At very low pH levels, aluminium and manganese are dissolved by acids and escape into the soil. These are poisonous to some plants. Symptoms of high pH levels in soil usually show as deficiencies of Iron, Boron, or Manganese. Unfortunately, these also result in yellowing of the leaves which makes detection a bit more difficult. Iron Deficiency With Iron deficiency, the leaf veins usually remain a deep green.
Boron deficiency shows up as twisted, distorted growth and often the terminal bud dies.
In turnip and beetroot, hollow, brown areas develop. With a Manganese deficiency the terminal bud stays alive, but the older leaves show yellow patches between the veins, and often dead spots appear on the leaves. If these deficiencies are induced because your soil has too much lime present, they cannot be corrected by applying the appropriate element, because no matter how much is applied, the presence of the excess lime in the soil locks up the elements and makes them unavailable to plant roots. The way to unlock them is to modify the pH level. The chart shows this quite clearly.