Kate at “Living the Frugal Life” has a great post on the merits and techniques of sheet mulching in the garden. Since this has been the key to soil improvement (and we have dreadful soil) in our garden, I wanted to highlight it.
Significant soil improvement is one of them. This isn’t exactly surprising; it’s routinely mentioned as the “other” benefit of the technique besides weed control. But knowing intellectually that it would help the soil didn’t quite prepare me for the fat earthworms I’ve been coming across. They’re not inordinately long as worms go, but they are rotund. Wider than a pencil by a long shot; embonpoint, even. I hope it’s not the case that the obesity epidemic has now spread as far as earthworms. But clearly these worms aren’t going hungry. Their presence is both an indicator of healthy soil as well as a guarantee that the soil will be even better over time. Every earthworm is a mobile factory of soil fertility, and I count each sighting as a blessing. I also see, year by year, healthier plants that are better able to withstand the vagaries of stressful growing seasons.
The other benefits of lasagna mulching all have to do with what I believe are leading indications of the changes that global climate weirding are going to bring to my region. More than one model of climate change that I’ve seen predicts routine summertime drought across much of the US. My immediate region is forecast to escape the worst of this trend, but still the summers could still be drier than they historically have been. The last two summers here certainly have been that way, whether or not they were part of an emerging new pattern. Mulching and good organic content in the topsoil are critically important for plants dealing with water stress. Mulching because it curbs evaporative loss of moisture. And high organic content because organic matter acts like a sponge, soaking up water and releasing it slowly as plants need it. Lasagna mulching provides for both of these.
The flip side of the dry spells predicted under the climate change models is a pattern of more violent storms. This may seem contradictory, but it really isn’t when you look at the meteorological explanations. Namely, a more energetic (warmer) atmosphere that is able to carry and move more water vapor. And in any case, whether it makes intuitive sense or not, this is exactly what we saw this year: About ten weeks of rain too insignificant to help the garden crops followed by a hurricane and a tropical storm that washed out roads, flooded farmlands, wiped out crops, and carried topsoil straight into the waterways, not to mention killing a few people and destroying a few homes. Our garden certainly took damage from these storms, and we had standing water in the portion of our backyard that is just barely lower than our garden. But careful inspection of the garden itself proved that we lost no topsoil at all to the heavy rains. Again, I believe credit goes to the lasagna mulching.
Most writers emphasize the merits of deep mulch for water retention, and those are very real. What I like about Kate’s post is that it also mentions the rarely-noted quality that sheet mulch makes a huge difference where there is too much water. I don’t just mean that it protects the garden from erosion, which it does, but areas that get flooded that are mulched simply do much better. We not only don’t lose soil, but we don’t lose as many plants to drowning. I’m not sure why – my guess is that the better soil structure makes it less prone to saturation generally, but the difference is quite remarkable.
I do find that have to rake off some of the winter’s mulch in early spring for planting here, because it does delay soil warm up, but that is the only negative among many positives (I haven’t even seen that we have more slugs and snails in the mulch, although ymmv).
My favorite benefit of all, however, is that sheet mulching permits people to do substantive garden expansions without any equipment at all – and now is the time to do it. Put enough layers of organic material on cardboard or newspaper over the winter and the material will both smother grass and weeds and break down enough to be plantable in spring. No digging, no painful sod removal, no tilling, no bringing huge quantities of weed seeds into the light. What’s not to love?
Sheet mulching is even doable on a farm scale, we’re finding. Rotting large bales of hay can be moved to our farm, combined with large quantities of goat and chicken manure (composted), brush piles and leaves left in bags on the street (the bags get laid down in long rows to mulch the beds) and while I can’t cover acres, I can make signficant spaces for further production. With a bulldozer or a tractor I could do more, of course, a la Sepp Holzer’s brush berms, but the results are pretty impressive already.