Reading Plowmans Folly and the author seemed to contradict himself by saying plowing is bad but also talking about how he disked a field the recompacted a few strips to reestablish capliary and transpalnt tomatoes into. I thought disking IS plowing so I did some Google research.
Let me make sure that I understand this correctly by using comparisons to tools I do understand. A molboard plow would be like using a spade to invert soil. A chisel plow would be like using a broadfork to loosen up the soil without inverting it. Disking would be like breaking up clods with a hoe. Do i understand these correctly?
Next question: at what point does it stop being "no til"? I read that chisel plows are used prior to planting in no til farms. Does that mean that no til draws the line at inverting soil and everything else is fair game?
I think anything that disturbs the the soil Surface is cultivation
Plowing is deep cultivation, inverting the topsoil 3in plus
Discing is surface cultivation and a sideways action
Direct drilling still cultivates a little in the seed bed
Well it's complicated by the fact that many tools can be used in different ways. A disc for example, typically can be adjusted from straight on to having the discs at a pretty severe angle. In the latter arrangement the discs act a bit like a moldboard and will slice into and turn over the soil, though not as deep. This can be primary tillage, but the disc is versatile and can be used for secondary tillage as well. The usual use is to incorporate residue and prepare for secondary cultivation, but this depends greatly on the soil and what you are planting. With the discs less angled it's more about tilth and cutting up crop residue and/or to make it easier to plow.
Andy summarizes it well but good like finding agreement on it. Many folks will disc repeatedly such that the surface is broken up very finely, down to whatever depth the disc is capable of... usually 6-18". In other words the disc is both primary and secondary tillage. Personally I consider this stupid and irresponsible but I've also done it so hey.
More commonly I use a disc to incorporate residue and prepare for bed-forming. If the soil moisture content is just right I only need 2-3 passes and no secondary cultivation. That's rare -- sometimes I'll follow with a spring tooth harrow to get a finer tilth and eliminate the ridges. Or I will bed form after discing and then use a rototiller that has very short broken tines to get a good surface tilth for about the top 2". I try to only disc once per season -- once the beds are formed they get replanted several times.
I do not consider any of this a good idea. While it's nice to see the dismembered bodies of gophers strewn about any tillage wreaks havoc on soil ecosystems.
Secondarily I use a disc when seeding cover crops. Just very lightly to cover the seed after broadcast seeding.
Chisel plows are usually used for deep ripping. Goes against my religion, but you can also use a single chisel to rip a line for planting, say trees.
I can't imagine finding agreement on where the line is for no til in part because every soil is different and the degree of til necessary to get a seed bed you can plant in is highly variable. But -most- of the time you have to do something to get a tilth that will support seed germination unless you can afford a really nice seed drill. And (usually) enjoy spraying herbicides on your land. Truthfully that's not anyone I know.
Yeah that's a better explanation, the drill I use for seeding cover crops and hemp, linseed, maize is huge but only 3m wide. A new one apparently costs $250k and up and I tow it with a big tractor. It seems to do a good job opening the ground putting in the seed and then closing the slot again to reduce moisture loss and weed germination. All done organically.
Generally speaking the seedbed only needs to be prepared in the top inch or two for shallow rooted annual's I think people often go too deeply and end up bringing up clay and other crap that then takes a lot of work to smash about. Depends on how fucked your soil is as to what you do. Or your budget.