No-Till Gardening Musings and Studies on the No-Till method of gardening and soil preservation

No-till without perennials is a non-starter since perennial roots are the primary soil builders and soil preservers – which Nature accomplishes effortlessly and with great economy. Perennial cover crops can be used in rotation to good effect, but then the land is tied up for long periods of time.

I’ve been experimenting with using the garden paths in rotation with the garden beds. This means having wide paths (4 ft in my case) and having them seeded with a polyculture composed of weeds, grass and an annual clover. Kentucky 31 fescue is the grass of my choice, since it is a bunch grass which avoids the labor of constant edging and provides open spaces for the annual clover and weeds, as well as facilitates in soil breathing.

It is understood that with constant mowing such paths do not root as deeply as would perennials used directly in the garden beds, but this can be manipulated by letting the grass grow during the last couple of months before switching to a garden bed. To provide the most stable humus it is best to let the grass and company go to seed.

I plan to use a three year rotation (3 years path, 3 years garden bed). I don’t feel annual cover cropping in the garden beds can be eliminated by this method but certainly reduced. I’ve found no information about this rotation so it needs experimentation. But there has been a great deal of experimentation using perennials in the garden beds where yields are maintained and carbon loss minimized with a rotation of three years perennials and 6-7 years garden crop. It would be interesting to see what, if any, carbon loss would result without tilling. This study was done in a temperate climate so results would be different in a tropical climate and with tropical soils, which typically have the most infertile type of clay, like the volcanic soils on the island of Kauai.

The specter of compaction in walked on paths must be addressed since maintaining soil air is every bit as important as providing available nutrients. Grass paths themselves help buffer the top 6” of the soil so soil compaction could be adequately buffered if the gardener would keep off the paths for some time following heavy rain. This may not always be feasible but should certainly be considered.

The conversion of the path to a garden bed would be the time to help relieve compaction with the same principles used in converting any non-tilled area to a garden bed. Commonly a heavy mulch is used to prevent light from reaching the soil surface. I like to use a layer of high nitrogen fresh grass clippings as the first mulch layer to attract earthworms and an abundance of tilth-creating microbes. If manure is available this would also be an excellent material in this layer as for some reasons earthworms are particularly drawn to composted manure (maybe the smell). If using a degradable light barrier (I use heavy duty kraft paper in rolls), this nitrogen-rich layer would be under the paper with a coarser mulch material on top. This mulch can be walked on without harm. The new path is ready to be mowed and walked on in about three months.

I’ve also found that in about three months, providing the mulch has been kept moist, the new garden beds are ready to be planted with a large seed crop, or transplants. With a fine seed crop another three months or so are needed, when the mulch will have become mostly humus.

I found an interesting report from Virginia Technology, an agricultural college which has been promoting no-till farming for fifteen years, saying “when looking at the long-term effects of continuous no-till farming for fourteen years we find a steady increase in carbon levels at the surface”. By now more than 50% of the farms in Virginia have switched to no-till. It is anticipated this will soon be 100%, with monies being paid to farmers sequestering carbon. Another important point mentioned is that nitrogen is more available to agronomic crops under no-till, which saves in fertilizer costs. Nitrous oxide is a greenhouse gas contributing to global warming and thinning of the protective ozone layer.

With no-till gardening there is a learning curve so I encourage people to start sooner rather than later, especially now with the impending food crisis.