I have to give credit where credit is due. I’m a member of the Tooele County Master Gardeners Facebook page. We get to exchange some great gardening ideas, tell about upcoming gardening-related events, and share good information. My friend Pat Jessie (who has been on the Spring Garden Tour many a time) is a regular contributor to the page. One recent article she posted was courtesy of a publication called “The Daily Dirt,” and it had to do with using manure in the garden.
Application of manure to the soil is an age-old practice. Like any practice that’s been around for so long, it’s easy to “know” things that aren’t necessarily true. I’ve found that many people believe that manure is a potent fertilizer. In reality, it’s not — but, it does a lot of things well and does greatly help your soil and crops — but not for the reasons you may believe.
Manure’s greatest contribution to your soil and hence your plants is the biomass that it adds in the form of organic material. The desirable percentage of organic material for gardening soil is between 4 and 6 percent. Our native soil around these parts is 1 percent or lower! So, by adding aged manure, you greatly increase the percentage. Because the materials are consumed ongoing through a variety of dynamics in the soil, aged manure or other organic material sources needs to be added ongoing.
All manure is not created equal, at least in the sense of value to the garden. Horse, cow, sheep, rabbit, goat and poultry manures are all usable in the garden plot; avoid manure from cats and dogs or other meat-eaters, due to disease risks.
What’s the big deal about organic material and why do we need to raise the percentage of it here in our area to be successful gardeners? The main benefit is the change to the soil structure so that it is not so dense, less compacted, is able to accept and release nutrients and moisture, and it’s easier for plants to put their roots in and through it.
Many gardeners, including this one, have been pleasantly surprised to see a robust earthworm population develop when organic material is regularly added and worked in with moderate cultivation. It seems that putting compost or aged manure into the soil “primes the pump” and provides a starting food source for the worms. The worms reciprocate by feeding then excreting high nitrogen waste, called “castings”. At the same time, they are physically aerating the soil by randomly and plentifully tunneling through it. Having plenty of earthworms is a strong indicator you are treating your soil right — and it’ll return the favor by sustaining what you plant in it.
The bottom line as far as organic content? You should apply it as often as you can, using manure, grass clippings, chopped straw, compost and mulch. The soil will constantly improve as you amend it.
Why is manure not as great a fertilizer as commonly believed? Manure has to be aged to reduce the amount of active ammonia and resulting nitrogen in it. When manure is first excreted, the moisture and nitrogen levels are quite high. If applied in significant amounts in this state, the nitrogen can act as an activator in the soil, “burning up” other nutrients, thus reducing their availability to your plants. That means you can get the exact opposite effect you were hoping for! The harsh amounts of nitrogen will subside and help the overall nutrient levels of the soil, but only after a period of time. That’s why you apply and work the manure in well before the time you want to plant.
When fresh manure is in a pile, it heats up as microorganisms go to work consuming the carbons in the waste. As nitrogen activates and processes in the pile, organic materials, such as grain fragments, undigested grass and bedding material will be broken down. If you dig into a pile of manure, and you smell ammonia, it still needs to age some more. Once stabilized, or aged, it’s ready to spread. However, during the aging, unless it’s covered, the pile is going to be exposed to the elements — both sunlight and moisture in the form of rain and snow. Nitrogen readily leaches out of the pile as moisture moves through it, and nutrients are further lost because of UV rays from the sun. Aged manure is less a fertilizer and more a compost.
I do need to mention that fresh or same-season manure can be spread, especially using mechanized manure spreaders. These allow “hot” manure to be spread thin over a wider area and watered or weathered in. Many home gardeners with a plentiful supply of fresh manure will apply it to larger areas in the late fall or winter, and till it in come spring time. The Amish still actively use this practice — applying the manure with horse-drawn manure spreaders on their fields when they are covered with snow. There are several benefits to winter application, assuming you are cold hardy! First, the ground is frozen, so rutting and soil compression is minimized. Rolling resistance for the spreader in reduced. Snow is white; manure is brown — so it’s easy to see what’s been covered and what has not. The cold holds the nutrient in the manure. As the snow melts, the manure is broken down, and the nutrients are unlocked and leached into soil in time for the growing season.
Having said all that, I don’t usually apply manure directly to the soil. Instead, it is an ongoing ingredient of our compost pile. It serves both to add bulk to pile, as well as provide a strong dose of nitrogen, which is needed to feed the microorganisms that will break down carbon materials. You need five ingredients to compost: 1.) “greens” (nitrogen contributors such as grass and shrub clippings, fresh manures, immature weeds, coffee grounds, tea bags, vegetable scraps), 2. )”browns” (carbon contributors such as sawdust, wood chips, chopped straw, shredded paper, old bread), 3.) Moisture, 4.) a small amount of native soil to contribute microorganisms, and, 5.) oxygen (provided by turning the pile weekly). By putting manures through the composting process you’ll assure that they are ready to be applied to the soil, and you’ll also greatly reduce the possibility the transmission of any pathogen that could be in the un-aged manure, such as E coli.
For those that keep poultry, you already have a great source of biomass and soil fertility. Keeps lots of straw, wood chips, sawdust, chopped weeds, or shredded paper for the birds to dig around in. Their natural constant scratching will continually churn the material, blending their dropping into the bedding. They’ll eat a lot of the weeds you thrown in, what remains will be churned up and be composted. By having an abundance of carbon materials (composting lingo: “browns”), the nitrogen in the bird droppings will begin breaking them down, while at the same time, all but eliminating typical chicken coop odors. The mixture is then removed one or two times a year. Not only do our chickens provide more than enough eggs for us, they also are an important part of our soil creation and improvement process here. Chicken manure is very high in nitrogen and should not be put directly on crops without aging — unless it’s been “pre-composted” as outlined above. Then, it can be spread on the ground, and watered in to further dilute the nitrogen and move it to the root zone.
Most all of the old bread, left over pancakes or waffles, potato and carrot peels, lettuce scraps and other non-meat or diary kitchen scraps go to the chickens now instead of to our compost pile. The chickens “pre-compost” these materials, and we get to reduce our feed bill. We approach early spring weeds, clump grass, and even binder weed the same way. The chickens all get first dibs. There’s something satisfying about seeing a pile of binder weed disappear down the gullets of your flock of chickens.
Jay Cooper can be contacted at firstname.lastname@example.org, or you can visit his website at dirtfarmerjay.com for videos and articles on gardening, shop skills, culinary arts and landscaping.