Keeping Soils Healthy Through the Winter

Podcast Transcript

Are You Tending Your Soil Microbes as Winter Approaches?

As the days are getting shorter and the weather’s getting colder, it’s tempting to put your farm or garden soil on the back burner, so to speak, and start thinking about:

  • how to store all the produce you just harvested
  • who to invite over for the holidays
  • or how to get all your receipts and expenditures reconciled before tax time rolls around.

This is understandable. After all, the only two things in life that any one of us must face up to are death and taxes. And while no one knows when the grim reaper is going to come, we can always count on the IRS to arrive in January. Safe storage (of your produce) and a little bit of gift exchange with friends, family, and business associates at the end of the year can help you ensure that some portion of your year’s wages actually goes to support causes you believe in before the government takes it away.

Just remember that if you get so involved with winter holidays and accounting problems that you ignore the several billion living, breathing, soil microbes outdoors; they could quit working for you and leave you paying the fertilizer salesman whatever the IRS left behind. So with that in mind, before you put all your farm and garden tools away for the winter, think a little bit about how those little creatures underground are going to get by, and make sure you have left provisions for them.

Keep Your Soil Moist Throughout the Winter

First of all, you want to make sure that your soil stays moist. Nature is going to help you out here. With cooler days and slower plant growth, more water is going to stay in your soil. If you live where it’s freezing and thawing in the winter, you’re doubly blessed because you’re going to get that frost heaving that breaks cracks into the soil and allows water to infiltrate. When the snow melts, it’s going to run down deep in those cracks and wait in the soil until you have plant roots, ready to take it up.

Hopefully you have a cover crop growing. I’ll talk more about that in a moment.

But even if you have left old crop residues like stubble, you will be helping Mother Nature keep your soil moist because on warm days dew is going to condense on that stubble, run down the stems, and follow the roots all the way into the soil below.

As the winter months pass, this soil moisture will accumulate. And if you’re farming on irrigated land, the savings made possible by even one less irrigation because of all that water accumulation during the winter can make the difference between profit and loss.

So keeping your soil covered with living plants, crop residues, or in smaller growing areas, even dry mulches, will not only keep your soil microbes alive; it will also help you save precious water.

Feed Microbes With Living Roots or Crop Residues and Mulches

Microbes also need food to eat; especially if you want them to grow and reproduce. And while some of your soil microbes will do a pretty good job fending for themselves in moist soil full of decaying roots from last year’s crop, other microbes, including some of the species that will work hardest to grow your crops next summer, have evolved to feed on specific sugars, amino acids, proteins, and phytochemicals that are produced by living roots.

This is why the living cover crop I mentioned earlier is so valuable. By growing cool season plants that survive through the winter, you’re basically fertilizing your soil and feeding those microbes all winter long.

Even if you live where it’s so cold that you don’t really see active growth during the winter, you’re still getting growth underground as long as those plants are alive. And the more species you have in that winter cover crop, the more fertility you’re going to build in your soil.

So instead of packing up your hose, if you would simply fill your rows with a mix of cool season oats, peas, cabbage, and other winter crops, you will be amazed at how quickly your summer crops spring forth next year.
When the soil temperatures warm up in the spring, you can literally mow down your winter cover crop, and then just plant right into the stubble.

Winter is Rarely the Best Time to Analyze Soil Biology

Now, while we’re talking about winter soils, I want to point out that I often get questions from students in my Microbial Analysis for Growers class about analyzing soil microbes in the winter. And while it’s possible to take soil samples during the winter, I don’t often recommend it. This is because even though some microbial species thrive in the winter, many other species will go dormant. Many species of bacteria and fungi form spores that lay dormant through the winter and your fungal hyphae will often deteriorate, if they aren’t simply shattered apart by the freezing and thawing of the soil.

So while you will have some microbial activity in the winter, you’re not going to have nearly the amount of microbial activity that you have in the summer. And if you’re trying to compare your winter soil population to your summer soil population, you’re going to be frustrated.

So unless you’re asking specific questions about the microbial communities that must be answered in the winter time, you’re most likely to benefit from waiting to do your analyses in the summer.

Living Soil Helps You Grow More Food With Fewer Inputs

Now, it’s already pretty obvious to regenerative growers that living soil is going to allow them to grow more crops and healthier crops with fewer chemicals, simply because the microbes will be making all the fertilizers, growth promoters, and pesticides their plants need. But I want to point out that this also has economic benefits because the microorganisms are free. And if you feed them properly, these microbes reproduce. So simply keeping your soil alive through the winter can have financial dividends if you’re growing that crop for a profit.

Keeping Soil Microbes Healthy is Good For the Environment

And since I like to talk about all four cornerstones, I’m going to point out that microbes in the soil during the winter is also good for the environment. Because anytime you have microbes growing underground, you are taking carbon that would otherwise go up into the atmosphere, and you’re converting that into amino acids, DNA, proteins, fatty acids, carbohydrates, and all these other things (ie:  foods) that make up living cells.

Now, yes, you’re going to have some microbial respiration, and so you’re going to have some of that carbon going back up into the atmosphere. But I assure you that if you’ve got a healthy population growing underground, Your net carbon movement is going to be into the soil.

So when your holiday guests start complaining about global warming and all the terrible things happening in our environment today, you can explain to them that you’re doing your part storing carbon right now.

Living Soil Supports all Four Cornerstones of Healthy Food Systems

Since that carbon is going to help you grow crops that make better food for healthy people, you’re actually hitting all four cornerstones simply by keeping your soil alive through the winter.

Winter Irrigation

Now, if you’re keeping a mulch and a cover crop, you may or may not have to irrigate.

In temperate climates with frequent precipitation, you won’t have to add any water at all. But where precipitation is rare and dry winter winds are the norm you should check your soil every week or so. Simply take a shovel, (I like to use a sharpshooter shovel) dig down 6″ to a foot (that’s about 20 to 30 centimeters if you use the International, or Metric System.). Scoop up a handful of that soil and feel it.

If the top inch or two of soil is frozen, it might be worth bringing a chunk inside and testing it as soon as it warms to room temperature.

If your soil is frozen solid more than a hand’s width down, don’t even worry about watering until the weather warms up. That frozen soil is going to seal the moisture inside. It will also insulate the soil below, so down there where it is moist and warm, your microbes are going to be active. And as for those plant growth supporting microbes in the top few inches of the soil where it is frozen, they just are not going to be doing anything significant at all until the soil warms up, so don’t worry about them.

It is worth mentioning that there are a number of moisture probes and sensors on the market if you prefer using gadgets that give you actual numbers. But unless you have a large area or a particularly high-value crop, simply feeling the soil for moisture will be your most cost-effective option.

Any time your soil does feel dry, be sure to water thoroughly. Water your trees, shrubs, and grasses. Water your cover crops. But also water any dry soil where you hope to grow plants next spring; because even if your plants are not growing now, your soil microbes can be. The more microbial activity you have now, the better your plants will grow when spring arrives.

Winter Soil Stewardship Requires Only a Little Effort

Since growth itself slows down in the wintertime, you’re not going to have to work as hard as you did in the summer. So go ahead, take your break, visit your family and friends. Just do so knowing that, that while you’re out doing these things, your soil is working for you.

Next time, I’m going to talk about mineral balancing. And because it’s winter time, because we’re moving into the holiday season, and because we’re all trying to do our best to avoid those colds, flus, and SARS viruses that are floating around, I’m going to focus this discussion on mineral balancing in your diet.

Until then have a great week.

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