Cover crops basics

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Hi,
Do we try to fix Carbon? Nitrogen? To enrich the soil? Or to structure it? Cover it? Do we try to limit weeding? … What are we talking about when we say “cover crop”?

I think we should create a resource page on the basics of cover cropping… Because cover cropping, when you look at the science behind it, and techniques already used, addresses many things at the same time. AND SO… is quite complicated to get it right first hand! for example, using the same vegetable mix, and same sowing timing:

  • if crushed a month or two before flowering you get only nitrogen, very small carbon fixing, very-very short term soil coverage (post crushing), and nearly no effect on structure… So it is more a fertilizer (=“green manure”)
  • whereas when crushed at flowering stage you get loads of carbon, a much better soil structure, a long term coverage, which will enable you to plant without adding any kind of straw or covering material, and eventually a better fertility…
    I won’t go into specifics right here, but this is just to say that, when talking about “cover crops” - and particularly in relation to fixing carbon, enhancing soil structure, fertility- we need to be precise and carefully understanding what we do.

Then, when you get to the basics, this becomes easy to handle.

So… first, I would love to share this video of Christine Jones, Australian soil scientist Christine Jones - Les communautés microbiennes des parcelles agricoles - YouTube
It is a video about microbial communities in soil, and changes in microbial diversity when you mix MANY varieties together, and how this eventuallywill enhance soil structure, water resources, fertility, etc.

You’ll get one of the few main principles : MAXIMISE the NUMBER of SPECIES in your cover crops!

You can go directly at 20min58sec to 30min22sec to get it straight: a story of a dairy farm settled on a permasoil in New Zealand.

From 30min22sec you will get more understanding : community tipping points, quorum sensing, critical densities, etc.

So, in my opinion: a very very interesting synthesis of Christine Jones researches… here summarising her understanding of what shook her first, in the field!

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I’ve seen that talk before but watched it again after seeing your post. I find it really inspiring.

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Christine Jones is great!!! But one thing I have never really understood is how to choose the species. Intuitively, you would want cover crop species that affiliate with the same types of microbes as your cash crops. The mixtures sold as cover crops are generally designed for farmers growing wheat or other grasses, either for human consumption or for pasture/fodder. For a vegetable garden, would you want cover crops that are more similar to the vegetable species you’re growing, like, for example … the arable weeds that are going to grow anyway, the minute you turn your back?

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HI @MashaZ , my intention is not to talk about companion cover crop, but more to talk about cover cropping BETWEEN your main crops: for example “winter cover crops” (from September to May here in my part of France, zone 8b or 9) , or from May to September for example, with other specifics like the Mustard/Daïkon one prior to planting onions in end February/March.

I don’t know much about companion cover cropping. I cannot tell you more about that.
If anybody knows more please do add some comments or links to videos, etc.

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Yes, that’s what I was asking about - what species to plant between crop seasons. What’s being sold here is combinations of oats, rye, rye grass, clover, vetch, etc.

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Here’s one possibility for sowing in late summer (now in our part of the world) as a cover crop with each botanical family on a new line:

Flax
Peas, fenugreek, broad bean
Mustard, kale, winter radish
Endive, lettuce, chicory
Chervil, parsley, coriander, dill, carrot
Corn salad,
Miners lettuce
Spring onions
Spinach, beetroot

The ground does not freeze here in winter. Most of the above will happily sit in the ground over our winter. I buy bulk seeds where I can but many are our own saved seeds.

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The western scientist in me, thinks – oh my – there’s so much to learn, and all this timing and all these choices matter!! However, the gardener in me is starting to tend much more toward trusting the soil life and the plants – they’re so much better at what they do than I am.

I’m going to try to explain what’s been on my mind. I think the biggest benefit of “cover crops” is to have living plants interacting with the soil life. (this ultimately creates all the benefits mentioned). A diversity of plants (across space and time) supports a diversity of soil life which supports my crop plants (which are also a diversity of plants interacting with the soil life). If you look at time as a mosaic as well as space – that is, companion planting has to do with space and cover cropping has to do with time – then the specifics of cover cropping might not matter as much as simply having something (or lots of things) growing. Sort of like how micromanaging the specifics of individual traits doesn’t matter so much in landracing the genetics of your crop varieties. Having plants, and better yet a diversity of plants, growing in the soil during times your “normal” food plants aren’t growing might be all you need. Having plants growing, without bogging down in any specifics, is like having just one jar of seeds per species.

Science, by it’s nature, has to be reductionist while it’s being performed – this sort of erroneously makes the details of timing, choosing plants, etc. seem like they’re very important. But they are most important under those controlled conditions. You have to structure and choose all these variables and controls very specifically in order to conduct the science in the first place, setting oneself up for missing the bigger picture. The results and details are cool and interesting, don’t get me wrong. Those scientific details are showing that we’ve been thinking of soil all wrong our whole western agricultural life. However, the big picture is that the soil life wants plants and plants want soil life. I think that letting them work it out over time while I, the grower, grows and eats and enjoys and supports all that life will work just as well as agonizing over details. This way, I agonize less over what and when to plant or cut, and instead plant when and what I can, and then cut them out of the way (if they’re in the way) when it’s time to plant the next crop. This seems to be working well for me. It doesn’t preclude observation and tinkering, but doesn’t restrict me to recipes created elsewhere under different conditions. The ecosystem and my plants seem happy, and my soil is making me happier and happier every year.

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Hi @HAnderson @MashaZ @RayS
Sorry Masha if I did not get what you say at first. I am not too bad but not fluent in English, so…
@heidi I get what you say and thank you for the details. I get all these specifics about science and reductionnism etc and thanks for putting that in these clear words. And I know how far we can be misguided by science, or also “in the name of science”, seemingly the new “God”… Starting from eugenism in the 20s: king science, in the name of saving the human species, sterilisation of the “feebleminded” first starting in California, then endorsed by all parties lines (at list theoretically) prior to Nazi atrocities, all in the name of science, or at least in the name of an applied logic: breeding science applied to the human population, of course channeled through the mindset of the powerful - and financed by them too… And that is just one far far away example!

So that is why I want get to principles AND giving the opportunity for those willing to go through scientific publications, field results, etc. Notably for those willing to see if blind spots there are. Sharing sources and resources. A logical chain is only as strong as its weakest link, so as we may be wrong, all those links can be shared, which does not mean that everybody will go through it, but at least some will…

Globally we loose soils and gardeners loose soils, and inter “cash crops” cover cropping starts addressing that main issue : regenerating - or at least not loosing your soils.

Going to principles is to me the thing to do: a hundred times more worthy than giving recipes, which may not be relevant in your place, if you want people to be autonomous.

And sure, the first principle is what you wrote: the continuity of life through the living plants:
“Having plants, and better yet a diversity of plants, growing in the soil during times your “normal” food plants aren’t growing might be all you need. Having plants growing, without bogging down in any specifics, is like having just one jar of seeds per species.”
Yes : 100% !!!
Without bogging down in any specifics, yes that is absolutely right : all soil life (bacterias, fungis, etc.) depends on living plants, then some on dead parts left. That is why it needs to be covered, by living vegetables.

I personally do not look at “science” prior to do gardening but find a few researchers very very inspiring, and tend to prefer some enlightened farmers to scientifics in general. Those are: Lucien SEGUY, Konrad SCHREIBER, Christine JONES and a few others, mostly french speaking. The reason why I am linking the video of Ch Jones is because her results are so stunning on such a poor soil, 5 months after this mixed cover crop for grazing… It is so crazy! The farmer had one of the poorest soil, his daddy and ancesters allways known it like that and then… just a few months after a highly diverse seeding, his soil changed of colour and structure… unbelievable…

Then she goes into the specifics (which may create boggus sure) and the things that I keep from this is:

  • the more species you put into your mix the better your soil life will be, because each plant tends to work with some fraction of the soil life
  • and once passed a number of species (10?) the results go crazy, the changes are dramatic: there is networking in the soil life happening that you do not have with just 1 or 2 or 3 species.

It could be revolutionnary, and much more practical than the Fukuoka approach, for example. And landrace gardening for sure is, to me, the corollary. I start landrace gardening on a soil not fertile at all, and will combine principles of regeneration of soils life with principles of landrace gardening.

In the global dire situation we are in, I am pushing cover cropping, with others. So to say: teaching sowing densities, timings and other technical things + doing group orders to ease the way for everybody. And it is not that complicated once you get the basics: from covering your soil with some living things, to maximising biodiversity, timings, etc.

@MashaZ for winter cover crops sown around the 15th of September I personally (and @isabelle) use two winter cereals (oats and rye), leguminous (faba beans, peas, vetsch, etc.), and one or two others like phacelia in small quantities. Since I understand what Ch Jones or Gabe Brown say, I will next year’s sow all the other winter cereals I will get my hands on (barley, subspecies of wheat) + adding crucifers and other families…

More on sowing densities, dates of sowings (with pictures of cover crops in my garden) and choices made in relation to soil fertility next…

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Yes, crazy indeed. It’s not clear what the tipping point is exactly. It seems the more species the better but it would be great to know if there is a ‘magic’ number. Another question comes to mind. Do we also need as many different plant families as possible? It would be fairly easy, for example, to find 10 species of leguminous plants (family Fabaceae) but this probably isn’t the idea.

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@RayS I remembered her saying to add as many different plant families as possible, which sounds logical as far as we know families tend to “work with” the same allies in the soil (fungi, bacterias, etc.).
Her website with all references is here: amazingcarbon.com
This page is fun : Who Knew? Cover Crop Cocktails are Commune Hippies | Sweet Bay Farm

… and then I listened to this video: "Secrets of the Soil Sociobiome" with Dr. Christine Jones (Part 1/4) - YouTube

Hear what she says at 29’14" “to get the maximum benefit from root mingling, you really want our plants to be in different families" then if you put "6 different kinds of plants together there is not a huge benefit of putting 6 different grasses together: if you could put plants from 6 different plant families then it is going to be much more beneficial”
(all explanations start at 27’)

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If you want to do a summer cover crop in some place of your garden, you can also buy a mix of seeds for birds : here in France you got in it many millets, amaranths, mohas, chenopodiums, peas, etc. etc. etc. so a really diverse mix of plants you would not even know where to find them if you wanted to sow them individually!!!.. just a tip

And then you could add sorghums, sunflowers, summer vetsch, etc… things easier to find

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@ThomasPicard Thank you for clarifying. I misunderstood principles for recipes. You are absolutely right that rebuilding our world’s soils seems to be vitally important. And, I also feel like at least it’s something that we can all help happen - it’s something we can do.

Christine Jones is wonderful and a great place to start! Her presentations are some of the ones that drew me in to soil biology. I am of two minds and hearts, I guess – all the details and science (which is fascinating and hopeful) and then the – I don’t quite have a word for it – essence, non-mechanistic – but whatever the word is, I see it as also what is underlying the philosophy of landrace gardening (which is also hopeful). It seems as though the genetics of landrace breeding will play an important role in boosting/reinstating these symbiotic chemical links between the plants and the microbiome that our yield- and chemical-focused plant breeding has destroyed – endophytes being an example.

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I wanted to share this webinar link for “Soil Life in Organic Farming: The Role of Soil Organisms in Soil Health and Resource Conservation”. Hopefully it works!

This is the direct link:2022.12.05_Soil Life in Organic Farming: The Role of Soil Organisms in Soil Health and Resource Conservation_0

This is how I got there to begin with in case the direct link doesn’t work. It’s listed on NCATT’s events page.
https://conservationwebinars.net/webinars/soil-life-in-organic-farming-the-role-of-soil-organisms-in-soil-health-and-resource-conservation-1/?sr=wp~ondemand

I thought this was a very good summary of the chemistry/biology of what’s happening between living plants and the soil life - the reason for planting cover crops. He also addresses plant diversity, humus-creation, and tilling rates.

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Brilliant idea!

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I arrived at that same conclusion some time ago. It’s fun to read about the mechanisms in play, maybe once in a while observe something that seems to match but I don’t have a microscope or a laboratory so all I really know is what the plants tell me.

I also pay little attention to cover crops or companion planting. There is pretty much always something growing, year-round. Sometimes I planted it, sometimes its weeds, it’s almost always all mixed up. An outside observer would see little rhyme or reason to how things are planted but the plants for the most part seem happy. I didn’t actually purposely develop my methods, the evolved mostly on their own, a product in no small part from my laziness. I was surprised as anyone that it works to fill the pantry.

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Hi,
I won’t try to convince anybody:
My vision is I am 100% in landrace breeding as much as 100% in all I can do to bring back life to soil.
To me tilling is a dead end as much as traditionnal heirlooms are.
I won’t choose between my two legs…
I would neither spend years defending landrace gardening on a cover crop forum… I would just say: “this is fantastic, and additionnal to what we do”… and go figure, look at Joseph book… which is exactly what I already do!
“off topic” : it is more to share what is to me an additionnal practice to landrace gardening, quite simple actually, which costs me 5€cent / year / square meter, and benefits the soil structure, water resource, fungi, bacterias, living things and eventually fertility…

So I’ll just be focusing on the few things to understand in order to do diverse cover crops between your main crops, from principles to what do we do tecnhnically. And adding a few links from farmers or scientists to understand these in a broader context, or to say if there is any bias, error, which could happen, as always.

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Thanks for the video, very enlightening. Explains why people have success with synthropic agroforestry/food forest concepts, for instance Mark Shephard with his STUN method.

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Great documentary! If i could get a tenth of thé results i’d be extatic!

I can’t grow Daikon radish. Parsnip will have to do. I have two types mixed and throw seeds about in thé beds.
For thé amount of seeds i drop i should sée a lot more adult parsnips. So i cherish these lonesome survivors and save their seeds.
Just to make a point, a principle as Thomas calls it. The principle being, how well do the covercrops germinate and live when thrown about. Do we not have to landrace our covercrops first? Or at the same time?

How to save seeds from thèse covercrops? Can we just harvest it all at once and spread it elsewhere to covercrop, or is an individual seedsaving approach better? Just go through the plot and harvest seeds of whatever happens to go to seed.
Why do i mention this? Because i don’t want to buy anything of nobody but especially from the agro-industrial complex. Ideally. And saving seeds from my soils will arm the seedcoats with beneficial bacteria anyway, spurring on soil inoculation with localized bacteria as an added bonus.

I move buckets of soil around as well now. If i go somewhere i collect a bucket and spread it on my land. Hoping something will stick. Anybody do that?

Another point i like to make. My girlfriend spotted wild leaks. They just grow in grasslands here a thousand kilomètres from where i live. I’ll post and ask at another topic later and more spécific, but it ties into this gigantic topic. It survives no watering and competes with grass. It makes small bulbs, just like some of my leaks only a lot more. I think it will flower as well. So i can get them into my leak grex. Rewilding my leaks genome.
I am in that way in principle adjusting leaks to behave as a better cover-crop. I am cover-cropping my landrace. Ha!
Sorry language purists!

I don’t like vetch, it ties everything, inviting molds in my opinion. But peas are in this group. So that will cover that family, i’d say. We’re maximizing family groups. Anybody a link to a handy oversight website covering family groups?

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I’d highly recommend every Gabe Brown YouTube video.

What are your resource concerns?
What plants can help deal with the resource concerns?

If you don’t know what your resource concerns are then you’ll just be planting alot of seeds and not seeing specific improvements.

Let’s say you have tons of litter on the ground from past years. Straw mulch, corn stalks, plant remnants, etc. You have carbon on top of the soil that isn’t being cycled. You need green material and nitrogen to be able to deal with it. Brassicas, legumes,… What is going to be very leafy and break down quicker? Like a compost pile you have lots of brown and not enough green.

Now if you have bare ground and all the mulch you’ve put down is quickly breaking down… the previous bit is only going to exacerbate your situation. You need carbon protection and microbe food. You want less green and more brown. More stalk and stem and dry material to cover.

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My main resource concern is water. There’s rarely enough water in my ecosystem. Are there any cover crops that are particularly good at keeping water in the soil for summer crops that follow?