Hi greendoctor, heritage,
I've been reading your posts on this thread. I just wanted to ask that if my summary of understanding here is accurate: For inland clay soils, the basic procedure for creating a soil makeup that provides better drainage is getting pH levels to about 7 and the Ca:Mg ratio to 7:1. Carbon sources add to the stability of clay soils as well as OM if it is (below 4%?). Be aware of possible man-made pollutants and salts. I noted also GD's post about using citric acid on alkaline clay soils to help "break it up" with sufficient irrigation of course. What about clay soils that are naturally acidic? Please correct or add to any of this.
And another question, do either of you have recommendations on any in-depth books or soil labs?