What does a soil fertility test primarily measure?

A soil fertility test primarily measures nutrient levels and pH balance because these factors are critical in determining the availability of essential nutrients for plant growth. Nutrient levels indicate the concentration of key elements such as nitrogen, phosphorus, and potassium, which are vital for various plant functions, including growth, development, and reproduction. The pH balance of the soil influences how well plants can absorb these nutrients; certain nutrients become less available to plants at extreme pH levels.

Understanding both nutrient levels and pH is essential for making informed decisions about soil management and fertilization. For example, if a soil test indicates low nitrogen levels, this information can help guide the application of nitrogen fertilizers to improve plant health. Similarly, knowing the pH can help determine whether lime needs to be added to increase alkalinity or sulfur to enhance acidity.

Other factors, such as soil texture and drainage, moisture and temperature, or soil erosion rate and organic matter, are important for overall soil health and management but are not the primary focus of a fertility test.