Appendices - Soil Essentials: Managing Your Farm's Primary Asset - page 146

Appendix 2. The pH (H 2 O) scale
pH reaction pH value pH reaction pH value

e x t r e m e l y a c i d < 4 . 5 s l i g h t l y a l k a l i n e 7.1-7. 9

very strongly acid 4.5-4.9 moderately alkaline 8.0-8.5

strongly acid 5.0-5.5 strongly alkaline 8.6-9.0

moderately acid 5.6-6.0 very strongly alkaline 9.1-9.5

slightly acid 6.1-6.9 extremely alkaline >9.5

neutral 7.0 — —