Here’s an excellent resource:

Root Development of Vegetable Crops

It’s from 1927, but I suppose veggies haven’t changed a lot  since then. We have many small rhubarb seedlings and I just looked up RHUBARB:

Summary.–The perennial root system of rhubarb is characterized by a thick, fleshy, main root which soon divides into numerous thick branches. These, like the other strong laterals, attenuate gradually and end in very fibrous rootlets. The main roots and their major branches pursue various courses from almost horizontal to nearly vertically downward. Long, slender, much rebranched laterals occur throughout and thoroughly occupy a soil volume with a radius of 3 to 4 feet and extending from the soil surface to a depth of 8 feet.

Relation of Root System to Cultural Practice.–A study of the root system explains why rhubarb flourishes in a deep, rich, mellow, well-drained soil rather than in one that is shallow or underlaid with a hardpan. Since it is an early spring crop, a soil that warms rapidly, such as a sandy loam, is best.

We’ll plant it into several areas outside and in the hoophouse and we’ll see how it goes with all the caliche.  We also plant very dense, but use AACT tea to provide nutrients to the leaves and roots and hopefully the plants will adapt.

Here’s the info on WATER MELONS and we’ll try some on our “hugels”, mounts of branches, wood chips that have been decomposing for over a year.