Soil Indicator Species

I've been mulling an idea the past few days and wanted to get some feedback on it: planting indicator species for various soil conditions including both PH and nutrient availability.

I don't have a lot of money to go soil testing dozens of sites around the property here, and doing so on an annual/bi-annual basis in order to monitor for changes or problems is way outside of what I'm capable or willing to do. I do know, however, that there are multitudes of plants, most of them considered "weeds", that can tell you exactly what's going on down there if you know what to look for. One of the classics is of course the hydrangea which will tell you the relative ph of the soil it's growing in by the color of the flowers, but what about planting other things to cover various nutrient availabilities?

They say vigorous patches of clover shows soil that's low in nitrogen, while less vigorous patches will indicate high nitrogen. Annual bluegrass is said to do better in soil with low calcium / high magnesium, healthy burdock indicates high iron / low manganese, and common chickweed will go wild in soil with high potassium / low phosphorous. Healthy dandelion often indicates low calcium and excessive potassium while healthy plaintain can indicate high chlorine and sodium levels. Vigorous mullein plants often indicate overly dry soil while common buttercup or yellow dock can indicate poor drainage. Patches of morning glory going nuts sometimes indicates hardpan and soil crust.

Am I crazy thinking that incorporating these various weeds into plantings is a bad thing? Am I crazier still thinking that these can be used as general indicators of the soil health? I mean, if we look at the weeds when we're surveying a site, why not keep them around and continue to look at them?

Tristan Vitali wrote: Am I crazy thinking that incorporating these various weeds into plantings is a bad thing? Am I crazier still thinking that these can be used as general indicators of the soil health?

Not in the least crazy!
While I wouldn't generally grow weeds specifically as indicators,
as permaculture's mostly about observation for me,
I spend a bit of time going 'hmm lots of x there, must be xyz conditions in that spot..."
I googled, and lo and behold an old thread came up where I'd mentioned a few books etc.

Leila Rich wrote: permaculture's mostly about observation for me,

Not just for you, but for all of us!

When a farmer wants to decide what to plant, he heads off to the financial pages and reads the USDA report about crop demand forecasts and calculates which has the best return.

When a permaculturalist wants to decide what to plant, he heads out to look at the land, see what's naturally growing on it now, what does that tell him about the soil? He looks over the lay of the land, where are the rivulets collecting into a natural swale? Then he digs up a handful of soil and checks its clay content, smells it, and looks for any worms or other critters in it. As he is feeling the dirt, he looks around for where South is, how is the sun arcing across the land and where any trees are casting shadows on it. Only then does he think of what he can introduce that will grow to make more than the sum of the parts.

Once you hone your observational skills, I don't think you need to introduce any "indicator species".