How to deal with slugs/crimping a cover crop

[copied from the Thinkific community]

2022-09-30T07:00:00Z
Slugs may not always be a problem if you go to the source of the problem: what they prefer to eat!
My friend, who has been cover cropping for nearly 10 years has no problems with slugs, even when he transplants a thousand young salads in the soil. Why?
Once his cover crop is down on the ground (in march, end of may, or end of august, depending on the cover crop mix), moisture develops, mould, fungi, and what slugs absolutely prefer? rotten vegetables. That is what they like most. They digest what has been decaying and will eat salads only if they have nothing else to eat, or if it is sick. One or the other.
He did not know that, he just saw it, and then went back to specialised libraries, and it was very clear, black on white: that is the normal slug biology.

Here in my part I here frequently people having problems with slugs, and - them willing to hear me or not! - I allways say the same thing: aren’t you putting the very thick and strong wheat straw on some kind of desert, right in the springtime, when the slugs wake up and are looking for something to eat? So it is frequent to hear “yes” to that question.
It seems to be a vicious circle until you get to these basics, which are
 untold!

I just join a picture of a young “winter” cover crop made from rye, barley and then (sorry, in french!), pois, vesce, fĂ©verole. Around the end of may Rye will be at least 2 meters high, with a huge root system (one third of its biomass) and I will put it to the ground, let it decaying, and then transplant nearly everything in it.

So you see it looks like putting some straw on the ground but it is not: you always keep vegetables alive in the ground, and rye and barley have huge root systems which you won’t see and will decay too, and be diggested, etc + the nitrogen fixing vegetables.

Starting on a poor soil it is good to start at one dosage/ha of cereales and one dosage/ha nitrogen fixing plants, then, as the soil biology improves, and as everything gest eaten faster by the soil biology itself, you will add more cardons and less nitrogen. For example my friend, who started cover croping in 2014 on one of we worse soils (acidic and hydromorphic), has went from this 50/50 mix to nearly 90/10.

The only drawback of that system is that the soil gets warm later in the season, so typically you will get tomatoes in greenhouse by the end of july when others have them by the end of june. Apart from that the soil structure and the soil fertility improves every year, without having to import many things

And I think landracing is a way to start getting vegetables really adapted to this system, happy to collaborate with fungi, endophytes, etc

the other drawback is that it is more about transplants than direct seeding. but it may change, because we are working on it. First field test with corn this year : it work as “direct throwing” into the cover crop, prior to put it on the ground. Nevertheless the smaller the seeds are the more difficult it will be, due to the thickness of the material once on the ground. my friend uses machete for carrot direct seeding, so it is quite labour intensive


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Wojciech G
I have solved entirely slugs problem in my garden using two methods together. First one was to place some objects on the ground where slugs hide for a day (like an old wooden planks). Every morning I was checking under them and collecting slugs. Second one involves an UV flash light. I was going for a walk when it’s been dark, slugs (and caterpillars, like tomato hornworms by the way) are glowing in the UV light, so it has been very easy to pick them up from plants. After systematic use of these two from the start of the season, I no longer have a slug problem. I know that this is not possible for large areas, but for small gardens like mine it works wonders.

hugo m
Love your winter cover crop Thomas!
So to pût it simply, you feed them. But the rotting plants feed your soils, which feed your plants.
And the snails prefer the decaying plants.

It dépends on the years whether i expérience problems.
It can change within two weeks as well!
The snails became slow and dissolved this year i noticed. Disease
 They did no more damage after.
I work at a farmer who had loads of covercrops. Sée if hé can give me some seeds.

I harvested quite some alfalfa seeds today. Which is rare on the granity soils where i live. It s some old variety.
If you or someone is keen?
I’ll post a picture later

Justin .
I really love that idea of the cover crop to deal with the slugs! When should we plant it? I have now been given permission to plant in a large garden, so I am hoping to learn what I should do to the grass lawn (take up the turf and turn it upside down then distribute the cover crop seeds? Or
) and when (maybe too late for Winter cover crop already?), to prepare for lots of TPS potatoes and tomatoes and a few other things. I’m in South West UK and on clay soil, the grass seems healthy. Any advice on this would be much appreciated!

Thomas P
Sorry for the mistake: I don’t use rye and barley but rye and oats in my cover crop

Ji @Justin . , it’s the best time to saw cover here in south west France, so I think you can still saw it in south Uk. My deadline here is prior to the 15th of november. I will have to create a specific post on this topic, because it is quite technical. It is all inspired by Fukuoka but adapted to our climates and a lot more precise than all he said.
To put it in few fords: and for “winter” cover crop:

  • Till once and for all
  • saw manually a mix of cereals (oats, rye) and leguminous plants (peas, vetch, faba beans), and you can add a few others that will flower at the same time
  • consider dosages like this: on a fragile/poor soil a 50/50 mix : 1 unit of cereals and 1 unit of leguminous plants. For example my “recipe” for this year :
  • cereals: 1 unit, share between 60% of rye and 40% of oats: as the rye I am using should be sawn at 50kg/ha when pure that means my dosage is 60%x50kg/ha=30kg/ha. oats should be sawn at 100kg/ha when pure so 40%x100kg/ha=40kg/ha.
  • leguminous plants, same logic, at 33% each (for me, and for this year): winter peas 80kg/haX33%=26,5kg/kg/ha, vetch 50kg/haX33%=16,5kg/ha, faba beans (special variety, not the one we eat) 150kg/hax33%=50kg/ha
    -recover slightly with straw or some organic material and
 let it rain!
  • by the end of may all these species are flowering together, you get the maximum of biomass and it is time these plants are the most fragile: you pull them down with a special tool very easy to fabricate, and then you can start transplanting.
    So you go from perennial to annuals: then the thing is to not let the annuals come back too strongly, so it may be a good idea to cover crop multiple times (winter AND summer cover crops) prior to cultivate vegetables: the more dense AND high the cover crop is the more fertile and “ready” your soil is.
    As years goes by, the cover crop grows denser and higher,AND it’s “diggested” faster by all the biology (fungi, bacterias, slugs, etc), so you add more cereals (straws and roots dense in carbon) to your mix in order to not let the soil “naked” by the end of the season, which will lead automatically to the come back of the perennials, which you have to weed manually, or using a temporary plastic tarp
 something that nobody likes.

So you see: may sound a bit esoteric at first, but then very logical process, and progresses.

@Julia D : I will try to do small patches for reproduction next year. By mid november I will have implanted a field test with about 50 to 80 varieties of different cereals I am getting from laboratories, farmers and french ngos. They are nearly all landraces: wheat, rye, oats, barley, and also spelt, emmer and einkorn.
I will saw from 100 to 200seeds of each varieties on places of about 1square meter, and will be looking for:

  • soil cover (how fast and how dense it grows prior to the winter)
  • how early it flowers (the sooner the better to implant cultures)
  • how high, and how heavy straws are, and how strong the root system is (the bigger the better)
    Then next year multiply the best and then little by little a more diversity-rich miw of cereals.

@Justin . :as it is be a bit late in season to bring all those species together, you may try to find one cereal and one leguminous plant, for example one rye and one vetch: use the dosage as indicated as if they were sawn and see what happens. It is quite a soild and land dependant approach, you may or may bot find it convenient for where you live.
As my friend Yann says: don’t start too big, a few square meters may be good to start seeing by your own eyes what happens, then if you like it, amplify. As a reminder and to see how good cover crops looks like at flowering time when the soil start getting rich enough I repost this adress: Photos - Site de lesjardinssauvages !
These photos are a few years old, cover crops now are higher (winter : 6 to 7 feet, summer: 8 to 12 feet) and denser

these were mine by the end of may this year. As you see rye is high: I am 6,5 feet tall. It would need to be a little bit denser to properly cultivate without having to weed too much throughout the summer season

and this is the tool I am using, it could be much shorter, and lighter. A patch of one hundred square meter was done in a quarter of an hour using that tool

Justin .
@Thomas P thanks for all the info! Wow I really have to hurry then! I’m also wondering, is end of May not a bit late for planting out potato and tomato seedlings? And, if I wanted to plant them earlier, can I just pull the cover crop down earlier?

And, regarding tilling, as I have no equipment, do you have recommendations of how to do that? And, is just turning the grass upside down (cutting the top layer, ‘turf’, and turning it so the grass is pointing downwards into the ground) a bad idea or is that a good substitute for tilling? Many thanks!

Oh and if anyone in the UK has suggestions as to where to get seeds for such cover crops in a hurry, I would be grateful to hear about it!

Debbie A
Hello, Thomas! Do you sow the next crop before flattening the cereal so that the seed will be covered? Do you have a video showing how to use the tool? Thank you for sharing your knowledge, especially the ratios of cereal to legumes.

Thomas P
@Justin . for your tomatoes and potatoes seedlings I think- but I am not absolutely sure in your place - it is not too late : for tomatoes it is ok, potatoes I don’t know. the thing is more to get big transplants, not small transplants, because the cover crop on the ground is quite thick.
Then: regarding tilling, I don’t know exactly what you will get doing that, personnaly I would ask neighbour for an appropriate engine, or, on a very small place, do it manually, with a traditionnal tool.
@Debbie A : yes the ratio is the most essential part most of us don’t know, or don’t get. I should add that - of course - you can add other vegetables (for example crucifers), but be careful with the flowering time: when a plant flowers it’s the moment it is the more fragile and the less likely to grow again, from the ground (bad bad scenario!!!), so it is better not to flatten it prior to flowering time.
I will find a video using the plank, but not shure I can upload it. Actually: with the tool you flatten AND HURT the cover crop: that helps bringing it to decay. See this rolofaca video: it is not cutting but hurting the plants
Rolofaca 4m - GREGOIRE AGRI - YouTube
Otherwise some plants grow again from the ground

@Debbie A :
I sow a summer cover crop prior to flatten the winter cover crop. From this year we know we can do it with corn. And actually (that will sound crazy but that is true :slight_smile: ) my friend throw potatoes at the appropriate density and then and flatten the cover crop. He has been doing it for 6 years, yields are OK. For the rest of it, we will do tests, from next year on. I think landracing will help selecting for vegetables that will germinate, go through the cover and then thrive. i think that will do with big seeds, and don’t have to much hope for little ones such as carrots

Debbie A
Thanks for the video and explaining the process. Have you tried broadcast sowing of seed into the stand of cover crop before flattening it? If I recall correctly from Fukuoka’s One Straw Revolution, he would sow seeds for the next crop just before cutting down the current crop’s stems which would act as mulch protecting the seed.

Debbie A
I would like to try alternating a winter cover crop with a summer crop of squash, hoping to also suppress some weeds in the process. Thank you for starting this discussion. Good stuff.

Justin .
Thanks again Thomas. And that sounds cool about throwing potatoes like that! Do they still end up growing underground or does he get a lot that are becoming green because near the surface? Also I would love to hear how you deal with that, like do you bury them then dig the soil to heap it up on the potatoes?

I look forward to that post you will post about this, your work sounds so interesting.

Thomas P
Potatoes just fall on the ground and then grow from this point, so you get some green ones, but you can reuse them next year as seedlings.
And actually, potato done like this is the only vegetable dependant on bringing some more straw or hay, at about 250g/square meter. Which we do not like. Because otherwise, the cover crop is digested too fast: you get too much weeds and too much green potatoes.
By the way, we have loads of colorado beetles in France, which we have to find and kill manually
 For all those reasons, and because potato is so cheap (yet!) we do not like too much cultivating potatoes: too labor and input (hay) intensive

@Debbie A if you want to do cucurbits first year without having a dense and high enough cover crop, or if you want or need to start directly from a meadow without tilling it you can consider reusing a plastic tarp around mid march and then plant around the 15th of may (that is my timing here in south west France nearby the Central Massif). By mid septembre you get your cucurbits, and can sow your winter cover crop. This is what I am doing reusing plastic tarps from farmers around my place: they use them for silage just one year, then have to recycle it: that is when I come
 See the picture here (my patch of moschatas), shoot on mid June, by the end of June you cannot see the plastic anymore, soil is entirely covered by vegetation. So no watering, I just added a handful of manure per plant and holes were implanted at one meter in every direction.
Another alternative: if you do cover crop this winter and your cover crop is not dense and high enough by the end of may you will have to bring some hay, from 500g/m2 to 1kg maybe. Otherwise it will get too weedy.

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This is good advice!

I’m not planning to do a cover crop, per se, but what I’m planning to do is similar. I am actively looking for edible crops I can sow in late fall and have grow through the winter for me. Cover crops tend to be the first place I look for ideas. What I really want is plants that can grow through the entire winter and spring without dying, and then I can harvest seeds and pull them out when it’s time for my warm weather crops. So, ideally, there won’t be much rotten material in my garden beds other than the deep wood chip mulch I want to put down.

Finding out that this is a good approach to deal with slugs is very encouraging! I haven’t seen any slugs yet, but I saw loads of snails last year, and they’re basically the same thing.

The UV light trick is intriguing. It may be worth buying a UV flashlight to go out in the garden during the late spring after a rainstorm, and look for snails to crush with a rock. (That’s my usual go-to method. It works.)

I’m revisiting this post because of problems I’ve been having with snails. Wish I had reread it earlier. Snails decimated my first sowing of moschata seeds, leaving only two seedlings. There are fresh lettuce and pea plants, but not much rotten material. (I’m surprised they are not eating the lettuce.) I will have to keep this in mind and plant some sort of cover crop this fall in preparation for next spring. In the meantime, I’ve gone through the beds and picked up as many snails as possible, sowed more moschata seeds, and have been going on nightly walks to keep them in check. So far, so good.

@ThomasPicard Thank you for the advice about using plastic tarps. I live in a residential neighborhood, so unfortunately, I think my neighbors would be rather unhappy to see the tarps. I’ve set down soaker hoses in my ‘meadow’ and cut down the vegetation next to the hoses. No tilling. I planted a variety of cucurbit seeds that have come up now. I hope some will be strong enough to compete with nearby vegetation, although I may have to do a little mowing to help them. Am I being too optimistic?

A thing that i did when i had European field slug problems, in the morning and evening i would collect slugs in a five gallon bucket with about two gallons of soapy water in it. Put a lid on the bucket and leave it in the sun. Keep adding slugs to it. It becomes a rather disgusting slurry in time. Apply that around your plants, using a watering can. The slugs don’t like it, they will avoid going there. It makes a good fertilizer for the plants, too.

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