I've looked into no till recently once again. Rodale institute has some nice information, as do some of the ag oriented universities, but I'm not too sure how well it applies to regions other than their own. They report that they are seeing more carbon sequestering in no till gardens, more beneficial soil organisms and thus better plant nutrient availability, better soil moisture retention, increased water penetration, all when no till is done in conjunction with organic methods. Sounds good if I were living in their climate and soil type. But I'm in the tropics with some funky soil that has low fertility when left to Mother Nature.
I have some areas on the farm that have had a natural, deep (over 6 inches) organic layer covering the soil for well over 20 years duration. I've dug down into that soil and found it to be dry, light colored, no worms or insect life, hydrophobic. This soil supports trees, ferns, grasses, and certain forbs. I've tried planting food producing plants into this soil without removing the duff layer, and it's been failure after failure. I've also tried tilling the duff into the soil and gardening. Very poor results but better than no till.
Honestly folks, a lazy low work no till method would be welcomed by this old person, but it isn't going to feed me on this farm anytime in the near future. Perhaps it's my tropical soil or my tropical climate, or maybe the fact that soil fertility was so dismal to begin with. But no till just doesn't support vegetable plants very well here. Even many perennial food plants gradually decline if organic material isn't scratched into the soil around them occasionally.
Now I do have to agree that no till can work with some food plants as long as the soil was initially improved, then maintained via the use of nutrient mulching. Examples on my farm include bananas, fruit trees, rosemary, parsley, pipinolas, sugar cane, chaya, and papayas. I'm also seeing gourds and pumpkins lasting a couple of years between tilling.
Yes, I till. I use a rototiller to incorporate organic material and other soil amendments into the top few inches. Few inches...yes. That's because I only have a few inches. My soil is shallow in most places though I do have a few deeper beds reserved for daikon, carrots, parsnips, and other deep rooted crops. Incredibly, some of the beds have only 3" of "soil"! That makes for some interesting tilling experiences.
So what really happens to my enhanced garden beds if I stop tilling? This year I've found out because the weather forced me to stop maintaining some of the garden area.
1- tropical grasses heavily invade
2- soil becomes dense as opposed to the light, fluffiness it had attained
3- some beds became waterlogged with poor drainage because the water laid atop or only penetrated 2-3 inches whereupon it pooled.
4- some beds returned to being hydrophobic
5- worms disappeared
Yes, the worms left or died. When I was lightly tilling between crops, I saw plenty of worms. I suspect that the tilling did indeed disturbed them, but they still could be found anytime I forked over the soil (think, harvesting potatoes). While reconditioning the fallow garden beds, I saw virtually no worms.
What veggie plants that were abandoned in the garden, did very poorly. Basically they stopped growing. No new growth. Tough & woody. Kale, turnips, onions. They surely weren't robust and happy. In the tilled soil they were actively growing and lush.
Perhaps in the future my soil will be fertile and organic enough to use no till methods. But I'm not sure because after all, this is the tropics. So for now I will do what works. I will till in soil additives between each crop.
One more line of thoughts.........
I have a friend who over the years has brought in truckload after truckload of county mulch and dumped it onto his rocky land. He lives on an old lava flow, so his ground is predominately lava chunks. In places, his "mulch soil" is 1-2 foot deep in his garden area. Now folks, he can truly grow via no till methods. He digs in garbage and other waste into spots around his garden, but he doesn't conventionally till or plow. For him, the no till approach works. But I have decades to go before I achieve such soil........unless someone volunteers to come here and spends weeks....no, make that months.... transporting county mulch and spreading it on my acres.