Most growers now understand the necessity for soil testing to avoid driving blind. This information is essential when designing crop nutrition programs, but you do need to understand the figures to make productive decisions.

All minerals affect other minerals and that influence may be negative or positive. If you follow the common NPK prescriptions favoured by many of the fertiliser companies, they usually remain the same year after year regardless of the soil test results. How can this be possible you may well ask? A crop removes a whole range of minerals and they need to be replaced. There is obviously more than NPK involved here but even the simplistic, NPK prescriptions, repeated year after year, do not gel from a soil science perspective. The amount of each of these three key minerals required each season will vary based upon many environmental and biological factors.