Should Plasticulture Be Accepted in Organic Agriculture?

Organic farming is a holistic system that focusses on the health of the agro-ecosystem and on the development of enterprises through sustainable practices (CGSB, 2015a). A true organic farm is thus meant to be socially, economically, and environmentally sustainable by naturally meeting the needs of the living soil such that the soil could then meet the needs of the crop.

Plasticulture, which involves the application of a plastic cover over planting rows, is a growing practice in Canada both on conventional and on organic farms (Davison, 2017; CGSB, 2015b). In fact, according to the Canadian General Standards Board (CGSB) (2015b), semi-biodegradable and non-biodegradable plastic mulches are part of the permitted substances list for organic systems. They can be used as a crop production aid so long as they are “[not] incorporated into the soil or left in the field to decompose” (CGSB, 2015b).

As rising concerns and information around plastic pollution and plastic chemical leaching emerge, should introducing plastic materials on organic fields be questioned further?

Benefits of Plasticulture

In Quebec, organic strawberry producers are making common use of this method to benefit from season extension (CRAAQ, 2012). Applying this cover on planting beds raises the temperature of soil, which encourages crop development earlier in the season and leads to earlier harvest (Lamont, 1991). Moreover, drip irrigation is typically installed under plastic mulch, resulting in less water losses from evaporation and more water applied directly to the plants (Bachmann & Earles, 2000; Lamont, 1991). The efficient use of water resources also means that organic fertilizers applied to the crop are less likely to leach out into the soil (Bachmann & Earles, 2000). Darker plastic mulches can be utilized as a form of weed control as well, in which the light needed for weeds to survive is diminished by the cover.

Overall, plasticulture is an innovative agricultural practice, especially for organic growers who must limit soil inputs while still protecting and encouraging crop development. Why then question its application?

Challenges with Plasticulture

As mentioned by the CGSB (2015b), in organic production, non-biodegradable and semi-biodegradable mulches must be removed and never left to decompose. It sounds simple enough, yet, this is one of the main issues with plasticulture (Bachmann & Earles, 2000; Lamont, 1991). This is due to the fact that the plastic cover is subjected to wear and tear over the growing season, which will cause it to lose its integrity and breakdown. Thinner and more biodegradable the plastic, more time-consuming and challenging the removal will be as well (Steinmetz et al., 2016). Therefore, plastic residue is left in the soil – intentionally or unintentionally – and will persist and accumulate over the years of plastic application (Liu et al., 2014; Schirmel et al., 2018).

In China, the high density of micro-plastics from mulch in the agricultural fields physically disrupted the agro-ecosystem and decreased crop yields (Liu et al., 2014). Chemical pollution of the soil has also been observed, as plastic is a synthetic material comprised of potentially noxious agents. For instance, common polyethylene plastic mulches contain phthalic acid esters (PAE), which hold compounds suspected to be cancer-causing and endocrine-disrupting (Steinmetz et al., 2016). PAE tend to also leach out of the plastic easily, making them available by the agro-ecosystem through atmospheric evaporation, groundwater or surface water runoff, and plant uptake (Steinmetz et al., 2016). Soil biodiversity, microbial activity and, ultimately, crop quality are at risk in these systems (Schirmel et al., 2018; Steinmetz et al., 2016). As consumers, we may be increasing our exposure to unwanted compounds (Steinmetz et al., 2016), even when buying organic produce.

Furthermore, there are challenges with proper disposal of the plastic mulch once recovered. Recycling is not typically possible when fragments of soil and organic agro-chemicals are found on the plastic (Steinmetz et al., 2016). These mulches thus often get redirected to landfills or will be incinerated in large quantities, which each cause significant pollution (Steinmetz et al., 2016).

Acceptable Risk?

Until further research is conducted on the long-term effects of plasticulture on soil quality and biodiversity, I wonder if this practice should be permitted in organic production. Plastic mulch can seem like a saving-grace for organic farmers, given the many short-term benefits. However, what if this “sustainable” practice is not sustainable at all, and that the crops may in fact be harmful? Perhaps, for the time being, the CGSB should strictly accept the other non-plastic mulches for field application.

 

References

Bachmann, J., and R. Earles. 2000. Season Extension Techniques for Market Gardeners. Horticulture Technical Notes. Fayetteville, Ark.: ATTRA.

Canadian General Standards Board (CGSB). 2015a. Organic Production Systems: General Principles and Management Standards. No. CAN/CGSB-32.310-2015. National Standard of Canada, Gatineau, CA.

Canadian General Standards Board (CGSB). 2015b. Organic Production Systems: Permitted Substances Lists. No. CAN/CGSB-32.311-2015. National Standard of Canada, Gatineau, CA.

CRAAQ. 2012. Bilan de la recherche en agriculture biologique au Québec. Available at https://www.agrireseau.net/references/9/References/BILAN_RECHERCHE_BIO_2012.pdf (accessed 8 Feb. 2019).

Davidson, K. 2017. Plasticulture: a light at end of the tunnel. The Grower. Volume 67 Number 09 P.M.40012319.

Lamont, W.J., 1991. The use of plastic mulches for vegetable production. ASPAC, Food & Fertilizer Technology Center. Manhattan, KS, USA

Liu, E. K., He, W. Q., and C. R. Yan. 2014. ‘White Revolution’ to ‘White Pollution’—Agricultural Plastic Film Mulch in China. Environmental Research Letters 9 (9): 091001–. doi:10.1088/1748-9326/9/9/091001.

Schirmel, J., Julius A., Markus P. K., and K. Muñoz. 2018. Plasticulture Changes Soil Invertebrate Assemblages of Strawberry Fields and Decreases Diversity and Soil Microbial Activity. Applied Soil Ecology 124: 379–93. doi:10.1016/j.apsoil.2017.11.025.

Steinmetz Z, Wollmann C, Schaefer M, Buchmann C, David J, Tröger J, Muñoz K, Frör O, and Schaumann GE. 2016. Plastic Mulching in Agriculture. Trading Short-Term Agronomic Benefits for Long-Term Soil Degradation?. The Science of the Total Environment 550: 690–705.

 

2 responses to “Should Plasticulture Be Accepted in Organic Agriculture?”

  1. naynaahmed says:

    1.Efficient and simple – readers know topic right away.
    2.Although plastic mulches provide benefits to crop production, sustainable organic farming framework may need to be reconsidered due to plasticulure and its risks.
    3.Information on benefits following with a smooth transition into challenges; and providing examples for each. Paper was cohesive, well- informed, and easy to read.
    4.When the author provides the rule that even semi-biodegradable covers need to be removed and never left to decompose; this effectively shows its possible risks. Which leads to the next compelling argument of plastic mulches effecting physical disruptions – this conflicts with the purpose of mulches.
    5.Avoid question titles with “should”, add stronger connotative words: i.e “conflicts with…” There are many case studies of soil quality based on changing seasons and crop rotations with plastic mulches – if there’s one based from Canada, can make the paper more informative since Canadian and Chinese regulations are different. Overall this paper was well-written and great execution for allowing readers to think what needs to be considered.

  2. alexineehlinger says:

    1- Efficient and interesting.
    2- The use of plastic mulch needs to be researched more in order to be sure that it does not harm the crop one way or another; but it should be banned from organic production due to its negative impact on the soil and human health.
    3- The strongest aspect of the blog is the examples given. These are from different countries (Canada, China…) which shows that plasticulture is more of a global culture and not specific to one area. And that the use of plastic mulch in organic production is asked in many countries across the world.
    4- The post’s most compelling information are the mentions of the rules or obligations linked to plastic mulch use in organic production. As well as facts, like how some chemicals from the plastics are released in the soil, such as the Phthalic Acid Esters (PAE) which could even lead to cancers and other health issues.
    5- I am not sure I understand what you mean in your last question “the crops may in fact be harmful?”, it is possibly just the phrasing that is wrong though. Other than that, I like the structure and questioning throughout the post.

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