Organic Matters - Remineralization of Soil
Growing Food Organically
by Jeff Johnston
When the glacial icesheets receded from North America, they left behind a legacy that has lasted thousands of years. These glaciers ground rock into powders as fine as flour and distributed them over wide areas. The soils created in these areas produced lush forests and abundant and nourishing crops. However, intensive industrial agriculture has “mined” these minerals from our soils for the past 100 years, resulting in lower quality foods with fewer nutrients to nourish us. Fortunately, there is something we can do to increase the mineral levels of our soils.
Remineralization is the process of adding rock powders (or dusts) to soils with mineral deficiencies. (Plants display characteristic symptoms when minerals are low. For example, hollow broccoli stems indicate a boron deficiency.) These minerals are divided into two categories: the nine essential macronutrients – nitrogen, phosphorous, sulphur, potassium, calcium and magnesium (plus carbon, hydrogen and oxygen); and the seven essential micronutrients – iron, manganese, copper, zinc, molybdenum, boron and chlorine. Sodium, silicon, and cobalt are essential for some plants, while others, like vanadium, are essential for some microorganisms.
Plants do not take up directly any minerals you add to the soil through remineralization. The minerals are first used by soil microorganisms in their life processes, which in turn create (or the microorganisms become) nutrients available to your plants. Research by David H. Miller of Oberlin College in the United States indicates that adding rock dusts “increase[s] the rate of decomposition of soil organic carbon, both in field test plots and pot test experiments.” As well, he found that “addition of dusts to composting materials raises the temperature of the composts,” which indicates that microbial activity has increased, speeding the production of finished compost.
Alan Reed of Cairn Tech, a Canadian company that sells rock dusts, reported in a conversation that covering tree stumps with dusts speeds their decomposition. Alan has dusted stumps on his property and witnessed beneficial fungi that assist the breakdown process, which soon reduced the stumps to soil materials.
Alan has been conducting on-farm research with a small farming community in Southwestern Ontario. According to Alan, “mineral complexes induced significant yields of hay per acre, which provided extended grazing and complete protein forages. Farmers have commented that animals no longer bare the ground while grazing, visibly eat less, show no signs of drought stress, and have increased yearly milk yields.” Root crops grow larger (his web site shows a photograph of 18-inch parsnips), have improved flavour and longer shelf lives, while corn grows more kernels and appears to be more resistant to drought. Crops grown with mineral enhancement reveal higher sugar indexes, which correlate to frost and drought resistance and less insect stress.
You needn’t limit remineralization to your crops. Work has been done to restore the forests of Germany using rock dusts, which have produced encouraging results. Research in the Appalachian Mountains has shown that dusting your forest soils will decrease tree mortality and increase the mineral content of tree tissues. Alan Reed reports that his forest floor biomass has increased six to eight inches, and water runoff has been reduced. Biodiversity has improved as well: Alan has found many new herbs, ferns, various tree species, and animal and bird species in his forest since remineralization.
Alan also keeps his own livestock. “Sheep, goats, horses, turkeys, ducks, geese, with each generation, become healthier, have increased bone density and are more attentive and interactive when raised on regenerated soils. Eggs have a richer color in the yolk, are larger and full of flavor.” Alan has found that his lambs weigh more than other lambs, and require less time to reach that weight, when they graze dusted fields.
There are many products available from the companies that sell mineral dusts. The best course of action is to determine what minerals are deficient in your soil (there are many public and private labs that will analyze your soil for you), then write, call, email or surf suppliers’ web sites for the products they carry that will best suit your needs. As with anything you buy, you can save money by shopping around for the most suitable product at the best price. You’ll save even more by purchasing in bulk with neighbors. You can apply the dusts by hand or shovel in small areas, with a fertilizer spreader for lawns and orchards, or with farm equipment or even aerial spraying equipment for larger areas.
As a permaculturist, I believe deeply in the principle of reducing off-farm inputs and making the farm, or garden, as self-sufficient as possible. While rock dusts are external inputs, they are required only periodically. With good compost management and crop rotations, along with the use of cover crops to reduce soil erosion, you may not need another application of minerals after “jump-starting” your soils and compost piles.
Jeff Johnston is a past president of Canadian Organic Growers and a Permaculture design course graduate. He has worked on conventional and organic farms, and gardens organically. This article was published in 1997.
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