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Feeding the Soil

Myriad of ways to give back to the soil.

By Susan W. Clark

Years ago, while trying to find affordable land to farm, we talked to a neighbor of the place we later bought. He advised us that the land was clay and not fit for growing much of anything. We overturned his wisdom, but it took time, mountains of organic material, and a commitment to continue soil building. In the following paragraphs I’ll review our on-farm practices, then off-farm material sources, and finally, some of our experiments that backfired.

Sustainable farmers strive to build soil so that land can be farmed into the distant future. We learned that the soil isn’t just bits of rock, but is filled with life. In addition to the visible creatures living in the soil, like worms, pill bugs, and moles, a universe of microlife inhabits our soils.

Feeding those hungry microbes is a basic part of sustainable agriculture. To do that, we need to replace what we take away. How can a farm replace the material that goes off-farm as harvest? At Natural Harvest Farm we constantly keep our eyes open for new – hopefully free - sources of soil food. An added benefit is that much of what we use diverts waste from a trip to the landfill.

On-farm soil feeding


  • Composting plant materials  - As harvests are readied for market, we keep trimmings for further use. Rabbits and poultry eat some, and we compost their manure. Trimmings not used for animals feed are composted. Non-invasive weeds are used in the same way. We offer orchard prunings to our small herd of grazing animals (sheep, alpacas, and a llama). What they don’t eat, we compost or use as firewood. After cider and grape pressing, we compost the leftovers, or use them immediately as mulch, especially to counter poison oak.
  • Mulching with weeds, grass trimmings, leaves - We mulch paths between raised beds with materials that change with the seasons, i.e., grass clippings, weeds, nutshells.
  • Manure from our grazing animals - We compost manures, usually mixed with off-farm straw bedding, and apply the finished product to annual and perennial plantings. Of course the animals spread some of their manure, helping to feed the pastures.
  • Green manuring and cover cropping - Soil microbes feed from plant roots, so when we harvest crops we don’t leave the soil bare, but plant it again so new roots can exude their microbe buffet.
  • Composting household waste - The great thing about farming is that there really isn’t much waste, but guilt-free leftovers. What we can’t eat we sort for composting or feeding animals, with both uses eventually feeding the soil.


Materials from off the farm


  • Purchased straw, especially oat straw as mulch and animal bedding
  • Shredded paper from offices and the homes of friends
  • Cardboard and feed sacks for layered mulching and weed control, sorted to avoid plastic, particularly plastic-lined paper sacks
  • Manure and bedding from the county fairground, when available, and from a neighboring horse farm
  • Street leaves from the City of Canby
  • Various other sources such as post-wine-pressing grape skins and seeds, wood chips from commercial tree pruners, stable cleanings from animal haulers and breeders, yard debris (after checking contents for nasty surprises), and anything else that will contribute to maintaining our soil fertility.
  • Neighbors’ waste solicited with a “Chipped Yard Debris Wanted” sign out front
  • Big cardboard boxes from mattress store for layered mulching
  • Bags of used coffee grounds from espresso stands
  • Vegetable trimmings and waste bread collected for us by the Quizno’s in Canby. This partnership diverts food waste from the solid waste system, helps feed our livestock, and eventually turns restaurant waste into material to enrich our soil


Three the hard way

City dump trucks stuck in the mud aren’t a pretty sight. Once the soil is soggy, we try to have them dump street sweepings on our firmest areas, but it only takes one wheel going too far to get mired in clay ooze. This wastes their times and ours, and dampens interest in return visits.

Landscape debris came with surprises in it. We pictured landscape debris as nice piles of innocuous leaves, grass clippings, and branches. We got some of that when we invited local landscapers to dump at our farm, but we also got some invasive plants that we’ll never get rid of without chemicals. This is an experiment worth avoiding.

Beware of the term “clean top soil.” The free soil we were given brought canary grass and the much-cursed morning glory, neither of which we had seen on our farm until then. Tons of the gunk did little to enrich our soil, and a lot to increase our workload.

Worth the work

We know that to farm and garden with a sustainable, multi-generational intent, we need to keep our soil fertile – to maintain good tilth. We’ve come a long way. Now our soil is home to a complex dance of microbial communities. Wildlife has returned to once silent meadows, and you can sink your hand into the veggie beds and find life.

We believe that if we keep feeding the soil it will support life sustainably. We’ve made progress, but there’s always more to learn.

Susan W. Clark is a writer and co-founder of the Oregon Sustainable Land Trust.


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