I cannot speak from direct experience on this one, but from what I’ve seen the first step with clay soils is to inject some good organic matter and microbial life in there via tillage and a possible heavy overwintered cover crop. Bed prep is key here. That would be my approach at least.
I’m on some heavy clay soil, and it can definitely be a challenge at this time of year when it holds on to all that winter melt and spring rain. But the upside is that it holds on to that moisture during the rest of the season too! From everything I’ve heard, it’s also a great nutrient bank. Farmers who are on those beautiful sandy loam soils are actually adding clay to them! Also, You’ll want to keep things covered up so as not to let it dry into concrete. It can be a challenge, but I’m enjoying it!
I'm on heavy clay. We could use it for pottery or paving highways. I broadfork then add a thick layer of compost to keep the moisture in. I plant right into the compost and don't seem to have a problem. I think aeration is key Otherwise you got a brick that water can't penetrate. In our 3rd year and it's getting better!
We are heavy clay here in Kentucky and the word is "Organic matter." When we got here my cousin attempting a 'back to eden' style so it was a field of wood chips.We abandoned that because it is ridiculous to plant into as is echoed in numerous posts on multiple threads here but the result is the top 5 inches or so under the wood chips looked amazing. She added NO compost. Just tilled and wood chipped. The weed pressure and other challenges really made that method undesirable (I'm pretty sure we were doing it wrong anyway), so I am really just echoing John Lewellen's post above with keep it covered and incorporate organic matter. Alternatively I'm thinking about over wintering a large root vegetable this year to try and break up the soil naturally. Or maybe sorghum? Hmm...
On heavy clay I think fall sown daikon would be a great choice to really dig down and break up the ground.
Have you (or anyone in here) planted daikon for that purpose before? I'm really intrigued by that idea. Do you leave the daikon in the ground to decompose or harvest them?
We really like radish for loosening tight soils. See my posts on radish in the cover crops & winter thread below for more info, including a graph from an experiment showing how deep the roots can go. To get the full benefit you don't harvest them, but let them keep on rooting until they winter kill.
I was on a very heavy clay soil in the past. The soil had a high CE capacity, and things grew very well, however I lost root crops in rainy seasons. Drainage was my main concern, and I think no-till could solve some of the issues I had. I could never work the soil early - no till would solve that. I’d raise my beds so that carrots wouldn’t rot when we had heavy rain. I’d broadfork and grow tillage radishes to loosen the subsoil, and I’d imagine that as the soil organic matter increased, the soil depth would as well.
I’ve always grown daikon (tillage radish), let it winter kill and rot in the ground - creates great pockets in that deep clay.
Good topic. I've often wondered in no till and hard clay soils if some tillage is actually beneficial and over rides the other negatives associated with it. With all the rains we've been having the soil gets very hard packed over time on its own.
We have had much better results with beds in which we tilled in the initial layer of compost as opposed to just "sitting it on top". We still broadfork our permanent beds before hand, but if you don't till in the initial round, the compost may wash out (leaching, runoff, not good things). Broadforking or chiseling before tilling in the compost also lets the rain work deeper through the bed. There's a greater weed pressure in those beds, as you don't get the mulching effect. But, from all I've seen, the approach should be diligent weed management in the first couple bed cycles (always be diligent, but you know what I mean here). To get around that a bit, build beds in advance and tarp, mulch, or cover crop. Also consider doing your soil test and mineralizing during that first big tillage event. Get a good soil test (a lot of people around here use Logan Labs). That will save you a lot of time down the road. My biggest piece of no-till advice is to get as much of a jump on preparing the beds before you have to start production.Given the rest of the site is amenable to veg production, you can begin to work with nearly any soil with enough time to build a good foundation.