How can Tom Doyle ("More Plastic Mulch!") improve the fertility and humus content of his soil year after year if he leaves his plastic mulch in place for a 10 to 20 year period? Seems to me that he's taking away from the soil without putting anything back. That's not natural gardening, that's robbery!
Give me good ol' rotten hay and the leaves from a nearby town any day.
Honeoye Falls, N. Y.
As a gardener, I have some serious reservations about black plastic mulch, especially a permanent one. F. P. Hughes talked about attempting to sterilize some ground with plastic in order to make a nice lawn, and I'm afraid it might be possible. Only I doubt that the mulch would select out dandelions and plantain (eat them, no?). It's possible you just might wipe out whole subterranean micro-populations. Soil health depends heavily on all the tiny beasties that live in it, and we don't know that those near the surface are not harmed by being constantly in total darkness with reduced air circulation. Light is essential to many life processes; we can't just assume that it's unimportant to soil life (there's a really good article on light as "nutrient" in the July, 1971 issue of Prevention magazine; worth digging up if only for the questions it raises).
Plastic doesn't feed the soil, either, and it makes it hard for the gardener to do so. Taking without returning equals depletion (theft, rip-off) I would think, even if the first years bring fantastic crops. The fact that this black plastic "works" should by itself be no selling paint to gardeners concerned about long-term soil health. Hard pesticides "work." So do chemical fertilizers.
I haven't used plastic sheeting in my own garden (I may, in a little corner, but I'm certainly not ready to turn my lone acre over to it). I'm skeptical about the material lasting 10 or 20 years in usable size. We put clear six mil plastic on the side of a drafty house once, and it was shredded to smitherines the second year. Wind got into pin holes and worked on it until the plastic was finished. It ain't cute hanging in the trees. More protected if flat on the ground, granted, but 10 years? Seems that one sharp-toed pooch on a spree could do enough damage to make a strip of the stuff useless.
On the other hand, when you finally go to discard the plastic, it resists. It won't break down in cooperation with nature, and burning it is a pretty poisonous prospect.
I hope we go easy with this new mulch, using it only in times of special need (say drought, or for tomatoes in an unusually cold season, etc.) till we're clearer about the consequences of its wholesale adoption. How do earthworms dig the environment that black plastic mulch produces? What's the microbe count in similar soils before mulch, after black plastic for one year, and 10 years? Any deficiency symptoms in plants after five years, 10 years? How does nature react after the plastic is removed? Do things quickly and naturally "green up" or is there a long recovery period, leaving the bare soil open to wind and water erosion? Fish in ponds are killed by raising water temperatures a few degrees. How about the effects of raising soil temperatures slightly over long periods of time?
We need to know if we have here a good earth-loving tool or just another paving material.
I love MOTHER EARTH NEWS, but would like to take strong exception to the articles on plastic mulch. Since plastic is absolutely indestructible, the only excuse I can see for using it in the garden is if you can get it from a source that was otherwise going to throw it out. But buy it deliberately? A thousand times NO!
I've achieved excellent weed and Bermuda grass control with several layers of magazines or newspapers, which cannot be recycled through industry in my area. Layers of this material allow moisture to penetrate and, after the first few days, becomes packed down and won't tear or blow away. Furthermore, newspapers decay after awhile and add nutrients to the soil, which plastics don't (if you use plastic, seems to me you'd have to plow in organic matter at the end of the growing season). The papers can be covered with grass clippings, leaves, wood chips, etc. to make them sightly.
The only advantage of plastic over other types of mulch to be in raising the temperature of the soil (but I wonder if in a desert climate like mine, the plastic would heat up the soil and plants TOO much and fry them to death). I've never tried it, but I understand that the use of flat rocks will produce the same insulating effect.
I don't think that we gardeners who like to call ourselves organic should be buying such things as plastic to use in our garden. We should be setting an example for others to follow.
Las Cruces, N.M.
About MOTHER EARTH NEWS' articles on plastic mulch RETRACT, RETRACT THEM.
I worked on a truck farm in Pennsylvania that used only
plastic mulch (six mil). True, it helps retard weed growth,
but it never, ever rots. And the business about 10 to 20
year use is pure crap. Plastic mulch only lasts a season,
unless you plant in the same slits the next year, and then
fertilizer has to be applied very carefully or it sits on
the plastic and runs off away from where the roots
At the end of the season, what with the dead pumpkin vines and a few frosts, it's impossible to pull the stuff up and dispose it in one piece. It cracks, and bits of plastic stay in the earth. We ended up by burning it in the fall.
Laying the sheeting isn't easy either, even with the kind of rig we used: a tractor-pulled plastic laying machine that digs furrows and then fills them in. Problem was that in any wind at all, the plastic wouldn't stay put.
As an alternative, I'd recommend straw or sawdust. Water can penetrate but weeds can't. If weeds do appear, they can be pulled and left lying in the garden as added mulch.
Why did MOTHER EARTH NEWS have articles on plastic mulch? Plastic is the most unnatural thing ever. It never decomposes and it creates pollution problems. I'm opposed to plastic mulch.
Sorry to see such a spread on plastic mulches. While they do have their positive aspects, they're ecologically expensive to manufacture and impossible to dispose of in any sound way. There are reasonable alternatives:
1. Those who use wood for cooking and heating find themselves with sheets of bark lying all over the wood chopping area. A thick mulch of bark should have nearly the same soil-warming properties as black poly, provide better aeration and (slowly) add humus to the soil.
2. Old newssheet is a fair mulch, if layered thickly, and will eventually break down into humus.
Both materials will add acidity to the soil but this can counteracted with wood ash. A light application goes a long way.
I'm sure other readers know of good mulches that add to the environment rather than foul it. Why not put that information together in an article? But please, MOTHER EARTH NEWS, plastics should be avoided as much as possible.
J. D. Cuddy
Re: "Plastic Mulch" and "More Plastic Mulch!" I'm very interested in reading such accounts of other people's experiments and experiences, and I intend to do my own experimenting with black poly in hopes of extending my growing season, but I can't imagine any other advantage to be gained from using it rather than a deep organic mulch. The latter is far cheaper, decomposes completely, adds much to the soil, retains water, and is at least somewhat more appealing to the senses. I've successfully "sterilized" an area in several different ways (cardboard, shredded leaves, newspaper) without spending a cent, and my mulch replenished the soil.
By the way, at the prices quoted it would cost me $67.50 for enough 1 1/2 mil plastic and $140 for enough six mil to cover a vegetable garden that only provides for four adults, one child and, occasionally, a few friends.
I reckon that if one had very little space and only enough time to "plant seeds or seedlings in already made holes and reap the abundant crop that gets bigger and better each year", plastic mulch might be suitable. As for me, I need more evidence before I'll consider investing a large chunk of my time and garden — not to mention my money — in plastic mulch
Michael L. Marty
One of the basic premises of organic gardening is not only to harvest a plentiful yield with few weeds, but also to produce fruits and vegetables that are as nutritionally valuable as possible This can only be accomplished by replenishing the soil before, during, or after every growing season. I read of no such provision in either article on plastic mulch.
Every crop depletes the soil of certain ingredients and after a period of years land can get "all worn out," so to speak. Nutrients must be returned to the soil in the form of organic mulch, compost, or green manure so that plants can absorb needed nutrients and return them to us.
For my part, I'll continue to keep my soil healthy so that it may keep me healthy.
San Diego, Calif
Well, gang, as you'll recall, we said that "we're still not convinced it's a good idea but there's definitely a growing trend (among some otherwise conservative organic gardeners, too) to plastic mulch". Quite frankly, nobody around here likes the idea either but (1) we've already run article after article on natural mulches, (2) it's our job to report on and bring to your attention alternatives of all kinds and (3) plastic mulches do seem to work — at least in the short run — for people like F. P. Hughes and Tom Doyle.
Whether the infernal plastic proves out over the long term or not (and we rather doubt it) remains to be seen, but it is the mark of a rational adult to at least consider an alien idea. Perhaps if a few more of us set up test plots where natural versus plastic mulch can be compared side-by-side over a ten year period, we'll do away with plastic in the garden once and for all ... or get a pleasant surprise when the godawful stuff surprises us with desirable results. Either way, and with no malice aforethought, we have learned something.
For our part, we'd say that gardeners who want to blanket their vegetable patches with a single sheet of something would be better off to "Carpet Their Gardens" with an old rug of natural fibres as suggested by John Krill in "Use Carpet as Garden Mulch." — The Editors.