AGRONOMIC AND ENVIRONMENTAL BENEFITS OF REINTRODUCING HERB- AND LEGUME-RICH MULTISPECIES LEYS INTO ARABLE ROTATIONS: A REVIEW

<List> <ListItem><ItemContent> ● Arable-ley rotations can alleviate soil degradation and erosion. </ItemContent></ListItem> <ListItem><ItemContent> ● Multispecies leys can improve livestock health and reduce greenhouse gas emissions. </ItemContent></ListItem> <ListItem><ItemContent> ● Ley botanical composition is crucial for determining benefits. </ItemContent></ListItem> <ListItem><ItemContent> ● Lack of livestock infrastructure in arable areas may prevent arable-ley uptake. </ItemContent></ListItem> <ListItem><ItemContent> ● Long-term (10–25 years) research is needed to facilitate evidence-based decisions. </ItemContent></ListItem></List> Agricultural intensification and the subsequent decline of mixed farming systems has led to an increase in continuous cropping with only a few fallow or break years, undermining global soil health. Arable-ley rotations incorporating temporary pastures (leys) lasting 1–4 years may alleviate soil degradation by building soil fertility and improving soil structure. However, the majority of previous research on arable-ley rotations has utilized either grass or grass-clover leys within ungrazed systems. Multispecies leys, containing a mix of grasses, legumes, and herbs, are rapidly gaining popularity due to their promotion in agri-environment schemes and potential to deliver greater ecosystem services than conventional grass or grass-clover leys. Livestock grazing in arable-ley rotations may increase the economic resilience of these systems, despite limited research of the effects of multispecies leys on ruminant health and greenhouse gas emissions. This review aims to evaluate previous research on multispecies leys, highlighting areas for future research and the potential benefits and disbenefits on soil quality and livestock productivity. The botanical composition of multispecies leys is crucial, as legumes, deep rooted perennial plants (e.g., <i>Onobrychis viciifolia</i> and <i>Cichorium intybus</i>) and herbs (e.g., <i>Plantago lanceolata</i>) can increase soil carbon, improve soil structure, reduce nitrogen fertilizer requirements, and promote the recovery of soil fauna (e.g., earthworms) in degraded arable soils while delivering additional environmental benefits (e.g., biological nitrification inhibition and enteric methane reduction). Multispecies leys have the potential to deliver biologically driven regenerative agriculture, but more long-term research is needed to underpin evidence-based policy and farmer guidance.