When I was at junior school we were taught about the pH scale, a scale which determines the level of acidity or alkalinity of the garden soil. I never realised then how important it was to become later on in my life. A soil with a neutral pH was 7. Anything that had a lower pH was acid soil and anything higher was alkaline. Most plants prefer to grow in a soil with a pH of about 6.5. Soils which have a higher pH (more alkaline) are likely to have problems absorbing trace elements such as iron or manganese which are identified by the peculiar effect they have on the look of the veins on the leaves. Soils which are really acidic create problems as well, but not quite so severe.
