Here is a copy of a pH chart that is essentialy the same with 3 pH meters that I own http://f1.pg.photos.yahoo.com/ph/byron101540/detail?.dir=/71a6&.dnm=e3d4.jpg According this chart as soil becomes more acidic, nutrient absorbtion drops Below a pH of 6.5 P. Below pH 7.0 Magnesium and calcium starts to drop. As soil become more alkaline Above pH 6.0 Iron drops above pH 6.5 Maganese drops. A sort of average of the 5 elements keeping the soil between 6.5 and 7.0 will yeild maximum absorpstion of all needed elements. L.B.