Using environmental DNA to assess soil health bioindicators and their relationship to crop nutrition and production under different agricultural regimes

This project is based at University of Sheffield

Background 

Soil degradation and erosion is a worldwide problem. Intensive agriculture has depleted carbon and aggregates, causing drainage issues, flooding and nutrient loss, and, therefore, poor crop production. Earthworms improve soil fertility, nutrient recycling, aggregate formation, water infiltration and carbon sequestration, and build in resilience in the face of climate change. Plants are known to grow better and increase nutrient uptake when earthworms are present. 

Objectives

This project will investigate how earthworm numbers and diversity are related to crop plant growth, production and nutrition under different agricultural regimes. We predict that agroecological practices that enhance biological communities, including earthworms, will promote soil health and resilience, and aid crop growth, nutrition and production.

Soil samples will be taken from the Large-Scale Rotation Experiment at Rothamsted, and from farm sites in the UK and Denmark with different tillage practices and cover crops, ranging from conventional to organic. To maximise replication among treatments, samples will be pooled from each plot or field and there will be two replicates per plot/field. Environmental DNA (eDNA) will be extracted and next generation-sequenced to measure earthworm diversity and abundance (doi.org/10.1101/2023.11.07.565975). Soil nutrients, carbon, aggregate stability and clay dispersibility, and crop health, nutrition profile and productivity will be evaluated using spectral and other standard methods. The relationships between soil, plant and earthworm metrics will be analysed using statistical models. Results will be discussed with farmers to highlight the identified advantages and benefits of specific practices over others.

Novelty & Timeliness

Soil is a critical resource and is currently eroding at an unacceptable rate, yet the global human population is increasing. Determining which practices and cropping techniques promote soil health and resilience, whilst improving crop production and nutrition, is understudied and vitally needed. eDNA is a novel technique for measuring biological indicators of soil health easily and efficiently. It is projected that global warming will cause a decline in grain micronutrient concentration. eDNA will enable us to link soil biological functions (earthworms) to improved soil health and crop nutrition.