Truly Effective Cover Crop Management

Good morning. I have a back yard garden, the annual portion of the garden is 300 sq ft divided among 7 raised beds.  I have a bit of additional room in large containers.  Maintaining soil quality and fertility is a struggle. I would prefer to use as little exogenous, bona fide fertilizer as possible. Mulching is great, but leads to a lot of bugs and slugs. Composting is great but is mostly about soil texture and soil biology than truly maintaining fertility.  I love to use manure but being urban bound, it requires just as much time/fossil fuel/hassle or more so than "fertilizer".  I have tried a few other things such as doing a "fish rotation" where I bury invasive carp acquired through my bowfishing efforts, but that requires a significant break in the garden space usage and does no favors to the soil quality because it requires lots of digging.

As such, cover cropping is an obvious approach and there are multiple benefits (added nutrients, organic matter, enhanced soil microbiological activity, decreased off-site transport) all the stuff we know about).  It does require me to "lay fallow" a garden bed or two, at least for a period of time while the cover crop grows. This eats into my food growing space.  Also, it is known that highest modulation of the nitrogen fixers happens as the plants get larger and ready to flower.  This means I either keep the cover crop in place for a good portion of the season or do a quick rotation and not get nearly the nitrogen I could.  There seems to be a lot of "grow cover crops, they are good" info out there but a paucity of info about their most effective time:space:nutrient gain in a garden setting such as mine.  Thoughts? Suggestions? Resources?

As a side note, two things.  First, I am going to seriously take on a project of making fish hydrolysate from the aforementioned carps.  This approach might truly be the panacea I need to maintain fertility.  Good nutrient ratios and the hydrolysate is said to enhance soil microbiological activity.  Second, my municipality finally has allowed chickens to be raised in the backyard setting.  This means I can include a chickens as rotation through my garden beds to control insects under mulch and add some fertility.  How long would five chickens need to be on 40 square feet working through mulch and weeds to increase actual fertility through their self-application of manure?

Hello,

There are many variables that will influence an answer. I do not know of any panacea.
What is the climate in your area ? The nature of the soil / dirt you are dealing with ? How is your growing season, what do you intend to grow and what is naturally occuring in your area ? How are nearby gardeners doing ? How much water do you need or store, when and where is it flowing ?

I would think about fertility first, before even planting your first crop. What (ideally perennial) nitrogen fixers do you have, what dynamic accumulators are growing in your area (comfrey, dock, thistles, dandelions, ...), what is your mulch source and when do you harvest / apply it ? What is your rotation, is it possible to intercrop pulses for nitrogen ?

Are there trees or hedges you could use for mulching in winter without compromizing your growing space, then rake the mulch in spring before you plant to expose slugs to every bird's eyes ? Do you have snakes when it is dry, or ducks / toads when it is moist ?

For chicken, I would say 'as long as the ground is fallow'. They will uproot everything they find, and their manure will burn the rest. Typically in autumn/winter after your last harvests.

Have a nice evening,
Oliver

I am no expert and have not used cover crops except for erosion.

Making and using compost, having access to wood chips and fall leaves, using compost tea, growing mushrooms might outshine cover crops.

I would recommend these from Dr Bryant Redhawk's Soil Servies:

https://permies.com/t/63914/Soil

https://permies.com/t/67969/quest-super-soil

https://permies.com/t/76498/biology-soil

https://permies.com/t/120453/Great-Wood-Chips

For small raised beds the slug problem with mulch is real, especially in wetter climates. One thing that helped me was switching to comfrey as a chop-and-drop rather than a traditional cover crop. It doesn't create the same damp mat that slugs love, breaks down fast, and the deep roots pull up minerals that surface composting can't reach. You can cut it several times a season and just lay it between plants.

My 'cover crops' are my vegetables. One easy suggestion is to buy a bag of beans in the supermarket and plant them all. Let them completely cover and smother the entire surface. So you get the benefits of nitrogen fixing but you also get useful food. No lost space. No lost time with beds out of production.

I sometimes use lettuce as a very early spring cover crop. In the fall I clip the dry stalks and save them in paper bags. In very early spring, February this year, I scatter the seeds thickly all over the garden. Once the hard freezes are gone the lettuce quickly sprouts and buries the garden in thousands of lettuce plants, a complete dense mat of lettuce that smothers most weeds. Very easy to remove if you decide later to plant something, and it makes excellent mulch. We are now eating the lettuce I sowed in February.

Squash also makes a great cover crop, though later in the year. Plant now, May to June and they will bury your garden. The goal is to have a heavy cover crop while not taking the garden out of production.

Anything that can conveniently be planted in beds rather than rows can be a good cover crop. Beets, carrots, turnips, lettuce. Broadcast the seeds rather than planting in rows to completely evenly cover the surface.

You have essentially what's called a "kitchen garden." My kitchen garden is 16 beds in a 40'x40' fenced in area (fenced to keep the varmints out.) The only really effective cover crops I can utilize in that space are winter rye, or winter rye with hairy vetch, and/or winter field peas. I can only use those on beds that will be planted in warm weather crops, such as: tomatoes, peppers, squash... Most of my other beds I want to be available for late March, early April crops, and winter rye needs to go until mid-May before I terminate it. I will sow buckwheat in between other crops however; buckwheat is a warm weather cover crop and improves soil tilth.  

You say you have clay/loom soil. That should be perfect for growing annual vegs. It seems like you're concerned with nitrogen mostly; is that right? What seems to be your particular issue? Do you see your plants suffering for a lack of N?

You say "Composting is great but is mostly about soil texture and soil biology than truly maintaining fertility. " I assume you mean that veg only compost has less nitrogen than animal manure compost; while that's true, veg compost is all I use, since I don't have animals and I don't bring any manure in from outside, and my plants do exceptionally well with it.

Nitrogen will be fixed by microbes, both on the leaves and stems of your plants, and in the soil. Use coffee grounds, and urine to boost N if needed.

I like your idea of making your own fish hydrolysate, assuming the carp comes from clean waters ( clean as in no excess harmful chemicals.)

Clay soil is full of nutrients, but it's usually locked up unless there is soil organic matter and microbes present. I would use compost, compost tea, tea and JADAM JWS to increase the soil biology, Soil biology feeds your plants directly, and also builds soil structure and fertility. When microbes have a flush in population, some will go dormant, and some will die; billions of dead microbes are necromass and that dead microbe load adds fertility to your soil in many ways--too much to talk about in one post.

How is your worm population in your garden beds?

In the beds that I am going to need to plant in early the next season, I usually prep them in late fall after a few frosts, assuming I don't have parsnips or carrots wintering over in them. I will cut dead veggis at the soil surface and keep the roots in the soil, and then add compost to the top and mulch with tree leaves, left over straw from my winter rye, or plant material from chop and drop. I will them add kitchen scraps, coffee grounds, et al right under the mulch in a compost in situ sort of manor. Come the next spring the beds are ready to plant into. I chop and drop weeds all season,

I see you have problems with slugs and mulch, I don't really have too many slugs so I can't offer too much; except I use in ground beds, not raised. I also keep small piles of sticks and rock piles around for ground beetles. Ground beetles and birds eat slugs.

Hopefully some of this rambling might help.

I found a winter cover crop.. It's medicago Arabic a, it grows in winter, very slowly and then in spring it explodes. Easy to spot the center and cut the biomass with seeds. It goes around  high plants instead of trying to suffocate them.
In the picture 5 minute job getting space ready for bush beans. Lots of root nodules are left in the soil. Great for the next generation of nitrogen fixers.

Pic shows sunflower, lettuce, arugula etc. All broadcast or volunteer. There are a bunch of other things growing here and there. Tomatoes, mint, horseradish. Goal is 100% coverage. Only trick is finding places to put my feet.