How is aluminium tested in your Complete Soil Analysis?

Aluminium reported in our Complete Soil Analysis is a Mehlich 3 aluminium level which gives us an indication of total aluminium levels. When we get > 1600 ppm Mehlich 3 Al, we normally check for exchangeable Al using KCl methods. So in acidic soils we use the KCl method for exchangeable Al, so we can accurately derive lime needs based on Al Saturation %.