I love lasagna, don't you? A flavorful concoction made of noodles, meat, cheese, and tomato sauce, layered in a deep pan and baked so the flavors meld. Yumm! My garden beds this year will be going lasagna.
Over the years I've tried several different techniques for the raised beds in my mountain-side garden. I have to use raised beds because the slope is steep enough that even a light rain washes away top soil that is not firmly pinned down by a thick carpet of grass.
Keeping the soil in these beds rich and productive has been my primary focus. When I established the beds I made my “dirt” using commercial compost, peat, and some native clay soil. I've added home-made compost each year. This involves digging-in the compost and turning the soil.
Lately I've been reading that turning the soil is not the best approach, but is a hold-over from large scale agriculture where the time and effort saved by plowing a field makes sense. In a garden, tiling and digging are less important as time savers when the soil structure is considered.
I started my quest when I began finding white fungus-like strands growing in the soil, especially near the wooden boxes, and asked myself, “What is that? And is it good or bad?” Research showed it is indeed fungus and it is good.
Briefly: good soil is more than just dirt. You know that. Good soil for planting needs a high degree of organic matter and oxygen to promote good plant growth. This fungus promotes this. But if it's ripped to shreds by digging or tilling, you lose that benefit. Thus, no-dig or no-till gardening has been gaining in popularity. Lasagna beds are a part of that school of thought. I started my trial of this method last fall.
We get a lot of fall leaves because we live in a forest, on most of our property I leave them lie. In the dog play-yard (which includes my garden) that is not practical, so I gather up the leaves in the fall and run them through a shredder. The shredded leaves are carted over to a storage bin.
As I take out the last of my summer garden, I strip off leaves and light stems and spread them in a thin layer in a garden box. The heavy stems and root balls of these pepper plants are too tough to break down quickly, so I'll run them through the chipper/shredder after the next batch of leaves. I also use the last of the seasons grass clippings, tree trimmings and, as the winter progresses, I add kitchen scraps and coffee grounds from in the house.
Using the formula recommended for compost: two parts brown (carbon) to one part green (nitrogen) I fetch ground-up dead leaves from my bin to layer over the green layer. Each new green layer gets a new layer of brown. These layers are why it's called lasagna gardening. I also sprinkle the brown layers with well rotted compost to get the process started.
A completed bed will be mounded up above the sides of the box because this will compact as the components react with each other and rot down.
Like any composting system, the beds need to be kept moist but, because the components are added in thin layers, the bed does not need to be rolled like a compost pile. By adding new layers of “lasagna” on top of the old bed each year, you keep the soil enriched and the boxes full, but do not destroy the eco-system that naturally develops in undisturbed organic soil.
In my book, anything that keeps the soil productive and reduces labor spent on turning soil has to be a good thing. Almost as good as a big pan of lasagna fresh from the oven.