Are veggie roots different at different levels?

Technical question, someone is bound to know pleeeease ...

In one of my Bookes there is a pic of toms with upper roots wanting water and lower roots seeking food.
Does this apply to other veggies too?

On my plot, some peeps feed the soil (manure, compost) around now, and some wait til Spring. Those who wait say 'the goodness leaches out into the soil'. The Spring party will dig manure and compost into the soil, so effectively they're putting the 'goodness' lower down.

If 'goodness' leaches into the soil from compost and manure, and lower veggie roots are seeking 'goodness' lower down, it would seem to be a good thing if nutrients were to percolate as far down into the soil as possible, helped by winter rain and worms?

Unrotted material applied to the surface in the form of mulch will temporarily deprive upper roots of nitrogen, but if the shallow roots don't mind, this temporary hitch in nitrogen supply could do no harm, especially if it increases the moisture level at the soil surface?

I guess I'm trying to figure out why laying on manure and mulching in the no-dig way seems to work so well. So the question is, do veggies have different types of root at different levels that take advantage of low nitrogen + moisture above, and nurrishment below? :rolleyes:

Or am I talking through my Hat :D

 

Hi supersprout,have a look through Digging,in edible gardening.