Soil is among the most important elements of gardening but is among the least understood. This is where your plants take up the majority of their water, oxygen and nutrients. During the winter, you’re going to be planning and purchasing many of next year’s vegetables so now is the best time to assess how your soil looks to set yourself up for success next year.
Different plants will remove different nutrients from the soil (and in different amounts) and you should strive to return the particular nutrients to the soil that have been removed. In addition, rain and irrigation during the season will have leached away some of your soil’s nutrients and those need replacing as well. When addressing these issues, your soil amendment efforts shouldn’t just take place when you’re planting next year’s crops. Rather, they should start in the fall to give the soil time to ‘fix’ the nutrients (i.e., make them available for use by your plants) next year.
To assess your soil quality and nutrient levels, there are various tests that can be purchased at a garden centre to give you the basic metrics: pH, nitrogen level, phosphorus level, and potassium level.
As an easy place to start, a pH test will tell you the acidity level in your soil. This is important as the acidity level affects which nutrients are available to your plants. Your soil pH can be tested in solution form (see picture, left) or using a soil pH meter (see picture, middle), which can be purchased at any garden centre. Optimal pH levels will vary by plant family but a good general range is 6.0 to 6.8.
Most other soil tests focus on nutrient levels. The three most important nutrients are nitrogen, phosphorus and potassium, each of which help your plants in different ways. These can also be tested using a special kit (see picture, left).
To have an even better understanding of soil quality, I usually opt for a more detailed soil analysis from a lab. This test is optimal since it provides other metrics such as organic matter percentage, and calcium and magnesium levels to help ensure plant health in the following year. It also provides details on less-known elements like copper, boron and sulfur, which will drive a lot of plant flavour.
To obtain these more detailed metrics (along with ideal ranges for a vegetable garden), take soil samples while the soil is still warm and use sterile/plastic tools so as not to taint the results. Make sure to combine soil from a few different places and depths (always 2”-6” below the surface – don’t just scrape soil off the top, get the soil at root-level) to get a comprehensive analysis. Then, for as little as $20 plus shipping, remit the sample to a lab such as A&L Laboratories or the University of Guelph. Their detailed report will help you learn a lot more about your soil and learn which amendments to apply now for maximum soil and plant health next year.
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