by Catherine Haug
I don’t have much experience at gardening, so I’m very interested in learning every aspect of the craft, including soil quality. My Dad had been an avid gardener in the 1950s and 60s when I was growing up; he hand-tilled the soil in the fall with debris from the harvested garden and some manure from the neighbor’s cow, then planted seeds in the spring. Or at least, that’s how I remember it.
But I’ve come to learn that if you want maximum nutrition in your veggies, it is not necessarily so simple. Your soil needs to have the right carbon:nitrogen ratio, be the right pH (level of acidity), and have the right kind of drainage for the plants you want to grow.
Soil for My First Garden
Zena and Gregg helped me condition the soil last fall for my first raised bed garden. A layer of straw was placed at the bottom of the bed, directly on the ground, to attract worms. Then compost, composted horse and chicken manure, and perlite were mixed with Creston topsoil, and placed on top of the straw.
Soil for Square Food Gardening
Mel Bartholomew, of Square Foot Gardening fame, recommends a mix of 1/3 each compost, peat moss and vermiculite. Well, here in NW Montana, we’ve all learned to shy away from vermiculite because of the trouble in Libby. So I would use perlite instead of vermiculite, just to be safe.
Lasagna Gardening and Sheet Mulching
Patricia Lanza advocates “Lasagna Gardening” which uses soil, peat moss and straw placed in layers like a lasagna inside a raised bed, along with composting materials such as yard waste, old manure and kitchen veggie scraps.
Sheet Mulching is a type of lasagna gardening, used to prepare lawns, or old, tired ground for gardening without tilling. First, cut down the grass or weeds in the site. Lay the clippings down and then add a layer of brown cardboard or newspaper (no colored ink) at least 12 inches thick, and overlapped by at least six inches to smother the grass and weeds. Wet the paper to make it stay put. This is followed by layers of compostable materials: straw, shredded non-glossy, paper (no colored ink), grass clippings, leaves, yard waste, non-animal food scraps, unfinished compost, are all good materials.
When selecting materials for these layers (or for your compost bin), consider the carbon to nitrogen ratio, which should be about 30:1.
- Carbon sources are organic materials that are dry or woody, and tend to be brown or dead: dry leaves, straw and newspaper are good examples.
- Nitrogen sources are “green” or wet, fresh material including non-animal food scraps, animal manure and green grass clippings.
- A 3 inch layer of dry leaves topped by an inch of food scraps provides a 30:1 ratio.
Better Garden Soil: Soil Maintenance
Simple Tips for Better Garden Soil,(3) an article by Barbara Pleasant in Mother Earth News (April/May 2009) suggests: “instead of thinking of your soil as an input-output system, treat it as a living food web that you feed and protect.”
It’s not just a matter of adding the right amounts of the right amendments (compost and such). There is much more to the story. Here are some highlights from this article:
Many plants cannot thrive without their companion fungi. When you add compost or mulch, you add starter colonies of these helpful fungi. But then you need to give them peace and quiet by minimizing soil cultivation which breaks up their hyphal networks (root-like extensions).
- Practice “stubble cropping,” or planting into soil without pulling out or chopping up the remains of the previous crop; and
- Ease back on bed renovations in fall to minimize harm. Instead, mulch over your spent beds in fall, and save your digging for spring. Good mulches include grass, leaves, hay or other organic materials
And, in the off-season, plant grassy cover crops like oats and winter rye, to turn your garden into fungi-heaven. Take a hint from nature: these beneficial fungi are always plentiful where deeply rooted grasses grow.
Soil pH (acidity)
You are advised to your soil’s pH before adding amendments. Most lab tests (arranged through your extension service) cost about $15, a small price to pay. Or you can buy a do-it-yourself test kit for under $10.
For most veggies, a pH in the range of 6.0 – 7.5 is best. Use organic:
- lime to increase the pH;
- sulfur to decrease pH.
Getting nitrogen right
You would be wise not to over-fertilize in the spring. General guidelines for nitrogen:
- Low-demand crops with short growing seasons, such as beans, squash, baby salad greens and cucumbers will likely do well without additional fertilization, provided the soil has been steadily improved with organic amendments for at least 3 years.
- More long-lived crops such as tomatoes, carrots and sweet corn need more nitrogen and benefit from a midseason side dressing with a high nitrogen fertilizer, such as alfalfa, cottonseed meal, or a blended organic fertilizer.
- Cabbage family crops are very nitrogen hungry: mix an organic fertilizer into the soil prior to planting (cabbage family seldom forge beneficial relationships with soil-borne fungi, so you can safely disturb their soil).
Mother Earth News: Build Better Soil with Free Organic Fertilizer (April/May 2008) by Barbara Pleasant suggests that most organic fertilizers on store shelves are “overpriced, and some are stunning rip-offs that reputable stores and catalogs should be ashamed to sell.”
This article uses nitrogen content as the basis for cost comparisons between different brands of organic fertilizers [NOTE: fertilizer content is expressed as Nitrogen:Phosphorus:Potassium, or N:P:K].
Packaged organic fertilizers range in price from $4 – $17,000 per pound of nitrogen. Grass clippings and yard waste, two of the best organic fertilizers, are free! It’s a no-brainer!
Develop a relationship with your soil; “respect it as a diverse community of living, breathing organisms,” that live primarily below the surface. In return, this community will “give you better soil and better harvest, with less work than ‘conventional’ methods.”
Thanks to Michelle Lomado-Patterson from St. Patrick’s Community Garden Committee, for turning me on to the article from Mother Earth News.
Stout Method (Deep Mulching)
This method is named for renowned organic gardener, Ruth Stout, and creates good rich soil.
“Over the years, Stout’s deep mulching technique (2) will help you build wonderful soil fertility plus conserve water. In the meantime, working some organic fertilizer (we like fish meal) into the soil while you are building the organic matter and fertility will pay big dividends” in your garden (1)
Stout’s method in a nutshell:
“Keep a thick mulch of any vegetable matter that rots on both my vegetable and flower garden all year round. As it decays and enriches the soil, I add more.” Ruth suggests that if you follow her method, once you’ve got a good fertile soil with excellent tilth, you won’t need added fertilizers as long as you keep adding mulch. (2)
What kind, and how much mulch?
For mulch she recommends “hay, straw, leaves, pine needles, sawdust, weeds, garbage — any vegetable matter that rots.” Recent research suggests alfalfa hay is the best, but use what you have, or what you can get. (2)
“I beg everyone to start with a mulch 8 inches deep; otherwise, weeds may come through, and it would be a pity to be discouraged at the very start. … You need at least twice as much as you would think.” (2)
Dick Clemence, Ruth’s A-Number-One adviser, says, “I should think of 25 50-pound bales as about the minimum for 50 feet by 50 feet [2500 square feet], or about a half-ton of loose hay. That should give a fair starting cover, but an equal quantity in reserve would be desirable.” (2)
Planting in mulch
This is done the same way you plant in soil: pull some mulch aside and add your seeds, then cover them with the mulch. (2)
Cautions for deep mulching
- “Be sure the mulch is not so dense and packed that the developing plants can’t find their way to sunlight.” (2)
- “If you have big problems with slugs or mice the deep mulch method can add to your troubles.” (2)
- Mother Earth News: http://www.motherearthnews.com/Real-Food/2007-04-01/When-and-How-to-Plant-Potatoes.aspx
- Mother Earth News: http://www.motherearthnews.com/Organic-Gardening/2004-02-01/Ruth-Stouts-System.aspx
- Mother Earth News: http://www.motherearthnews.com/Organic-Gardening/Better-Garden-Soil.aspx
- Mother Earth News: http://www.motherearthnews.com/Organic-Gardening/1999-04-01/Lasagna-Gardening.aspx
- Square Foot Gardening: http://www.squarefootgardening.coml
- Sheet Mulching: http://www.agroforestry.net/pubs/Sheet_Mulching.html