7 Feb. 2014
Edited 22 Apr. 2014
Edited 3 March 2016
Recently an acquaintance gave us a bag of magazines, which were promoting organic and sustainable gardening and living. While I was perusing the pages of one that advocates sustainable urban living, I could not restrain my laughter. Contained within the covers of this publication was picture after picture of plastic garden products. Handles on garden implements, artificial lumber for raised beds, fencing, compost bins, the ubiquitous plastic flower pots, plastic mulch, row covers and PVC piping for frames were just a few examples of the items that this monthly considered to be useful and sustainable. None of these items were identified as being made from bioplastic*; so one can only assume that they were formed from petroleum-based chemicals. Further investigation of some of the companies who made these products revealed that these items were formed from recycled plastic and strong plastic, but the word bio was not mentioned.
There are many uses for petroleum-based plastic in our world but not outdoors or in the garden. Why?
Ray The Warrior Son of the Sun
The life sustaining orb that maintains our existence on this world is not a friend of petroleum-based plastic. UV rays from our Sun wreak havoc on the chemical structure of oil based plastic. Sunlight breaks down or degrades plastic into small pieces and invisible chemical molecules. These molecules and other chemicals, such as UV stabilizers, which were added to the plastic resin during manufacture, can leach into the soil and the air.
PVC, Polyvinyl chloride, resin identification code #3, which was used to construct frames in the above magazine, is considered to be toxic. PVC can be a serious health risk during its life cycle 3. It contains phthalates and the heavy metals 1 lead, cadmium, and/or organotins2. Some manufacturers of PVC recommend painting PVC pipe if it will be exposed to sunlight for an extended period of time. PVC mulch and row covers are prohibited from use by organic growers 6.
The container in the pictures below is made of Polypropylene or PP, resin identification code #5. It was being used in my greenhouse to bottom water plants. It was exposed to the sun for about four months before it fell apart. Apparently this container was not intended for outside use and had not been treated with ultraviolet inhibiting chemicals.
Evidently, the chemicals we apply to our skin to protect it from UV rays are some of the same chemicals applied to plastic to protect it from sunlight 7. Sunscreen lotion is for external use only and not intended for consumption. If sunscreen has to be reapplied ever few hours, how much ultraviolet inhibitor is used to extend the usefulness of plastic garden products and what happens to it as it wears away? 3-3-2016 Here is an interesting article about the chemicals in sunscreen. http://www.ewg.org/2015sunscreen/report/the-trouble-with-sunscreen-chemicals/
Agricultural cloth or floating row cover is a plastic product made from Polypropylene and it is exposed to the sun for long periods of time. It is approved for organic growing. Most brands are UV stabilized. One distributor of row cover made of PP, Johnny Select Seed, describes its covers as “Most effective, least toxic, form of insect control.”4 Nontoxic means benign or non-hazardous. What does “Least toxic” mean? Is there a known toxic element to this product?
Silver Bullet or the Elephant in the Room
Thirty years ago, when my husband and I worked for a conventional farmer, our boss and the other farmers in this area were using black plastic mulch. It saved time and labor because it helped prevent weeds and kept moisture in the soil. However, by the end of the season it was falling apart. Small bits of black plastic were always floating across the ground and tangling with vegetation. Some larger pieces that were hiding in the soil would bind up tractors and plows. We tried it in our garden only once. Although we were diligent about removing it, small pieces of black plastic kept surfacing for several years after.
Progress has been made, however, and biodegradable sheet mulch, made from corn starch and more expensive than oil-based plastic, is available. However, it is not certified, as of 4/22/2014, for organic uses because of the GMO contaminated corn issue and there is the other important related issue of using food crops to make fuel and plastics, fodder for another rant.
In the 1980s, agricultural cloth was introduced. Since then it has been embraced by the Organic community and promoted by major Universities as a form of chemical free growing and not detrimental to beneficial insects.
Contrary to current propaganda, innocuous as they may appear, row covers do present a hazard to beneficial bugs. Insects get tangled and trapped in the small fibers on the surface of the fabric while others, particularly bees, find their way into the protected area but can’t get out again and die.
Three years ago, in our quest to be more organic, we bought a roll of agricultural cloth. Last year we bought another. Since that time, however, we have decided that row covers are not environmentally sound. In spite of the fact that it was UV stabilized, exposure to the elements causes the fabric to thin and tear easily. A few days ago we picked several small pieces out of our fig tree and boundary hedge. Its loss of mass was visually evident. Where did the missing chemical fibers go?
Since their introduction, the use of row covers in conjunction with plastic mulch or alone, has increased exponentially. Thousands of acres are now being covered with these sheets of chemical compounds for the purpose of growing food. Is this really a good idea?
In 2011, the University of Agriculture at Krakow published a study of the effects of agricultural fleece or row cover and heavy metal accumulation in Chinese cabbage. The study concluded that Chinese cabbage grown under row cover contained higher levels of cadmium, lead and manganese than cabbages grown in an open field.5
Is agricultural cloth and plastic mulch the silver bullet of organic growing and sustainable living or are these chemical covers the DDT of the Twenty-first Century? Con
*Bioplastic – a type of biodegradable plastic derived from biological substances such as vegetable fats and oils and corn starch rather than from petroleum.
New Information – posted 11/12/15
Is Organic Farming Sustainable?
The Biggest Source Of Plastic Trash You’ve Never Heard Of
I rechecked these sites on 8-16-2015
- http://agr.wa.gov/FoodAnimal/Organic/docs/3007 Mulch Factsheet.pdf pg. 2 Edited 8-16-15
- http://www.syrgis.com/category/applications/uv-stabilizers This site is no longer active.