The Real Poop on Manure
The soil of a great garden is like one of Grumpy's posts. It's loaded with manure. But slinging this stuff isn't as simple as it sounds (although it sure is fun). Use the wrong kind or misapply it and your plants could shrivel instead of thrive. So take a nice, warm seat as Grumpy gives you the poop on using nature's black gold.
First A Little Housekeeping But before we step in up to our knees, we need to get something straight. There is only one correct way to pronounce "manure" and it is not "min-YER." Anyone who says, "min-YER" has min-YER between the ears. The correct pronunciation is "muh-noo-er." Let's not speak of this again.
What Does Manure Do? It stinks -- at least it does when it's fresh and you didn't grow up in a hut made out of it (thinking Paris Hilton here). But it also contains three essential plant nutrients -- nitrogen (N), phosphorus (P), and potassium (K) -- not in high amounts, but enough to do the job back in the day before components of inorganic fertilizers were mined or made from natural gas. By quickly returning livestock manure to the soil, farmers maintained the soil's fertility. Of course, this wasn't the ideal situation, as fresh manure can contain weed seeds, plant pathogens, and parasites. It can also burn plants.
Enlightened gardeners like you know that manure's best use is not as a fertilizer, but rather as a soil conditioner. It is all organic matter (sweet!), which is the best stuff you can mix into clay soil to loosen it or sandy soil to hold it together. Its presence adds billions of beneficial microbes to soil, suppressing bad microbes and making nutrients available to roots. Plus, it increases the numbers of hard-working earthworms that stir and loosen soil.
Serve Up the Right Stuff Unlike human beings, livestock manure is not created equal. So let's grab our shovels and dig deep into the details of the three most widely available flavors -- uhh, types.
Horse manure is often the most readily available, but is relatively low in nutrients. Cow manure is the next most available and probably the best all-around, as it contains a balanced level of N, P, and K in moderate amounts. Chicken manure boasts more than twice the nutrients of the other two and is considered "hot," since its elevated level of quick-release nitrogen can burn plants if you use too much. A friend once spread chicken manure on his lawn that was so fresh it still had feathers. His grass turned white. Then it clucking died.
Compost That **** So don't use fresh manure! Use manure that has been composted for a year or so. The easiest way to do this is to mix it with straw or hay, pile it up somewhere out of the way, and leave it. Unlike fresh manure, composted manure doesn't smell or attract bugs. The composting process also generates heat that kills most weed seeds and pathogens.
Attack of the Killer Compost One thing that composting won't do is remove persistent pesticides that may have been applied to pastures where livestock were grazing. Joe Lamp'l, one of the good guys in this business and host of the PBS show, Growing A Greener World, discovered this the hard way this past summer.
He amended the soil in his new raised bed vegetable garden with copious amounts of horse manure he'd composted for a year. But instead of flourishing, his tomato, eggplant, pepper, and bean plants appeared stunted with distorted foliage. When Joe asked the farmer who'd supplied the hay for his horses if he'd sprayed anything on his grass, the farmer said yes -- picloram. Picloram is a herbicide used to control broadleaf weeds. It's very persistent -- it takes years to break down. In fact, even after passing through the digestive tract of a horse and being composted for a year, it was still killing broadleaf plants. The lesson here -- before adding livestock manure to your garden, make sure it comes from pastures that haven't been sprayed.
Bagged Manure -- Costs More, Less Risky Don't have horses, cattle, or chickens nearby? Not to worry -- composted manure is readily available in many forms at your garden center. Sometimes it's in bags, like Black Kow.
Buying composted manure in bags costs more. But at least you know it doesn't contain weeds and herbicides. Sometimes, composted manure even comes in teabags you can use to make manure tea. (I'm not kidding.)
My friend in California, rancher Annie Haven, produces two manure-based soil conditioners from organically-raised, grass-fed livestock called Authentic Haven Brand Natural Brew. You steep the little bags in water, just like tea bags, brew a few gallons of manure tea, and then water your plants with the magic elixir.
Have a cup! It's jolly good! Grumpy takes his with a little milk.