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Do low growing, nitrogen-fixing cover crop companions help or hinder?

 
dan long
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The cover crop that comes to mind is low-growing, annual, preferably winter killed clover. One would broadcast these either after vegetables are established or just before transplanting vegetables (making it much easier to rake the seeds into the soil).

Advantages: nitrogen fixing, weed suppression, beneficial insect attractant, moisture retention?, suppressing splash up onto vegetable leaves, biomass generation, trap crop for symphians, shading (for those who are growing mushrooms alongside their vegetables).

disadvantage: competition for water, competition for nutrients (pretty much everything except for nitrogen), decreased air circulation

The advantage of low growing cover crops is that they wont compete for light so long as their companions are tall enough (not necessarily a great companion for strawberries or lettuce) and annual/Winter killed means that they will be much easier to smother or turn under.

However, do the advantages outweigh the water and nutrient competition? The downfalls of competing for water are surely going to depend on climate (this is probably a less a problem in the PNW than it is in southern California). That being said, air circulation is more important in the PNW that Cali. Perhaps this is inviting mold disease in humid climates and drought in arid climates? Perhaps one could do this in the rainy season but turn under or smother the clover before the dry season. I see no way around competition for nutrients aside from adding extra fertilizer/compost which really cancels out the advantage we get from nitrogen fixation.

Im thinking that tall or vining, nitrogen hungry crops would be best suited for such a strategy. tomatoes, corn, amaranth, quinoa, kale, cabbage, pumpkins and squash all come to mind as well as anything that is trellised. I imagine that this would work exceedingly well in Three Sisters, sown 2 weeks after beans and squash and 4 weeks after corn.

I can't really think of a way around nutrient competition. At first i thought the competition probably wouldn't be THAT intense, but then i thought if it's a non-issue then why would low growing dandelions or plantains stunt vegetable growth if they are growing during the rainy season and aren't blocking sunlight? I can come up with no answer other than: intense nutrient competition.

What's your two cents?

 
R Scott
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Location: Kansas Zone 6a
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Bare dirt loses moisture and leaches off nutrient if it does rain. So it isn't a dichotomy (but it seldom is, is it?)

The moisture thing is very close, depending on weather and soil type. A cover crop usually uses a little more moisture than bare dirt, but it is increasing the soil holding capacity so it is a net gain over time.

Usually nitrogen is the one your focus crop really needs--the others have a surplus that can be shared.
 
Charles Tarnard
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Location: PDX Zone 8b 1/6th acre
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In places where I've adequately thinned, the intercropping has worked rather well. In places where I just let the stuff go like mad, they can choke out the plants a little.

I have buckwheat that I thinned (thought I removed) when I seeded a bed and they are all living happily together in a jungle of craziness. I have crimson clover that I only just thinned in a few other areas and things struggled there. I have some spring peas in places other places and they can be a problem because they're pretty grabby. If you try to thin the peas, they like to take things with them.

If you provide some decent space, or really let your actual crop get a good head start you'll probably be fine. I don't think two weeks will be enough lead time as most of my covers grew faster in their early stages than the crops they were planted around.
 
dan long
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Charles Tarnard wrote:In places where I've adequately thinned, the intercropping has worked rather well. In places where I just let the stuff go like mad, they can choke out the plants a little.

I have buckwheat that I thinned (thought I removed) when I seeded a bed and they are all living happily together in a jungle of craziness. I have crimson clover that I only just thinned in a few other areas and things struggled there. I have some spring peas in places other places and they can be a problem because they're pretty grabby. If you try to thin the peas, they like to take things with them.

If you provide some decent space, or really let your actual crop get a good head start you'll probably be fine. I don't think two weeks will be enough lead time as most of my covers grew faster in their early stages than the crops they were planted around.


The advice about 2 weeks not being long enough is particularly helpful. That will proabably save me from a REALY bad year.

How does one thin a cover crop? It seems impractical to get down on my hands and knees so that I can pluck out the straglers the way i might with lettuce.
 
Charles Tarnard
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My space is very small, so that is exactly what I did. I did scythe the cover crops once or twice, but once I had plants I wanted in there that became pretty impractical. Scything was pretty much the same as mowing the grass, the peas and clover were hardly phased by it and only needed a few weeks recovery time.

I won't be using cover crops again during the growing season the way I did this year. If I do use them again, I'll wait until I see my crop seedlings establish then mix them in in a much lower concentration. My plan now is to use them as a place holder for beds from late fall through winter.

Just re-read the OP edit::: Where I live, there's no need to rake the seeds into the soil. If the soil is ready, the seeds of clover, buckwheat, and peas will put a root in it.

 
R Scott
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You can be a lot less surgical with cover crop. Any long handled weeder or corner of a hoe.
 
Charles Tarnard
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Here's a pic of my buckwheat bed and another bed that was dominated by peas.

The buckwheat was almost completely cleared before seeding and the peas weren't. The corn and quinoa I planted in the bed with peas never came up. The pumpkins and cabbage are doing alright, but we finally broke down and cleared the area. We'll see what the change does.

This isn't a perfect comparison, the buckwheat bed gets way more water and different sun conditions, but the peas never seemed to mind the different conditions.
KIMG0265.JPG
[Thumbnail for KIMG0265.JPG]
Buckwheat interplant
KIMG0266.JPG
[Thumbnail for KIMG0266.JPG]
Peas domination.
 
dan long
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Charles Tarnard wrote:My space is very small, so that is exactly what I did. I did scythe the cover crops once or twice, but once I had plants I wanted in there that became pretty impractical. Scything was pretty much the same as mowing the grass, the peas and clover were hardly phased by it and only needed a few weeks recovery time.

I won't be using cover crops again during the growing season the way I did this year. If I do use them again, I'll wait until I see my crop seedlings establish then mix them in in a much lower concentration. My plan now is to use them as a place holder for beds from late fall through winter.

Just re-read the OP edit::: Where I live, there's no need to rake the seeds into the soil. If the soil is ready, the seeds of clover, buckwheat, and peas will put a root in it.



Its too bad to hear that the quinoa and corn didn't make it. Maybe this is acceptable with vigorous plants like your pumpkins but not so much with others than cant tolerate the competition.

It almost makes me wonder if it might not be LESS work to forego the living mulch and just cultivate the weeds the traditional way then just undersow the cover crops after the very last cultivating like everyone else does it. Dont fix it if it aint broken, right?

 
Charles Tarnard
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I have corn and quinoa, just not in the beds that had a heavy cover presence. I'm still pretty new to most of this myself so these tempered successes are still wholly acceptable so long as they're providing educational opportunities.

There is a lot of merit to the idea of foregoing any covering until your crops are in. My best areas have the no cover crop, but they also have no competition from grasses, so it's a balancing act between smothering the grasses and smothering your crops.
 
Peter Ellis
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Location: Central New Jersey
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On the "competiton" issue - it seems to me that I have read a number of discussions about how much plants benefit one another, rather than compete with one another where nutrition is concerned. Certainly watching Skeeter's videos, he is pursuing maximum photosynthesis, covering every inch with living plants as best he can.

I am under the impression that thorough vegetative cover saves more in terms of water than may be lost due to competition among plants.

I am currently operating under the theory that the only problem area of competition is sunlight, and so you want to plan for layers that can manage well at the layer where they will fit in your planting scheme. The other concern would relate to climbing tendencies and making sure climbers are matched with capable support plants. Don't really want the peas pulling down the rye, for example, but they might do well with jerusalem artichokes or sunflowers - probably need to give support plants a good head start too.
 
dan long
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Peter Ellis wrote:On the "competiton" issue - it seems to me that I have read a number of discussions about how much plants benefit one another, rather than compete with one another where nutrition is concerned. Certainly watching Skeeter's videos, he is pursuing maximum photosynthesis, covering every inch with living plants as best he can.

I am under the impression that thorough vegetative cover saves more in terms of water than may be lost due to competition among plants.

I am currently operating under the theory that the only problem area of competition is sunlight, and so you want to plan for layers that can manage well at the layer where they will fit in your planting scheme. The other concern would relate to climbing tendencies and making sure climbers are matched with capable support plants. Don't really want the peas pulling down the rye, for example, but they might do well with jerusalem artichokes or sunflowers - probably need to give support plants a good head start too.


actually, since writing this post, my garden has gone through a very hot dry spell and the only place where plants don't exhibit major water stress is one section that is overgrown with weeds. There are not short weeds either, they are twice the size of everything in that bed except for the corn (I causally sowed some leftover seeds of many varieties). I strongly suspect that the weeds sent some taproots down into the compacted soil and the vegetable roots followed them down. Furthermore, I saw one of two bees i have seen this year today hovering on the flowers of these "weeds" (I live near lots of rice paddies that are regularly sprayed) and I found 3 radish plants that escaped the cabbage moths by hiding under the "weeds".

I am pretty confident that a permanent living mulch would be nothing but beneficial now.
 
William James
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Location: Northern Italy
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dan long wrote:
I am pretty confident that a permanent living mulch would be nothing but beneficial now.


I'm pursuing the same dragon. Trying to come up with species for perennial living mulch right now.
http://www.permies.com/t/38256/permaculture/Polyculture-design

William
 
jimmy gallop
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Every year I plant at least one garden randomly with different stuff some years do better than others.
I always scatter corn,sunflowers,sorghum,okra,and flowers in my regular garden that is planted in rows.
Just enough to provide some shade and diversity for insects.
Plant some sorghum and watch the many different kinds of bees come to sample it.
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