Since last fall I've been doing a little more no-dig experimenting in my garden, and the results have been satisfying enough to warrant my continuing the trials in the years ahead.
Last year, when frost had done away with the heat-loving tomatoes, squash, peppers, etc., I sowed the empty beds to winter rye - a common enough practice among many gardeners. They generally dig in, or rototill, the green rye early the following spring in a soil-building practice known as green manuring.
The winter rye takes up many of the soluble plant nutrients that might otherwise leach away during the winter and releases them again in the spring through the natural process of decay when they are plowed in. The cover crop also serves to protect the soil from erosion during winter. It is a commendable practice, which I amended somewhat this spring.
The tremendous root growth of rye adds considerable organic matter to the soil even if the crop is not dug in. Moreover as tests at the Rodale experimental farm in Pennsylvania have shown, transplants grow well in sod that has been killed with a mulch. So why not substitute rye for sod?
I bent the growing rye stems over and covered them with a heavy, wet newspaper which, in turn, was covered with a shredded-leaf mulch to make the beds look more attractive. (I have since realized that the rye need only be cut down and the effort of mulching with paper dispensed with. More about that later.)
Under this mulch the rye quickly died off and planting in the beds was done, using a bulb planter. I simply cut a hole through the mulch into the root-filled soil, threw in a handful of compost, and set out the transplants - cabbage, ruby lettuce, broccoli, eggplant, and peppers.
Because the month of June broke all previous records for rain and cool weather in this corner of Massachusetts, initial growth was slow. While the lettuce appeared unaffected and the cabbage made moderate progress, everything else stood stil. My concern that the new planting method was the cause of this no-growth moderated at the sight of the peppers and eggplant in an adjoining conventional bed, dug over and unmulched. They were equally unresponsive.
Then followed a hot and dry July. As the soil warmed up, the plants responded with quite rapid growth. The cabbages all headed up nicely and currently are producing their second crop of heads, the lettuce excelled, and the Gypsy pepper plants have yielded abundantly since the first week in August.
At this mid-August writing, the eggplants are as big as any I have grown and the fruit is just starting to form.
The broccoli produced a mixed bag. Those set out early headed up as soon as the warm weather arrived, but before the plants themselves were big enough to produce heads of any substance. Those set out in mid-June did far better, growing rapidly through early July to head up nicely at the end of the month. Now all the plants are producing moderate secondary heads.
That rye boasts a massive array of roots was obvious to me as I dug the planting holes. As I see it, the handful of compost provided part of the food for the plants. As the rye roots subsequently decayed, they added still further to the available plant nutrients. They also improved soil structure. Most important, soil microorganisms on which the vitality of the soil depends reproduce most abundantly in and around the roots of plants.
My soil is very light, but soil probes of the bed treated in this manner revealed a look and feel of substance to the soil that adjoining beds lacked, even one where rye had grown but was dug in in the spring. It also needed less watering during the dry weeks of July. Earthworm activity in the soil was considerably more noticeable in this bed than anywhere else.
I have not personally worked in heavy, clay soils, but available literature suggests that just as grass roots add substance to light soils, so they lighten heavy soil. The vigorous roots force apart the platelike soil particles of clay, thus allowing moisture and air to penetrate. Then as earthworms consume the decaying roots, their tunnels further improve aeration.
Next year I will repeat the experiment, but adopt a simpler approach. I'll simply cut down the rye and plant directly into the stubble. As an afterthought, I did just this on a very small patch of rye this spring and the results were equally promising.
The cut rye can be used directly as a mulch or taken to the compost bin. Just recently I read in an issue of the Gardens for All magazine that a gardener had planted directly into the stubble of winter wheat and was delighted with the results.
Another option is to switch the cover crop to annual rye, otherwise known as rye grass. Unlike rye, the cereal, it does not overwinter, so that planting can take place directly into the dead thatch, avoiding even the need to cut down the rye. Annual rye grows vigorously in the cool fall weather to about 15 degrees F. , much as does lawn grass. It also produces vast quantities of fibrous roots, which should do as much for garden soil as winter rye.