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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. [1]
Disposal of plastic mulch is an environmental problem. Technologies exist to provide for the recycling of used/disposed plastic mulch into viable plastic resins for re-use in the plastics manufacturing industry. [2] However these methods are not very effective due to contamination by agrochemicals of the plastic. [3] Other concerns include residual microplastics in the soil which can have negative effects on soil ecologies, including microbes and earthworms. [3] [4]
The idea of using polyethylene film as mulch in plant production saw its beginnings in the mid-1950s. Dr. Emery M. Emmert of the University of Kentucky was one of the first to recognize the benefits of using LDPE (low-density polyethylene) and HDPE (high-density polyethylene) film as mulch in vegetable production. Emmert also wrote on other topics such as the use of plastic for greenhouses instead of glass and plastic in field high tunnels. Approximately 2,500 square miles (6,500 km2) of agricultural land utilize polyethylene mulch and similar row covers for crop production in the world. Laying plastic polythene (mulch) down over mounds formed in the soil was also pioneered in New Zealand in the mid fifties by strawberry growers in the Auckland area. By 1960-61 all strawberries grown commercially in New Zealand were grown through black polythene usually laid by hand. The plastic promoted growth, conserved moisture brought on early fruiting and restricted weed infestation. The earliest polythene laying machines were in use in New Zealand by the mid 1960s and were very similar to the machines sold today. The very first machines were designed by growers and built by small engineering/fabrication workshops, usually under the careful guidance and supervision of the farmer. Each machine for many years was generally similar to the last, with the occasional modification to improve performance.
The use of plastic mulches along with the use of drip irrigation has many benefits such as:
The use of plastic mulch alters soil temperature. Dark mulches and clear mulches applied to the soil intercept sunlight and warm the soil, allowing earlier planting as well as encouraging faster growth early in the growing season. White mulch reflects heat from the sun, effectively reducing soil temperature. This reduction in temperature may help establish plants in mid-summer when cooler soil might be required. [5]
Plastic mulches reduce the amount of water lost from the soil due to evaporation. This means less water will be needed for irrigation. Plastic mulches also aid in evenly distributing moisture to the soil, which reduces plant stress.[ citation needed ]
Plastic mulches prevent sunlight from reaching the soil which can inhibit most annual and perennial weeds. Clear plastics prevent weed growth. Holes in the mulch for plants tend to be the only pathway for weeds to grow.
The use of drip irrigation in conjunction with plastic mulch allows one to reduce leaching of fertilizers. Using drip irrigation eliminates the use of flood and furrow irrigation that applies large quantities of water to the soil, which in turn tends to leach nitrogen and other nutrients to depths below the root zone. Drip irrigation applies lower amounts of water with fertilizers injected and thus these fertilizers are applied to the root zone as needed. This also reduces the amount of fertilizer needed for adequate plant growth when compared to broadcast fertilization.
Plastic mulches keep ripening fruits off of the soil. This reduced contact with the soil decreases fruit rot as well as keeps the fruit and vegetables clean. This is beneficial for the production of strawberries, for example. [6]
The plastic mulch covering the soil decreases the crusting effect of rain and sunlight. The reduction in weed quantity means a decreased need for mechanical cultivation. Weed control between beds of plastic can be done using directly applied herbicides and through mechanical means. The soil underneath the plastic mulch stays loose and well aerated, with the mulch protecting the soil it covers from erosion. [1]
The use of plastic mulch creates a practically weed-free area around the plant, removing the need for cultivation except between the rows of plastic. Root damage associated with cultivation is therefore eliminated. Due to these factors, the use of plastic mulch can lead to an improvement in the overall growth of the plant. [7]
There are many disadvantages to using plastic mulches in crop production as well.
The benefits from using plastic mulch come at a higher cost than planting in bare soil. These costs include equipment, the plastic film used as the mulch, transplanters designed for plastic beds, and additional labor during installation and removal of mulch films. Specialized mulch application equipment must be used to install plastic mulch beds into a field. These machines shape the soil and apply the plastic to the prepared soil. Transplanters designed for plastic mulch can be used to plant the desired crop. Hand transplanting is an option, but this is rather inefficient. The removal of plastic mulch also contributes to a higher cost through additional labor and equipment needed. Specialized designed undercutting equipment can be used to remove the plastic from the field after harvest.
If conventional plastics (e.g. PE) are used as mulch films, they are likely to accumulate in soil, since the removal and the correct disposal of these plastics are technically and economically burdensome. [8] This accumulation could cause both crop yield reduction and environmental problems. [9] Biodegradable polymers are polymers that can be degraded by the naturally occurring microbial community in an environmental system. They provide a more sustainable alternative to conventionally used plastics for mulch films. Providing the same benefits as detailed above, the problem of plastic accumulation in soils could be solved. [10] Aliphatic polyesters and aliphatic-aromatic co-polyesters have shown to be promising groups of biodegradable polymers. [11]
The use of plastic mulch requires a unique application process to ensure proper placement of the plastic film. This application process begins with preparing the field the same way one would for a flat seed bed. The bed must be free of large soil clods and organic residue. A machine called a plastic layer or a bed shaper is pulled over the field creating a row of plastic mulch covering a planting bed. These beds can be a flat bed which simply means the surface of the plastic mulch is level with the inter-row soil surface. Machines that form raised beds create a plastic surface higher than the inter-row soil surface. The basic concept of the plastic bed shaper is a shaping box which creates the bed, that is then covered by plastic via a roller and two coulters that cover the edges of the plastic film to hold the plastic the soil's surface. These plastic layers also place the drip irrigation line under the plastic while the machine lays the plastic. It is somewhat important that the plastic is rather tight. This becomes important in the planting process.
Planting also requires specialized planting equipment. The most common planting equipment is a waterwheel type transplanter. The waterwheel transplanter utilizes a rotating drum or drums with spikes at set intervals. The drum or drums have a water supply that continuously fills the drum with water. The transplanter rolls the spiked drum over the bed of plastic. As the drum presses a spike into the plastic, a hole is punched and water flows into the punched hole. A rider on the transplanter can then place a plant in the hole. These drums can have multiple rows and varied intervals to create the desired spacing for that particular crop.
Raised-bed gardening is a form of gardening in which the soil is raised above ground level and usually enclosed in some way. Raised bed structures can be made of wood, rock, concrete or other materials, and can be of any size or shape. The soil is usually enriched with compost.
Weed control is a type of pest control, which attempts to stop or reduce growth of weeds, especially noxious weeds, with the aim of reducing their competition with desired flora and fauna including domesticated plants and livestock, and in natural settings preventing non native species competing with native species.
Polyethylene terephthalate (or poly(ethylene terephthalate), PET, PETE, or the obsolete PETP or PET-P), is the most common thermoplastic polymer resin of the polyester family and is used in fibres for clothing, containers for liquids and foods, and thermoforming for manufacturing, and in combination with glass fibre for engineering resins.
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.
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.
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.
Although PET is used in several applications, as of 2022 only bottles are collected at a substantial scale. The main motivations have been either cost reduction or recycle content of retail goods. An increasing amount is recycled back into bottles, the rest goes into fibres, film, thermoformed packaging and strapping. After sorting, cleaning and grinding, 'bottle flake' is obtained, which is then processed by either:
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.
Bioplastics are plastic materials produced from renewable biomass sources, such as vegetable fats and oils, corn starch, straw, woodchips, sawdust, recycled food waste, etc. Some bioplastics are obtained by processing directly from natural biopolymers including polysaccharides and proteins, while others are chemically synthesised from sugar derivatives and lipids from either plants or animals, or biologically generated by fermentation of sugars or lipids. In contrast, common plastics, such as fossil-fuel plastics are derived from petroleum or natural gas.
Polyester is a category of polymers that contain the ester functional group in every repeat unit of their main chain. As a specific material, it most commonly refers to a type called polyethylene terephthalate (PET). Polyesters include naturally occurring chemicals, such as in plants and insects, as well as synthetics such as polybutyrate. Natural polyesters and a few synthetic ones are biodegradable, but most synthetic polyesters are not. Synthetic polyesters are used extensively in clothing.
This is an alphabetical index of articles related to gardening.
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.
Biodegradable plastics are plastics that can be decomposed by the action of living organisms, usually microbes, into water, carbon dioxide, and biomass. Biodegradable plastics are commonly produced with renewable raw materials, micro-organisms, petrochemicals, or combinations of all three.
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.
A plastic bottle is a bottle constructed from high-density or low density plastic. Plastic bottles are typically used to store liquids such as water, soft drinks, motor oil, cooking oil, medicine, shampoo, milk, and ink. The size ranges from very small bottles to large carboys. Consumer blow molded containers often have integral handles or are shaped to facilitate grasping.
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.
Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptability, plus a wide range of other properties, such as being lightweight, durable, flexible, and inexpensive to produce, has led to its widespread use. Plastics typically are made through human industrial systems. Most modern plastics are derived from fossil fuel-based chemicals like natural gas or petroleum; however, recent industrial methods use variants made from renewable materials, such as corn or cotton derivatives.
Microplastics are fragments of any type of plastic less than 5 mm (0.20 in) in length, according to the U.S. National Oceanic and Atmospheric Administration (NOAA) and the European Chemicals Agency. They cause pollution by entering natural ecosystems from a variety of sources, including cosmetics, clothing, food packaging, and industrial processes.
Biodegradable additives are additives that enhance the biodegradation of polymers by allowing microorganisms to utilize the carbon within the polymer chain as a source of energy. Biodegradable additives attract microorganisms to the polymer through quorum sensing after biofilm creation on the plastic product. Additives are generally in masterbatch formation that use carrier resins such as polyethylene (PE), polypropylene (PP), polystyrene (PS) or polyethylene terephthalate (PET).
The plastisphere consists of ecosystems that have evolved to live in human-made plastic environments. All plastic accumulated in marine ecosystems serves as a habitat for various types of microorganisms, with the most notable contaminant being microplastics. There are an estimate of about 51 trillion microplastics floating in the oceans. Relating to the plastisphere, over 1,000 different species of microbes are able to inhabit just one of these 5mm pieces of plastic.
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: CS1 maint: location missing publisher (link)One major drawback of most polymers used in agriculture is the problem with their disposal, following their useful lifetime. Non-degradable polymers, being resistive to degradation (depending on the polymer, additives, conditions etc) tend to accumulate as plastic waste, creating a serious problem of plastic waste management.
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: CS1 maint: multiple names: authors list (link)The contamination of agroecosystems by microplastics (MPs) has raised great concerns recently. Plastic mulching has contributed a lot in the building of MP pollution in farmlands. This technique has been in use for decades worldwide because of its immense advantages, preferably in drier and colder regions. The physical extraction of plastic mulches at the end of the growing season is very laborious and ineffective, and thus small pieces of mulches are left in the field which later convert into MP particles after aging, weathering, or on exposure to solar radiation. MPs not only influence physical, chemical, or biological properties of soils but also reduce crop productivity which could be a threat to our food security. They also interact with and accumulate other environmental contaminants such as microbial pathogens, heavy metals, and persistent organic pollutants on their surfaces which increase their risk of toxicity in the environment. MPs also transfer from one trophic level to the other in the food chain and ultimately may impact human health.
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