Years ago, before our understanding of soil chemistry was thorough, certain plants were used to indicate soil quality.
The Beech tree, in Indiana at least, was a prime indicator of well drained, fertile, and deep soil. If Beeches were large and in abundance, you had some good soil on your hands (though many roots to grub out). Settlers apparently fought for these sites. Beech is also a great tree, with very good quality wood, and it even makes little edible nuts (if you can get them before the squirrels do)–an advantage over the Oaks to which it is closely related.
Another plant that was used to indicate soil quality, particularly in regards to its usefulness for growing annual crops, was Red Clover. Like all clovers and Alfalfa it wants a close to neutral pH and fairly high calcium levels (65% base saturation), at least compared to most grasses. Unlike grasses, it fixes its own nitrogen, so it will not tell you about that, but at least it is a whole lot quicker than a Beech tree! Generally speaking, if you can grow Red Clover, in time and with proper fertility management, you can grow just about any farm crop or pasture or hay plant, because Red Clover itself is a prime soil improving plant. Two years of a Red Clover hayfield, or better, a cover crop (where it is simply mowed and not taken off the field), can transform a worn out field into a recovering field on its way to abundant fertility. In fact, the major historical rotation where my farm is located was corn then peas (cow peas, as soybeans weren’t around) then Winter Wheat then Red Clover and/or Timothy hay for 2 to 3 years then back to corn. Yea, it was a lot of hay, but there were millions of horses back then that needed it.
Red Clover is also about the most aggressively competitive small plant,too. It has broad leaves that form a canopy about one foot to 18 inches above the ground that adversely effects even bad weeds like Canada Thistle and Sour Dock. If you are careful about keeping the canopy dense and keeping the clover ahead of weeds, it cleans the field pretty well (but not as well as herbicides, for which Roundup Ready Alfalfa could be used). The time to mow Red Clover is when about 10% two 50% of the plants are in flower. For applications like this I recommend seeding Red Clover at 12 or more pounds per acre. I use Gallant, a greatly improved variety sold by Cisco.
A key advantage of Red Clover is its remarkable ability to “frost seed.” Simply broadcast Red Clover just about any time in the late winter or early spring in just about any old way and it will germinate and grow, even in an old sod or a moldboard plowed moonscape. Most experts give all sorts of recommendations about frost seeding, but I have found it has more to do with the species and its seedling vigor than with anything else. Red Clover is the best, White Clover and Sweetclover are good, and Alfalfa, Orchardgrass, Fescue, Ryegrass, and Timothy are mediocre, while and everything else I’ve tried doesn’t work very well. Many Brassicas (Radishes and Turnips) have such incredible seedling vigor you can seed them in August and they sprout and grow. In fact, Red Clover does too. This is so contrary to conventional thinking that two of my neighbors don’t really believe it, but my best Red Clover hayfield was seeded simply by broadcasting into some pretty sorry dead Oats in mid August.
Fortunately, we no longer have to rely on plants to tell us what soil is like (though they remain very useful). For under $20 we can get thorough soil tests done. It may seem like a considerable amount of money, especially if you are sending in dozens of samples, but really it is a bargain because it will be what determines the quantity of various soil amendments applied. I use the S1 and S3 tests from A&L Great Lakes. That and USDA soil surveys can tell you an awful lot about your place before your really begin to study it, which you should do of course. Try to find locally tuned guidance on drainage if you can, because this is a big part of it, too. I highly recommend the book Biological Farmer by Zimmer to get you off on a program of amendment. I’ve read the first edition, which was at my library. Zimmer is a William Albrecht disciple, and I am too, at least in that I think squirting nitrogen (which is 80% of the air) on fields is stupid, and that farms should have on-site organic matter generation as the cornerstone of the fertility program, not annual dumping of manufactured fertilizers.