I believe that the early researchers, Extension and industry personnel and growers involved with plastics were visionaries, though they didn’t really comprehend at that time that they created “The Agricultural Plastic Revolution” or the tremendous impact that plastics would have on agriculture – particularly the horticultural industry.
Plastic polymers came out of the labs of World War II. The early plastics that these pioneers worked with came out of the construction industry and initially were sheet plastics. The growing plastic industry was looking to expand and so they reached out to universities around the country to see if they had some new usage ideas. Thus in 1960, Dr. George Marlowe of the University of Kentucky invited 55 industry and university colleagues interested in the applications of plastics in agriculture to Lexington for a conference on the subject.
This first annual conference on “Use of Plastic Film in the Production of Horticultural Crops” was dedicated to Kentucky’s Dr. E.M. Emmert for his pioneering work in the horticultural use of plastic films. A second meeting, called the National Horticultural Plastic Conference, took place in Roanoke, VA. At the third meeting in 1962, the attendees proposed the bylaws to form the National Agricultural Plastics Association (NAPA) which later became the American Society for Plasticulture (ASP).
In NAPA’s bylaws, the objectives of the organization were clearly stated:
- Bring together those who are concerned with any phase of the knowledge of plastics and their uses in agriculture.
- Promote a better understanding of the problems and the progress among those concerned with research on and education of plastics and their uses, those who are concerned with production of plastics and those who use plastics in their agricultural practices.
- Publish scientific and practical information of value concerning agricultural uses of plastic.
- Improve general agricultural and horticultural practices through the use of plastic products at lower cost to the ultimate consumer.
This defined a clear purpose that existed throughout the duration of NAPA, and then ASP, which was dissolved around 2009. The function was transferred to the Plasticulture Working Group in the American Society for Horticultural Science.
Thus, plasticulture was introduced into the agricultural vocabulary – meaning “systems to produce horticultural crops, especially vegetables, that utilize plastics.” The plastics may be mulch films, drip irrigation tapes and tubes, row covers, low tunnels, high tunnels covered with clear plastic sheeting or more permanent greenhouse structures to produce vegetable transplants and greenhouse vegetables.
It can also include plastic connectors for drip irrigation, harvesting boxes, picking containers, packaging materials and a host of other uses around today’s farms. It’s also new machinery associated with the application of the plastics and drip irrigation tape and possibly soil fumigation developed and introduced to farmers.
The development of plastics completely revolutionized growing systems for many horticultural crops in some geographical areas and several major vegetable crops, such as tomatoes, cucumbers and lettuce grown in greenhouses, or tomatoes, peppers, muskmelons, watermelons, eggplants and squash grown in the field. The production of strawberries was likewise radically changed from the conventional matted row system to the plastic-mulched annual hill system of production.
The use of plasticulture in the production of selected horticultural crops continues to expand throughout the U.S. and the world. Systems of production currently utilize various plastic mulching materials, drip irrigation, fertigation, row covers, container-grown vegetable transplants or direct seeded crops and unheated, plastic-covered high tunnels that increase early harvest, total yields and the overall quality of vegetables produced.
Plastic mulches currently in use are either nondegradable/conventional, wavelength-selective or degradable. Conventional mulches can be further subdivided into either smooth or embossed surfaces, with black being the most common color (although other colors have been introduced). The highly reflective surface plastic mulches have been shown to aid in reducing the incidence of virus symptoms on late season summer squash.
The degradable mulches disintegrate, depending on their formulation, in the presence of sunlight over certain time intervals or are biodegradable when in contact with the soil. Degradable or biodegradable mulches have come about because of disposal problems associated with the nondegradable/conventional mulches.
Wavelength-selective mulches were created to combine the benefits of opaque black film (weed control) and clear mulch film (warmer soil temperatures that promote earliness). Two common colors of wavelength-selective mulches are green and brown.
The use of drip irrigation or micro-irrigation has allowed growers to increase the application efficiency of water and reduce the total amount of water used by as much as half when compared to other methods of irrigation, such as overhead sprinkler or furrow irrigation. Allocation of water resources and preservation of water quality are becoming critical in many vegetable-producing areas.
The utilization of drip irrigation has also allowed vegetable producers to practice fertigation (injection of fertilizer into the drip irrigation system), resulting in efficient feeding programs that greatly reduce the potential for fertilizer leaching into groundwater and other water supplies.
The use of plastic mulches plus drip irrigation has promoted the development of double or triple cropping systems that allow efficient/intensive use of land and water resources, especially in areas of limited land. These cropping systems allow growers to harvest the equivalent of two to three acres of produce off one acre of land.
Row covers have evolved from clear plastic sheeting to porous products made of spunbonded polyester, such as Reemay, and spunbonded polypropylene, such as Agryl P-17. They are lightweight and float over the vegetable crop, thus eliminating the need for wire hoops or supports.
These floating row covers are available in sizes up to 50 feet wide by 1,000 feet long. They are primarily used to increase daytime soil and air temperatures, maximize plant survival, obtain earlier and higher yields and exclude insects. They may also provide several degrees of protection against freezing temperatures, especially the heavier weight materials.
The disposal/recovery problem associated with many of these plastic components that are not degradable will be solved through a combination of recycling, incineration and reuse where possible. Remember, we do not have a plastic disposal problem – we have a people problem. People do not dispose of plastics properly and are causing the pollution that we see on land and in the ocean.
These products are an excellent fuel; if incinerated properly with the appropriate burner technology, they could go a long way in reducing the problem of disposing of plastic waste.
The bottom line is that researchers, Extension and industry folks, growers and others will continue to improve on the work of early visionary leaders to ensure that the plasticulture revolution will continue to provide tools for modern horticultural operations. They will make sure that the tools are available to utilize the spent plastics in a responsible manner.
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