from GM seed having increased sevenfold over the same period. And the real prize for the chemical companies — chemical sales — have increased even more.
No-till broccoli. You can see how weeds start to sprout as the crimped residue breaks down.
Credit: Andrew Mefferd
How we could think that dousing the majority of our farmland in hundreds of millions of pounds of any chemical could come without negative consequences is beyond me. This is also why the largest seed companies in the world — like Dow and Monsanto — are chemical companies. They want to sell seeds, but what they really want to sell are the chemicals that go with their seeds. That’s why they breed plants that go with their own proprietary chemicals; so buying their seed locks farmers into buying their chemicals, too.
So what ties all the organic no-till techniques together? The answer is the use of mulch; all the different systems use mulch in one form or another instead of tillage. And they all include a step for either killing the weeds in the top part of the soil (solarization and occultation) or suppressing the weeds from germinating (mulches applied or grown in place).
To make sense of them, I’ve broken the systems into two broad groups based on whether they use biodegradable mulches or not. This is because the type of mulch affects how it is managed. In no-till non-biodegradable (usually plastic) mulches are usually removed before planting the crop, whereas the biodegradable mulches are typically left in place during crop growth.
Each of the two groups can be further broken into two subgroups, for a total of four. The non-biodegradable mulches are broken into opaque vs. clear plastic mulches. Use of opaque mulch is called occultation, and use of clear plastic mulch is called solarization.
The biodegradable mulches can be broken down into whether they are grown in place or brought in from elsewhere and applied to the soil. These methods are not used to the exclusion of each other. Many growers use more than one in conjunction with another one, based on field conditions and what they are trying to accomplish.
This is the system that I first learned, where a cover crop is grown and then killed in place, to form a physical barrier between weeds and the crop. It’s the same idea as using plastic mulch to suppress weeds around a transplanted crop. Except instead of using a plastic mulch to suppress weeds, the mulch is grown in place and killed before the crop is planted.
I don’t focus on this method in this book, because it has been covered by one of the originators, the Rodale Institute’s Jeff Moyer in his book Organic No-Till Farming. Like the other methods I do describe, it’s a very simple concept. The basic method is to grow a cover crop until it is in the flowering stage, and then kill it using a roller-crimper.
This practice is much simpler in conventional agriculture, where herbicides can be used to kill a cover crop at any stage. It is not feasible to let a cover crop grow until its natural death at maturity, because it also sets seed when mature and would re-seed itself.
“As with all things in life, timing is everything. This couldn’t be truer when it comes to organic no-till,” said Moyer in Organic No-Till Farming. Getting the timing right is crucial for this method to work. Planning must go backwards from the planting window of the cash crop. A cover crop must be planted that can be killed when the cash crop needs to be planted.
The cover crop must be planted thickly and have enough biomass to get good suppression of weeds that want to germinate. Planting a cover crop either requires tillage or having a no-till drill to plant into an un-tilled field. So those wishing to practice this method with no tillage at all need to get or have access to a no-till drill. Rye has become a popular cover crop for this method, because overwintered rye can be terminated at the right time for a lot of spring crops.
Fennel with margined leatherwings in front of no-till broccoli.
Credit: Andrew Mefferd
When the right stage is reached, the most common method of organically terminating a living cover crop is to use a roller-crimper. A roller-crimper is an implement that consists of a cylindrical drum on its side that is driven over the cover crop to mash it down and flatten it. Just knocking most cover crops over would not be enough to kill them, however, so fins are added usually every 5–7 inches to the length of the drum to crimp the cover crop stems and stop the flow of juices up and down the plant. It is mounted most commonly on a riding tractor, but there are smaller models for use with walking tractors.
Once the cover crop is terminated and flattened, the cash crop can be transplanted into it. Since there isn’t a loose, friable seedbed as with a tilled bed, transplants have to either be put in by hand with trowels or by mechanical means.
One of the simplest ways to mechanically prepare a killed mulch bed is to run a tractor over it with a no-till planter. Coulters can be added to mechanical transplanters to cut a path through the mulch for the transplanter shoes. A less mechanical, cheaper method is to use a toolbar with fertilizer knives or something similar attached (not for applying fertilizer, just for loosening the soil), and a straight coulter in front to cut through the residue in front of the knife.
The least mechanical option is to use a trowel to simply dig transplanting holes out of the mulched bed. Shawn Jadrnicek developed a method for using a bulb transplanter to dig transplanting holes out of the bed. This way the holes can be prepared without bending over, which may speed things up (see his guest chapter for more info on this).
When done properly, this method can work very well, with the flattened cover crop preventing weeds from germinating around the cash crop. It is important to get a dense, even stand of the cover crop, for a weak or patchy stand will not suppress weeds adequately. The cover crop needs to be terminated at the exact right time. Done too early and the cover crop may regrow and not form a mulch. Done too late and the cover crop will have mature seed, which will germinate and compete with the cash crop.
Timing is also important when planting the cash crop. It needs to be planted as close to when the cover crop is crimped as possible. The crimped cover crop will only suppress weeds for a finite amount of time, after which it will start breaking down and allowing weed growth. When timed right, some cash crops, like pumpkins or winter squash, may form their own canopy, continuing to suppress some weeds after the mulch starts to break down. Other crops simply get a head start and become established without competition before weeds start to grow.
This method is advantageous when trying to do no-till on a larger scale. Instead of buying or making a mulch material, all you buy is the cover crop seed and the equipment to terminate it with. In my experience this works well for transplanted vegetable crops that develop into a fairly large plant, like tomatoes and winter squash. For farms looking to grow a larger field of a transplanted crop, like a pumpkin patch, this could be a good technique.
As strong as this method is for larger acreages, it has a number of disadvantages for smaller acreages in mixed vegetable production. In addition to requiring a higher level of mechanization, the mulch keeps the soil cooler than bare soil would.
Harvesting broccoli for no-till yield trials. Different treatments were compared to gauge the effectiveness of the treatments.
Credit: Andrew Mefferd
There was a story in the September 2001 issue of Growing for Market, “The Search for Organic No-Till,” in which Ron Morse was extensively quoted. Regarding the planting delay, he said, “Not all vegetable crops are suitable for no-till. Planting will be several weeks later than conventional planting dates for three reasons: First, the cover crop tends to keep the soil moist and cold in spring; second, the cover crop has to get big enough to make a good mulch; third, the farther into blooming the cover crop is when mowed or rolled, the more easily it will be killed. Trying to kill a cover crop before it’s flowering increases the chance that it will regrow; in fact, some growers wait till vetch is 50 percent in bloom before mowing it.”
“For anything where you don’t need earliness, you need to take a serious look at no-till,” Morse said. “Pumpkins are the classic example of that. No-till is the way pumpkins are grown now in many states.”
“Other crops that have succeeded with no-till include cabbage, tomatoes, cucumbers, potatoes, winter squash, and fall broccoli (which Morse likes to grow on a crop of German millet and soybeans),” the article said.
One of the most notable disadvantages is that this method requires more equipment than the other no-till methods. Below a certain farm size, it just doesn’t make sense to invest in a tractor and all the associated equipment. To get started with this method, you have to either till a field or have a no-till drill to plant your desired mulch cover crop into an un-tilled field. So the first option of plowing a field to establish the cover crop is not going to work for those who want to be strictly no-till.
The investment in equipment is considerably higher for this method than the other no-till methods. An alternative way to practice the roller-crimper method without owning a tractor would be to do it with a walk-behind tractor, a rototiller, and a roller-crimper. This would require less of an investment than with a tractor. It would probably necessitate tilling to get the cover crop planted, though, because as of this writing there aren’t any no-till drills for walk-behind tractors that I’m aware of. So still on a very small scale, the mulch grown in place method would necessitate more of an investment in equipment than the other organic no-till methods.
Along with the higher investment in equipment for this method comes a higher level of complexity and planning. Remember, the cover crop only has a certain window when it can be killed. Roll it too early, and it will re-sprout and spring back up. Roll it too late and it will have set viable seed, and your cover crop will be a weed. So you have to make absolutely sure that rolling happens at the right time or it won’t work. Look at Shawn Jadrnicek’s guest article and see the great deal of planning that goes into his roller-crimper system. The planning and execution of this method is much more complicated than, say, occultation, where you put a tarp on the bed you want to plant until it’s time to plant it.
The higher level of complexity corresponds to a decline in flexibility. The cover crop only has a certain window when it can be rolled, and the mulch only suppresses weeds for a limited amount of time before weeds start growing through. This translates to a limited planting window for crops. This works well for single plantings of cash crops that fall in the planting window for a given cover crop, for example, planting grain or winter squash or tomatoes following a rolled rye cover crop.
However, most small, diversified vegetable and flower farms rely on multiple succession plantings throughout the year to provide a steady supply of a variety of crops. Rolled cover crops are not conducive to numerous small plantings of different crops through the year and quick bed turnover.
Because the soil is not thoroughly pulverized and tilled, as with a rototiller, the rolled cover crop method tends to result in a rougher seedbed than traditional tillage or the other no-till methods in this book. This is not a problem for transplanted crops or relatively large-seeded crops like grains or winter squash, but it can be problematic for small-seeded directly sown crops like salad mix.
Mulches grown in place make the most sense for long-season crops that have a planting window in the spring that corresponds to the weed suppression window of a rolled cover crop. For less upfront investment and mechanization, and increased simplicity and flexibility, see the other methods described in this book. Rolled cover crops can integrate well into a diverse market farm, for example, when planting a pumpkin patch or a field of tomatoes. A crimped cover crop can also be a great solution to provide effective no-till weed control on larger acreages. For most small diversified farms, however, one of the other methods in this book is probably a better solution.
Another biodegradable option that is more flexible than mulch grown in place is biodegradable mulch that is applied when and where needed.
Almost anything that biodegrades and stays in place can be used as an applied biodegradable mulch. This can include thick layers of compost, cardboard, paper mulch, unrolled hay bales, straw, or leaves. In many areas, there may be by-products of other industries that could be used for mulches. For example, nut shells, wood chips, spent brewers grains, and many other organic materials might be available locally. If these materials are by-products of other industries it may mean that they are available for free or for low cost. Though the price may be right, it is important to consider the impact on soil health of anything used.
Wood chips, for example, can have great long-term benefits for raising OM and fungal components of soils. However, a large addition of raw wood chips can have a near-term negative impact on growing conditions by tying up nitrogen as the soil biology digests the wood chips.
Harvesting an assortment of no-till brassicas.
Credit: Andrew Mefferd
Almost any organic matter can be put to good use around the farm, as long as it is used properly. In the case of the wood chips, as with much other raw, high-carbon organic matter, you would likely be better off composting the wood chips by themselves, or adding them as the high-carbon component of a compost pile, rather than adding them directly to the soil. (See Tobacco Road Farm’s recipe for high-carbon compost on p. 307 and a similar recipe in use by Natick Community Farm on p. 241.)
Simplicity is one of the advantages of applied biodegradable mulch. In the most basic form, mulch is applied to the growing area before planting. The crop is planted into the mulch and it prevents weeds from growing. This should result in less weeding over time as new weed seeds are not stirred up through tillage.
The greatest number of no-tillers that I was able to get ahold of were somewhere in the applied biodegradable mulch group, aided by solarization and/or occultation. My guess is that this method is the most popular because it is relatively simple, and because most farms already have access to mulch and tarps, so it’s not hard to try. Even though this is by far the biggest category, there is a big range of practices within it, from growers who use deep mulches almost exclusively with little or no solarization or occultation, to growers who use tarps predominantly with very little mulch. Look to the interviews for inspiration on how to find the right mix for you.
I’d like to break the biodegradable mulchers down into three subgroups. There is one set of techniques associated with deep straw mulch, a separate method for using compost and other loose mulches, and one for using cardboard.
Mulches conserve moisture by blocking evaporation. They may decrease the amount of watering necessary, so they can be a good option for dry areas. Since, unlike plastic mulches, they stay in place after the crop is removed, biodegradable mulches contribute to building soil organic matter as they break down in the soil.
The disadvantages of many applied biodegradable mulches are the opposite of the disadvantages of biodegradable mulches grown in place. They are usually more time-consuming to apply on a square foot (area) basis, so they may be more effective on smaller areas.
Mulches grown in place take advantage of mechanizing the process of applying the mulch for efficiency, in this case planting and then rolling and crimping the cover quickly by tractor. This is where the scale becomes important in determining the best method. Applying cardboard mulch on an acre, for example, would take much longer than rolling a cover crop using a tractor on an acre.
There are materials and methods that can be used to more rapidly apply a biodegradable mulch, to make this method more time efficient on a larger area. Materials like rolled paper mulch or round bales of hay or straw can be deployed more quickly over a larger area.
Another way to speed the application if you want to use loose biodegradable mulch like compost is to mechanically apply it with a spreader of some type. Manure spreaders typically don’t apply an even or heavy enough layer to be useful for this. Making multiple passes with a traditional manure spreader, and raking or otherwise evening out the results, is one possibility. Another is to get a drop spreader, which lays down a much more even layer than a regular manure spreader. See the Resources section for suppliers.
Once the planting area is prepared, for example by using solarization or occultation to kill the weeds, paper or hay/straw can be rolled out over the beds to continue suppressing weeds during the growing season. Seeds or seedlings can be planted right into the mulch.
Solarization and occultation are two closely related methods that make use of non-biodegradable mulches to kill and break down the existing vegetation. Occultation is the word for tarping — putting an opaque barrier down to kill vegetation and compost it in place. Solarization is the word for using a clear tarp to cook the weeds.
Occultation is stale seedbedding without the flames. If you’ve ever set a bucket down on a grassy area, forgotten about it, and come back a few weeks later, you’ve done occultation on a very small scale. If you forgot about your bucket for long enough, a perfect brown circle where the grass died and vanished smiled back up at you when you picked your bucket back up.
Someone realized that if they did this on a grander scale, they would have a nifty way of getting rid of existing vegetation and preparing the ground for crops. The first time I was exposed to it was in Jean-Martin Fortier’s book The Market Gardener. In it he talks about how he uses occultation, along with tillage, to get rid of vegetation, and as a placeholder to keep an area weed free until he can plant it.15
I feel almost silly explaining how occultation works, it’s so simple. Though it’s worth understanding why and how it works.
A little of the broccoli we harvested for yield trials. It was donated to a food bank.
Credit: Andrew Mefferd
Occultation cuts plants off from light, starving them and causing them to die. When black tarps are used, they heat up in the sun, speeding up the process. Once the vegetation is dead, all manner of soil life moves in and does what it does: breaks down the now dead organic matter. In the warm, moist conditions under the tarp, weed seeds also germinate and then die due to lack of sun. So occultation can get rid of the vegetation on the surface of the soil, opening the way for planting crops, and also reduce the weed seed bank at the same time. Since, when you are not tilling, you don’t bring new weed seeds up to the surface from below, over time occultation should deplete the weed seed bank.
How long occultation takes depends on the temperature: it works faster in hotter weather. Growers interviewed for this book reported anywhere from three to six weeks, depending on the season. Figure out what works for you under your conditions. But keep in mind that occultation does not have to proceed to the point of bare soil to be effective. When they didn’t have time for the biomass to break down completely, some growers raked the partially decomposed organic matter off of beds to reveal a plantable surface.
Solarization takes advantage of the greenhouse effect to kill whatever is under it. It’s as simple to do as occultation: just lay a piece of clear plastic down on whatever you want to kill and leave it there until it is dead.
In the summertime or in a hoophouse, this can be really quick; 24 hours may be all that is needed. Other times of the year it will take longer.
For solarization, all you need is a clear piece of plastic. It’s a great use for old greenhouse plastic. For occultation, all you need is an opaque tarp. Used silage tarps can be a cheap, durable, reusable source of tarp material. See the Resources section for more about this, including a source for reused silage tarps.
Occultation and solarization are similar enough that their advantages and disadvantages can be looked at together. They have the same benefits of the other no-till methods, in that they don’t need specialized equipment or use any fossil fuels, and are efficient of space. Whether you grow on raised beds or on flat ground, you don’t have to remake beds or smooth the ground with these methods, as you would with tillage. You don’t have to wait for the ground to dry out to get on the field either.
One of the disadvantages of these methods is that they take some time — more in the case of occultation, less in the case of solarization. In any event, they’re not immediate, like say rototilling a bed and coming back and planting it, so they take some planning.
Another disadvantage is that they work more slowly at colder, less sunny times of the year. Even in the summer an unexpectedly cloudy patch may slow the methods down, especially solarization. And depending on your weather, solarization may not work in the winter where you are. Perennial weeds may continue to be troublesome, as deeply rooted ones may have enough reserves to survive the darkness of occultation or the heat of solarization.
A much simpler no-till tractor seeder. A coulter in front cuts the residue, while a shank (not pictured) loosens the soil, and the seeders (in back) drop the seed. It could be adapted to setting transplants by hand by taking the seeders off and transplanting into the furrows left by the coulter and shank.
Credit: Andrew Mefferd
Ultimately, occultation and solarization can be great methods for breaking land in and getting started with no-till as long as you use their disadvantages to your advantage. While occultation in particular is not fast, it is a great, easy method to open new ground. For example, if you can look ahead and see that you are going to need additional land to grow on next season, throw tarps down the previous fall, or even the previous summer (the longer the tarps are down the better). When the snow melts the following spring, you should be able to pull the tarp back to a fairly clean planting area. If the black side is up, the tarp may even speed up snowmelt in the spring for earlier planting.
No-till is about figuring out how the core techniques of plastic mulches (occultation and solarization), applied organic mulches, and mulches grown in place apply to the individual farm’s weather, weeds, and resources. I don’t think there’s any one-size-fits-all formula; it is my hope that growers can read this book and pick and choose the techniques that will make no-till work for them.
Among the growers surveyed, there was quite a bit of diversity. Some emphasized fast rotations of quick crops, some took their time with longer crops. Some used a lot of compost, some didn’t. Some cover cropped, some didn’t. Some do everything with hand tools, some had tractors and machinery. The point is they all have found ways to be profitable and build soil, even though their no-till systems may be quite different.
It might seem contradictory to hear both from people who like and don’t like raised beds in the same book. But what works well for one grower may not work well for another. Success in farming is such a mix of climate, personality, soils, goals, personal style, and a thousand other things that go into a system, that I wanted to profile what is working and let you decide what to try on the path to developing your own successful system. Here are some tips and themes that developed over the course of the interviews.
It’s all about the mulches and the biology. All of the no-till systems use some sort of mulch at some point to either smother or suppress weeds. One thing that is going to happen if you are increasing organic matter and not using chemicals is that you will get increased biological activity in your soil.
Increasing biological activity is important because it breaks organic matter down and makes nutrients available to plants. Biology is the driver behind soil function. The more diverse and redundant, the more stable the soil system.
Before starting a no-till system, a lot of growers do something to kill weeds preemptively like mulching with cardboard, straw, occultation, solarization, or even one last till to set the stage for lower weed pressure. The longer weed suppression can go on before starting the no-till system, the cleaner the no-till beds will be. Starting the previous season is the ideal situation. Prepping beds in the fall and tarping them as a placeholder over the winter may be the fastest way to get back in the ground in spring.
Tarps are very versatile. In addition to being used as placeholders, they can be used to hold moisture, and impermeable tarps can exclude moisture during wet times of the year.
Fast bed turnovers will make the most of quick crops like salad mix. Season-long crops like many of the flowers may benefit from the efficiency of simply putting a tarp on a crop in a space that can’t be cropped again that season. When going quickly between short crops, if the previous crop was fertilized it may not be necessary to add more fertilizer or compost.
Some growers that use a lot of compost for mulch make or source a high-carbon compost so they can add high amounts of organic matter without excessive amounts of fertility. For recipes, see Tobacco Road Farm p. 305 and Natick Community Farm p. 237. Many growers added a lot of compost in the beginning to raise their SOM quickly, then tapered off compost application or started using high-carbon compost.
Perennial weeds can be a problem for no-till systems because they store energy in their roots, so they can’t be smothered as easily by mulch.
The pattern I saw on many farms is that the longer they’ve done no-till, the better it works. Since much of the weed pressure on farms comes from the annual seed bank in the soil, the longer they got away from stirring those seeds up, the fewer weeds they had.
One way to break in some no-till beds and get a crop at the same time is to grow a vining crop like winter squash, melons, or pumpkins, planted through a tarp or other heavy mulch. The plants can vine out over the mulch while occultation is taking place.
The deep straw mulch and roller-crimper method can work well for hot areas where it is advantageous to keep the soil cool and mulched.
Many of the growers made use of free sources of mulch: wood chips, manure, straw, even beer filters in Urbavore Farm’s case. See what’s available in your area.
Think about all the plants, animals, and people on your farm. The buildings and infrastructure that give it its feel. One of the most difficult things about writing this book was to capture the feel of being on these farms without making it longer than it needs to be.
Visiting with each one of these farms was incredibly inspiring in its own way. I’m sure every one of them thinks there is a lot more I could have said about them, and that would be true. Many of these farms have their own resources, ranging from online courses, to on-farm workshops, to books. If you are intrigued by any of these farms, there is much more to each of them. I encourage you to seek them out in the Resources section if you want to know more.
I know I didn’t get to you all! Between time and number of pages I knew there was no way to get to everyone. If you are interested in having your no-till story told either through Growing for Market or perhaps a future edition of this book, get ahold of me and let’s do an interview or a visit.