building soil with cover crops

The literature that I've read says that it's better to build the soil with a cover crop before planting a food forest. I've got 5 acres of field that has been mowed for the last several decades, but the soil is still pretty decent. We are next to a flood plain so it may not drain as well as one would like. My plan is to till it, probably over a week or so since my tiller has an 18" width. Then I'm going to sow by hand;

march 1: 5lbs white clover, 5lbs sweet clover, 25lbs annual ryegrass
mid march(ish): 50lbs field peas, 25lbs cow peas, 50lbs barley, 10lbs mangels
mid may(ish): 10lbs millet, 25lbs buckwheat

Going by Johnny's seed recomendations it should be enough seed to plant about 5 acres. Anyone foresee a problem with that? The plan is to till it under in the late fall. I'd rather have some good forage crops coming up than weeds and regular grasses. Then maybe we will plant something like oats for the winter. Hopefully a year or two of this will build up some good humus.

I'm guessing it would be best to till with the blades in reverse to break up the grass, but it is so slow! Would running the blades forward make it a lot harder for the cover crop to get established? It is much faster!

I don't like tilling unless you are building raised bed gardens. It destroys too much soil biology. I would say to use a chisel plow or subsoiler and tractor to loosen and disturb the ground without totally destroying the cover. If you have access to a tractor or can rent one. Around here you can get someone to come in and plow and till a garden plot for a really good price--worth the money vs. the time you would spend fighting a tiller.

Hi Drake, Welcome to permies!

I guess my first question is why till at all? you can do chop and drop to cover over what you don't want there, you can cut and flip sod to give you access to soil. Tilling is going to kill all the micro life in your soil so you will have great fertility in that soil but its going to take a while for those life forms to breed back up. From some of the video's and stuff that I've read, when you cut grass it cauterizes the roots below to match the amount of grass stalk above. Those roots break down and build your soil from the bottom up. You can add mulch on top and do the two things at once. If you are set on tilling, make sure you only have to do it once. And not once per year, once per forever.

If you are planting a food forest, you'll want mulch more than anything to choke out the surrounding grasses so your trees have better access to nutrients and water. So cut your grasses and weeds down, use that as your chop and drop mulch for when you do plant your trees.

Plus if you are on a flood plain, then you want the roots there as little pathways for the soil to absorb the water deeper where the trees are going to get it.

i wouldnt till it, tilling will lose you organic matter and give you a huge weed problem. decide where your main trees are going and mulch those ares to kill the grass and feed the soil then plant your trees keep doing this for the different levels and then for the ground cover you could leave the grass and get chickens to turn the grass into rich fertilizer or use mobile chicken netting to kill off the grass then plant tillage radish, peas, beans, vetch and rye.
grass builds soil almost as well as anything else given a long enough recovery time, you already have grass so why not use it, when you grass is going dormant you can broadcast rye and vetch as an added soil builder.

some of your canopy trees will take many years to mature so why not get them in as quickly as possible and enjoy their bounty all the sooner.

well I already have a tiller and a couple hundred pounds of seed. let the great experiment begin!

Just posted a link to a free pdf on building soil with cover crops in this thread

use the seed, sell the tiller, you asked for advice do you want any?

Tillage "destroys soil biology" "kills all the microlife"? - In a humid temperate soil, you DO change microlife, and reduce some elements, but you also increase other elements. I have been looking into experimental evidence on this, and IF you are choosing your methods well, you are able to create broadscale shift from grasses to forbs and trees using tillage, while having no lasting effect on biota. You will break up fungus for one season, get a pulse of bacteria, even surface dwellers like springtails and mites will come surging back with the huge pulse of decaying biomass. We are already talking about a bacteria dominated system since there isn't a lot of wood in the soil. However, by radically shifting herb layer composition you can radically change system dynamics, increasing nitrogen fixation, and tap rooted species. We are not talking here about 10 years of 5 times a year tillage with ammonium salts thrown on top. The soil is powerful--I think we should give it some credit, and not discard useful tools without some really solid evidence.

tilling will lose you organic matter and give you a huge weed problem?
"weed" is the plant you don't want. In this case, the weed you might not want is 5 acres of established grasses which will be hell on your young woody trees, especially if you are maintaining with hand tools, and are planting small stock. At a 5 acre scale, you want to have a clear vision of what the site will look like over a 3 year period till when your woody plantings take off. A five acre pasture with whips looks like a maintenance nightmare... no time to do anything but fight grass for survival. I think the take home is to know you species, both whats in the standing pasture and the seed bank, and how they make a living. Then you can predict rather than react.

Cut and flip where you want access to soil? - I'm not sure how this scales to 5 acres, and it does absolutely nothing for some perennial weeds. Chisel plow will not give you a seed bed or allow you to dramatically shift the herb layer. In my experience planting woody plants into sod is a labor intensive pain in the ass, either a ton of work to make it flat, or lots of chuck to stab with you scythe when you are trying to favor your trees during the dry down (again... assumptions about climate... perhaps safe given the seed mix proposed.)

I'd like to see some more evidence before I discard tillage as a tool for transitioning a site from (in my case) Eurasian grasses in a humid temperate climate to food forest at large scale.

march 1: 5lbs white clover, 5lbs sweet clover, 25lbs annual ryegrass
mid march(ish): 50lbs field peas, 25lbs cow peas, 50lbs barley, 10lbs mangels
mid may(ish): 10lbs millet, 25lbs buckwheat

So I think the mix of species introductions depends on the future trajectory you are trying to set, and how that relates to where you want to go. You could shift your pasture to include more legumes, and probably get "soil building" -- but that won't set up for a dramatic shift in composition that launches a food forest.

A cover/till/cover/till cycle in my mind is less about soil building and more about breaking down populations of perennials you don't want to be strong in your final mix (in particular rhizomatous grasses). So if you are going for weed control... I would do a first till, let the existing sod resprout, then do a second till right before sowing time. I'd time sowing based on when your soil temp will be warm enough to rapid germination, but not so late as to lose the moisture. In my climate March is too early. I'd do a single sowing, and then let it run through late summer (doing a second till, sow for overwintering if I had water, or running through next spring if I didn't. You could also hay, and start in-situ compost piles for early planting sites.

If you are doing tillage, consider soil test, and adding rock powder as necessary. Rare opportunity to incorporate lime or rock phosphate.

If you have uncertainty (it sounds like you are trying to transition 5 acres in an experimental way with tillage using only a rototiller.) You might consider reducing your experiment size.

At 5 acres in my climate I'd favor one year of covercrop/tillage ending in a diverse fall planting heavy on legumes and tap rooted species, into which you plant your woody systems in strips.

just ramping up the diversity around here...

mature grass is high in carbon and is therefore a good fungal food, roll the grass once it is mature and zero till your cover crop seed into the residue, tillage has been proven to favor bacterial domination and tillage ruins soil structure in the long term by degrading glomulin and creates new hardpan at the plowing depth, a heavy mulch around your trees will let virtually nothing through, plant your guilds in straight lines wit 15-20 feet between and you will still be able to use machinery in the rows.

My question is do the seeds need to be filled/composted over/mulchedbover or have dirt put on top for them to grow. I also would like to broadcast leguminous cover crops to start the food forest process. I may just have a chicken tractor and when I move broadcast the seeds where they were. I know some birds will eat seed but will they eat all or am I wasting money?

You can use a rake and/or cover with mulch/straw.

I think Paul's point is that tillage CAN be a tool to establish a no-till system. I think there is a difference between using a plow the first year and never again and using a plow every year.

However, I would personnaly avoid using the plow to control "weeds" and would use grazers, but that is my opinion.

I think a machine like the one in the video might be a better approach to plant trees on a large scale.

I'm looking into renting a seed drill for a similar project size and goal to the op. Not sure about a seed mix, differing seed sizes, and existing plant dominance. Sorghum is a weed inhibitor so my plan was to let that take over for a season and reasses along the way.

After all is said and done, it's your property to do with as you see fit. If you are going to till, then till. If not, then don't. In the end just let us know what route you take and how the results are lining up to your overall plan for the site.

Here is another option of what could be done with a tiller, build swales. Mind you it would need some welding.



https://permies.com/t/32247/homestead/Grant-custom-swale-plow

Adrien Lapointe wrote:Here is another option of what could be done with a tiller, build swales. Mind you it would need some welding.



https://permies.com/t/32247/homestead/Grant-custom-swale-plow

I don't have access to that particular type of plow, but it's cool. I think my friend in VA got something similar for his bcs.

Soon enough I will have the cash to pay one of my neighbors for use of a tractor.

I like getting both side's perspective, thank you all.

I used to be very anti-till when I had read Gaia's garden, but now that i've read the food forest books that's changed. It seems like you can increase topsoil depth with the right combination of cover crops and plow(s). I don't have them right now.

The main reason I'm tilling is because I figure it gives whatever I'm planting an edge over the grasses.

Hi Drake. No worries, give it a go. Tilling is something to be avoided in later years once your systems are established. There are good reasons for this. However, if you need to till, then by all means do it. I had a 20 tonne excavator deep rip about an acre here a few years back (and no till since, just chop and drop the herbage), and the results have been amazing. After the deep ripping, I applied - by hand - a thin mix of mulch / mushroom compost / worm castings (and some tea) and compost to the surface, some seed and didn't do anything else. In a just a few years the top soil is now at about 15cm (just shy of 6 inches) at that location when before it was like concrete. Please don't be put off!

Just to clarify a theory or two. For me, while tillage is still in the tool kit, I am not convinced that its purpose is "soil building". I think of tillage as a disturbance, that lets you jump in and change species composition. I'd expect that a good perennial pasture with legumes and other forbs mixed with grass would build soil faster than a till/plant cover cropping regime. The only advantage of the later would be if you want to try to control understory composition.

roll the grass once it is mature and zero till your cover crop seed into the residue

The only examples of this I have heard of (by the Rodale people, not seen) are using a crimper followed by a drill on an overwintered annual grain in spring to put in a main crop. I suspect that nice annual grain stand was established on a seed bed. I'd love to learn more about how people are using rollers or crimpers. I just haven't seen much substance beyond what rodale put together. At smaller scales I have introduced new species (red clover) using close mowing and oversowing, or better yet, chickens and seed balls (micro tillage?) but have only been able to nudge community composition... the existing pasture has a lot of resources in place and bounces back faster than the seeds.

Isn't the existing pasture a "cover crop". I think of a cover crop as a temporary crop planted on bare ground following a main crop for soil improvement or erosion control. If you have a reasonable pasture maybe it is working fine? Maybe all it needs is a nudge in composition... but if there are not legumes in it already, I wonder why... are calcium or phosphorus levels low from past ag practices? (Yes repeated tillage does degrade soils).

I think tilling in strips (possibly with earthworks) seems like a great way to introduce a mix of tree crops, while getting a yield on the remaining pasture using electric fence and minimizing the footprint where you are trying to turnover composition.

In terms of chop and drop... I have had to use around 4-6 units of chop, onto 1 unit of drop, to get enough mulch to change community composition beyond just adding a few new species to the existing pasture. Always interested in exactly what other people say when they say chop and drop in a pasture setting as maintenance for young trees, particularly if you are talking about a 2-0 or 2-1 seedling. I would use a tree planter if I had a fast growing tree that doesn't mind growing in grass. Some species (many native trees as demonstrated by Fourth Corner Nurseries up in Bellingham) grow very poorly in Eurasian sward.

Contact your local NRCS/USDA office and they'll give you tons of info. Your district may have a roller/crimper to rent but they may not have one for small acreage. Or, they may know how to modify a tool you have to roll/crimp.

I just attended a soil building workshop and they were really pushing no till but the farmers interviewed in the video we watch were all growing large acres of mono-crops like soy & corn. Be sure to tell them you're not using chemicals because there are different methods if you are.

Chris McLeod wrote:Hi Drake. No worries, give it a go. Tilling is something to be avoided in later years once your systems are established. There are good reasons for this. However, if you need to till, then by all means do it. I had a 20 tonne excavator deep rip about an acre here a few years back (and no till since, just chop and drop the herbage), and the results have been amazing. After the deep ripping, I applied - by hand - a thin mix of mulch / mushroom compost / worm castings (and some tea) and compost to the surface, some seed and didn't do anything else. In a just a few years the top soil is now at about 15cm (just shy of 6 inches) at that location when before it was like concrete. Please don't be put off!

that sounds promising. I forgot to mention that I'm a mushroom farmer, so I've got several tons of spent straw and sawdust/wheat bran substrate composting or ready to be composted.

Would old hay be useful as mulch, as long as it's been sitting for at least a year, maybe two? A lot of neighbors down here seem to roll hay and then just let it sit there.

I've got several tons of spent straw and sawdust/wheat bran substrate composting or ready to be composted.

Would old hay be useful as mulch, as long as it's been sitting for at least a year, maybe two? A lot of neighbors down here seem to roll hay and then just let it sit there.

Lots of good conversation here. The one thing I will add is that annual cover crops or "green manures" do not build humus. They introduce Nitrogren. Woody crops -- or the spent straw and sawdust/wheat bran you mention -- do build humus. As do the decomposing roots of mown pastures.

Also, as far as grazing to control weeds, I don't see how this could be anything less than a major pain in the butt when you've got a field full of little trees. How will you protect them? Our sheep killed several of our fruit trees this year, and our cows kill large trees over time by rubbing them to death.

And in my experience hay makes good mulch, but it will have seeds in it, no matter if it's been sitting for a couple years. If it's hay from a local field, it will be full of seeds of the local pasture plants, though, and can kickstart good pasture growth.

Matt Smaus wrote:The one thing I will add is that annual cover crops or "green manures" do not build humus.

I disagree. The pdf I linked to earlier has some good charts on cover crops and what they will do for you.

Sorghum is listed as a great soil builder, and yields 8-10,000 lbs of dry matter/acre/yr. Annual Rye is listed as a pretty good soil builder, and yields 2-9,000 lbs of dry matter/acre/yr. Barley is about the same.

Matt Smaus wrote:
Also, as far as grazing to control weeds, I don't see how this could be anything less than a major pain in the butt when you've got a field full of little trees. How will you protect them?

Here is a simple solution to protect young trees.



Mark Shepard goes as far in his STUN (Sheer Total Utter Neglect) technique as to not protecting the trees at all, according to what he said at the Guelph Organic Conference.

Our sheep killed several of our fruit trees this year, and our cows kill large trees over time by rubbing them to death.

Timing is of the essence. There are many many examples of sylvopasture systems where animals are grazed between mature trees without ill effects.

Here is a thread that points to many resources about agroforestry practices (including sylvopasture): https://permies.com/t/32643/forest-garden/USDA-Agroforestry-resources

I'll second the comment about woody material building soil better than greens. Also, re livestock - probably the largest thing you might put through the area for the first few years is chickens. Confined at high densities for a week or two they can also provide enough soil disturbance to allow direct sowing of cover crop seeds if you want to change to balance away from grasses.

Personally I have no problems with tilling or digging soil when getting a system established, but I'd avoid it becoming an ongoing routine. There was a video posted a while back about holistic orchard management - lots of clever things with multiple varieties and lots of chop and drop mulching.

Also, have you thought what size trees you are planting? I'll be putting in some full standard fruit trees over the next year - to my mind they make best use of the space by letting you use more of the ground beneath for guild plantings (berry crops, alliums, comfrey, cultivated blackberries, rhubarb, clovers etc...).

Do you need to do all five acres at once - that sounds like a huge amount of work as all of that area will need intensive management and care at athe same time (weeding, watering if you get a drought in the first few years, hand planting of your guild plants and other mulch crops). Why not do a smaller area per year and keep some sheep on the remaining pasture for a little longer?

Have you seen Geoff lawtons food forest video where he shows a series of strips that have been cultivated by chickens before establishing a multiple species food forest.

Woody material contains more lignin, which is part of the humus building process. Green material does contains lignin; but a bit less and with more cellulose.

green manure crops do build humus. if you have all this spent straw and sawdust then you could use that as your mulch around the trees, far better than tillage. it has been proven that with proper managment pastures can build an inch of soil a year, that would be very hard to beat.




these three guys in these videos are amazing innovators and are leading the way in soil building and soil health, the concepts they bring up are mind blowing and far beyond anything bill mollison wrote on soil building.
carbon is far more important than nitrogen in healthy soil.
the first video is colin seis who invented pasture cropping, this is the direction i would go in to change your soil and prepare it for the forest to come.
remember if you use animals in a food forest you can virtually eliminate the need for nitrogen fixers.

Here's the word from "Managing Cover Crops Profitably". I was being simplistic (speaking from memory) by saying annual cover crops don't build humus, but I wasn't totally off the mark -- legumes don't but grasses do.

Soil scientists may argue over how to classify the various soil organic components. Most will agree, however, that there is a portion that can be called the "active" fraction, and one that might be called the "stable" fraction, which is roughly equivalent to humus. There are many categories in between the active and stable fractions.

The active fraction represents the most easily decomposed parts of soil organic matter. It tends to be rich in simple sugars and proteins and consists largely of recently added fresh residues, microbial cells and the simpler waste products from microbial decay.

Because microorganisms, like human organisms, crave sweet stuff, compounds containing simple sugars disappear quickly. Proteins also are selected quickly from the menu of edible soil goodies. When these compounds are digested, many of the nutrients that they contain are released into the soil. Proteins are nitrogen-rich, so the active fraction is responsible for the release of most N, as well as some K, P and other nutrients, from organic matter into the soil. The easily decomposed proteins and sugars burn up almost completely as energy sources, and don't leave much behind to contribute to organic matter building.

After the microorganisms have devoured the portions of the active fraction that are easiest to digest, a more dedicated subset of these microorganisms will start munching on the more complex and tough material, such as celluloses and lignins, the structural materials of plants. Since cellulose is tougher than simple sugars, and lignin breaks down very slowly, they contribute more to the humus or stable fraction. Humus is responsible for giving the soil that rich, dark, spongy feeling and for properties such as water retention and cation exchange capacity.

Plant materials that are succulent and rich in proteins and sugars will release nutrients rapidly but leave behind little long-term organic matter. Plant materials that are woodier or more fibrous will release nutrients much more slowly, perhaps even tie up nutrients temporarily (see Tillage, No Tillage and N Cycling, p. 21), but will promote more stable organic matter, or humus, leading to better soil physical conditions, increased nutrient-holding capacity and higher cation exchange capacity.

In general, annual legumes are succulent. They release nitrogen and other nutrients quickly through the active fraction, but are not very effective at building up humus. Long-term use of annual legumes can increase soil humus, however, some research suggests (429).

Grains and other grasses and nonlegumes will contribute to humus production, but won't release nutrients very rapidly or in large quantities if incorporated as they approach maturity. Perennial legumes such as white and red clover may fall in both categories -- their leaves will break down quickly, but their stems and root systems may become tough and fibrous and can contribute to humus accumulation.

well even legumes do contribute to humus production but it depends on the legume eg. bean stalks are high in carbon. dont forget about the microrizzal relationships formed by the roots of legumes and other crops. legume roots are important humus builders as they break down and legumes are generally high in protein which will increase worm biomass and that is extremely important.

Pretty good thread, nice back and forth.

Matt Smaus wrote:legumes don't but grasses do.

Legumes contain lignin and cellulose. They build humus.

Even the quote you posted says so.

drake schutt wrote:I forgot to mention that I'm a mushroom farmer, so I've got several tons of spent straw and sawdust/wheat bran substrate composting or ready to be composted.

Would old hay be useful as mulch, as long as it's been sitting for at least a year, maybe two? A lot of neighbors down here seem to roll hay and then just let it sit there.

Yeah go hard with all of it. I chuck everything here at the pasture / herbage and it all disappears. My only hesitation is the sawdust which I'd spread a bit more thinly than all of the others. It can be quite acidic and in a thick layer will take quite a long time to decompose. How about getting some of those mushroom spores into it?

The old hay would be excellent to get onto the surface in late winter / early spring. Depending on how cold it is in your area. It is forst free here, so anytime is good. However, sometimes top dressings in much colder areas can keep the sun off the soil and slow the warming up process.

However, as a suggestion, I would throw all of that hay into the chicken enclosure and let them, turn it, eat the seeds and manure into it and then apply it to the pasturage. If you want to speed the process of decomposition even further, then if you have a slasher or mulcher get into it and break up the hay into smaller components. It is like turbo charging nature because you've increased the surface area.

The winter rains here combined with milder temperatures, tend to make the rounds (rolled hay) ferment and sprout when they are left out in the elements. This can be desirable for some species of farm animal.

Johnny Niamert wrote:Legumes contain lignin and cellulose. They build humus.

Even the quote you posted says so.

Well, to be fair it says that annual legumes are mostly succulent and nitrogenous, with only some research indicating otherwise. I've read some of that research and it's back and forth. Depends on a lot of other things, frequency of tillage and oxidation and such. Perennial legumes are another matter, altogether. But I agree, CJ, nice thread with good back and forth!

Thanks guys, this is helpful.

On the organic matter pools questions...
Brady & Weil 2008 conceptually divide OM into Structural C and Metabolic C (high N low lignin) verifying the concept of metabolic C not contributing to "Slow and Passive OM pools". However they state that "This active pool provides most of the readily accessible food for soil organisms and most of th the readily meeralizable nitrogen. It is responsible for most of the beneficial effects of structural stability that lead to enhnaced infiltration of water, resistance to erosion and ease of tillage." (sorry about the fast typing). However I suspect this kind of conceptual model might apply most strongly to systems that are constantly disturbed by tillage, such that soils that are less disturbed don't need the level of protection provided by big pools of metabolic carbon to create all the goo to rebuild soil structure... low/no till soil structure remains intact with lower metabolic carbon budgets. Shock grazing and root cutting from ripping/chisel plowing might have a similar effect in loading a recoverying soil with metabolic Carbon.

are these soil organisims fungal or bacterial?

A plow is a tool, no better and no worse than any other tool,
an axe, a gun, or anything.
A plow is as good or as bad as the man using it. Remember that.


Quote Dr Elaine Ingram

Tillage is very dependent on what implement is used. For example, a light raking is not detrimental at all to speak of, a single harrowing, same thing. A single moldboard plowing usually doesn't hurt soil life much to speak of, although the worms still usually head for the hills, and the microarthropds have to be convinced to come back.
Let's go to the other extreme – rototilling, and the damage using that implement is immense. We can often detect impacts of rototilling for 30 to 35 years, especially if nothing was done to rejuvenate the system after that rototilling.
Key line plowing can be minimally detrimental, although the shattering of the soil profile can make the worms and arthropods leave for a time.
The thing to be especially taking note of is how much the structure in the soil is damaged. A light till, little damage, may not pick up any significant change. Destroy the structure completely, massive damage can be detected.

http://www.youngfarmers.org/forum/soil/question-for-dr-ingham-1/

stephen sinnott wrote:are these soil organisims fungal or bacterial?

It depends. Usually both, but prairie/cropland is usually mainly bacterial and forest is primarily fungal.