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Soil Testing, Part 1

© Deborah Turton

There are a lot of recommendations about testing your soil. The ultimate soil test is how well your plants are doing. If your plants are healthy, have plenty of blooms and are producing nice fruits and vegetables, then you probably don't need a soil test. Plants do well in healthy soil. As a general rule, one inch of good compost a year should be enough to grow most annual fruits and vegetables. To help your plants even further, you can spray a kelp formula every other week. Kelp contains lots of micronutrients and hormones that help plants prosper.

However, if your plants aren't doing well and compost doesn't help, a soil test can help you decide how to improve your soil.

Standard soil tests measure plant nutrients; pH, how acidic or basic (sweet or sour) your soil is; organic matter, the amount of once living matter in your soil; soil texture, the percentage of silt, clay and sand particles; and cation exchange capacity, how well your soil holds nutrients.

Soil Nutrients To my way of thinking, soil testing of nutrients is good for telling you generalities, but not specifics. Why? Originally nutrient testing was an aid for synthetic chemical farming. With this type of soil, there was not a lot of biological activity to help store nutrients or make them more readily available to plants. Therefore, the determination of nutrient amounts needed to grow a given crop was pretty straight forward. There were no complicating' factors such as microbes, worms, beetles, mulch, etc. Plus, synthetic fertilizers were developed to be quickly available. Therefore, nutrient labels only give you the amount released within one year of application. But natural fertilizers can slowly make the nutrient available over a period of five years. Therefore, the actual amount of the desired nutrient may be much higher than the bag says. If you were to use the fertilizer based on the label, you could end up with too much of a nutrient.

So test results from standard labs may lead you to add too much of a given nutrient. You should use these recommendations as guidelines. If the results state that you are very low in one nutrient, e.g. phosphoreus, then add phosphorus to your soil. But not in the amounts recommended. You can decrease the recommended amount by up to 75%. Wait a few months and see if your plants are responding. Be patient. If your plants still need help, then add a little more. You can always add more fertilizer later, but if you add too much, it can be very difficult to balance your garden soil again.

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