Biochar application to temperate grasslands:challenges and opportunities for delivering multiple ecosystem services

Grasslands(natural,semi-natural and improved)occupy approximately one-third of the terrestrial biosphere and are key for global ecosystem service provision,storing up to 30%of soil organic carbon(SOC).To date,most research on soil carbon(C)sequestration has focused on croplands where the levels of native soil organic matter(SOM)are typically low and significant potential exists to replenish SOM stocks.However,with the renewed push to achieve“net zero”C emissions by 2050,grasslands may offer an additional C store,utilising tools such as biochar.Here,we critically evaluate the potential for biochar as a technology for increasing grassland C stocks,identifying a number of practical,economic,social and legislative challenges that need to be addressed before the widescale adoption of biochar may be achieved.We critically assess the current knowledge within the field of grassland biochar research in the context of ecosystem service provision and provide opinions on the applicability of biochar as an amendment to different types of grassland(improved,semi-improved and unimproved)and the potential effect on ecosystem provision using a range of application techniques in the topsoil and subsoil.We concluded that the key question remains,is it possible for managed grasslands to store more C,without causing a loss in additional ecosystem services?To address this question future research must take a more multidisciplinary and holistic approach when evaluating the potential role of biochar at sequestering C in grasslands to mitigate climate change.

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

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 grassclover 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.,Onobrychis viciifolia and Cichorium intybus) and herbs(e.g.,Plantago lanceolata) 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.