It wasn’t that long ago when manure was thought of as a waste product. Recommendations were to dump it over the bank and use commercial fertilizer for crops. Many loads of manure got dumped into streams, so it would wash away. Out of sight, out of mind!
Manure may be a biological waste from an animal, but it shouldn’t be discarded in a poop-like manner.
Cow manure will supply your soil with organic matter, phosphorus, nitrogen and potassium. Manure contains organic matter that is nutrient rich and readily decomposes to release those nutrients over time.
One cow averages about 20 tons of manure per year. An application rate of 20 tons of manure per acre is realistic and will provide your soils with many nutrients. Soil, manure or leaf tissue tests will confirm what you need and how much to apply for the crops being grown. The organic matter fraction will improve the cation exchange capacity and possibly the pH of the soil. It has been shown where soils that received manure actually had better tilth and increased pore space.
The type of barn and animal housing makes a difference in manure types. Solid manures come from bedded pack, tie stalls and stanchion barns, where chocolate milkshake consistency manure comes from free stall barns. Cattle on pasture use the direct deposit method. They give the cow pie back to the pasture where they just harvested some grass, a fair exchange I believe.
How the manure is stored will also make a difference in the amount of nutrients lost or saved.
If manure is stored in an earthen pit, concrete tank or large big blue steel tank, the manure is stored without oxygen and will go anaerobic. A crust will form over the top of the manure and the nutrients such as nitrogen will be less likely to volatilize and go into the atmosphere.
Fresh liquid manure that is applied to fields should be plowed into the soil as soon as possible. This will help prevent nutrient loss to the atmosphere and from runoff if applied during a rain. The downfall of liquid manure is that along with the loss of nitrogen to the air when spread, there is manure like perfume that fills your senses. To some of us, it is the smell of farmers making a living. To others it is a vile smell and they say, ”farmers should not be farming here.” Those folks think their food just magically appears at the store all along thinking: who needs farmers anyway? Most of us know better.
Composting manure allows oxygen into the mixture. Aerobic microbe activity reduces the volume of manure due to the breakdown of the organic portion of the manure and the bedding. There is also the loss of moisture through evaporation or leaching during the compost process. Composting manure concentrates the organics and nutrients. Compost should also be incorporated into the soil so you conserve nutrients. Compost is stable, and when applied to the land releases nutrients over time. Composted manure is also food for earthworms and other soil critters.
Earthworms are a sign of a healthy soil that has the right amount of oxygen, organic matter, nutrients and moisture. Earthworms improve drainage and the oxygen levels in soil by their burrowing. An added benefit is that the worm casts are rich in nutrients.
Did you know that at one time there were wildlife biologists stating that manure should be spread at the upper edges of wetlands on moist soil so it would promote earthworm habitat. Yes, along managed wetlands so there would be a large population of worms for woodcock to eat. Food for the woodcock! I think that is an idea worth pondering. Too many nutrients are a problem, but so is the lack of nutrients. Wildlife management is about habitat, and food is vital to habitat creation.
Plants, whether vegetables and fruits for human use, or food plots for wildlife all require nutrients to live. During a plant’s growth, the roots absorb nutrients and the plant grows. The growth requires lots of nutrients that come from the soil. When they are harvested, there is a loss of nutrients to the soil. You are depleting the bank account so to speak. You need to feed the soil once again to complete the cycle. The earth giveth and the earth taketh away!
This means manure is actually a food for your soil, not a waste product. Those cow pies are really culinary delights for earthworms and soil microbes that are a great benefit to your soil structure, organic matter content and moisture holding capacity. With proper soil and manure management, your soil health will improve. Healthy soils, healthy food, healthy cows, healthy people and a healthy farm economy!
The next time you are walking your pasture kicking cow pies, remember it’s not just a biological waste product; it’s a three course meal along with a dessert for your soil, delivered fresh from the factory.
Those bovines are part of the recycling process. They get feed from the plants that get their food from the soil. So order a slice of that cow pie for your plants, worms and microbes to eat, and don’t let it wash away.
I read an old quote somewhere: “A wise man doesn’t kick a fresh cow pie.” I think that still holds true today!
It’s Memorial Day week, and I want to say “welcome home” to all the Nam vets that never got the welcome home they deserved.
Rich Redman is a retired District Conservationist for the USDA Natural Resources Conservation Service and an avid outdoorsman. His column will appear regularly. He may be reached at firstname.lastname@example.org.