Building Happy Soil For A Happy Garden
By Carrie Hargrove, initially published as a Farm Your Yard episode on KBIA in the Spring of 2016
For the last 7 years, I have spent a lot of time with rotting food. I could tell you some things that would surprise you about the decomposition of different things. For example, avocado skins just don’t break down. Neither do egg shells. Fur really doesn’t go anywhere either. And while it takes a long time to break down, bread from Panera will turn blue as it does- lots of preservatives in that one. This revelation is most likely absolutely disgusting for some people, but it doesn’t really bother me. I can see past what is happening right at this moment in the early stages of decay to see what it will be in a year: the world’s best compost. At the Urban Farm we make some really good compost that we sprinkle over our beds and put in our potting mix to give the soil and our plants a little boost.
Ok, so first things first: you should drop the $10 to get a soil test. The University of Missouri has a soil lab that will test soil samples for any number of nutrients, with the standard, basic test running you $10. The turnaround time is pretty good as well - within just a couple of days the analysis will be emailed to you. This test will tell you some things that are helpful, like the pH of your soil, the levels of P, K, and those of several micro-nutrients. This is worthwhile info. For example, if you have enough P, there is no reason to rock phosphate to your garden. The basic soil test just gives you a starting point for knowing what soil amendments your garden needs.
This is a good time to point out that amending your garden’s soil is not necessarily the same as fertilizing. Amending the soil with compost is a long-term soil building strategy, whereas applying Miracle Grow is just feeding the plant. A common refrain in organic gardening is “feed the soil, not the plant”. Meaning, that if you have super healthy soil, your tomatoes will grow string and healthy as well. Not that I’m against fertilizing, not at all. It is just that fertilizing and amending the soil are different strategies that can be complimentary in a robust gardening scheme.
Ok, let’s start with everyone’s darling: homemade compost. Up to a quarter of our trash is made up of things that rot. Think about that for a second. Not only are we throwing away a ridiculous amount of food, which means we are wasting a ridiculous amount of food, but we are using a substantial amount of landfill space for things that will breakdown on their own. Yes, I am using this platform to tell everyone to start composting. Even if you don’t garden, composting is a no brainer for waste stream minimization. Ok, I am stepping down from my soapbox now. Back to using compost in your garden.
Think about compost like a sourdough starter. Good compost will contain whole worlds of beneficial bacteria, fungi, and other invertebrates. When you are adding compost to your garden, you really are adding these populations, with the hope that they will proliferate. So, you are starting with a little bit, but that little bit will keep growing over time. Adding an inch or so of compost to your garden once a year, preferably in the fall, will do your garden well. When you add the compost, you can till it in, or you don’t have to. Tilling it in has a more immediate benefit, but just adding it on top works just fine. We call this top dressing, and that is a better mimic of what happens in nature. The compost will percolate through the soil with rain and freezing and thawing.
Also, just like a sourdough starter, you have to feed the compost and the soil in your garden to keep those all-important soil communities thriving. There are lots of things you can add to your garden that will make it happy. These include: grass clippings (only if you don’t spray your lawn), used coffee grounds, and ground up leaves. During the growing season, you can add these things around the edges of the garden, or in the walking paths, or you can use them as mulch around your plants (be careful with the grass clippings- they get hot and can burn plants if too close). Adding them in the fall and over the winter is a good idea as well. The more soil organisms you have in your garden, the faster these additions will break down.
You can also add inorganic amendments to your soil. These are usually rock dusts, like rock phosphate or lime- things that don’t break down over time. Like compost, and the other organic amendments, these are long term soil building ingredients that are important sources of nutrients for your plants and the little guys that live in the soil. Unlike the organic amendments, these rock based ones would be more dependent upon the soil test you take.
Another amendment you can add is bio-char. Bio-char is wood that has been burned very slowly, which creates a substance that looks and feels kind of like charcoal for the grill- with the important difference being that it is not toxic, as charcoal briquettes are. Bio-char has to be dug pretty deep in the soil, like a couple of feet, and it acts like a little hotel for all of the good things that live in the soil. Bacteria, fungi, and other microorganisms live in and around biochar. It provides them habitat to proliferate, which is a good thing for the gardener. Like compost, a very small amount of bio-char goes a long way.
You might have picked up a common refrain throughout this monologue, and that is put stuff in your garden that is good for the things that live in the soil. That is the essence of organic gardening. A successful garden is wholly dependent upon the bacteria, fungi, worms, and myriad other minute subterranean organisms; organisms who, in the course of day to day life, excrete waste, slime, and other substances that the plants can’t get enough of. So, if the soil is happy, and your tomatoes are happy, you, gardener friend, will also be happy.
For more information on how to take a good soil sample, and where to send it to, visit http://soilplantlab.missouri.edu/.