Please welcome Elizabeth Murphy, author of the book Building Soil: A Down-to-Earth Approach: Natural Solutions for Better Gardens & Yards. Today Elizabeth gives us the dirt on building healthy soil by feeding it. Here are her tips on finding the best amendments right in your own backyard (or kitchen).
It’s a fundamental fact of life: we all have to eat. It’s even true for our gardens. Well, not our gardens, exactly, but the soil that grows them.
When I look at a green, vibrant garden, I see a well-fed soil. Soil is more a plant repository; it’s an underground universe of beating and breathing organisms, responsible for providing nutrients, holding onto water, resisting pests, and making soft, fluffy garden beds. Because of this, feeding the soil with organic amendments is my first and foremost gardening priority.
What is soil food? Almost anything. Anything that was once alive, that is. Compost, the tried and true soil food staple, is only one of many organic amendment options for the creative gardener. In fact, most backyards provide a wealth of free soil food resources that we can use without composting or processing. Adding kitchen scraps, yard trimmings, and garden plants directly to garden soils feeds microbes and transforms neighborhood “waste” into food for your family and community.
Tried and true, compost remains the go-to organic soil food for home gardeners everywhere. Add it by the wheelbarrow load in the spring and fall or use it as rich, organic mulch. Make it yourself, buy it bagged, or purchase from a reputable business. Though invaluable as an organic soil builder, compost does take a lot of work to make or haul. Meanwhile, valuable nutrients are lost during the composting process. In fact, contrary to popular belief, compost doesn’t replace fertilizers. If using compost, ensure your garden plants get enough nutrients from other sources.**
Depending on where you live, find manure from neighbor farms or bagged at the garden store. Manure nutrients vary from batch to batch and type of animal. Nitrogen-rich chicken manure can replace fertilizers, while composted horse manure won’t. For maximum nutrients, add fresh manures at least 2 to 4 weeks before planting. To avoid problems with pathogens and weed seeds, use manures after hot composting (most purchased manure is pre-composted).
Fall leaves provide an unparalleled and free resource for improving and enriching soils. Like compost, leaves won’t replace fertilizers, but they work wonders to improve soil condition and build organic matter. For instance, they help break up and soften heavy clay; at the same time, they increase the fertility and water in porous sandy soils.
Work fresh or composted leaves directly into the soil when preparing gardens. If using fresh, shred first and dig into soils in the fall or spread as a thick fall mulch. For composted leaf mold, throw the leaves in a pile, a plastic bag, or a garbage can and forget about them for a few months. They make an awful smell, but turn into a garden delicacy that you can add to soils a few weeks before planting.
Instead of turning and hauling compost and manures, I’d rather spend my time relaxing in the garden. That’s why I grow my own soil food, using green manures. Green manures convert sunlight and, in the case of legumes, nitrogen from the atmosphere into organic matter and nutrients. Green manure roots also break up hard soils, without disturbing microbes. Except for the cost of some seed, they are absolutely free.
Use green manures whenever you have a gap between planting times or garden rows. Depending on your region, there are many fall or spring varieties. I use fast-growing buckwheat to build organic matter in the summer. In the fall, I like a combination of daikon radish or ryegrass to soften soils and red clover and vetch to add nitrogen. Turn green manures under to feed soil a few weeks before planting.
Waste Not, Want Not
Waste not, want not is what I call the broad category of “everything else.” These are the free, organic soil food resources I find everywhere I turn – grass clippings, seed-free weeds (avoid noxious weeds at all costs), tree trimmings, and garden debris right from my own backyard; coffee grounds, kitchen scraps, or food processing waste from my community. Instead of composting, I use them raw by turning directly into garden soils weeks to months before planting. When trimming perennials, I chop into the soil or lop and mulch right where I’ve cut them. I layer grass clippings, leaves, and food waste on gardens that I’ll plant next season, creating juicy friable beds without tilling. The key is to recognize organic “waste” for what it is: free soil food. Recycle these materials to keep soils healthy, happy, and well-fed.
**Note: For soil building, both high-nutrient (manures or grass clipping) and low-nutrient (compost, composted horse manure, or leaf mold) organic amendments are important. The first stimulates soil life and fertilizes garden plants, while the second builds long-term soil health, though may require some other source of fertilizer to balance it out. Generally, I avoid using very low-nutrient materials, like wood chips, except as mulch.
This quick and dirty guide gives a few of the soil food options on almost any block or backyard. But don’t stop here. Let your imagination discover the wealth of resources in your own community. For a more detailed soil food guide, check out Building Soil or my website, Dirt Secrets. Whatever you choose and however you use amendments, feed soils regularly and often to grow gardens that keep getting greener over the seasons.
Elizabeth (Ea) Murphy is a soil scientist and author of Building Soil: A Down-to-Earth Approach (Cool Springs Press, 2015). She shares her experience as an agricultural extension agent, soil science researcher, and passionate gardener to help people bring soils to life.