More Manure, Less Peat Moss, Please!
Each spring, it makes me crazy to see well-meaning people load up on bales of peatmoss. I know they think they are doing a Good Thing but sadly, they are not. All kinds of sphagnum peat moss are harvested by destroying boggy natural habitats. That’s sad enough, but even more sadly, this is senseless destruction, because peat moss isn’t helpful for our soil or plants.
For one thing, peat moss is very low in nutrients and it degrades to fast to make a truly helpful soil conditioner. In addition, it is very acidic, which does not help balance our already acid Northwestern soils. In fact, peat moss is so acidic that it can kill bacteria, which is why sphagnum moss was used as bandaging material for centuries (maybe millennia). Wounds packed with clean sphagnum moss had a better chance of healing cleanly, and it was still used for British troops during WWII.
Once Dry, Dry Forevermore
It really makes me crazy when I see peat moss recommended for top dressing. Top dressing is the final layer of a garden bed, usually consisting of an inch or two of fine textured mulch such as compost or aged dairy manure. This layer conserves moisture, suppresses weeds, and promotes rapid root growth.
That old standby, peat moss, makes a horrible top dressing and is a remarkably poor mulch, drying to an impervious, water-shedding (rather than water-conserving) mat in no time. Peat is very difficult to rewet in garden soils and peat based potting mixes, which is annoying and very hard on plants. Peat based potting mixes are light in weight, which is good if you are carrying the pots around, but also means wind can rock plants easily, distressing the roots.
Peat’s Hidden Dangers
Though fresh peat is highly acidic, by the time it is dried and baled, it can harbor spores of fungal diseases that can be dangerous to handlers. Nursery workers are warned by law to wear double gloves and micron filtration masks when handling peat moss. The gardener is not told anything, yet those who use peat moss regularly are at risk for fungal pneumonias and other illnesses.
Finally, peatmoss is not a renewable resource except in glacial terms. If you visit bogs that have been harvested for many years, you can see plainly that cuts made a century ago have barely begun to heal. Bogs are delicate, intricate environments that host hundreds of living fauna and flora. When bogs are destroyed by peat mining, companies are now forced to “restore” them, but the artificial, “managed” bogs never achieve the biodiversity of the original habitat.
If peat is not a truly renewable resource, manures definitely are. One thing we can count on is that poop happens. However, it does matter which manure we choose. Initial testing of various kinds of animal manures at Oregon State University in Corvallis show that animal manures vary widely in their qualities. Horse manure, for example, is often contaminated with worming agents that continue to kill worms in compost and soil after passing through the horse. Horse manure mixed with bedding may contain clopyralid, a long-lasting pesticide that remains active indefinitely (it especially affects legumes, nightshades, and composites, which covers a lot of floral ground).
Instead, I use aged dairy manure as a soil amendment and as top dressing. Recent research indicates that a mulch of dairy manure can slow down or even halt the growth of certain soil pathogens, notably several root rots that are prevalent in the native soils of the Northwest.
Let’s Do Use Dairy Manure
Most modern dairies have holding pits where manure is stored. The barns are washed down daily and the manure accumulates in the holding pits. The nitrogen-rich effluent is drawn off and returned to the fields where alfalfa and other fodder is grown. The washed manure is sold as an excellent soil amendment. Dairy manure from an organic dairy will not contain bovine growth hormone, steroids, or other “prophylactic” medications.
Dairy manure differs from steer manure in several important ways. For starters, it is nearly always far less salty. Steer manure is gathered from stockyard holding pens, where salt licks encourage animals to drink lots of water. The resulting manure often has a very high salt content, which can burn young plants and seedlings. Steer manure is very apt to contain hormones and steroids as well.
Here’s a link to Ken Druse’s article on peat moss (which I like since he agrees with me):