Soil Amendments 101

Once you have your test results, soil type, texture, and ph balance, you can identify the correct amendments and the proper amounts needed to build your soil. The array of amendments can be quite dizzying, but to help clear it up we will break it down into three groups: those that add organic matter to the soil, those that add a mix of nutrients into the soil which are designed to feed your garden over several years, and those that adjust the ph balance of your soil. In the first group you have amendments such as compost, hummus, peat, mulch, coir- an amendment made from recycled cocont fiber, aged animal manure, and green manure- or crops that you plant and then till under to add their vegetative mass to your soil. The second group consists of seaweed, ground rock, greensand, and soil conditioners. All of these will add a mix of nutrients to the soil and will break down more slowly than the vegetative fiber, feeding your soil over the course of several years- as in the case of greensand, or over the space of one complete growing season- as with seaweed. And in the third group we have amendments such as woodash, potash, lime, and sulfur which all go toward adjusting the ph balance of your soil to the ideal range of 6-7 that your plants need to efficiently use the nutrients in the soil. These additives are used over time, as they will not effectively adjust the ph balance of your soil in just one growing season but over the course of a several growing seasons. The best time to apply these amendments is in the fall.

For the purposes of this article we will focus on the first group of amendments, organic matter, and how and when to add those in order to attain the desired soil texture. Going back to your soil test, what is the texture of your soil? Clay, silt, or sand? Sandy soil needs 3-4 inches of rich organic matter such as well-rotted manure or finished compost worked 6 inches down into the soil. Add an additional two inches each year at the end of the growing season to maintain good soil balance. Plants in sandy soil should be well mulched to preserve water, as sandy soil dries out quicker than most without additional covering. Clay soil has the opposite problem, as it retains

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