What is an optimum soil pH?
Most nutrients are at their maximum availability in slightly acidic, neutral or slightly alkaline soils. At the same time, most phytotoxic forms of Aluminium and Manganese are at their minimum concentration in this pH range. Emil Truog did some outstanding work over 60 years ago and his conclusions on how pH affects the availability of nutrients are still widely used today. How to measure soil pH? Soil pH may be measured on site using a colorimetric kit and a fresh sample. More reliably, it can be measured in a laboratory, using a prepared sample and a pH probe. As pH is usually measured as one of a suite of soil tests to assess fertility, the laboratory option is quite practical. How does soil pH vary with depth? pH varies within the soil profile. The pH of the whole soil profile or any horizon cannot be predicted by measuring surface soil pH. An undesirable pH in a lower soil horizon can constrain plant growth. How does soil pH vary within a paddock? In general, soil pH varies with s