Degradation in soil (WP2)
Biodegradable mulch film used in agriculture. Photo: Martin Haarr, Agri Råd
Biodegradable mulch film is used in agriculture to increase soil temperature, maintain soil humidity and limit weed growth. Contrary to conventional (non biodegradable) mulch film, biodegradable mulch film does not need to be removed from the field after use, and can simply be ploughed into the soil. But how fast does it degrade in soil in cold climatic regions like Norway?
Before this project, the fate of biodegradable plastic mulch in soil was unknown under Nordic conditions.
In this work package, we have investigated the in situ degradation in soil of the two types of biodegradable mulch films most used in Norway, under various climatic conditions, soil types, soil depths and agricultural practices.
The field study involved the burial in soil of 300 mesh bags containing biodegradable mulch in 6 farms in Norway (Rogaland, Agder, Viken) and their follow-up/retrieval over up to 2 years. The role played by NIBIO, Norsk Landbruksrådgiving (NLR) and Agri Råd was crucial to the success of this long-term field study.
We have demonstrated that degradation occurs, albeit at a slower pace, with worse-case scenarios for complete degradation in Norwegian soils lying between 2.5 and 9 years, depending on climatic conditions, soil properties and agricultural practices. Beside higher soil temperature, higher soil organic matter content has been shown to accelerate degradation.
Here is the scientific article summarizing our experiment: In situ degradation of biodegradable plastic mulch in Nordic agricultural soils
Here is a short video (in Norwegian, 14 min) where the results from our field study in soil are presented.
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Abstract
Since the 1950s, the use of plastics in agriculture has helped solving many challenges related to food production, while its persistence and mismanagement has led to the plastic pollution we face today. A variety of biodegradable plastic products have thus been marketed, with the aim to solve plastic pollution through complete degradation after use. But the environmental conditions for rapid and complete degradation are not necessarily fulfilled, and the possibility that biodegradable plastics may also contribute to plastic pollution must be evaluated. A two-year field experiment with biodegradable mulches (BDMs) based on polybutylene adipate terephthalate (PBAT/starch and PBAT/polylactic acid) buried in several agricultural soils in mesh bags showed that also under colder climatic conditions does degradation occur, involving fragmentation after two months and depolymerization by hydrolysis, as shown by Fourier-transform infrared spectroscopy. The phytopathogenic fungus Rhizoctonia solani was found to be associated with BDM degradation, and the formation of biodegradable microplastics was observed throughout the experimental period. Between 52 and 93 % of the original BDM mass was recovered after two years, suggesting that accumulation is likely to happen in cold climatic regions when BDM is repeatedly used every year. Mass loss followed negative quadratic functions, implying increasing mass loss rates over time. Despite the range of climatic and edaphic factors, with various agricultural practices and vegetable productions at the study locations, the parameters that significantly favored in situ BDM degradation were higher soil organic matter content and temperatures.
Authors
Claire CoutrisAbstract
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Abstract
Stadig flere bønder bytter ut tradisjonell landbruksplast med bionedbrytbar plastfilm som kan freses rett ned i jorda etter bruk. Nå er forskere i gang med å undersøke hvor nedbrytbar den faktisk er under norske forhold.
Abstract
Stadig flere bønder bytter ut tradisjonell landbruksplast med bionedbrytbar plastfilm som kan freses rett ned i jorda etter bruk. Nå er forskere i gang med å undersøke hvor nedbrytbar den faktisk er under norske forhold.
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Conference lecture – Plast og mikroplast i jord: hvilke utfordringer står vi overfor?
Claire Coutris
Authors
Claire CoutrisAbstract
No abstract has been registered
Abstract
Vi har alle hørt om problemene plast i havet kan føre med seg. Men plast havner også i jord, blant annet via avløpsslam, biogjødsel og fra plastbruk i landbruket. Akkurat hvor mye plast det er snakk om er imidlertid uvisst.
Abstract
Vi har alle hørt om problemene plast i havet kan føre med seg. Men plast havner også i jord, blant annet via avløpsslam, biogjødsel og fra plastbruk i landbruket. Akkurat hvor mye plast det er snakk om, er imidlertid uvisst.
Abstract
Vi har alle hørt om problemene plast i havet kan føre med seg. Men plast havner også i jord, blant annet via avløpsslam, biogjødsel og fra plastbruk i landbruket. Akkurat hvor mye plast det er snakk om, er imidlertid uvisst.
