Improve soil and reduce greenhouse gases through regenerative gardening
“Soil remediation is a process of developing the life of the soil by introducing beneficial bacteria and fungus in their living state.”
— Frank Holzman, “Radical Regenerative Gardening and Farming,” 2018
Jerry and I recently rented an excavator, and I found a brand-new thrill unearthing the large root balls of cut gorse, which had created an almost impenetrable wall of shrubbery 15 feet tall at our new place in Bandon before we spent the last year leveling it to stumps. Although I was excited about clearing away the last remnants of gorse, I was less than thrilled about the dry, sandy earth from which the highly invasive shrubs had finally released their formidable grasp.
What a discouraging stretch of dead dirt! It made me long for the sticky black clay in my yard in east Medford.
Yet, it’s no wonder the disturbed soil that allowed the gorse to thrive was so depleted. The area used to be a network of dusty tractor paths on a farm that was split into smaller acreage decades ago.
Not much else but gorse could grow over the abandoned compacted roads, so the noxious mighty-weed proliferated for 30 years. Its expansive root system exhausted the sand of precious nutrients and moisture. And the greedy gorse gave nothing back but fallen, highly flammable, dead needles and countless seeds, which can germinate after lying dormant for 40 years.
If ever a soil was in dire need of remediation, this is it. As it turns out, fall is an ideal time to replenish the soil, after growers have harvested their summer crops (or 30-year-old gorse shrubs) and before winter crops are planted.
I recently spoke with Scott Goode, environmental scientist and founder of the soil replenishing group Nourishing Systems. Scott made me feel more hopeful about improving the soil through a process called regenerative gardening.
Not only will regenerative gardening turn lifeless soil into life-sustaining, life-giving loam, Scott assured me, practicing regenerative gardening will help reduce the emission of greenhouse gases into the atmosphere. Even better, the collective regenerative efforts of gardeners and farmers will make a difference toward moving carbon dioxide out of the atmosphere and into the soil where it can be used by plants to produce nutrient-dense, high-quality food.
Sequestering and building carbon levels in soil is the driving focus of regenerative gardening and farming.
“It will become the most important feature of agriculture, more valuable than crop production,” Scott said.
Conventional growing methods aren’t very effective at building carbon in soil, sequestering only 20% of the CO2 present in the air. Organic, regenerative methods do a much better job of building carbon levels because they are based on a deeper understanding of soil biology, thanks to newer technology that has produced more efficient tools for complex soil analysis.
“Now we know you don’t need to add nutrients to the soil (by using fertilizers); instead, we need to enrich the soil with lifeforms that make nutrients available to the plant,” Scott explained.
I was surprised when he told me plant roots aren’t designed to extract nutrients from the soil in order to feed the plant. Roots are more efficient at supplying nutrients to soil micro-organisms that feed the plant by building connections between the roots and beneficial bacteria and fungi.
A teaspoon of healthy garden soil can have one billion bacteria and several yards of fungal filaments, but depleted soils need help. The good news is we can increase the number of micro-organisms and build healthy soil by consistently adding a mixture of brown (high in carbon) and green (high in nitrogen) organic material at a ratio of around 25 to 1. Scott recommends digging 18-inch-wide by 24-inch-deep trenches between garden beds where the compost will be readily available.
Earthworms and micro-organisms will quickly move into the compost to feed, breaking down the biomass and producing humus. Another way to add organic matter is by planting cover crops in the fall that combine annual grasses and legumes, such as rye grass and fava beans or field peas (buckwheat makes a good summer cover crop).
To replenish my soil in Bandon, Scott suggested I plant a cover crop mixture, along with daikon radishes that will loosen compacted earth and add carbon as they decompose. I’ll spread a layer of composted horse manure when the cover crop shoots emerge, and then I’ll cover everything with rice straw for the winter. Next spring, I’ll mow the cover crop down, plant a summer crop of buckwheat, and allow the overwintered cover crop to decompose. Next year, my soil will look, feel and smell very different.
With organic matter and increased microbial activity in the soil, plants will capture more carbon dioxide from the air and transport the CO2 through their roots into the earth. Scott calls this an elegant, natural process of nutrient cycling. The key is to add more organic matter to the soil than what is taken out or used up.
Scott will share his knowledge about regenerative agriculture in two presentations at this year’s Winter Dreams Summer Gardens Symposium, hosted by the Jackson County Master Gardener Association from 9 a.m. to 4:30 p.m. Saturday, Nov. 2, at the RCC/SOU Higher Education Center, 101. S. Bartlett St., Medford. The cost is $45 if registered by Oct. 20; $55 afterward. Find details at www.jacksoncountymga.org.
Rhonda Nowak is a Rogue Valley gardener, teacher and writer. Email her at Rnowak39@gmail.com. For more about gardening, visit her blog at http://blogs.esouthernoregon.com/theliterarygardener/ and check out her podcasts and videos at https://mailtribune.com/podcasts/the-literary-gardener.