The purpose of soil analysis is to assess the adequacy, surplus or deficiency of available nutrients for crop growth and to monitor change brought about by farming practices. This information is needed for optimum production, to avoid transferring undesirable levels of some nutrients into the environment and to ensure a suitable nutrient content in crop products.

Stressed plants grow more slowly, may show unusual growth patterns and give reduced yield. Stress affects crops directly, for example by reducing the rate of photosynthesis and so growth. However, there are other, less obvious effects within the plant.

The use of potash does not have an environmental downside, but lack of K can reduce efficient plant uptake of N and P. This video looks at the issues including cross-compliance and good practice.

An introduction to potassium, including an introduction to PDA, the role of potassium, the potassium cycle, and the principles of potassium recommendations.