Friday, June 22, 2012

Hugelkultur experiments: Amped-up sheet mulch

Hugelkultur, which is German for "hill-culture," is basically a fancy term to describe a way of building soil using rotting wood and excess branchy material.   The technique is to throw your rotting logs, branches, brambles, into a pile (or a dug out trench) and cover them with smaller material- leaves, sod, etc, and some soil on top.  The outcome is a garden bed that holds onto water for longer, has a slow steady input of nutrients from breaking down organic matter, is full of air channels that feed soil life, and create microclimates.

Building soil has been topmost priority in the garden here-- as quite literally what was here was "building" soil, heavy, compacted clay--  and I was reminded of how far we've come yesterday as I was digging in an area I had not yet dug in, to prepare for the building of a deck on the granny unit.   My pick ax bounced off the hardened familiar layers of compacted clay soil, gravel, and black plastic and I was oh so grateful that those familiar layers are now mostly gone from the back yard after years of digging them out and adding organic matter.  I'm not sure what the reasoning behind it was... weed control perhaps? but its had the effect of doing exactly the opposite of what healthy soil should be doing.   Anyhow, continuing to ask the question of how to build soil appropriately brought up hugelkultur, a term I'd first heard from our neighbor down the street.

Here is a nice sketch of an example of hugelkultur from Sepp Holtzer.

Our branch pile has been growing this spring from pruning, and rather than let it take over the yard or figure out what else to do with it, throwing it back into the soil to try another sheet mulch system seemed like the perfect solution.

I altered the implementation of the hugels here from what I'd read based on available materials, and thoughts about climate.  The rotting logs were omitted (didn't have any), and rather than mounding them up-- which seemed like a way to lose moisture in this climate, at this time of year-- we dug out trenches and filled them- so hopefully they'll act like swales, to capture rainwater, in the winter as well.  So perhaps it would be more accurate to call them amped up sheet mulched beds, not hugels.

A month or so into the existence of these beds, my thoughts are that one, rotting wood is perhaps an important ingredient as something that already has sufficient moisture in it, and two, timing of implementation is important, especially in dry climates like this one.  My hunch is that the two hugels here might actually need MORE water, to get going, because they were one, built with branchy material, and not much in the way of logs, and two, built just as northern California is entering the time of year where things start getting really dry- from wind, sun, and lack of rain.

The sheet mulched beds we've created here in the past supports the timing hunch- the ones that were created during or prior to the rainy season seemed to get a better start.

More observations and experiments with soil building to come...

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