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Agroecology – a Rapid Evidence Review (University of Aberdeen)

1. Outline

The Climate Change Committee (CCC) commissioned the University of Aberdeen to undertake research and analysis to improve the Committee’s understanding of agroecological farming practices. This report presents the findings of a rapid evidence review, setting out the scientific evidence on the environmental impact of agricultural practices that are used in agroecology that are proposed to enhance productivity and resilience of agroecosystems. 

2. Key messages

  • Due to still-limited scientific knowledge or low practical on-farm experience the majority of the agroecological farming practices (AEFPs) reviewed have only a low or medium implementation level in UK agriculture today.  
  • AEFPs with a relatively low level of integration such as: intercropping, multispecies leys, ley-arable rotations, perennial cereals and vegetated strips can generate high level of agroecological transition. The time delay before ecological benefits are realised from these AEFPs means that significant investment, training and re-design of the farm business may be required.
  • A number of AEFPs that score high in agroecological principles such as rotational cropping, cover crops, legume crops, and permanent pastures are already well integrated in UK’s agriculture, indicating that there are opportunities to speed the agroecological transition with relatively low investments. Of the nineteen AEFPs, fifteen showed positive impact on soil carbon stocks.
  • No tillage, reduced tillage, pasture cropping, retention of straw, cover crops, silvoarable and the conversion of temporary grassland to permanent pasture can reduce productivity at farm level, although yield losses are typically less than 10%. 
  • Agroecological practices such as no tillage, retention of straw, organic manure and cover crops can increase GHG emissions. However, significant knowledge gaps remain in understanding the net impact on GHG emissions from adopting the majority of AEFPs reviewed, particularly regarding changes in methane emissions from adoption of AEFPs in ruminant livestock systems. 
  • In the Balanced Net Zero Pathway Scenario, agroecology could be introduced through practices such as: low carbon farming, options to release agricultural land, as well as use of agroforestry and hedges. In particular, agroecological approaches could be implemented in the measures targeting the improvement of livestock diets and health, soil measures, and higher agricultural productivity.