Plasticulture

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Plastic mulch used for growing strawberries Plasticulture.jpg
Plastic mulch used for growing strawberries

Plasticulture is the practice of using plastic materials in agricultural applications. The plastic materials themselves are often and broadly referred to as "ag plastics". Plasticulture ag plastics include soil fumigation film, irrigation drip tape/tubing, plastic plant packaging cord, nursery pots and bales, but the term is most often used to describe all kinds of plastic plant/soil coverings. Such coverings range from plastic mulch film, row coverings, high and low tunnels (polytunnels), to plastic greenhouses.

Contents

Plastic used in agriculture was expected to include 6.7 million tons of plastic in 2019 or 2% of global plastic production. [1] Plastic used in agriculture is hard to recycle because of contamination by agricultural chemicals. [1] Moreover, plastic degradation into microplastics is damaging to soil health, microorganisms and beneficial organisms like earthworms. [1] [2] Current science is not clear if there are negative impacts on food or once food grown in plasticulture is eaten by humans. [1] Because of these impacts, some governments, like the European Union under the Circular Economy Action Plan, are beginning to regulate its use and plastic waste produced on farms.

Types of plastics used

Polyethylene (PE) is the plastic film used by the majority of growers because of its affordability, flexibility and easy manufacturing. [3] It comes in a variety of thicknesses, such as a low density form (LDPE) as well as a linear low density form (LLDPE). These can be modified by addition of certain elements to the plastic that give it properties beneficial to plant growth such as reduced water loss, UV stabilization to cool soil and prevent insects, elimination of photosynthetically active radiation to prevent weed growth, IR opacity, antidrip/antifog, and fluorescence. [3] [4]

Polypropylene (PP) is often used for agricultural plant packaging cord.

Applications

Greenhouses and walk-in tunnel covers

A greenhouse is a large structure in which it is possible to stand and work with automated ventilation. High tunnels are hoop houses, manually ventilated by rolling up the sides. Greenhouse and high tunnel films are usually within the parameters of 80-220μm thick and 20m wide, and have a life span between 6–45 months dependent on several factors. [4] Monolayer polyethylene films are better suited for less extreme environmental conditions, while multilayer covers made of three layers, one EVA19 layer inserted between two low-density polyethylene layers has been shown to have a better performance under harsh conditions. [5]

Small tunnel covers

Small tunnel covers are about 1m wide and 1m high, and have a thinner polyethylene film than the large tunnel covers, usually below 80μm. Their lifetime is also shorter than that of the larger versions; they usually have a usable life span of 6–8 months. Use of small tunnels is less popular than both the more expensive but durable greenhouses/walk-in tunnels and the cheaper plastic mulch. [4]

Plastic mulch

Plastic mulch in a field near Merstone, Isle of Wight, UK Plastic mulch, nr Merstone, IW, UK.jpg
Plastic mulch in a field near Merstone, Isle of Wight, UK

Plastic mulching is when a thin plastic film is placed over the ground, poking holes at regular intervals for seeds to be planted in, or placing it directly over plants in the beginning stages of growth. The films remain in place for the duration of the cultivation (usually 2–4 months) and usually have a thickness of 12-80μm. The main functions of plastic mulch are to insulate and maintain a consistent temperature and humidity of the soil, preventing evaporation of moisture from the soil, minimization of seedtime and harvest, prevent weed growth, and to prevent erosion. Pigmented [6] or colourless films can be used, each with specific advantages and disadvantages over the other. [4]

Black films prevent weed growth, but do not transmit light to heat up the soil; clear films transmit light and heat the soil, but promote weed growth. Photosensitive films have been developed that are pigmented to prevent weed growth, but still transmit light to heat the soil. These photosensitive films are more costly than either the clear or black polyethylene sheeting. [3] Black plastic mulch controls evaporation from the soil and improves soil water retention. Plastic mulching proved to reduce irrigation requirements in pepper by 14-29% because of elimination of soil evaporation. [7]

Flowering time was also reduced in okra when black plastic mulch was used; the plants reached 50% flowering 3–6 days earlier than un-mulched plots. Plant height in okra was significantly increased with black plastic mulch use compared to those grown in bare soil. Evaporation from soil accounts for 25-50% of water used in irrigation, using plastic mulch prevents much of this evaporation and thus reduces the amount of water needed to grow the crop. [8] This conservation of water makes plastic mulch favourable for farmers in dry and arid climates where water is a limited resource. As the second most used ag plastic in the world, the volume of plastic mulch used every year is estimated at 700,000t. [4]

Origins and development around the world

The first use of plastic film in agriculture was in an effort to make a cheaper version of a glasshouse. In 1948 Professor E.M. Emmert built the first plastic greenhouse, a wooden structure covered with cellulose acetate film. He later switched this to a more effective polyethylene film. After this introduction of plastic film to agriculture it began being used at a larger scale around the world by the early 1950s to replace paper for mulching vegetables. [4]

By 1999 almost 30 million acres worldwide were covered in plastic mulch. Only a small percentage of this was in the United States (185 000 acres), the majority of this plastic growth was happening in economically poor areas of the world and previously unproductive desert regions, such as Almeria in southern Spain. [9]

The largest concentrations of greenhouses around the world are mainly found in two areas, with 80% throughout the Far East (China, Japan, Korea), and 15% in the Mediterranean basin. The area of greenhouse cover is still increasing at a fast rate, during the last decade it is estimated that it has been growing by 20% every year. Areas such as the Middle East and Africa are growing in their use of plastic greenhouses by 15-20% per year, compared to the weak growth in more developed and economically stable areas such as Europe. China leads the world's growth at 30% per year, translating into a volume of plastic film reaching 1,000,000 t/year. In 2006 80% of the area covered by plastic mulch is found in China where it has a growth rate of 25% per year; this is the highest in the world. [4]

Since its introduction in the 1950s, plastic film has been designed and developed to increase produce yield, increase produce size and shorten growth time. Developments in plastic film include durability, optical (ultraviolet, visible, near infrared, and middle infrared) properties, and the antidrip or antifog effect. Recent developments in this area include UV-blocking, NIR-blocking, fluorescent, and ultrathermic films. [4]

Large-scale usage in southern Spain

The "sea of plastic" covering 20,000 ha of the Campo de Dalias around El Ejido and Roquetas de Mar in southern Spain NASA photo of plasticulture, Campo de Dalias, Spain.jpg
The "sea of plastic" covering 20,000 ha of the Campo de Dalías around El Ejido and Roquetas de Mar in southern Spain

The use of plasticulture in agriculture is growing rapidly, perhaps nowhere more visibly than around Almería in southern Spain. The eastern approaches to Almería, north of the airport, are densely covered, as is a large area further northeast, surrounding the towns of Campohermoso, Los Pipaces and Los Grillos (close to Níjar).

The densest concentration lies about 20 km southwest of Almería, where almost the entire Campo de Dalías, a low-lying cape, is now under plastic (an estimated area of 20,000 hectares). Further west, a similar, but smaller, coastal plain around Carchuna, southeast of Motril, is similarly enveloped. The technique is not restricted to the plains; it is also applied to wide terraces on the sides of shallow valleys, as the valley north of Castell de Ferro shows.

Elsewhere along the Costa Tropical and the Costa del Sol, particularly between Almería and Málaga, fruit trees growing on terraces in steeper valleys may be covered with vast tents of plastic netting.

Environmental aspects

As (non-biodegradable) plastics are used in agriculture, there is a risk of it ending up in the soil, thus polluting it in the process.[ clarification needed ]

Recycling

One significant component of plasticulture is the disposal of used ag plastics. Technologies exist which allow for ag plastics to be recycled into plastic resins for reuse in the plastics manufacturing industry. [10]

Recycling of plastic mulch is difficult because the mulch is often wet or dirty. Thin mulch breaks down quickly, and can be impossible to pick up for recycling once degraded. [11]

Legislation on plastic use in agriculture

In the European Union, Directive 2008/98/EC on waste management is in place, of which article 8 states "each member state may introduce the ERP concept into its own legal framework in addition to deciding how to encourage manufacturers to participate in the prevention, re-use, recycling and recovery of used plastic products." [12] In addition, in 2018, the European Commission published a communication laying out a strategy for plastics in a circular economy. It mentioned curbing plastic waste and littering, for instance by reducing single-use plastics, tackling sources of marine litter at sea, restricting the use of oxo-degradable plastics and curbing micro-plastics pollution. [13] [ clarification needed ] In 2020, the EU finally released its Circular Economy Action Plan. It included a set of measures to reduce plastic litter and address the presence of microplastics in the environment. It also expressed addressing sustainability issues by developing a policy framework on biodegradable or compostable plastics. [14]

See also

Related Research Articles

<span class="mw-page-title-main">Greenhouse</span> Building made chiefly of transparent material in which plants are grown

A greenhouse is a structure that allows people to regulate climatic conditions, such as temperature and humidity. There are many different designs of greenhouses; however, in general these buildings include large areas of transparent material to capture the light and heat of the sun. The three most common transparent materials used in the roof and walls of modern greenhouses are rigid plastics made of polycarbonate, plastic films made of polyethylene or glass panes. When the interior of a greenhouse is exposed to sunlight, the internal temperature rises and shelters the plants from cold weather.

<span class="mw-page-title-main">Horticulture</span> Small-scale cultivation of plants

Horticulture is the cultivation of plants in gardens or greenhouses, as opposed to the field-scale production of crops characteristic of agriculture. It includes the cultivation of fruits, vegetables, nuts, seeds, herbs, sprouts, mushrooms, algae, flowers, seaweeds and non-food crops such as grass and ornamental trees and plants. It also includes plant conservation, landscape restoration, landscape and garden design, construction, and maintenance, and arboriculture, ornamental trees and lawns.

Season extension in agriculture is any method that allows a crop to be grown beyond its normal outdoor growing season and harvesting time frame, or the extra time thus achieved. To extend the growing season into the colder months, one can use unheated techniques such as floating row covers, low tunnels, caterpillar tunnels, or hoophouses. However, even if colder temperatures are mitigated, most crops will stop growing when the days become shorter than 10 hours, and resume after winter as the daylight increases above 10 hours. A hothouse — a greenhouse which is heated and illuminated — creates an environment where plants are fooled into thinking it is their normal growing season. Though this is a form of season extension for the grower, it is not the usual meaning of the term.

<span class="mw-page-title-main">Mulch</span> Layer of material applied to the surface of soil

A mulch is a layer of material applied to the surface of soil. Reasons for applying mulch include conservation of soil moisture, improving fertility and health of the soil, reducing weed growth, and enhancing the visual appeal of the area.

<span class="mw-page-title-main">Water conservation</span> Policies for sustainable development of water use

Water conservation includes all the policies, strategies and activities to sustainably manage the natural resource of fresh water, to protect the hydrosphere, and to meet the current and future human demand. Population, household size and growth and affluence all affect how much water is used. Factors such as climate change have increased pressures on natural water resources especially in manufacturing and agricultural irrigation. Many countries have already implemented policies aimed at water conservation, with much success. The key activities to conserve water are as follows: any beneficial reduction in water loss, use and waste of resources, avoiding any damage to water quality; and improving water management practices that reduce the use or enhance the beneficial use of water. Technology solutions exist for households, commercial and agricultural applications. Water conservation programs involved in social solutions are typically initiated at the local level, by either municipal water utilities or regional governments.

<span class="mw-page-title-main">Dryland farming</span> Non-irrigated farming in areas with little rainfall during the growing season.

Dryland farming and dry farming encompass specific agricultural techniques for the non-irrigated cultivation of crops. Dryland farming is associated with drylands, areas characterized by a cool wet season followed by a warm dry season. They are also associated with arid conditions, areas prone to drought and those having scarce water resources.

<span class="mw-page-title-main">Plastic mulch</span> Plastic film used in the role of mulch

Plastic mulch is a product used in plasticulture in a similar fashion to mulch, to suppress weeds and conserve water in crop production and landscaping. Certain plastic mulches also act as a barrier to keep methyl bromide, both a powerful fumigant and ozone depleter, in the soil. Crops grow through slits or holes in thin plastic sheeting. Plastic mulch is often used in conjunction with drip irrigation. Some research has been done using different colors of mulch to affect crop growth. Use of plastic mulch is predominant in large-scale vegetable growing, with millions of acres cultivated under plastic mulch worldwide each year.

Drip irrigation or trickle irrigation is a type of micro-irrigation system that has the potential to save water and nutrients by allowing water to drip slowly to the roots of plants, either from above the soil surface or buried below the surface. The goal is to place water directly into the root zone and minimize evaporation. Drip irrigation systems distribute water through a network of valves, pipes, tubing, and emitters. Depending on how well designed, installed, maintained, and operated it is, a drip irrigation system can be more efficient than other types of irrigation systems, such as surface irrigation or sprinkler irrigation.

<span class="mw-page-title-main">Row cover</span>

In agriculture and gardening, row cover is any transparent or semi-transparent flexible material, like fabric or plastic sheeting, used as a protective covering for plants, usually vegetables. Covers are used to extend growing seasons, and reduce undesirable effects of cold, wind and insects. Row covers can reduce the drying effect of wind, and can provide a small amount of warming in a similar way to unheated cold frames, greenhouses and polytunnels, creating a microclimate for the plants.

<span class="mw-page-title-main">Living mulch</span> Cover crop grown with a main crop as mulch

In agriculture, a living mulch is a cover crop interplanted or undersown with a main crop, and intended to serve the purposes of a mulch, such as weed suppression and regulation of soil temperature. Living mulches grow for a long time with the main crops, whereas cover crops are incorporated into the soil or killed with herbicides.

Polyethylene or polythene film biodegrades naturally, albeit over a long period of time. Methods are available to make it more degradable under certain conditions of sunlight, moisture, oxygen, and composting and enhancement of biodegradation by reducing the hydrophobic polymer and increasing hydrophilic properties.

This is a glossary of environmental science.

<span class="mw-page-title-main">Xeriscaping</span> Water conserving landscaping method

Xeriscaping is the process of landscaping, or gardening, that reduces or eliminates the need for irrigation. It is promoted in regions that do not have accessible, plentiful, or reliable supplies of fresh water and has gained acceptance in other regions as access to irrigation water has become limited, though it is not limited to such climates. Xeriscaping may be an alternative to various types of traditional gardening.

The environmental impact of agriculture is the effect that different farming practices have on the ecosystems around them, and how those effects can be traced back to those practices. The environmental impact of agriculture varies widely based on practices employed by farmers and by the scale of practice. Farming communities that try to reduce environmental impacts through modifying their practices will adopt sustainable agriculture practices. The negative impact of agriculture is an old issue that remains a concern even as experts design innovative means to reduce destruction and enhance eco-efficiency. Though some pastoralism is environmentally positive, modern animal agriculture practices tend to be more environmentally destructive than agricultural practices focused on fruits, vegetables and other biomass. The emissions of ammonia from cattle waste continue to raise concerns over environmental pollution.

The term cropping system refers to the crops, crop sequences and management techniques used on a particular agricultural field over a period of years. It includes all spatial and temporal aspects of managing an agricultural system. Historically, cropping systems have been designed to maximise yield, but modern agriculture is increasingly concerned with promoting environmental sustainability in cropping systems.

Sustainable landscaping is a modern type of gardening or landscaping that takes the environmental issue of sustainability into account. According to Loehrlein in 2009 this includes design, construction and management of residential and commercial gardens and incorporates organic lawn management and organic gardening techniques.

Mechanical weed control is a physical activity that inhibits unwanted plant growth. Mechanical, or manual, weed control techniques manage weed populations through physical methods that remove, injure, kill, or make the growing conditions unfavorable. Some of these methods cause direct damage to the weeds through complete removal or causing a lethal injury. Other techniques may alter the growing environment by eliminating light, increasing the temperature of the soil, or depriving the plant of carbon dioxide or oxygen. Mechanical control techniques can be either selective or non-selective. A selective method has very little impact on non-target plants where as a non-selective method affects the entire area that is being treated. If mechanical control methods are applied at the optimal time and intensity, some weed species may be controlled or even eradicated.

<span class="mw-page-title-main">Subsurface textile irrigation</span>

Subsurface Textile Irrigation (SSTI) is a technology designed specifically for subsurface irrigation in all soil textures from desert sands to heavy clays. The use of SSTI will significantly reduce the usage of water, fertilizer and herbicide. It will lower on-going operational costs and, if maintained properly, will last for decades. By delivering water and nutrients directly to the root zone, plants are healthier and have a far greater yield.

<span class="mw-page-title-main">Canal lining</span>

Canal lining is the process of reducing seepage loss of irrigation water by adding an impermeable layer to the edges of the trench. Seepage can result in losses of 30 to 50 percent of irrigation water from canals, so adding lining can make irrigation systems more efficient. Canal linings are also used to prevent weed growth, which can spread throughout an irrigation system and reduce water flow. Lining a canal can also prevent waterlogging around low-lying areas of the canal.

<span class="mw-page-title-main">Agricultural technology</span> Use of technology in agriculture

Agricultural technology or agrotechnology is the use of technology in agriculture, horticulture, and aquaculture with the aim of improving yield, efficiency, and profitability. Agricultural technology can be products, services or applications derived from agriculture that improve various input/output processes.

References

  1. 1 2 3 4 "Why food's plastic problem is bigger than we realise". www.bbc.com. Retrieved 2021-03-27.
  2. ↑ Nex, Sally (2021). How to garden the low carbon way: the steps you can take to help combat climate change (First American ed.). New York. ISBN   978-0-7440-2928-4. OCLC   1241100709.{{cite book}}: CS1 maint: location missing publisher (link)
  3. 1 2 3 Allingham Yael (1992). [Plastic Sheets for use in Agriculture]. United States Patent.
  4. 1 2 3 4 5 6 7 8 Espí E, Salmerón A, Fontecha A, García Y, and Real A.I. (2006). Plastic Films for Agricultural Applications Journal of Plastic Filming and Sheeting, 22(85):e85-102.
  5. ↑ Adam A, Kouider S.A., Hamou A, Saiter J.A. (2005). Studies of polyethylene multi layer films used as greenhouse covers under Saharan climatic conditions Polymer Testing, 24(7):e834–838.
  6. ↑ "Beyond the colour of mulch (White/ Black mulch) - Agriplastics Community". 31 August 2018.
  7. ↑ Abu-Awwad A.M. (1998). [Effect of mulch and irrigation water amounts on soil evaporation and transpiration] J. Agron. Crop Sci., 18:e55–59.
  8. ↑ Ramakrishna A. et al (2006). [Effect of mulch on soil temperature, moisture, weed infestation and yield of groundnut in northern Vietnam] Field Crops Res., 95:e115–125.
  9. ↑ Miles C, Kolker K, Reed J, Becker J. Alternatives to Plastic Mulch for Organic Vegetable Production. Washington State University, 2005.
  10. ↑ Plastic mulch film recycling process Archived 2008-05-18 at the Wayback Machine Agricultural plastics recycling website, accessed 07.09.08
  11. ↑ Mancl, Karen. "Agricultural plastic in the U.S. and China: A blessing or a curse?". Agri Communicators Inc. Retrieved 12 December 2020.
  12. ↑ Agricultural plastics european regulation: principle
  13. ↑ "Legislative train schedule".
  14. ↑ Circular economy action plant text

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