View source for Plastic mulch

{{Short description|Plastic film used in the role of mulch}}
{{More citations needed|date=January 2013}}
[[File:20110829-FSA-XX-0029 - Flickr - USDAgov.jpg|thumb|Blueberry plants growing through plastic mulch]]
'''Plastic mulch''' is a product used in [[plasticulture]] in a similar fashion to [[mulch]], to suppress [[weed]]s and conserve [[water]] in [[agriculture|crop production]] and [[Landscape architecture|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.<ref name="Particulate">{{cite book |last1=Bradney |first1=Lauren |last2=Wijesekara |first2=Hasintha |last3=Bolan |first3=Nanthi S. |last4=Kirkham |first4=M. B. |title=Particulate Plastics in Terrestrial and Aquatic Environments |chapter=Sources of Particulate Plastics in Terrestrial Ecosystems |edition=1 |publisher=CRC Press |year=2020 |page=9 |isbn=978-0-367-51140-1}}</ref>

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.<ref>[http://www.rkoindustries.com/id26.html Plastic mulch film recycling process] {{Webarchive|url=https://web.archive.org/web/20080518090210/http://www.rkoindustries.com/id26.html |date=2008-05-18 }} Agricultural plastics recycling website, accessed 07.03.08</ref> However these methods are not very effective due to contamination by [[Agrochemical|agrochemicals]] of the plastic.<ref name=":0">{{Cite web|title=Why food's plastic problem is bigger than we realise|url=https://www.bbc.com/future/bespoke/follow-the-food/why-foods-plastic-problem-is-bigger-than-we-realise.html|access-date=2021-03-27|website=www.bbc.com|language=en}}</ref> Other concerns include residual [[Microplastics|microplastics in the soil]] which can have negative effects on soil ecologies, including microbes and earthworms.<ref name=":0" /><ref>{{Cite book|last=Nex|first=Sally|title=How to garden the low carbon way: the steps you can take to help combat climate change|date=2021|isbn=978-0-7440-2928-4|edition=First American|location=New York|oclc=1241100709}}</ref>

==History==
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 {{convert|2500|sqmi|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.

==Benefits==
The use of plastic mulches along with the use of [[drip irrigation]] has many benefits such as:

===Soil temperature===
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.<ref>{{Cite web|url=https://agriplasticscommunity.com/beyond-the-colour-of-mulch-white-black-combination/|title = Beyond the colour of mulch (White/ Black mulch) - Agriplastics Community|date = 31 August 2018}}</ref>

===Soil moisture retention===
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.<ref>{{Cite web |date=2025-02-12 |title=Plastic Mulching: Using Thin Film Covering To Enhance Soil Protection And Crop Growth {{!}} Afrimash.com - Nigeria |url=https://afrimash.com/plastic-mulching-using-thin-film-covering-to-enhance/ |access-date=2025-06-08 |website=afrimash.com |language=en-US}}</ref>

===Weed management===
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.

===Reduction in the leaching of fertilizer===
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.

===Improved crop quality===
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.<ref name="Scientia Horticulturae 2019 pp. 602–608">{{cite journal | title=White-striped plastic mulch reduces root-zone temperatures during establishment and increases early season yields of annual winter strawberry | journal=Scientia Horticulturae | volume=243 | date=2019-01-03 | issn=0304-4238 | doi=10.1016/j.scienta.2018.09.018 | pages=602–608 | url=https://www.sciencedirect.com/science/article/pii/S0304423818306289 | access-date=2022-01-20| last1=Deschamps | first1=Stephen S. | last2=Whitaker | first2=Vance M. | last3=Agehara | first3=Shinsuke | s2cid=91724681 | url-access=subscription }}</ref>

===Reduction in soil compaction===
{{see also|soil compaction (agriculture)}}
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 [[herbicide]]s 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.<ref name="Particulate"/>

===Reduction in root damage===
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.<ref>{{Cite web |date=2021-06-18 |title=What Is Mulch? – Important Things You Should Know - The Detail Guys |url=https://www.thedetailguysmd.com/what-is-mulch/ |access-date=2022-10-09 |language=en-US}}</ref>

==Disadvantages==
There are many disadvantages to using plastic mulches in crop production as well.

===Cost===
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, [[transplanter]]s 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.

===Environmental concerns===
{{see|plastic pollution|microplastic|soil contamination}}
If conventional plastics (e.g. PE) are used as mulch films, they are likely to [[bioaccumulation|accumulate]] in soil, since the removal and the correct disposal of these plastics are technically and economically burdensome.<ref>{{cite journal|author=Kyrikou, I., & Briassoulis, D.|year=2007|title=Biodegradation of agricultural plastic films: a critical review|journal=Journal of Polymers and the Environment|volume=15|issue=2|pages=125–150|doi=10.1007/s10924-007-0053-8|s2cid=195331133|url=https://www.researchgate.net/publication/226058099|quote=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, [[polymer additive|additives]], conditions etc) tend to accumulate as [[plastic waste]], creating a serious problem of plastic waste management.}}</ref> This accumulation could cause both [[crop yield]] reduction and [[environmental problems]].<ref>{{cite journal|author=Rillig, M. C.|year=2012|title=Microplastic in terrestrial ecosystems and the soil?|journal=Environmental Science & Technology|volume=46|issue=12|pages=6453–6454|doi=10.1021/es302011r|pmid=22676039|bibcode=2012EnST...46.6453R}}</ref>
[[Biodegradable polymer]]s 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.<ref>{{cite journal|author=Tokiwa, Y., Calabia, B. P., Ugwu, C. U., & Aiba, S.|year=2009|title=Biodegradability of plastics|journal=International Journal of Molecular Sciences|volume=10|issue=9|pages=3722–3742|pmc=2769161|doi=10.3390/ijms10093722|pmid=19865515|doi-access=free}}</ref> Aliphatic [[polyester]]s and aliphatic-aromatic co-polyesters have shown to be promising groups of biodegradable polymers.<ref>{{cite journal|author=Müller, R. J.|year=2006|title=Biological degradation of synthetic polyesters—enzymes as potential catalysts for polyester recycling|journal=Process Biochemistry|volume=41|issue=10|pages=2124–2128|doi=10.1016/j.procbio.2006.05.018}}</ref>

==Application==
[[Image:Vegetables grown on plastic mulch.JPG|right|thumb|Raised [[vegetable]] beds covered in plastic mulch.]]
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 [[coulter (agriculture)|coulter]]s 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==
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.

==See also==
*{{annotated link|Plasticulture}}
*{{annotated link|Rubber mulch}}
*{{annotated link|Living mulch}}

==References==
{{reflist|1}}

==Further reading==
*{{cite journal |last=Lamont |first=W. J. Jr. |year=1993 |title=Plastic mulches for the production of vegetable crops |journal=HortTechnology |volume=3 |issue=1 |pages=35–39 |doi=10.21273/HORTTECH.3.1.35 |doi-access=free }}
*Marr, C.W. 1993. Plastic Mulches for Vegetables. Kansas State University. October: 1-3.
*McCraw, D. Motes, J.E. 2007. Use of Plastic Mulch and Row Covers in Vegetable Production. Oklahoma Cooperative Extension Fact Sheets. 1-5.
*{{cite journal |last=Rice |first=P. J. |year=2001 |title=Runoff loss of pesticides and soil: A comparison between vegetative mulch and plastic mulch in vegetable production systems |journal=J. Environ. Qual. |volume=30 |issue= 5|pages=1808–1821 |doi=10.2134/jeq2001.3051808x |pmid=11577890 |url=https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=2662&context=usdaarsfacpub |display-authors=etal|url-access=subscription }}
*{{cite journal |last1=Steinmetz |first1=Z. |last2 = Wollmann |first2 = C. |last3 = Schaefer |first3 = M. |last4 = Buchmann |first4 = C. |last5 = David |first5 = J. |last6 = Tröger |first6 = J. |last7 = Muñoz |first7 = K. |last8 = Frör |first8 = O. |last9 = Schaumann |first9 = G.E. |year=2016 |title=Plastic mulching in agriculture: Trading short-term agronomic benefits for long-term soil degradation? |journal=Sci. Total Environ. |volume=550 |pages=690–705 |url=https://www.researchgate.net/publication/292784097 |doi=10.1016/j.scitotenv.2016.01.153|pmid=26849333 |bibcode=2016ScTEn.550..690S }}
*{{cite journal |last=Wittwer |first=S. H. |year=1993 |title=World-wide use of plastics in horticultural production |journal=HortTechnology |volume=3 |issue=1 |pages=6–19 |doi=10.21273/HORTTECH.3.1.6 |doi-access=free }}
* {{cite journal | last=Khalid | first=Noreen | last2=Aqeel | first2=Muhammad | last3=Noman | first3=Ali | last4=Fatima Rizvi | first4=Zarrin | title=Impact of plastic mulching as a major source of microplastics in agroecosystems | journal=Journal of Hazardous Materials | publisher=Elsevier BV | volume=445 | year=2023 | issn=0304-3894 | doi=10.1016/j.jhazmat.2022.130455 | article-number=130455|quote=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. }}

== External links ==
{{Commons category-inline|plastic mulch}}

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[[Category:Agriculture]]
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