To give plants any hope of reaching or exceeding their proportions at maturity, plants need the best possible soil. This soil doesn't come on any truck. It only develops when humans cultivate plant communities in conjunction with cultivating bacterial, fungal, and invertebrate communities in a landscape.
Once the choice is made to redesign low-yield, high-maintenance gardens (like lawns) into high-yield, low-maintenance gardens, uncertainty about soil fertility fades away. Lab tests help, especially to determine lead contamination, but chemistry is only part of the system in a self-sustaining ecology. The installation of a diverse mix of exotic and native plants and annual application of woody and nitrogen-rich amendments results in an ecology that snowballs toward greater and greater fertility and abundance. The more mature the landscape grows, the more abundant will be its biomass production, generating a cycle of successes building on successes.
Good soil precedes success in the garden. In fact, it might be that the future success of our civilization depends on soil amendment. As David Holmgren (co-originator of the permaculture concept) said, increasing the humus content and the diversity of life in soils “is arguably the greatest single contribution we could make to ensure the future survival of humanity” (Holmgren, 37). In other words, we’ll know we’re on the right track when the soil beneath our feet is soft, spongy, full of organic matter and mulch, and abundant with soil life (Hemenway, 182).
High-yield gardens are in constant flux, preferably with regular pulses of fertility. Composting begins with the permaculture ethic of "produce no waste" and ends with lush abundance of soil life and plant life fertility. The biodynamic gardeners and Oregon Tilth both know that double digging depleted Willamette Valley clay (only when the soil is dry) can revitalize a soil profile that suffered from architectural or agricultural degradation. Medium or smaller urban sites (especially the flat ones!) benefit greatly from less intrusive keyline channeling, rain garden digging/trenching, and swale digging in conjunction with hugulkultur biomass composting. Damage from any digging to soil mycorrhizae, even double-dug plots, requires healing with compost, manure, animal bedding, etc. Hugelkultur, mulching, spreading manure, cover cropping, guild planting, and biodiverse native planting, and other strategies all represent multi-pronged approaches to cultivating well-draining, friable, humus-rich, infused-with-magic, lovely black soil.
Hugelkultur, or mound culture, involves building planting beds by burying woody biomass. It's important there be large quantities of nitrogen in the form of dead leaves, manure, or compost in the hugelkultur formulation. The mass of wood at its core will lock up much of the nitrogen in the soil, so it's important to have an abundance for the first plants to grow in the mound. Twigs, branches, and logs must be cut to size to eliminate air pockets. Logs can fill larger mounds in more open spaces and go in the center or border smaller mounds. A concave top makes for a less hydrophobic bed. The mounds can immediately grow grain, vegetables, perennials, shrubs, and trees.
This "meditation wheel" stepstone path and hugelkultur planting bed went in where once there was 2 dimensional lawn overrun with grape hyacinth. The mound pictured here was constructed using at least 3 cubic yards of woody biomass culled from the landscape. Instead of being trucked off to be processed by fossil-fuel powered machines, this material enriches the soil from which it came.
The site above was photographed 6 months after a fig, blueberries, creeping time, oregano, yarrow, slough sedge, strawberry, native rose, and mahonia were installed. The culinary potential and the evolving beauty of this garden space enliven what was 2-dimensional grass monoculture.
In the forests of the Pacific Northwest, Red Huckleberry (Vaccinium parvifolium) prefers starting life in a fallen tree log rather than the soil. Turning “yard waste” into hugelkultur deepens the ecology of the site, transforming a once barren site into a fertile, productive garden.
Composting in Place:
Very commonly, kitchen waste all goes to in one place, the compost heap. Of course, that's a better spot than into the back of a diesel-powered truck. However, composting in a heap requires future work to turn and spread the rewards. A useful alternative is composting in situ, or applying kitchen waste to the soil in a new place each time. A bowlful of kitchen waste composted in place is one less shovelful that has to be shoveled, transported, and spread later. This is as easy as digging a hole the size of the kitchen waste, dumping it in the hole, and covering it up.
This keeps compost heaps from being a waste of nutrients. Toby Hemenway pointed out that the black earth under his compost pile demonstrates its inefficiency. “I usually trundle this rich earth to the garden too, but it’s telling me that complex and life-giving metabolic liquors are oozing out of the pile, washing onto the margins, and being wasted” (Hemenway, 70). Siting the heap under a tree would eliminate angst over wasted ooze. The active gardener usually finds they strike a balance between singular heaps and composting in situ by maintaining numerous small piles of compost at regular locations.
Sheet mulching deeply restores soil by massively cultivating the soil life. The precise recipe for the sheet mulch may be altered to fit the site. The site pictured below got the works.
The soil was so compacted that even dandelions were stunted. One inch of manure (not pictured) was the first amendment added to the depleted, compacted soil.
After spreading the manure, 1/4 inch of paper and cardboard went down to suppress weeds and retain water. An additional coating of manure went over the paper.
A one-foot layer of straw covered the manure. Straw can seed annual rye grass. This annual cover crop can be highly beneficial to building soil life communities, but can be annoying if unexpected.
Following the straw came a good two to three inches of mushroom compost.
Two inches of chipped wood topped the layers with a water retaining, weed seed stopping coat.
The results from these labors? See below. Newly installed plants riot up to their mature heights with unparalled health and vigor. Working with nature through sheet mulching produces the healthiest, most vigorous gardens ever built.
The trees shown here were actually quite mature when they arrived at the site, and this picture was taken 2 years after the garden was installed, but the overall abundance and beauty of this once bare-patch of clay is staggering.
Hemenway, Toby. Gaia’s Garden: A Guide to Homescale Permaculture. Chelsea
Green Publishing Company: White River Junction, Vermont. 2000.
Holmgren, David. Permaculture: Principles & Pathways Beyond Sustainability.
Holmgren Design Services: Hepburn, Victoria, Australia. 2002.