I recall being a bit impressed the first time I read about a gardening technique called “sheet composting.” It wasn’t the actual garden article or terminology that was impressive. Nope; I was impressed with myself because I was already sheet composting and didn’t even know it. I’d always just called it mulching.
There is an assortment of sheet composting methods and instructions out there for the learning. But they all have to do with adding a thin layer of organic material to the soil and letting it compost in place.
The thinking on all of them is it takes less labor over time than managing the traditional compost bin or pile. More serious composting requires turning for aeration and then hauling and spreading the finished compost and tilling it in.
All dead plant parts will eventually decay into compost with time, moisture, heat, bacteria and fungi. While a well-managed composter can speed up the process, merely putting the stuff on the ground and leaving it be will assure its decay.
The reason I say just adding a new layer of mulch every few years is indeed sheet composting is because the mulch slowly rots from the bottom.
The micro-bugs are in the dirt and digest the mulch at a slow snail’s pace. Veteran composters are familiar with the Carbon:Nitrogen Ratio.
The C:N refers to the balance between cold dead stuff like straw or fallen leaves and “hot” stuff like green grass clippings, animal manure or kitchen leftovers.
The ideal C:N is 25:1, meaning 25 parts carbon to 1 part nitrogen. Organics like sawdust, wood chips and cardboard are in the range of 350:1.
The “hottest” organics are the manures and alfalfa at about 13:1. For mulch, we typically use high carbon material like pine straw, leaves, bark, etc. The only drawback to them for composting is it takes a long time, which is why they make good mulches in the first place.
The downsides of using high nitrogen materials alone with no added carbon products is they will cause a bad stink while composting. Besides, the high carbon stuff is more plentiful and usually free.
Some folks go to way too much trouble explaining something as simple as sheet composting. One “expert” repeats himself about the goal of sheet composting being to mimic the forest floor.
Okay, leaves fall every year and slowly rot from the bottom up. Got it.
Taking the forest floor concept to another level, there is a form of sheet composting called hügelcultur. That’s German and the compost method so named goes way back in that part of Europe.
Still mimicking the forest floor, with decaying logs and all, hügelcultur compost begins with a layer of logs and then leaves and grass and other organics are piled on top. Quoting now, the decaying wood “increases its porosity, serving as nurse logs and providing ecological facilitation to seedlings.”
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Terry Rector writes for the Warren County Soil and Water Conservation District, 601-636-7679 ext. 3.