How best to test soil

Question: Are those over-the-counter soil tests any good?

Answer: While using an over-the-counter soil test is much better than doing no soil test at all, it’s typically much more accurate and as cost-effective to send your soils to a soil testing lab.

Many state universities have soil testing labs. There are also private soil testing labs like Soil Control Labs in Watsonville, CA. These labs will walk you through the best way to collect a soil sample and offer a range of analyses including how acid your soil is and what fertilizers it may need.

For more information, including some labs around the United States where you can send soils for testing, visit: https://www.soils.org/discover-soils/soils-in-the-city/soil-contaminants/soil-testing

–Answered by Sally Brown, University of Washington, and Kristen McIvor, Pierce Conservation District, Tacoma, WA

Have a question for Soils Matter? Post it as a comment below, or email us at soils-matter@soils.org.

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3 responses to “How best to test soil

  1. What happens to the microbial life in the soil in containers with severe freezing winters? Can organic fertilizers like greensand, compost, manure, and wormcasting be used? Would liquid ones like fish or kelp be better? Or should “synthetics” be used? Does microbial soil life need to be re-introduced each spring?

    • We are just beginning to be able to understand the microbial life in soils thanks to increasingly sophisticated genetic tools. Any soil scientist can tell you that each gram of soil contains about 6 million microbes, but ask them to measure the population demographics and they will be lost. For example, I’m involved in a study looking at a microbial group known as the Archaea in different soils. Archaea are a type of microbe that can oxidize ammonia. We’ve seen that the Archaea family trees are different in different crops and even at different times of the year, but we have very little idea of why. So to your question: I can’t tell you exactly how those 6 million microbes survive a hard freeze, but either they do or they have friends who will come take their place. The best thing you can do for them is to provide organic matter to the soil when it thaws out. The microbes use the carbon in the organic matter as a food source, while they use the nutrients (nitrogen, phosphorus, etc.) in the organic matter the same way people do. I would definitely avoid synthetics because they just provide the nutrients without the “food.”

      –Answered by Sally Brown, University of Washington

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