I’m always writing about perennials and no till, but I actually do a lot of annual gardening. My family’s farm has a CSA for about 20 shares that uses about 3 acres of tilled gardens.
Mortal Tree is my exposition on alternative methods, so of course I wanted to try growing annuals in a passive, no till setup.
That’s what the keyholes at the front were supposed to be; with perennials thrown in for propagation, and greater efficiency.
After two years of the first “system” (or lack thereof) there are two problems: lack of fertility, and weeds. Of course everyone has those problems, but the system was supposed to keep these to a tolerable level.
As it is, aside from mache, annuals just aren’t satisfied with the fertility. This year I didn’t harvest anything but what the perennials willingly supplied.
Ideal weed level is pulling a few weeds as I inspect the garden on a pleasant evening. Instead, I found myself clearing whole beds only to have them full of weeds again in a month.
I’ve scrutinized the system and found two problems: lack of mulch and lack of fertility in general.
The year of high fertility
I got the idea I wasn’t cycling enough nutrients from the lack of vigor the annuals and their self seeding progeny showed. I wasn’t sure how much more I needed. Normally the tillage and compost in the big gardens makes everything grow without complaint. Now that I’m trying to make this work with comfrey and other in-system nutrients, without tillage, it’s not.
Martin Crawford has several tables in Creating a Forest Garden that really pin down nutrients and how much different plants need, and how much different sources offer. He has a light, moderate, and heavy cropping category, then annuals.
Most of the perennial vegetables he places in the light cropping category. It takes about two cut comfrey per square meter to sustain these plants, which is about what I am applying. To sustain annual cropping takes 60 cut comfrey for that same area. Problem found.
The amount of fertility I’m accustomed to working with in the annual gardens is simply an unnatural surge of nutrients. Compost is extraordinarily rich in nutrients compared to bulk green mulch.
Also, tillage forces more oxygen into the soil, breaking down those nutrients at a faster rate. The keyholes had this advantage at first because I dug out the paths and piled up the soil to make the beds.
Problem is, the mulch apparently needed for the annuals would drown most of the perennials. In response I’m moving all the perennials out, and making the keyholes completely annual.
The best comparison I have for this so far is a keyhole bed I have near the Willow Garden in its fourth year of no till.
It has a dug out path and raised beds too. It has one comfrey for its mulch and fertility source. As a result, I’ve had to bring in more mulch to sustain the system.
For instance, I brought in a lot comfrey from the Willow Garden to drown out some quack grass (Agropyron repens) that had moved in. It was rather effective at suppressing it. Besides some vegetable mallow over the summer, it was enough to grow some nice cabbages.
In the food forest, I’m not supplying 60 cuts of comfrey per keyhole per year. I’ve got 12 beds with an average of 1.3 square meters each. It would take several hundred plants.
When faced with a large surge of energy in a design, I always try and disperse the blow across many sources.
Young regrowth on a coppiced amorpha
According to Martin’s fertility tables, one amorpha, based on mature canopy size of about six feet in diameter, provides the equivalent nitrogen of 20 cuts of comfrey, or 10 comfrey plants; lespedeza about the same. I’ll throw some of these in the patch so the roots sloughing off after coppicing can feed the comfrey. They need nitrogen themselves.
This still requires more space than I’ve allocated to the annual’s mulch patch. So I’ll grow some annual cover crops on the keyhole beds once in a while to fill the gap -careful to choose crops that will die when cut, frosted, or heavily mulched since there won’t be any tilling.
To really cinch the deal I have the food forest rabbit’s manure. I let a bucket of it sit out to catch rain, and harvest the resulting “tea” to feed establishing beds right now. In time it can be exclusively for the annuals.
Achieving this much mulch in the food forest will take a while. I’m moving out the perennials first, and planting the whole thing in lots of annual cover crops. The first plant to start yielding mulch will likely be comfrey, though I might just mulch their own patch the first year to ensure they are established. The next year the N-fixers will be ready for light coppicing, then full production. I’m assuming three years before that point, but I’m quite excited to the see the results. I’ll keep you posted as it goes along.