Tilling the soil is an ingrained practice with age-old thinking behind it, but there are pros and cons to taking your old rototiller for a quick spin about the yard. For some people, vigorously turning the soil or not turning the soil is almost a religion and a silver bullet solution. Like in most aspects of life, the reality is every gardening practice has its tradeoffs. There is no one perfect solution.
Tractors pulling huge cultivators down rows of crops to remove weeds, or the weekend warrior whipping out the rototiller to work the vegetable patch over in early spring, are familiar sights to all of us. These practices constitute high tillage systems. Turning the soil, under the right conditions, temporarily increases soil structure, removes large weeds and incorporates soil amendments, among other benefits. There may be a few applications where one might consider turning the soil over. The downside includes increased erosion, long-term loss of soil structure, loss of organic material (humus), destruction and/or disruption of soil biota key to plant growth and health, increased compaction, increased weed production, and reduction in surface water quality.
If frequent turning of the soil leads to poor soil, water and plant quality, what are the alternatives? There are many, which broadly fall into two basic groups: low-till and no till. Low till, as the name implies, combines different methods (cover crops, aged manures) of improving soil fertility with infrequent (i.e. once a year) tilling . No till systems rely often on mulches, direct seeding, crop residue and inclusion of perennial crop systems, just to name a few methods.
Nature is the best at “tilling” and building healthy productive soil, so the best practice is leaving soil undisturbed. But in any system where there is human intervention, there is going to be some level of disturbance, even if it is only initially.
Tillage is usually discussed in the context of food production, but how does this apply to ornamental bed systems? First of all, I would say you do not have to think of it as separate systems. Mix the edibles right in among the flowers.
Wellfield Botanic Gardens utilizes largely no till practices, including organic mulches, chop and drop, select hand removal of weeds, creating intentional plant communities and plant guilds, along with a limited use of annuals. The only tillage occurring on the property these days might be from grading the land for a new garden or planting one of our seasonal beds in the Annual Garden. Here organic matter is simply laid on top and gets “incorporated” through the planting process and natural processes. No rototiller required. The transition to a low till or no till system takes multiple steps and time, but the long term benefits outweigh the drawbacks in my mind.
Josh Steffen, Horticulture and Facilities Manager
2 thoughts on “High Till, Low Till, No Till, Until?”
There are SO many variables. I prefer to till quite a bit of organic matter into the soil in moist regions of the Santa Clara Valley. The soil is great, but there is not much forest around to keep up the organic matter. At my former home in town, there was so much fallen valley oak foliage that there was not much use for organic matter. In parts of the Santa Cruz Mountains, there is so much redwood debris that some must be raked of of the surface. The tannins have an herbicidal effect on the soil.
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