to dig or not to dig

I keep reading about how important it is not to dig, cultivate or disturb the soil. However, then in the "how to actually feed yourself" department, people recommend root crops such as oca, potatoes and Crosnes. So here are my questions:
1. Should we be growing root crops at all, if harvesting them is damaging?
2. Is there a way to grow root crops which is the *least* damaging? How do we grow them successfully without a lot of irrigation also? Are there inter-planting guilds people have tried that they've found successful? I've tried mulching with straw with minimal success. I'm thinking of inter-planting spring peas this year.
3. Is there a way to harvest root crops which causes the least amount of damage? I've read the suggestion of growing crosnes and oca together with the idea of harvesting them at the same time and only disturbing one area at a time.
4. Are there recommended procedures to follow up harvesting with? Oca and Crosnes are harvested at a time of year when it's not really possible to start something else right away in our area (Pacific North West - rainy and dark). This year I mulched with rabbit bedding I get from a friend with a small lot and a lot of rabbits. It's got a lot of wood shavings in it, but I'm hoping the benefits will out way the negatives.
Thanks Jay

It's OK to dig. A little soil disturbance is a good thing. Earthworms churning the soil around aerates it. So does yanking out a radish or turnip. Even a mole or gopher digging a tunnel provides a path for air to get to the roots so they don't get all anaerobic and die.

What's NOT good is turning entire acres of soil upside down so that all the roots (and soil fungi) can dry out in the sun. And then doing it again. And then doing it again. Like my neighbor who would go till his field another time for something to keep him busy. That is the destructive kind of digging that kills everything living in the soil. It's also what commercial agriculture relies on to kill insects and pathogens. Kill off the bad along with the good, we don't need the good when we have Monsanto to help us.

Back in the days of plowing fields with a team of oxen or horses, fields got tilled ONCE in the springtime, that's it. That was just the right amount of disturbance and was fairly sustainable. What we do now with cheap fossil fuel isn't.

Jay Angler wrote:
2. Is there a way to grow root crops which is the *least* damaging? How do we grow them successfully without a lot of irrigation also?

Addressing just the irrigation part of your question:
I've read that even in the Pacific Northwest you can have hot dry summers, but trust me when I say that ours are hotter and drier in SoCal. The biggest benefits I've found are from:
(1) adding lava sand at 40 lbs per 500 sq ft (yes, the shipping cost is more than the product cost, but it's something you do once). The porosity of lava sand holds water and improves cation exchange, but doesn't hold excess water during heavy rains.
(2) 4 inches of mulch around root crops once they get established. Unlike the lava sand, this must be continually renewed.

Unless you are harvesting by machine or trying to get every last tiny tuber, you really shouldn't be disturbing the soil that much. Oca pulls out of the ground pretty easily, only upturning the area right around the base of the plant, and you're probably dropping almost all the soil back into the hole. That's just the bull's eye of a pretty large diameter that was covered by the plant. I make use of this to plant broad beans among the oca about the beginning of October. They will grow on and off through the winter and you can drop them in the spring before planting again. Short peas also work well interplanted with oca and add to the soil if you don't run them all to the end.

If you live west of the Cascades, go with maximum spacing for canopy closure (about 30 inches for oca) and you probably won't have to do much irrigation.

I think it's a good idea to dig the soil in the very beginning to get the really big stones out and maybe debris if you live suburban.
After that I would use simply a hoe and hoe lightly. If that is enough your soil has the right consistence.
Roots are mostly pulled out and sure everyone must eat roots and they are part of the crop rotation. Burdock is a bit more difficult to get out.

Jay, many things are very much a matter of scale, or degree. As has been pointed out, there are many creatures living in our soil, if we have good healthy soil, that are actively digging through it. Our plants are sending their roots down, pushing through the soil (daikon is also known as "tillage radish" because of the way its tap root pushes down deep into the soil, right?).

It is not that the soil should be absolutely undisturbed. Indeed, that would be bad, as it would mean none of the various organisms that ought to be there pushing the soil around were there doing their jobs.

It is the case that man has a bad habit of overdoing things - like turning the soil over again and again. It dries out, organic matter oxidizes, the wind erodes the topsoil. Lots of bad things can happen to land that is repeatedly tilled. And even conventional large scale agriculture has been catching on to the "no-till" idea.

But, there are plenty of seeds that need to actually be put in the ground, not just broadcast over it - so you have to do a little disturbance there. Occasionally you have a weed that needs to be pulled, so there's a little disturbance there. Sometimes you have root crops, that have been pushing the soil around forming their tubers or tap roots that you will need to disturb the ground a bit more to harvest them.

As long as you are not turning over the soil over a large area, it is not a big destructive thing. Disturbance creates opportunity as well as disruption. Taking out the potato makes room for something else to grow there, and the bit of soil churning may bring the seeds of something else to a place where they can germinate. And that may translate into you having weeds in your garden - or it may mean that last year's lettuce seed that had self-sown now gets a chance to grow.