Plowing helps with weed control as overturning soil kills growing weeds and prepares the soil for planting with a pass of various tractor-pulled implements. You may notice, however, that some farm fields are not plowed, yet corn or other crops are grown in them without first overturning the soil. This new form of agriculture is becoming more common as positive results are shared among growers. And a focus on soil health is a major part of this growing movement.
No-till farming uses seed-sowing equipment that cuts an opening in the soil surface and injects or applies seeds within that opening, while minimizing soil disturbance. Why is minimizing soil disturbance important? Because soil that is minimally disturbed contains a higher quantity of living organisms in the form of soil bacteria, mycorrhizal fungi, and small insects and earthworms.
Think of these living organisms as an enormous herd of microscopic cattle, munching and manuring the field day in and day out. Their diet consists of organic material in the soil (in the form of plant and animal residue) as well as sugars exuded from living plant roots. Their waste product is a form of fertilizer that feeds growing plants. In the case of mycorrhizal fungi, they produce a substance called glomalin which helps bind together soil particles into larger aggregates (which increases air space, drainage and the moisture holding capacity of the soil). When soil is overturned with a plow, the population of these beneficial organisms declines.
No-till farmers who actively practice Conservation Agriculture include additional techniques to maximize soil health. Their methods include:
1. Planting cover crops: The sugars exuded into the soil to feed soil life can be increased by always having a living root in the soil. Cover crops can accomplish this, plus provide additional benefits, such as crowding out competing weed species, fixing atmospheric nitrogen and storing it in the soil for future fertility, and penetrating deep into soil with long tap root varieties (such as tillage radish) to draw up nutrients from deeper subsoils and bring them to the surface for other plants to utilize. Those deep tap roots also break through compacted subsoils, creating additional space for drainage and worm activity. Cover crops are also referred to as “green manure” since their growth and decomposition increases soil organic content.
2. Crop rotation: You’ll often see a field of corn one season followed by a field of soy beans the next. This common two-crop rotation allows soils depleted of nitrogen after growing corn to be replenished with nitrogen after growing soy, thanks to the nitrogen fixation these legumes provide. Crop rotation also reduces the buildup of soil-borne pests and pathogens that persist in fields after a growing season. If the next crop in the rotation is not susceptible to the pest or pathogen, the risk of crop damage is reduced or avoided altogether.
3. Intense animal grazing: This is a practice that is growing in popularity for the quick soil-building results that follow. Mimicking the behavior of herd animals on wild grasslands, such as bison on the old mid-western prairie or herds of zebra, water buffalo and gazelles on the African savanna, intensive animal grazing is a management practice of grazing cattle or other livestock in a small patch of field grouped tightly together for a day, then moving them over to a new small patch of fresh pasture the next day. Use of portable electric fencing makes this management possible and the fencing causes the herd to remain in a tight-knit group, like wild herds protecting themselves from predatory wolves or lions. The day of intense grazing quickly mows down the plant surface and while leaving a thorough covering of manure to feed the rapid regrowth of plants in that spot. The action of the animals’ hooves pierces the surface soil, increasing moisture penetration and soil contact with decomposing organic matter.
Learning from the professional growers among us, we home gardeners can also incorporate Conservation Agriculture techniques at home (on a much smaller scale) by keeping a growing root in the soil for as much of the year as possible, minimizing soil disturbance, rotating our vegetable crops, and adding composted manure as a soil amendment. Please note, I added “composted” in front of manure, as fresh manure in your garden will damage your plants and add the risk of feeding bad bacteria to your family in their next fresh salad. So, make sure that the manure you are using is well composted (a year old or more is safe). Protecting the soil in your garden with these Conservation Agriculture techniques will benefit you in the long run with increased nutrients in the food you grow, reduced dependence on inputs such as chemical fertilizers, pesticides and herbicides, and reduced watering.
