We had a great soil health and fall gardening workshop on Thursday August 27th. Build It Up invited Mike Hubbs of the TN Assoc. of Conservation Districts to come speak and opened the talk up to the public. We put the invite out on a few listserves and left it at that. Over 40 people showed up to hear about soil health and no-till gardening methods! Who knew it was such a popular subject?
Our presenter, Mike, was a fun and engaging guy. Mike’s been working for TNACD and the NRCS for over 30 years and you can tell he’s passionate about the subject. He had a Power Point presentation that ran through the basics of soil health: what it’s made of, what it looks and feels like, and then got into the meat of the matter: how to build it.
For existing gardens, the transition is fairly easy: Cover Crops. Mike is really impressed by a farmer in Central Ohio, Dave Brandt, who’s been farming conventional no-till since the late 1970s. Brandt started with clover in 1978 and now uses and sells a mix with 12 species in it. He has higher yields, healthier plants, fewer weeds, and lower inputs than his neighbors. Brandt did a side by side test of his no-till with a conventional till plot on 15 acres. The conventional tilling and spraying cost him $536 per acre, whereas total inputs on the no-till with 12 species cover crop mix cost $294 per acre.
Because Brandt’s soil is so full of microbial life, he is considering switching to organic seed to save money. Organic corn seed is $40 per acre whereas GMO seed is $140 per acre. He doesn’t have weed issues and the soil life is balanced to the point where pathogenic fungi and bacteria are not issues. The conventional wisdom is that organic farming is more expensive and less productive than conventional farming, but if you concentrate on soil health, it turns out the opposite is true.
This is all fascinating news, but Mike did spend the majority of the presentation on what home gardeners can do. He recommended that folks use cover crop mixes with as many species as possible with a mixture of cold and warm season grasses, cold and warm season nitrogen fixers, and broadleaf plants like buckwheat and brassicas. Potential additions include cereal rye, winter barley, oats, brown flax, sunflower, buckwheat, daikon radish, Ethiopian cabbage, winter pea, hairy vetch, crimson clover, cow pea and sunn hemp. Dave Brandt’s company, Walnut Creek Seeds, sells a variety of standard and custom mixes for gardeners and farmers.
To get a new garden started, Dave had three recommendations. First, which we won’t be using, was to spray glyphosate on the grass and then apply cover crop seeds. Once the cover crop was mature, crimp it down to create a mulch on the soil and plant garden crops into it. The second option is to smother the grass with at least a foot of organic matter. Let it sit at least 3 weeks and then plant into it. In the fall, plant a cover crop and then crimp it in the spring. Third (and he said this one in a whisper), you could till up the grass the first year and then work with deep mulch and cover crops to repair the damage in future seasons.
Tilling pumps a lot of oxygen into the soil, which temporarily increases microbial activity. The microbes eat all the food and then die when it’s not replaced through good soil practices. It also destroys the soil structure, which will form aggregates under no-till conditions increasing space for water and oxygen in proper levels. Good soil aggregates will naturally help the soil retain water when it’s dry and drain well when it’s too wet. Tilling also destroys earthworms, which naturally turn over soil, create aeration tunnels and provide valuable fertilizer in the form of worm castings. In a healthy no-till acre, you can find the equivalent of the weight of two cows in worms and other soil life. You really do have an “underground herd” you are caring for!
My favorite bit of new information was about the important role that brassicas play in the cover crop mix. Brassicas, or cabbage family plants, are great nutrient scavengers, locking up nitrogen and important trace minerals like calcium so they don’t leach out. They have very deep tap roots, so they can draw up nutrients from several feet below the soil surface. Then they winter kill, slowly decomposing over the cold months adding organic matter and the nutrients they’ve absorbed back into the topsoil. Daikon or “tillage” radishes easily grow more than two feet deep and can be used to break up hardpan and dense clay soils that have been damaged by tilling or other kinds of compaction.
We are going to use season extension techniques to keep growing cold hardy vegetables as late into the year as we can. However, on any areas that won’t be under production, we’ll be spreading cover crops and mulch. Keeping living roots in the soil at all times and feeding the “underground herd” are keys to reducing the need for the backbreaking effort of tilling each spring. In Permaculture books that I’ve read, they emphasize that nature gives back 10 times what you put in, good or bad. By making the effort to use cover crops, keep the soil covered and not tilling, the benefits given back are so much greater than the sum of the individual efforts.