Should we reduce the use of plastics in agriculture?

Cusworth, Samuel and Stevens, Carly and McAinsh, Martin and Davies, Bill (2023) Should we reduce the use of plastics in agriculture? PhD thesis, Lancaster University.

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Abstract

Plastic use in agriculture has transformed agricultural systems worldwide, facilitating the production of fresh produce in yield-limiting conditions, extend the growing season and improving the food security of many regions. As global food systems come under increasing pressure from the future impacts of climate change and other global crises, the need to provide a stable, readily available supply of healthy, nutritious produce is increasingly important. Whilst plasticulture is considered an effective measure to maintain food security and increase agricultural productivity, there is a global call to reduce plastic use in agriculture. The impact of plastics from ‘cradle-to-grave’ are overwhelmingly negative, thought to compromise long-term agricultural productivity, human and planetary health. Even though there is an urgent call to reduce plastic use in agriculture, we are not equipped with an adequate knowledge base to assess and reevaluate plasticulture. Our understanding of plasticulture and its importance in food systems has not yet been comprehensively assessed. In parallel, the implications of plastic use in agricultural systems are not fully understood, in particular the quantification of microplastics in agricultural soils and risks to future agroecosystem functioning. This thesis presents a review of the UK food system and a meta-analysis to explore the relative importance of plasticulture. The meta-analysis found that plasticulture is key to increasing the yield of globally-important crops in agricultural systems worldwide. This is followed by a nationwide survey, soil archive analysis and a mesocosm experiment that investigate microplastic concentrations, fate and impacts in agricultural soils. The nationwide survey suggests that plastic crop covers are a significant contributor of microplastics to agricultural soils. Analysis of the Rothamsted soil archive revealed that agricultural soils are receptors of microplastic pollution from different agricultural sources and non-agricultural sources which predate modern plasticulture. A mesocosm experiment was used to determine the effects of microplastics on soil and crop health, as well as the influence of soil and crop type on microplastic transport. The results from the mesocosm experiment indicate microplastics pollution affects agroecosystem functioning. This thesis is an essential contribution to producing a comprehensive assessment of plastic use in agriculture in future food systems. The findings from this thesis highlight an urgent need to reassess plastic use in agriculture. Sustainable plasticulture will be vital to build the resilience of a future food system that prioritises human and planetary health.