LAUSR

Abstract In agriculture, the use of plastic mulch (plasticulture) is globally increasing. Besides beneficial effects on crop yield and quality, possible adverse environmental effects associated with plastic mulch are currently under debate. Aside from the obvious disadvantages of substantial amounts of (micro)plastic waste, adverse effects on soil quality and biodiversity might be assumed. We compared the effect of plastic mulch and organic mulch (straw) systems in strawberry cultivation on soil invertebrates and biological activity in an observational field study in the Upper Rhine valley, Germany. Soil invertebrates were collected using pitfall traps and Berlese-Tullgren-funnels, earthworms by hand sorting. Soil biological activity was determined using bait-lamina sticks and the MicroResp™ system. Soil samples from test fields were analysed for physicochemical and microbial parameters. Despite minor effects on soil physicochemical parameters, our results showed that the mulch system had a significant effect on the community structure of soil invertebrates. In strawberry fields with plastic mulch we found a decreased taxonomic richness and taxonomic richness decreased with increasing soil temperature. About 50% of the analysed taxa had significantly lower abundances in plastic mulched fields compared to fields with organic mulch. No investigated taxon had a higher abundance in plastic mulched fields. Soil moisture was the most important environmental variable in explaining invertebrate abundances. The soil microbial activity was significantly lower in plastic mulched fields than in fields with organic mulch. Our results indicate that even little shifts in abiotic (e.g. temperature, water content) and biotic (e.g. food availability) conditions associated with the plastic mulch system can have strong effects on soil invertebrates and soil microbial activity. Hence, plastic mulch might pose a threat to soil biodiversity and related ecosystem functions in agroecosystems. We call for further studies analysing the influence of plasticulture, to better evaluate the long-term consequences on agrobiodiversity and soil quality as well as sustainability.