Mathew Trotter wrote:
Robin Katz wrote:Matthew,
I'm intrigued by the hugelpath concept. I can see the water storage aspect but keep thinking that the path would end up with more growth than the area around it due to a higher moisture content. Is your idea that the path would be similar to the old irrigation troughs between rows of crops? I look forward to your results from this year. Our area has the same summer drought and there is no way that I can/will water all the garden beds that I plan to put in place. We've been going the hugel mound route since our soil is rocky as hell and I won't be digging those buggers up.
Hey Robin! I was planning to do a whole post on the Hugelpath once I finished setting it up and had some time to test it out. It's definitely theoretical at this point, but I'm hoping that theory will pan out as I do some testing. Basically, I'm trying to combine and maximize the benefits of a number of different designs will minimizing the negatives for my climate. Namely, it's inspired by hugelkultur, terra preta, ollas, worm towers, deep mulching, and a lot of Elaine Ingham's work (plus probably more techniques that I'm spacing on at the moment.) I think the only thing that's missing here would be to set them up on contour, but that might be excessive. I'll try to break down how the Hugelpath relates to each of these other technologies.
The relation to hugelkultur is probably obvious, even if "Hugelpath" is a bit of a misnomer since it is indeed not a mound. But since "hugel" has pretty much become synonymous with wood, it made sense. The problem with hugelkultur in my climate is that they don't maximize water harvesting; being a mound, in heavy rain events they will shed water in excess of what they can absorb and that water will run off of the property (or hopefully into other water catchment strategies.) By inverting the shape, water will shed INTO the hugel rather off of it. But with 8 or 9 months of nearly non-stop rain, even though I want to capture and hold onto that rain for use during the drought, I don't want it directly in the root zone of my plants where it can cause root rot. Instead, like an olla, this mass of spongey material will wick water into the adjacent beds as the plants use up water and dry out the soil relative to the hugelpath.
It's a little more complex of a mix than your typical hugelkultur, as it aims to mimic the composition of Amazonian terra preta a little more closely. In addition to wood and green material (which would ideally include yard waste, kitchen scraps, etc.) it also contains biochar and fired clay (this is nothing special, just clay that was fired as a result of them burning slash piles on the property, but I would go out of my way to fire clay pellets or tiles if I didn't already have an abundance of fired clay.) In addition to the water holding capacity of biochar, it also provides nutrient holding capacity (so that the nutrients from the rotting organic mater don't leach out) and lots of surface area for microbial life to cling to and proliferate. Fired clay is the part of terra preta that most people miss, thinking that biochar is the only important element. I'd argue that fired clay is at least as important as the charcoal. Unglazed pottery functions as a wick which is why ollas are effective for irrigation, but what's especially cool about pottery is it's ability to wick water up against the pull of gravity. I found a video that demonstrates this perfectly:
That means that the pottery can help pull the water that we've stored upward towards the plant roots as the soil begins to dry.
In a way, the hugelpath will theoretically function like a worm tower. Put all of the organic matter in one spot and then utilize the worms and other soil life to transport it into the adjacent beds. And because the path is dug out below the compaction zone it will allow the free transfer to soil life and organic matter between the zone above and below the compaction. And if Elaine Ingham's work (and the anectdotal work of many before her) holds true, the increased soil life should be able to start breaking down the remaining compaction from all sides. And Dr. Ingham's work has indicated that simply balancing the soil life can massively drought proof a patch of soil (to the point that they almost got fined for watering a lawn during water restrictions... even though they never actually watered it.)
The whole path is then capped with a "deep" mulch of wood chips to keep the weeds at bay. Initally it isn't that deep, maybe only 3 or so inches (though I could certainly dig my trench deeper if I felt that more mulch was warranted.) But the idea is that as the logs rot down the path will sink and more wood chips would be added to keep the apparent level of the path even with the beds (even though the actual soil level is much lower.) In my experience, woods chips soften the soil pretty rapidly, so even if weeds manage to germinate they're relatively painless to remove. I used wood chips around the first batch of fruit trees that I planted, and about a year later I was able to pull out a roughly 2-foot dandelion root with my bare hands and no straining and without breaking the tap root. But ultimately the idea is that anything that germinates won't have the energy to make it through the mulch, and anything that blows in won't be able to get down to soil in order to germinate.
In a way it also functions like a dry land chinampa. The bed is surrounded by water on all sides, but because it's stored in wood you're able to access the bed without boats. I'm not expecting to gain the kind of thermal benefit that chinampas receive by being surrounded by water, but I did see a great example the other day of how even swales can keep soil from freezing or allow it to thaw faster as temperatures increase, which means I might actually gain a thermal benefit as well. And that's just from the water. The biological activity on all sides of my beds may actually create some thermal benefit, just like you get with traditional hot beds.
The idea is that if I were able to take a 3-foot soil core from my bed now, and in 4 to 5 years (or possibly much sooner than that), I would find that the organic mater from the path had infiltrated the bed. I don't know if it'll actually work out that way, but that's the hypothesis I'm working from.
I started working on this path a year ago, and the problem has been that it's had a good 6-12 inches of water in it any time I've actually had time to work on it. Now that I've switched up my strategy and started filling the path from one end, I no longer have water pool in the bottom of my trench. The 10-15 feet of wood, biochar, fired clay, etc. that I've been able to add has been sponging up the excess water and keeping the bottom of the trench relative dry compared to what it was like when it was empty.