Healthy Soils Produce Many Benefits

One Thin Application of Compost Will Draw Down Almost a Ton of Carbon Per Acre Per Year

Emiel Molenaar

Many recent scientific papers and news articles have presented the numerous benefits from applying compost to our agricultural and range lands. The practice sequesters carbon in our soils, giving rise to the label carbon farming. Applying a thin layer of compost enriches the topsoil, makes the grasses or crops grow more vigorously, multiplies soil microbes, and retains more moisture—the combination of which pulls carbon from the atmosphere into plants, which in turn feeds the microbes. When augmented by managed livestock grazing, the cycle is further enhanced. A pilot project on the Chamberlin Ranch in Santa Ynez Valley is in its third year and, although not all the data have been analyzed, the initial results show great promise: one thin application of compost will draw down almost a ton of carbon per acre per year and is expected to continue for 20 or more years.

Dennis Allen
Paul Wellman (file)

The federal Natural Resources Conservation Service program and California’s Healthy Soils Initiative are promoting using cover crops, large-scale spreading of compost together with no tillage (no plowing), and avoiding pesticides or synthetic fertilizers on ag and range lands. The purpose is to continually improve and regenerate the health of the soil, which then improves plant health, nutrition, and productivity. These practices, sometimes called regenerative agriculture, allow nature’s processes to flourish while increasing the soil’s organic matter, fertility, texture, and water retention and the growth of trillions of subsurface organisms. The ensemble of these qualities yields health and protection to plant roots and consequently to the plant itself. Regenerative agriculture addresses many concerns: soil health, pests, drought, weeds, yield, and climate change.

Humans have been depleting soil of carbon for hundreds, if not thousands, of years. Today, a lot of ag land has a soil carbon level of 1-2 percent. Where regenerative practices have been adopted for 10 or more years, the carbon level has risen to 5-8 percent. Each additional percent of carbon in the soil is considered equivalent to $300-$600 of fertilizer stored underground.

As urban dwellers, we can follow these same practices by making compost using kitchen food scraps and trimmings from plants together with some brown (carbon) mulch. Even when space is limited, tumblers can make rich compost in a few square feet of space. Small plots can grow a lot of food by strategically placing fruit trees, perennial food plants, and seasonal vegetables in close relationship to each other. The application of compost and mulch lets nature do much of the work. The key is to never have bare, exposed soil. Using this approach greatly reduces the need for water, as the soil retains more moisture and for longer periods.

We can each have better nutrition, more contact with nature, and, in a small way, a positive impact on climate change.

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