adjusting the biointensive numbers for sheet mulch

I am trying to figure out how many square feet of our community farm should be planted with each vegetable based on the number of people eating out of the garden. How to Grow More Vegetables has lots of very handy charts, which explain how many square feet to plant for so many pound os vegetables per person. And I intend to plant densely, as they recommend.

However, I will be using sheet mulch instead of double dug beds. Should I half the "beginner" expected yield, or, in other words, plant twice the square feet they recommend? Or could I get roughly a beginning biointensive yield out of sheet mulch beds?

I am a big fan of John Jeavons and his work. My experience is that the yield numbers on the charts are not very useful at all. There is so much variability. John said that the high yield number is the single record yield from anywhere in the world for a given crop. The medium yield number is what a skilled gardiner can expect after a few years of following the biointensive system to build their soils. The low number is basically a conventional average. None of these numbers would have much of any applicability to your situation.

I would focus on growing things that you can make use of surpluses, like tomatoes or potatoes. Too much lettuce is just a waste. Cucumbers that can be eaten fresh, or fermented into pickles that last a year, are a much better crop.

Yield is so highly variable over time. The amount of area you need for baby spinach at 35 days is many times the area needed for mature spinach at 55 days. When will you harvest? How would you calculate yield areas? There is so much variation over time. All the leafy greens are like that.

Green beans produce a few at first, then explode with production, then taper to a trickle. At what stage do you calculate yield? Sorry to belabor the pattern, but I think you see what I'm saying.

John Jeavons has devised a genius simple system for sustainable food production. His quanitification of things goes a little too far, as even he acknowledges when you talk with him. Yield is so variable depending on climate, soil fertility, and gardener skill. I wouldnt even try to calculate things like how many square feet to grow how many pounds of broccoli, the only thing you can guarantee is that you wont be even close!

good luck!

Gilbert Fritz wrote:I am trying to figure out how many square feet of our community farm should be planted with each vegetable based on the number of people eating out of the garden. How to Grow More Vegetables has lots of very handy charts, which explain how many square feet to plant for so many pound os vegetables per person. And I intend to plant densely, as they recommend.

However, I will be using sheet mulch instead of double dug beds. Should I half the "beginner" expected yield, or, in other words, plant twice the square feet they recommend? Or could I get roughly a beginning biointensive yield out of sheet mulch beds?

Gilbert, how did your 2014 experiments pan out?

If you add 24inch of compost on top of the cardboard you effectively have 'bio-intensive' soil. I would up the carbon content with some biochar/twigs and some foliar spray/water kefir.

As for the yield, overseed and harvest micro-greens. To make your numbers look good, do mostly vegetables and add carbon+soil life/foliar spray to up your harvest.

S Bengi wrote:If you add 24inch of compost on top of the cardboard you effectively have 'bio-intensive' soil. I would up the carbon content with some biochar/twigs and some foliar spray/water kefir.

As for the yield, overseed and harvest micro-greens. To make your numbers look good, do mostly vegetables and add carbon+soil life/foliar spray to up your harvest.

24 inches of compost? Where would you get that much?  Or typo maybe? Or English meaning of the word: potting compost? Though still a significant amount of material!

John Jeavon bio-intensive farming requires 24inch of double till soil.
Less and you have too much root competition, and not enough water storage between rain/water events.
A much bigger diversity of soil life esp with cardboard creating a barrier/quasi-container bottom.
If the compost is too rich dilute with twigs/biochar for carbon or even onsite dirt(possible weed seeds).
If root crops are going to be planted 24inch seems almost like a min.
Bio-intensive farming is low-till/no-till, so after some settling this dept of soil will go down+erosion+harvest+dirt on hands/produce.

Sorry, I didn't document things . . . I tend to be great at coming up with ideas/ plans, very bad a following through on them!

I do remember that we had mountains of tomatoes in 2014. However, I now don't think sheet mulching is an idea way to grow standard vegetables on a large scale. It didn't keep the bindweed out, just made the bindweed harder to deal with. It tended to dry out. Most vegetables are ruderal species adapted to disturbed mineral soil. It was actually more work that tilling; spreading a foot of wood chips, cardboard, and manure over a quarter acre garden is back breaking, and the soil underneath didn't fluff up like it was supposed to.

I think that initial tillage followed by crimped cover crops would be a good low-till system for large scale vegetables. But I have not tried it yet, just looked at the projects of others.

24" of compost seems completely impractical to me unless someone had an extremely tiny garden.  I use a couple inches at a time and I never have nearly enough, and that is with 6 bins going full time, and my 30 chickens making a lot more.

Square foot gardening relies on adding about a foot of material. Often with a weed barrier in between. It isn't compost though but basically a peat lite mix containing lots of vermiculite.

In my own garden starting with shallow clay topsoil I've added a lot of sand to the more intensive part of the garden. I took the loads of sand a wheel barrow at a time and dumped them in rows. The sand is the raised part of the raised bed. I haven't so far mixed it in. One caveat it's sandy subsoil I bought direct from a farmer who started selling it after realizing an alfalfa field was too well drained not washed sand.  You could do a sort of lasagna gardening method to change your soil depth and properties using compost, sand, vermiculite, or whatever you could get a hold of, possibly including topsoil from paths or from waste areas.

hau Gilbert, for such a garden size you might want to map out (plot) same sized areas then use a crop rotation plan that allows for two or more growing seasons before that first crop returns.
There are several organic farmers that are doing this for large scale soil growing (in this system it is about growing the soil nutrients not what vegetables go where) with great success, they are now (4th year) at the point of no addition expenses.
The tilling comes as a one pass to turn under the cover crop.

I know of another farm where they rotate pasture on a 3-4 year setup, the pasture plants grow for 3-4 years while being grazed in a rotation of cattle then the pasture is turned under and planted in vegetables for 2-3 years before going back to pasture.
Again the system is more about growing soil than what it produces.

Redhawk