"Lasagna" Beds

After double digging my heavy clay soil, I decided there must be a better way. After researching, I came across the lasagna gardening idea, which looks awesome. I have a few questions about this process to help me better understand its concept.

1. Is the goal to build the soil below and above the ground or just above?
2. If the goal is to build the soil below the ground too, would tilling the ground before setting the sheet mulch help the process?
3. Is adding plant matter from plants grown in the beds enough to maintain the fertility of the beds or must more outside input be brought in to keep it going?
4. Why is the cardboard/newspaper important? Could it not be substituted with leaves for example?

1. Is the goal to build the soil below and above the ground or just above?

The prime objective is to create good soil above, but if some earthworms move in and help the soil below, well that's an added benefit.

2. If the goal is to build the soil below the ground too, would tilling the ground before setting the sheet mulch help the process?

Tilling, digging, or otherwise loosening hardpan will help the process.

3. Is adding plant matter from plants grown in the beds enough to maintain the fertility of the beds or must more outside input be brought in to keep it going?

Extra plant matter from outside is always welcome. If you are starting off with depleted, compacted soil that is not supporting any growth, something has got to give, and that will be your back as you tote in more organic matter.

4. Why is the cardboard/newspaper important? Could it not be substituted with leaves for example?

If you start with cardboard as the lowest layer, any bindweed or bermuda grass that tries to tunnel under will find it difficult to break up for the surface. Multiple sheets of newspaper work almost as well as cardboard.

5. Why should I add biochar to a lasagna bed?

That's the most important layer of all. Not only does it help retain water and nutrients, it provides a home for soil microbes and it also builds and sequesters soil carbon.

I've experimented with just about every published gardening method. Early on I discounted Patricia Lanza's Lasagna Gardening technique as being a novel means of composting. After much trial and developing my own methods as best I can, I end up with, of all things, a method which is consistent with Lasagna Gardening. It's easy, effective, simple, and most importantly for me, it is VERY productive. If you've not tried it, get out there and get your hands dirty.

My response to your questions

1. Is the goal to build the soil below and above the ground or just above?

The ultimate goal is a deep, rich soil bed. If you only put effort into the surface, the nutrients will leach into the soil below. Worms will thrive, they will do the job of tilling for you. As roots from your plants grow, they will reach deep into the soil where they will break it up more with each crop, then decay, adding their organic material directly into the ground.

2. If the goal is to build the soil below the ground too, would tilling the ground before setting the sheet mulch help the process?

It can, but if you are not adding material before tilling, there will be some degree of resettling, making your effort vain. If you skip the step, the roots and worms will do this job, and do it better.

3. Is adding plant matter from plants grown in the beds enough to maintain the fertility of the beds or must more outside input be brought in to keep it going?

If you put back in what was taken out, there is no net gain. There will be the same level of biological activity, although the diversity of the lifeforms will change as a result of your efforts. If you want to increase the activity, add more life supporting organic material from many different sources.

4. Why is the cardboard/newspaper important? Could it not be substituted with leaves for example?

I use leaves. I can't say enough good things about leaves. Leaves are the best thing in the history of the known universe. Add them, then add some more. I smother a new bed with a foot of leaves and let them rot down. If left untouched, you'll have a layer of leaf mold under a top layer of undecomposed leaves. Only good comes from this. As the leaves decay they will allow some grass and weeds to penetrate. What I observe is an entirely different variety of species than in the pathways between beds treated this way. It's night and day over a distance of a few inches. The lignin in the leaves are decomposed by fungi ONLY, so this method establishes the foundation for nutrient distribution within the soil.

5. Why should I add biochar to a lasagna bed?

I still have not tried working with biochar. I cannot answer from experience.

1. Above/Below--who cares? The plants don't care as long as the total profile is good.

2. Now that I have a small tractor and subsoiler, I have almost entirely given up on the tiller. I run the subsoiler to break the hardpan, then build the beds on top. I put some good compost into the rip lines and some tea if I have it to boost the biology deep, but I find just loosening the soil enough for the worms to have an easier time is the key.

3. Maybe if you are not harvesting anything. Bio-intensive uses like 3 beds for biomass/fertility for every bed you are growing food. Geoff plants 7-10 support trees for every productive tree in a swale. I see a trend there...

4. It really depends on what is growing in the soil you cover. Just leaves will not stop aggressive grasses. A single layer of cardboard won't stop aggressive grasses with stored root energy.

Thanks for all the feedback. It really does sound like a great method.

R Scott - 3 beds to support 1? That's a lot of space required. That's pretty disappointing indeed. How did people in the past maintain their food supply since it's so difficult to develop closed-loop systems?

I also have clay (silt) soil, so I am forgoing much of the digging in favor of this lasagna style. I will still dig six inches in, add wood, then wood chips, then grass, then leaves, then add the top soil back, then maybe leaves once more. Aside from the mountains of free wood chips at our county facility, everything else is near our zone 1 area.

I just hope these lasagna beds don't get too hot when created in the spring instead of the fall...

Hi George, everything I've read is that the wood chips will break down too fast and rob Nitrogen. But I guess since you're adding grass and other organic matter, that is replacing the nitrogen lost?

“How did people in the past maintain their food supply since it's so difficult to develop closed-loop systems?”

For everything that is taken from the earth there needs to be a return. It can be in the form of manure, kitchen scraps, animal carcasses, green plant clippings/refuse, etc.

Other than items made of metal, my grandparents had no ‘trash’ that had to be taken to a dump or landfill. I don’t think one even existed in the part of the country that they lived in at that time.

Most things were just buried in trenches and those trenches were ready for planting by the next year. By alternating trenches there was always one trench ready for planting and another for trash.

I started doing the same a few years ago.

After about 3 years of this a true living soil was established and I was amazed at how quickly things, even poultry bones, were broken down into black earth.

Brandon Greer wrote:Hi George, everything I've read is that the wood chips will break down too fast and rob Nitrogen. But I guess since you're adding grass and other organic matter, that is replacing the nitrogen lost?

It's a concern. I am willing to find out what happens, especially since I will have other sources of N. Plus, the chips are free and I'm looking for a lot of resource to make these beds deep and long lasting. There will also be logs in the bottom, a la hugel, so that adds even more of an N sink. Perhaps I will have to source some manure...

I should say these wood chips come from a huge mountain of wood chips (30 feet tall?) that is breaking down the chips all the time, so there is a good amount of dirt (maybe 50%) in these chips. It's not like the 1 yard bags you would get if you were landscaping. I think that will mitigate some of the N sink.