Agroforestry, soil health and delivery of public goods

Agroforestry is the practice of deliberately growing trees in combination with arable crops and/or pasture on the same piece of land. It is seen as a sustainable land management practice, where trees and agriculture co-exist to provide multiple benefits. Therefore growth and innovation in agroforestry has the potential to improve farmland productivity, resilience and diversity while maintaining and/or improving the provision of other ecosystem services, via improving soil health, sequestering carbon and slowing water runoff. While long-established in sub-tropical and tropical climates, uptake of agroforestry in temperate agricultural systems has been slow, particularly in the UK. In order to realize this potential, there is urgent need for greater understanding of how planting trees in temperate agricultural systems impacts upon soil health indicators and thus helps to reduce flooding and mitigate climate change. While literature reviews have shown that agroforestry can increase the amount of carbon stored in the soil and thus help to mitigate climate change, the majority of studies (~80%) were located in tropical and sub-tropical climates, with less than 20% in temperate climates. It is unclear how long it takes to see an improvement in soil health and whether planting trees on pastures has the same benefit for soil health as planting trees on arable land. Recent studies in the UK have shown that planting trees on farmland can increase soil infiltration rates. However, these studies were carried out at one site. In addition, it is not clear if similar impacts would be observed in lowland agricultural systems; highlighting the need for further research. The major aim of this project is therefore to determine the impact of agroforestry on soil health, in particular its impact on soil carbon storage, soil structure and hydrological properties.