FIG. 4. A soil pH that is too low or too high favours magnesium deficiency
in plants
N.B. 1. This was a sandy soil.
2. The crop was oats.
3. The magnesium deficiency,
judged on external symptoms, is expressed by an index from 0 to 5. 5
indicates severe yellowing in 100% of the plants; 0 indicates that there
was no evidence of deficiency; 1-4 describe
intermediate external symptoms of deficiency. From STENUIT
