pat-michigan - 7/23/2009 19:01

We saw our pH drop from 7.4-7.8 in the top 6" to almost neutral in 15 yrs. We've tried sampling at different depths in the same spot, but more for informational purposes than for forming a management practice. We have had some occasions where we've applied lime on fields that would have been unheard of 20 yrs ago. I don't know that its really ever been low enough to justify from a nutrient standpoint, but for the chem's I liked to use it was a help. I think.

I'm not 100% sure why our pH is heading south, but it was a very welcome development regardless. Going back to soil test from the 50's on some of our ground, conventional tillage was trending to a higher pH. 7.5+ is a bear to manage.

I don't know if that helps you at all. 3" seems pretty shallow to try to change a specific management practice for, but I'm saying that from a farm with fairly even soils. I'd think it might be interesting for you to do say, a 0-3, a 0-6, and maybe a 0-8 sample and look for any big differences. I don't know that the knowledge is out there to make an accurate recommendation in 1" increments from a depth standpoint. I've never did a lot of grid sampling in the past , but our farm is now all grid sampled. I'm excited about watching for different practices or philosophies and how that may change yield or characteristics.

Lastly, one thing I tried to keep in mind: up until very recently, everything everyone knew about soil sampling and recommendations was based on a conventional till system. I find it very hard to bring that same info over to a long term no-till system and make sense out it. Not trying to make excuses for anything or try to make it more complicated, just an observation.