September 9, 2018

Soil Building Experiment #1

Last month I shared what I've been learning about soil building ("Carbon: What I Didn't Know"). The nutshell version is that soil microorganisms are what make (build) new soil. Here's what I've learned summarized:
  • Soil bacteria break down compost and mulch into organic matter
  • Soil fungi build organic matter into new soil
  • Both feed on carbon provided by
    • the plants
    • the mulch
  • Conclusion: Feeding soil microorganisms = building the soil

Building soil in a small area such as a garden is relatively easy. The gardener applies compost and mulch, and the microorganisms do the rest. We can further facilitate the process by allowing the mycorrhizal fungi to grow and create a network. This is where the no-till technique comes in, because tillage destroys the network.

I will readily admit that we have been tilling, so a big part of these experiments is trying to figure out how to switch to no-till, especially for larger production areas where garden beds aren't practical.

The area we chose for our first soil building experiment is where our row of fruit trees grow, outlined in red in the map below.

See "Carbon and Soil Building: Designing a Plan" for map details.

There are two apple trees, two pear trees, and a small cherry tree down the middle with elderberry bushes along the fence. In the past we've cut the grass there and dried if for hay. Here's how it looked from the bottom of the slope (right edge on the map) before we began.

Planted with sorghum-sudan grass for a hay crop.

Before we did anything we took a look at the soil itself. We dug two samples, one at the top and one at the bottom.

Sample dug at the top of the area.

This sample is typical of soils in the southeastern United States. Any place on our property where we've had to dig (for fence posts, huglekulture swale beds, etc.) this is what it looks like: sandy loam topsoil and red clay subsoil. The sand doesn't hold water, so in hot weather our topsoil dries out quickly after a rain. And it contains just enough silt so when it dries out, it's as hard as concrete!

The bottom sample looks a little better.

Sample dug at the bottom of the area.

The top inch or two has roots and clumps of soil clinging to the roots (clumps are good; they mean soil microorganisms have been busy), but it contains little organic matter and is mostly the same sandy loam.

Excellent soils are said to look like black cottage cheese, and obviously we have a long way to go! It is possible to build soil with only cover crops, but we hoped to give it a jump start. We took stock of our own resources and decided to add some of this...

Aged manure from cleaning out the old goat barn.

This is what Dan scraped out of the former goat barn after we moved the goats. Some of that manure is years old, but it's been under roof, so there has been no nutrient leaching.

Also this...

Mulch pile from the tree trimming company.

Earlier this summer our electric company hired tree trimmers to clear everything away from the utility lines. Dan asked if we could have some, and they dropped off two loads of chipped wood and leaves. Here's what we decided to do.

First I trimmed back the trees and bushes. Then I broadcast a cool season cover crop mix of wheat, oats, winter peas, Daikon radishes, and crimson clover. The fibrous roots of the small grains add biomass below the soil surface, the peas and clover are legumes which fix nitrogen in the soil, and the large roots of the Daikons help loosen the soil. I also read they are nitrogen accumulators and store nitrogen in their roots.

Next Dan cut the grass back with our mulching lawn mower.

Trimmed back, planted, and mowed. The brown patch
at the bottom wasn't from tilling. That's the grass you
saw in the "before" photo, dead and brown from mowing.

The grass clippings covered the seed like a light layer of mulch. I covered that with a layer of the old manure,

then a layer wood and leaf chips.

A week later it was starting to grow.

We hit a hot dry spell about that time, so I was concerned about the seedlings drying up. Even with hot days and no rain for three weeks it continued to grow well.

Here's how it looks now.

One month after planting.

The plan is to let this cover crop grow all winter, then underseed it in the spring. The cover crop will be cut down, leaving the clippings to mulch the new seed and add more carbon to the soil. The idea is to alternate cover with harvest crops to build healthy, productive soil.

Soil building is a slow process, usually measured in years, so I realize it may take awhile to see improvement in future soil samples. Even so, we've  already seen a response.

Ten inches of new growth.

New growth on one of the apple trees! I can't tell you how much that lifted my spirits.

This is a long post, I know, but it will serve as a record of what we did, as well as our starting point for measuring progress in the future.

Soil Building Experiment #1 © September 2018


Kathy said...

Be cautious about getting anything from tree trimmers where you don't know the trees of origin. Some people (or cities) spray trees with things you may not want in your garden or mulch. You could also potentially wind up with wood/leaves that are toxic to gardens. Best to ask what type of wood/leaf they trimmed before accepting delivery.

Appreciate all the info on carbon and documenting your process! Makes me think differently about how to proceed with my own gardening. Thanks!

Valerie said...

Hi Leigh, still following you from your weaving days. Thought you might find this Sally Fox (the colored cotton lady) article interesting.

She talks a little bit about building soil carbon.

Toirdhealbheach Beucail said...

Thanks for sharing Leigh. I will be interested in seeing the results as well.

Leigh said...

Kathy, that's the exact opposite of what the Back To Eden gardening people say, LOL. I have seen some areas where the power companies use herbicides to control vegetation near power lines. If that was the case, we wouldn't have asked.

Valerie! How nice to hear from you! You took your fiber blog down? I've heard fo Sally Fox but had no idea about growing cotton to add soil carbon. Thanks so much for the link!

TB, thanks! I'll be interested in the results too, LOL

Kev Alviti said...

Great job. I've been running my chickens through the orchard in tractors to help buidl the soil, but in truth our soil is deep already and most things will grow like crazy.

Unknown said...

Hello Leigh, just wanted to drop a line and say hello. I've been offline for quite a while but i do drop in from time to time (while stuffing food into my face at lunchtime at work). I do intend to start writing again but i have a major project to finish first (mystery?). Your posts on soil are very interesting and informative and i look forward to watching the progress. I wish i had a poo source other than having to buy it (very processed). Some good poo (i like cow pats) are hard to find in a city of 4 million. Cheers, Lynda (Living in the Land of Oz).

Thistle Cove Farm said...

The soil is the life blood of growing things; you're doing well.

Leigh said...

Jean, this is becoming a wonderful learning experience. So many things I never knew about soil and so far it is much easier. Results will be the real test, but I feel pretty good they will be good ones.

Kev, you are so fortunate to have good soil! But you are so wise to not take it for granted. Active soil building is a resource for now and the future too.

Lynda! So good to hear from you. I've visited your blog on occasion and thought you'd given it up altogether. But sometimes life is just like that. Getting the right resources is always a challenge. Can you keep rabbits or pigeons?

Ed said...

Living in the part of the country where the soil is black and "cottage cheese" in nature, I have to say your soil looks like something I might expect near Chernobyl! I never get used to it when visiting my brother down south. I hope your efforts work well.

Leigh said...

Ed, well, both soils are biologically dead. Our advantage is that ours aren't radioactive! Unfortunately most folks, including the university and cooperative extension experts pretty much say this is it and there's nothing we can do about it. After watching those Gabe Brown videos, however, I think there's a lot we can do to improve it. Really hoping our experiments this year are steps in that direction.

Kathy said...

HA! I disagree with "nothing you can do about it." At the very least, what you're doing will loosen the soil you have and create new top soil. Just a matter of how long it takes. I'd be interested to see your soil samples in same spots in 2-3 years! Your apple tree is proof things are improving already.

Chris said...

An exciting project to see progress. I have to say, those cover crops look way better as a ground cover, than the grass did. Will you mow them down, next spring, or will the snow kill them off, for you? Do you even get snow, where you live?

Leigh said...

Kathy, exactly! I plan to keep a photo record of our progress over the years, and am excited to watch it improve as we go along.

I read an interesting online article not too long ago (that I wish I'd bookmarked) which made the comment that farmers who are using and promoting diverse cover crop mixes to build soil are "ahead of science." It went on to explain that research methods are limiting in that at best they can evaluate a 2 or 3 specie cover crop mix, but once you get to a mixture of one or two dozen types of seed, the variables become too broad. In one of agronomist Ray Archuleta's videos, he points out that our current scientific method is reductionist in its approach. In terms of control groups, it has to narrow down factors to the nth degree. But the reality is that these natural processes are highly symbiotic and interdependent on many factors. Allan Savory is another one who baffles modern thinking with his intensive use of livestock to regenerate desert into grasslands. Educated people want to argue his methods too, because they don't make sense compared standard recommended livestock practice. Yet he's the one getting results and they aren't. I think Masanobu Fukuoka said it best - that science cannot really know anything. It's so much better to simply be a part of the natural process and enjoy the results, than to try and make it conform to our own economic goals.

Chris, yes, we do get snow! Usually one snowfall for the winter, but some years we get none. Our winters can go either way: mild enough for cool season crops to be green all winter, or cold enough to kill everything off or at least make it go dormant. Either way, that current cover crop is all annuals and only meant for a season. If the cold doesn't kill it, we will either mow it down when it's time for spring planting, or even better, put up our electric netting and let the goats graze it down and then finish it off with the mower.

Mike Yukon said...

This is so interesting. I will surely follow all updates as time goes on. Thanks for making the effort to take the photos and posting.

Leigh said...

Mike, thanks! A good record is invaluable. I can't tell you how many times we've come back to blog posts to get dates and details of things we've done.

Tina T-P said...

Thinking about you today - you're not in the path of the Hurricane are you? T.

Leigh said...

Tina, so good to hear from you! We're on standby as we watch the hurricane's path and they're telling us to expect a lot of wind and rain this weekend. Hopefully it will be nothing more than that!

Leigh said...

Jean, thank you for asking. :) Our wind and rain was nowhere near as bad as the forecast, which is a huge relief.