One of my goals as a gardener is to better understand the science behind common gardening products and practices. This interest led me to Jeff Gillman and Maleah Maynard’s book “Decoding Gardening Advice: The Science behind the 100 Most Common Recommendations”. When I picked up the book, I was very curious to learn how well my favorite gardening recommendations held up to the latest scientific research. With the notable exception of compost tea, which the authors don’t recommend, I was pleased to learn that they consider my other core gardening practices to be well supported by science. Specifically, they consider the following three recommendations as good advice: Add organic material to all garden soil before planting Create an environment favorable to earthworms Use vermicompost to improve garden soil Today I thought I’d take a look at these recommendations and talk about why Gillman and Maynard think they’re good advice. According to the authors, “[compost] is without a doubt the most important soil amendment you can add to the garden”. They recommend adding 2 to 3 inches of compost to the topsoil every year if possible. They also recommend adding an additional 2 to 3 inches to established perennial beds and no till gardens. I was happy to see that the authors agree with my position that “regular applications of organic matter may even provide enough nutrients to make additional fertilizer unnecessary…” Getting into the specifics, they cite organic matter’s ability to improve drainage in clay soils and increase water retention in sandy soils, as well as its ability to hold nutrients and increase the amount of oxygen that reaches plant roots. According to the authors, “even if you start with the worst dirt imaginable, turning compost into the top few inches of soil each year (or even adding it as a top-dressing that you do not turn in) will significantly change the quality of soil just a few seaso will significantly change the quality of soil just a few seasons. The second recommendation is related to the first, because the best way to increase the earthworm population is by adding organic matter to the soil. Earthworms break up compacted soil and create tunnels that allow water and air to circulate more freely through the soil. They also break down organic matter, incorporate it into the soil, and leave behind castings that concentrate nutrients and make them more plant available. To sum up, the authors say “earthworms are nature’s tilling machines. They do a great job of making nutrients, air, and water available to plants”. Finally, the authors believe that the recommendation to use vermicompost to improve garden soil is good advice, and point out that vermicompost typically has a higher nutrient content than compost. Here we’re talking about the castings produced by red wigglers and other composting worms that are typically kept in worm bins to process food scraps. The authors cite a number of benefits from vermicompost, including its ability to improve soil structure, attract more earthworms to the surface, improve water-holding capacity, and nourish plants by making soil nutrients more available. To sum up, the authors say “vermicomposting is an inexpensive and very good way to boost the health of soil”. So, though, the authors don’t recommend the use of compost tea, they do recommend the rest of what I consider to be the core of my gardening practices – namely, adding organic matter to the soil, creating an environment favorable to earthworms, and using vermicompost. Because I’ve had great results while using compost tea, however, I’m not planning on abandoning its use in response to the book. Instead, I’ll test compost tea in a field trial next year in hopes of better assessing its effectiveness and make a decision at the end of the field trial. If you didn’t see the video in which I talked about the authors’ take on compost tea, and are interested in learning more, there’s a link at the end of this video and in the description below. there’s a link at the end of this video and in the description below. Well, that’s all for now. Thank you very much for watching, and until next time remember you can change the world one yard at a time.