While no-till gardening is not a new practice, information has traditionally centered on agricultural field crops. Home gardeners are catching on.
“The concept of no-till has been around for a couple of decades, but research has been very focused on field crops like wheat and corn,” says Oregon State University Extension Service Horticulturist Erica Chernoh. “There’s not much on vegetable production or fruit. There’s a lot to learn, and research is ongoing.”
No-till gardening minimizes soil disruption, which compacts the soil and destroys the pathways that channel air and water through the soil. When a tiller cuts through soil, the structure is weakened, which can cause compaction and increase runoff.
Tilling also disrupts the microorganisms and other soil dwellers that live in the top few inches and are essential for soil and plant health. Soil microbes, some of which have a symbiotic relationship with plants, cluster around roots and, as they feed on organic matter and each other, secrete nutrients that feed plants and substances that act as glue to bind soil particles into larger aggregates that keep soil pores open.
Long strands of fungal hyphae can hold the aggregates together. Earthworms and other organisms also create pore space.
Weed seeds, some of which can remain dormant in the soil for years, come to the surface under the blades of a tiller, then germinate and become problematic. A big part of no-till gardening is keeping the soil protected with a mulch layer, leaving the seeds in place and suppressing weeds.
No-till has its disadvantages, too. Covering the soil makes it more difficult to direct seed into the bed, especially for home gardeners who don’t have large seed drills. Mulch also keeps the soil from warming up as quickly in spring as unmulched beds. However, the benefits far outweigh the drawbacks.
“Mechanical tillage does have its place, especially in the formation of new garden beds with high compaction and low organic matter,” Erica says. “In most cases, however, nonmechanical approaches to working with soil can help you accomplish your goals without the negative effects of tilling on your soil.”
Soil coverage is an important concept in a no-till system. For home gardeners, this can be achieved by using cover crops or mulch. Mulch protects the soil from rain and wind, which can cause erosion. In early spring, pull back the mulch layer from the bed to allow sunlight to warm the soil.
One method of no-till gardening often referred to as sheet mulching or lasagna gardening features layers of organic materials to create a healthy growing medium. Organic materials are used to create a garden bed.
Cover crops are a big part of no-till farming but can be challenging for home gardeners because many need to be tilled in or sprayed with an herbicide to terminate the crop. If using a winter cover crop, plant in early fall and mow in spring after flowering but before the plants set seeds and become weeds. Transplant or direct seed into the fine cover crop mulch layer.
If using cover crops, select one that can be killed by cold temperatures or mowing rather than tilling or herbicides. Austrian winter peas, crimson clover or fava beans are good options.
When cleaning up the garden at the end of summer, cut off the tops of cover crop plants and leave the roots in the soil. There’s less disruption, and the roots will decompose and provide food for microorganisms. The clippings can be used as mulch.
For more information, see the Extension article “Three Methods for No-Turn Cold Composting” at https://tinyurl.com/yc7pcyez. Information courtesy of Oregon State University Extension Service.