One of the first jobs new vegetable gardeners are often taught to do each spring is till – or at least deeply dig – the soil. Three key reasons are given for this annual rite of spring: to aerate the soil, to “work in” fertilizer and organic matter, and above all, to control weeds. However, research has been finding that regular tilling of gardens is detrimental to soil health and that it can actually increase weed problems.
For the same reasons that many farmers are switching away from plowing their fields to “no-till” practices, vegetable gardeners have been switching to beds that they never till or walk on.
What tilling does to the soil
Rather than making soil “lighter” and looser for better root growth, tilling pulverizes the soil into smaller particles that settle closer together, says New York soil scientist Dr. Lee Reich in his book “Weedless Gardening” (Workman Publishing Co.) That results in soil that compacts tighter in the long run.
Tilling the soil when it’s wet – which many eager gardeners do in spring – leads to even worse compaction, especially in clayish soil.
Tilling, digging, and walking on wet, clayish soil forces oxygen out of the soil’s air space, leading to clods and more compaction when it dries.
Reich says tilling also harms drainage by upending the soil’s natural texture that earthworms, freezing and thawing, and channels from dead roots create throughout the different-sized soil particles. The settled, compacted soil left behind often ends up draining poorly.
Washington State University Extension says tilling the soil also disrupts the soil’s natural “food web” – that community of earthworms, nematodes, fungi, bacteria, plant roots, and billions of other microorganisms responsible for breaking down nutrients and feeding plants.
One result is that organic matter in the soil decays faster than plants can use it, meaning wasted resources.
Another detriment is that tilling increases the loss of nitrogen in the soil. Penn State University researcher Dr. Denise Finney found that tilling encourages this most important of plant nutrients to dissipate into the air, especially when the soil is left uncovered and tilled or plowed heading into winter.
Finney found that tilled and bare soil is more prone to erosion as well, particularly when the soil is on a slope.
Tilling and weeds
As for weeds, the University of New Hampshire Extension says that while it’s true tilling uproots and kills existing weeds, it at the same time stirs dormant, buried weed seeds to the soil surface. With the improved warmth and light there – plus watering of the new garden plants – those weed seeds germinate with abandon.
Reich says he’s found that weed problems in his own garden decreased as he stopped tilling. That finding jives with research from the U.S. Department of Agriculture.
Reich keeps a lid on weeds by 1.) cutting them off or pulling or hoeing them ASAP while disturbing the soil as little as possible, and 2.) topping the soil at the end of each growing season with an inch of compost.
Whenever working in the garden, try to disturb the soil as little as possible, and limit or avoid tilling. Mulch and weed preventers are anti-sprouting aids that can be used whenever you can’t avoid soil disturbance to prevent exposed weed seeds from growing.
Preen Garden Weed Preventer blocks new weeds from germinating in your garden for up to 3 months and is labeled for use around 200 established flowers, vegetables, trees, and shrubs.
Preen Garden Weed Preventer Plus Plant Food blocks weed seeds from germinating in your garden for up to 3 months, and gives your plants a boost of plant food for beautiful, radiant blooms.
Preen Natural Vegetable Garden Weed Preventer contains corn gluten meal for a natural way to keep weeds from sprouting in your vegetable garden. Providing 4-6 weeks of weed protection, Preen Natural can be used around any plant, including established vegetables, herbs, and fruits.
