In case you missed it, your farmer’s soil test has evolved. It all started out as a test to determine the availability of N-P-K in the soil. These tests had a lot to do with synthetic fertilizers and measured the chemical content of the soil. These numbers represent three different compounds: Nitrogen, Phosphorous, and Potash (Potassium). The N-P-K numbers are now on every fertilizer bag label (a government requirement) to give the buyer the percentage of these materials found in the fertilizer. In my opinion, the N-P-K numbers on a bag of synthetic fertilizer tells us how much “chemical trash” is in it.
The soil test has since evolved to account for the dozens of micro-nutrients and other elements that are essential to plant growth such as sulfur, hydrogen, oxygen, carbon, magnesium, etc., and the measure of organic matter in the soil. The micro-nutrient soil test better measured the chemical composition in your soil. However, not until very recently, has there been a readily-available soil test to measure the amount of beneficial soil organisms that help your plants to flourish and to fight off pests and diseases. Now you can quickly assess the life in your soil with a qualitative soil test from the Rodale Institute: Soil Life Testing.
To learn more about the history of soil analysis see the Explanation of N-P-K by Clean Air Gardening. It is a great article. In summary, what it says under the Alternatives to Using Fertilizers paragraph is:
“You might not need much fertilizer at all in your yard or garden. Here’s why. Many professional gardeners say that little to no additional potassium and phosphorus are needed in our soils as these elements are present already. However, we need to liberate these elements with proper soil aeration, soil drainage, beneficial soil organisms, etc.”.
We strongly agree with this statement. See our article about Compost Tea.