Let’s talk Dirt(y)!
What is soil?
Soil is a mix of eroded rock and organic matter. Over millions of years rock breaks down to tiny bits and may mix with decayed organic matter. Organic in this sense refers to anything that was once alive. Very low organic levels result in sand or gravel, at the other end of the spectrum, high levels of organic matter and low mineral content result in peat, or compressed organic matter with very little mineral content. Neither extreme is very good for growing vegetables. Fortunately for us, most gardeners’ native soil falls somewhere between the two. According to Wikipedia, “On a volume basis a good quality soil is one that is 45% minerals, 25% water, 25% air, and 5% organic material, both live and dead.” Notice the inclusion of air and water. I think it is easy to overlook these as intrinsic components of soil.
It’s a living thing
Healthy soil is a living thing (cue the Electric Light Orchestra!). Full of microbes, bacteria, tiny insects, and worms, healthy soil is teeming with life. It not only physically supports your plants providing stability, it also supports your plants nutritionally with the micronutrients and trace elements your plants need for good health.
Drainage – neither too wet nor too dry
Drainage is important to good soil. It keeps plants from standing in water – a situation that can rapidly lead to root rot and plant death. You can improve the drainage of your soil by adding organic material, and by adding vermiculite/perlite. The organic material will “loosen up” the soil and the vermiculite will help retain moisture, releasing it as the surrounding soils dries out.
Improving on Nature
People can spend a small fortune and/or spend years trying to improve their garden soil. It is possible. Improving garden soil usually involves the addition of amendments. Here are the most common ones.
If you have time, you may add compost, leaf mulch or other decayed organic material to your planting beds over the course of several years. In time, you’ll have rich organic soil for your vegetables to thrive in. A single truckload of compost dumped into your beds will improve them, but the real benefits won’t be felt for several years of continued improvement.
Most people I know are impatient and don’t want to wait several years, let alone one growing season; especially when just getting started. I recommend jump starting your garden with purchased compost and simultaneously starting a compost pile.
Whole books are devoted to compost, as the joys of composting are many and include reducing the amount of waste going into landfills, improvement of garden soil, fantastic results in garden production. Good plant based compost is a great addition to your garden’s soil.
I’ll cover composting further in a future article.
Animal dung is great for your garden in moderation. Often you can get fresh manure free for the asking if there is a small stable or farm with animals nearby. They have to get rid of it or it just piles up.
There are two warnings regarding manure.
Fresh manure is too “hot” to apply directly to your vegetable beds. What does this mean? It means there is too much fresh nitrogen and it can damage or kill your crops. (There is one exception that I know of – rabbit dung – which can be directly applied to your garden beds.) Thankfully the solution is easy.
Use old poo.
Old manure has had the time for beneficial bacteria to break down the nitrates into nitrites that plants can use. Make sure the manure you use has been aging for at least 6 months or until it is dark and crumbly and not identifiable as manure. Alternatively, purchase your bags of manure from the gardening center. This manure has gone through the aging process so it is less likely to burn your plants.
Last year I added some horse manure that I thought had sufficiently composted. It stunted and “burnt” some basil plants early in the season. As the summer wore on, and more rain fell, this problem resolved itself, and the basil grew strong and healthy.
Be aware, composted manure is high in salts and over time, the salts can build up and be detrimental to plant growth. Be judicious in the use of manures.
For many years, people used peat as a soil amendment or conditioner to loosen up clay, or clumpy soil, or to add moisture and air retaining properties to garden soil. Peat is decomposed, compressed sphagnum moss. Peat is readily available and very effective as a soil conditioner. But there is a problem. Peat takes a long time to form, making it a resource that while renewable, may not be sustainable in the long term. It’s estimated two-thirds of all peat consumed is by amateur gardeners! Recently there has been more awareness of this and suppliers are working on alternatives. Coir or the husk fibers from coconuts hold promise as a sphagnum peat replacement, but as yet have not achieved wide spread use. It is however, what I will be using in the future.
Add coarse sand (.5mm- 1mm) to heavy clay to improve drainage. This works by adding open spaces, allowing air and water to flow more freely.
DIY or “make your own soil”
Some people will choose to amend the soil they have on site by adding amendments, that is manure, compost or coarse sand as mentioned above. In a boxed raised bed, if you choose, you can create your own soil!
Squarefoot Gardening instructs you to mix 1/3 by volume each peat moss, vermiculite, and manure. This is known as “Mel’s Mix.”™ Use care when choosing your manure as discussed above. Mel suggests you use five different kinds! This might be possible but I had a bit of difficulty finding five different kinds of manure. I used three with good result. I suggest letting this mix be a starting point, especially for beginners because it does work, and takes the guesswork out of ratios.
As I continue, I suspect the composition of the soil in my beds will tilt towards homemade compost and coir “peat”. I do have some coarse vermiculite left so that may go in as well. I also have access to horse stall muck, as well as chicken coop muck.
If you want to be sure about your garden soil and the nutrients it holds (remember plants drink, so water soluble minerals and micronutrients are sucked up along water in the soil) you can test it. I have never tested my soil and have had good results. That is not to say testing your soil is not worthwhile. Knowledge is power and if through testing, you find that your soil is grossly lacking in proper plant nutrition, then you can, (ahem), make amends.
There are two basic ways to test. One is to buy a kit and test it yourself. The other would be to send in soil samples to your local university agricultural extension for testing.
I’ve seen kits at the local growing centers and in the gardening aisles of the big box stores. A little on-line research will give you some idea of their usefulness.
Local university extension
You can of course take and send samples off to your university agricultural extension they will test it either for free or for a nominal cost.
Stay tuned, in the interest of science I’ll compare results between at least two soil “testers” and the results I get back from the local university.
Soil is the basis of a productive garden. Fortunately you can improve on what nature gave you or even create your own from scratch! Take care of this basic and most important element and you’ll be greatly rewarded!
Until Next Time, Keep Digging and Eat Well!