What is the effect of leaving some of the vegetable crops up over the winter—how does that improve soil conditions?
Intentionally or unintentionally, many gardeners have left plants in their gardens over the winter. This is actually a good thing…and something everyone should consider on a yearly basis!
Scientists – specifically agronomists and soil scientists – refer to the plant “litter” that remains after a harvest as “residue”. Leaving the residues in place over the winter, instead of pulling them up or tilling them into the soil surface, provides numerous benefits for the soil and your garden.
Farmers keep crop residues on their fields for the same reason home gardeners should consider them! Credit: Fabian Fernandez
Plant residues reduce erosion and the loss of valuable topsoil. Residues cover soil and protect it during the non-growing season. Crop residues catch rainfall. This reduces the impact that individual rain droplets have with the soil surface. Residues also slow down any flow of melting snow over the soil. Both help protect the soil structure, keeping it intact for next year’s crops and gardens.
Having plant residues on the soil surface also prevents something called soil crusting. You may have seen that during a very heavy rainfall, the soil won’t absorb any water. Even worse, sometimes little streams form on dry soil, then become larger streams. This carries away the soil and its important nutrients.
When there is no plant residue left to cover the soil, it can form a crust. This reduces the soil’s natural ability to soak up rain and snowmelt, and can increase erosion. Credit: Kate Norvell
Residual plant material reduces weeds by covering and shading the soil. Weeds are often early spring germinators, and residues inhibit their growth. They limit the amount of soil that is available for weed germination and growth. Crop residues reduce the resources and space that weed seedlings require to grow.
Plant residues provide shade, regulating soil temperature. This keeps soils cooler during the non-growing season to the early part of the next growing season. Cooler soil temperatures provide more suitable conditions for soil microbes. Microbes are necessary for maintaining a productive soil for crop growth. (To learn more about soil microbes, read this Soils Matter blog post: https://soilsmatter.wordpress.com/2015/07/14/is-it-true-bacteria-live-in-the-soil-isnt-that-bad/).
Cooler soil temperatures also aid in the retention of soil moisture, which in turn is favorable for seed germination in the spring and crop growth.
Plant residues provide a source of organic matter for the soil. Organic matter is essential to soil health. It helps create an environment supportive of crop growth. Organic matter provides an energy source for soil microbial populations, which results in faster decomposition rates, releasing essential nutrients for crop growth. Soil organic matter also helps maintain good structure of the soil itself. This further reduces erosion and improves water infiltration and soil aeration.
Crop residues provide micro-habitats that protect and benefit the germinating plant seeds and establishing seedlings.
Answered by: Kelley House, Certified Professional Soil Scientist, Duraroot & Kate Norvell, Certified Professional Soil Scientist, Certified Professional Agronomist, North 40 AG, Inc.
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Thanks for the info, it consolidates my being a lazy gardener, by leaving stuff in the garden. But I usually till it in in Spring. Is this the right thing to do?
Thanks for the question! Briefly, if you can avoid tilling as much as possible, it can be better for the soil. Poking holes to plant your new seeds or plants, and gently pulling up any dead plants works best. For more on “to till or not to till” read here! https://soilsmatter.wordpress.com/2014/01/09/to-till-or-not-to-till/
I’m a soil scientist but also a gardener. I generally agree with the comments that plant residue retention on soil is a good thing, but don’t forget the potential for disease carry-over from one season to the next on that plant residue. This is not an issue with all plants, but with some (e.g. tomatoes). Remember, too, that a “disease-resistant” variety is not “disease-proof.”
Great points, Dennis. In the March 1 leaf litter blog post, we do say “Unhealthy plants – say leaves with powdery mildew or other diseases – of course should be removed.” Thanks for adding that information here. SF/editor
Reblogged this on Big N Barley Men and commented:
I stumbled across this article from the Soil Science Society of America. The growers we’re following implement the principles described in this article. It reiterates our soil health cookbook.
Soils Matter, Get the Scoop! 
Thanks for the repost…and saying our info is “tantalizing”! Love it.
I meant every word of it! Thanks for posting.
Thanks for the info, it consolidates my being a lazy gardener, by leaving stuff in the garden. But I usually till it in in Spring. Is this the right thing to do?
Thanks for the question! Briefly, if you can avoid tilling as much as possible, it can be better for the soil. Poking holes to plant your new seeds or plants, and gently pulling up any dead plants works best. For more on “to till or not to till” read here! https://soilsmatter.wordpress.com/2014/01/09/to-till-or-not-to-till/
I’m a soil scientist but also a gardener. I generally agree with the comments that plant residue retention on soil is a good thing, but don’t forget the potential for disease carry-over from one season to the next on that plant residue. This is not an issue with all plants, but with some (e.g. tomatoes). Remember, too, that a “disease-resistant” variety is not “disease-proof.”
Great points, Dennis. In the March 1 leaf litter blog post, we do say “Unhealthy plants – say leaves with powdery mildew or other diseases – of course should be removed.” Thanks for adding that information here. SF/editor
Reblogged this on LEGUME LABORATORY and commented:
Great information for improving your soil…by not doing much at all!
Reblogged this on Big N Barley Men and commented:
I stumbled across this article from the Soil Science Society of America. The growers we’re following implement the principles described in this article. It reiterates our soil health cookbook.
Thanks for reblogging! SVF