What are the advantages of certified soil-biodegradable mulch films?

Mulch films made from cerified soil-biodegradable plastics provide significant benefits where retrieval and recycling of conventional plastics pose serious problems. They are specifically designed to biodegrade effectively in situ and can therefore be incorporated into the soil postharvest.

Due to their soil-biodegradability, certified soil-biodegradable mulch films help to stop leakage and the accumulation of microplastics in agricultural soils, unlike conventional plastics when these are not completely removed or properly disposed of. Especially thin nonbiodegradable mulch films (with thicknesses typically below 30 µm) have a poor collection and retrieval management, which can lead to a worrying level of plastic pollution in the fields.

Certified soil-biodegradable mulch films do not cause loss of agricultural topsoil. Even where conventional mulch films are removed from the fields, they are often heavily contaminated with soils and plant residues up to 60-80% of the initial weight of the film (see Figure 2 below). (2, 3)

Not only does the collection of non-biodegradable mulch films cause removal of topsoil (166 kt/yr in Europe) (4) , but it also inhibits the recycling process. Additionally, certified soil-biodegradable mulch films represent a useful tool to reduce plastic waste at source, since they avoid completely the production of a category of plastic waste difficult to be collected and disposed of in the first place.

Certified soil-biodegradable mulch films have been in use commercially since over 20 years, mainly for the cultivation of vegetable crops, where they have proved agronomic efficiency similar to the non-biodegradable mulch films (5) in terms of:

• Increase of soil temperature and retention of moisture leading to a better plant establishment and growth as well as early crop production compared to the bare soil,
• Reduction on the weed competition and better use of nutrients leading to a higher production and better quality of the crop compared to the bare soil, • Increase in the development of a root system compared to bare soil, leading to a better crop development,
• Decrease in the use of phytosanitary products (specifically herbicides). (6, 7) Certified soil-biodegradable mulch films, thanks to their end-of-life characteristics, can as well be introduced as technical tools on crops such as maize, rice, vine, and processing tomato, which generally cannot benefit from the use of conventional mulches. (8)

(2) Briassoulis et al.: Experimental investigation of the quality characteristics of agricultural plastic wastes regarding their recycling and energy recovery potential. Waste Management 32(6): 1075–90.

(3) See Kasirajan, S., Ngouajio, M. Polyethylene and biodegradable mulches for agricultural applications: a review. Agron. Sustain. Dev. 32, 501–529 (2012) for an overview.

(4) Eunomia, Conventional and biodegradable plastics in agriculture, 2021; website: https:// www.eunomia.co.uk/reports-tools/conventional-and-biodegradable-plastics-inagriculture/

(5) Abbate C. et al., Agriculture 2023, 13, 197. https://doi.org/10.3390/agriculture13010197

(6) Tofanelli, M.B.D.; Wortman, S.E. Benchmarking the Agronomic Performance of Biodegradable Mulches against Polyethylene Mulch Film: A Meta-Analysis. Agronomy 2020, 10, 1618.

(7) Kasirajan, S., Ngouajio, M. Polyethylene and biodegradable mulches for agricultural applications: a review. Agron. Sustain. Dev. 32, 501–529 (2012).

(8) For vine: Emmanuelle Gastaldi, Francois Touchaleaume, G Cesar, Christophe Jourdan, P Coll, et al. Agronomic performances of biodegradable films as an alternative to polyethylene mulches in vineyards. Acta Horticulturae, 2019, XXI International Congress on Plastics in Agriculture: Agriculture, Plastics and Environment, 1252, 10.17660/ ActaHortic.2019.1252.4. hal-03706046