Soil Health 101
9 times out of 10, I'd say that the garden advice I'm giving to my clients are soil-related. Seriously! I know all of the things we consider the good stuff--the plant, the flowers, the fruits--those are all what we focus on because it's what we can see. But the success of that plant largely relies on what's going on beneath the surface.
It's super easy for a nerd like me to be tempted to take a deep dive into soil right here. Give me a podcast about the soil microbiome and a trowel and I'm the happiest person alive, but I know that that's not everyone's cup of tea. So for now, I just want to provide some insight that every gardener should know. I'll break it down into some digestible pieces and I hope you're able to take something away from it all. Whether you plant in the ground, in raised beds, in grow bags, or in containers, the principles of soil health apply to you! So here goes...
Soil Life = Plant Life
There is an ecosystem beneath our soil that is so complex that we're just beginning to ...ahem... scratch the surface of. But there's one definitive thing that it always comes down to: the soil is alive, and if we want our plants to live, we need to keep that soil alive. And when we do, our plants are happier--fewer pests, fewer diseases, increased size and yield, and less work for us.
The potting mix that we get at the big box stores is not soil. It's dirt--AKA dead soil. Yes, it provides structure to our plants, but it's not providing much more besides some minerals if we're lucky. Studies have shown that even those claiming to have beneficial fungi are dead by the time they reach our markets.
So what makes it soil? LIFE. Bacteria, microscopic organisms, fungi, worms, bugs. All of it. They all depend on the decomposition of organic matter to survive, and the easiest way to feed them is to keep giving them organic material. It's that simple! So what is organic material?
Anything that was once alive and is not alive anymore is considered organic material in our gardens. Leaf litter, cropped plants, grass clippings, veggie scraps, manure, shredded branches, compost whatever. Lay it on top of the soil and it will decompose, and the soil below it stays healthy as it begins to break down that material and use it as food. In return, it feeds the roots of the plants.
Feed the Soil
Joe Lamp'l, AKA Joe Gardener, has a phrase that I think about every time I'm out in my garden: "Feed the soil, and let the soil feed the plants." All happy plants want are water and nutrients. The roots are in that soil to find and transfer those things, and when they are not present the plant does not thrive.
Throughout the past century, it has become a societal norm to provide plants with what they need synthetically by feeding them with fertilizer. The problem with practices like that is that it does nothing to address the lack of soil health. So what happens? The soil continues to die while the plants appear healthy because they're getting their nutrients from the gardener and not the soil. The gardener keeps buying and applying fertilizer because it appears to work, and the soil health continues to decline. Then boom: dependency. I adamantly believe that this is where the "Miracle Gro has always worked for me" argument comes into play.
But when your soil is healthy and well-fed, it returns the favor. Nature wastes nothing. The byproducts of all the decomposition happening in your soil are the nutrients your plants need to survive.
So what can you do to keep your soil healthy? It's actually a lot cheaper, and a lot less work.
1. Stop Tilling
Seriously! Study after study after study reveal that the soil microbiome is at its strongest and healthiest when undisturbed (Derpsch, et al, 2010). The less you can disturb the soil, the healthier your plants will be. The bonus? Finished compost not only feeds your soil, but it keeps it from getting compacted (or it loosens compacted soil), so add layers of compost and let the soil do its thang if that's your issue. Think about it: if the top foot of your soil (the "topsoil") contains the most life and nutrients, and you're constantly ripping it apart and asking it to start over again each year, then you're going to be starting at ground zero every season. Tilling also digs up all those weed seeds that were dormant because they didn't have light before. Plus, it's a ton of work. Who needs all that!?
2. Feed it.
Your soil is Seymour, and it's hungry... so give it what it wants! If you don't have space to make your own compost, you can still find very affordable options locally. Instead of bagging your leaves, shred them and toss them in your garden in the fall. It doubles as a great mulch, as do grass clippings! The more diverse the sources of organic material, the more satiated your soil will be (Tahat, 2020). Some local farms may even have aged manure (and the aged part is important) that you can load yourself for low or no charge. Feeding your soil is about utilizing what nature provides--it doesn't have to be expensive or complicated.
3. Mulch it
Think about it... nature never leaves soil exposed. The second the earth is disturbed, something somewhere finds it and lays down some roots. It does not want to be exposed. To avoid this Emperor's New Clothes situation, lay down some mulch. Organic mulch is best--and by that, I mean anything that came from the earth originally. That way, you're feeding the soil as it breaks down. Bonus! Mulching retains moisture in the soil--a key element to keeping it alive (Manna, 2018). It also keeps the soil from compacting from the impact of rain or watering. Compacted soil keeps air from getting in there between all those particles, and without air the microbiome dies. On top of that, organic mulch yields higher nutrients in the soil (Pal, 2017). Obviously the added bonus of weed suppression is a key factor as well! Can't get your own? I suggest shredded hardwood if you're going to buy it. It's cheap, goes a long way, and breaks down in a growing season. And it looks nice!
*A word of caution: avoid dyed mulches. Even if the dye isn't toxic, it may be being used to disguise undesirables in your mulch. Stick to the natural stuff.
4. Chop, drop, and roll.
Like all good things, our growing seasons come to an end eventually and when they do, we do not need to waste those plants! They're perfectly good materials that will decompose nicely in your soil. Why put all that back-breaking work into your garden when you can chop down those plants, drop them right on top of the soil, and roll out of there? Not only does it act as mulch, but it feeds the soil when sources are scarce in the off season. And those roots that were creeping all through that soil? They'll break down, leaving channels for water and air. Yes, please.
5. Embrace balance.
All those things that are living in your soil depend on one another to keep that little ecosystem thriving. When we spray pesticides, fungicides, and antimicrobials (like vinegar), they're leaching into the soil and killing all those things. Instead, think of the soil like our immune system. A strong immune system keeps our body healthy and better able to fight off disease, and the same thing goes for our plants. Healthy plants may get some bugs, but it's rare that they'll be taken out by them. Giving them what they need to stay healthy will keep that balance in check.
6. Cover Crops
If you want to get fancy, you can plant some cover crops in the off seasons. These are plants that fix nitrogen, provide organic matter, and even reduce compaction depending on what you grow. I like to plant a mix of tillage radish, field peas, and oats. The winter freeze kills them and they act as a mulch that I then just bury in compost in the spring. There are other types that will emerge again in spring, and they have benefits too, but they do need to be managed more closely and cut down before seeding.
So what can you do this fall to maintain a healthy soil? Say it with me: feed the soil. Instead of bagging all of your leaves, shred some up and throw them in a layer on your garden. Or ask your landscaper to save your grass clippings or, even better, throw them in there for you. "Borrow" some bedding from your friend's chickens or rabbits to throw in there. Or grab some finished compost by a certified compost dealer. Even peeing in your garden provides some nutrients! (You're welcome for the visual... but we all know there are plenty of men out there who love to pee outside... why not do it in the garden!?). I like to do this in the fall so that it has time to break down over the winter. And plant some cover crops if that's what you're into!
Compost. Do so at least two or three weeks before you plan on planting so that it marinates. This will be your "fertilizer" over the growing season. I just throw it right on top; no digging here!
Testing Soil Health
Often, we make assumptions about what our plants need and we start adding cocktails of fertilizers to help compensate for what our soil is missing. But to be honest, I haven't used fertilizer in quite some time. Soil is complex and scientific and nature is amazing. I can't look at it and tell what it needs, but there are people who can! Get a soil test from your local extension office. Ours go to Virginia Tech, and they'll do a complete soil test and tell you what your soil has and doesn't have. Then you can plant the right cover crops, or add the right materials that have the benefits you need. I get one every fall for every garden space. They're cheap and save tons of money on fertilizer. I can't tell you how many times somebody has advised someone with plant issues to fertilize with something without ever seeing a soil test! It's impossible to know what your soil needs without actually finding out what your soil needs. Get the tests this fall and you'll be happy you did! **Note: they often recommend fertilizer on the soil test but it's based on agricultural practices; find out what your soil needs, and use soil health practices to provide it.
I hope you found this enlightening! I've done years of reading and research on soil health, and these were the main takeaways I feel all gardeners should consider. I want all gardeners to be successful, and that success really does start with our soil.
Derpsch, R., Friedrich, T., Kassam, A., & Li, H. (2010). Current Status of Adoption of No-till Farming in the World and Some of its Main Benefits. International Journal of Agriculture and Biological Engineering, 3(1).
M. Tahat, M., M. Alananbeh, K., A. Othman, Y., & I. Leskovar, D. (2020). Soil Health and Sustainable Agriculture. Sustainability, 12(12), 4859. https://doi.org/10.3390/su12124859
Manna, K., Kundu, M.C., Saha, B. et al. Effect of nonwoven jute agrotextile mulch on soil health and productivity of broccoli (Brassica oleracea L.) in lateritic soil. Environ Monit Assess190, 82 (2018). https://doi.org/10.1007/s10661-017-6452-y
Pal, P. K., & Mahajan, M. (2017). Tillage system and organic mulch influence leaf biomass, steviol glycoside yield and soil health under sub-temperate conditions. Industrial Crops and Products, 104, 33–44. https://doi.org/10.1016/j.indcrop.2017.04.012