Effects of biodegradable plastic film mulching on soil microbial communities in two agroecosystems

Abstract

Plastic mulch films are used globally in crop production but incur considerable disposal and environmental pollution issues. Biodegradable plastic mulch films (BDMs), an alternative to polyethylene (PE)-based films, are designed to be tilled into the soil where they are expected to be mineralized to carbon dioxide, water and microbial biomass. However, insufficient research regarding the impacts of repeated soil incorporation of BDMs on soil microbial communities has partly contributed to limited adoption of BDMs. In this study, we evaluated the effects of BDM incorporation on soil microbial community structure and function over two years in two geographical locations: Knoxville, TN, and in Mount Vernon, WA, USA. Treatments included four plastic BDMs (three commercially available and one experimental film), a biodegradable cellulose paper mulch, a non-biodegradable PE mulch and a no mulch plot. Bacterial community structure determined using 16S rRNA gene amplicon sequencing revealed significant differences by location and season. Differences in bacterial communities by mulch treatment were not significant for any season in either location, except for Fall 2015 in WA where differences were observed between BDMs and no-mulch plots. Extracellular enzyme assays were used to characterize communities functionally, revealing significant differences by location and sampling season in both TN and WA but minimal differences between BDMs and PE treatments. Overall, BDMs had comparable influences on soil microbial communities to PE mulch films.

Soil Microbial Communities Associated With Biodegradable Plastic Mulch Films

“…Differences in bacterial communities between bulk soil and agriculturally-weathered BDMs indicated a preferential enrichment of specific taxa on plastics during field trials. We observed enrichment of distinct communities on plastics in both TN and WA; however, the communities were not identical between locations, indicating that influence of different climates and soils could have resulted in the selection of different communities (Bandopadhyay et al, 2020). The preferential enrichment of fungi on agriculturally-weathered plastics compared to bulk soil is supported by previous literature reporting fungal isolates obtained from buried mulch pieces (Moore-Kucera et al, 2014).…”

“…Sequence data can be accessed at Sequence Read Archive under BioProject ID PRJNA631499 for the plastic samples. The sequences for the soil samples can be found under BioProject ID PRJNA564156 (Bandopadhyay et al, 2020).…”

​Effect of Mulching on Crop Production under Rainfed Condition: A Review

“…Shashidhar et al (2009) reported more number of bacterial, fungal and actinomycetes colonies found in Cassia sericea (32 CFU x 105/g), paddy straw (53 CFU x 104/g) and sunhemp (53 CFU x 103/g) mulched plots over other treatments respectively. Bhagat et al (2016), Bandopadhyay et al (2018) and Bandopadhyay et al (2020) also reported the similar results of the plastic films on the enhanced soil microorganisms activity.…”

Current and emerging biodegradable mulch films based on polysaccharide bio-composites. A review

“…Thus, to contributed to their adoption and reinforce the current knowledge gaps, impacts of BDMs on environmental sustainability are still scarce (Bandopadhyay et al 2018). A novel study included the comparison between four BDMs (three commercially available and one experimental film), a biodegradable cellulose paper mulch, a nonbiodegradable PE mulch, and a no-mulch plot over 2 years on the soil microbiota of two geographical locations, Knoxville and Mount Vernon, USA (Bandopadhyay et al 2020). The bacterial community structure was determined using 16S rRNA gene sequencing and revealed differences by location and season.…”