The benefits of agroforestry

Traditionally there’s been a hard separation between the disciplines of agriculture, horticulture and forestry. You focus on one and you don’t mix. This mindset has been reinforced by the CAP and the lack of clarity over whether grants may be lost from introducing trees onto land used for agriculture. There have been only vague promises so far from Government on “public money for public goods” as part of its plan for agriculture post-Brexit.

Our new reality is shaped by the ratcheting of the need to reduce greenhouse gases and increase carbon storage, with pressure from both from government policy and public awareness. This has been backed up by sector initiatives like the NFU’s 2040 goals ‘Achieving Net Zero’. Whatever form Brexit takes, the drive to carbon neutral agriculture is providing a new impetus for changes to the nature of British agriculture. More specifically, there’s the urgent need for more tree-planting. Scientists internationally have argued that planting more trees is the most effective - cheapest, most straightforward - way to absorb carbon on a vast scale. The UK’s Committee on Climate Change wants 1.5 billion trees across the nation by 2050, 30,000 hectares a year. Despite the national campaign, levels of tree-planting are falling short (13,400 hectares of trees were planted in the year to March 2019).

Agroforestry ties together the loose ends of this picture. It offers farm businesses a means of becoming net absorbers of greenhouse gases, a way to reduce air and water pollution (e.g. ammonia emissions, nitrate leaching and soil erosion), improve on-farm biodiversity - as well as the opportunity to maintain food production, secure price premiums, and find new sources of revenue.

What’s needed is sensible land management, with eyes open to the benefits of integrating different forms of farming with trees. Intensive arable and livestock systems can produce high yields per unit area and labour, but they can also have the kinds of negative environmental effects that will increasingly need to be accounted for. Some British farms are already practising agroforestry - free range egg farms for example - but the full range of practices and their potential tend not to be recognised.

Silvopastoral systems such as wood pasture and parklands, which combine trees with livestock and can provide animal welfare benefits, are the most common form of agroforestry in the UK. Sheep farmers in upland areas in particular are becoming more aware of the advantages of providing shade and shelter. There are silvoarable systems which combine trees with arable and horticultural crops.

Examples include large estates and small farmsteads that are giving over land for growing strips of produce between trees, such as organic vegetables, chillis and elderflower for cordials. The Prince of Wales’s farm at Highgrove in Gloucestershire includes 1,000 different species of apple planted in rows which helps to reduce the pest pressure of intercropped organic vegetables.

The other main form of UK agroforestry is the use of hedges, windbreaks and tree planting next to rivers. There is also forest farming such as the harvesting naturally occurring speciality foods like mushrooms and honey, decorative and handicraft products, and mulches and botanicals. And, of course, there’s the wood itself for fuel. The UK is currently one of the world’s largest importers of wood pellets (from the USA, Canada and Latvia) for use as bioenergy feedstock.

Environmental benefits from agroforestry are clear and well-established, and will be the primary driver for change in coming years. Cranfield has been looking at the evidence around agroforestry for the past 27 years, including experimental work on silvoarable and silvopastoral systems. Although financial revenues and viability vary with the specific location and conditions, we can be certain that the increasing appreciation of the societal and economic benefits of agroforestry by farmers, policy makers, researchers, and consumers will mean it plays an increasingly important part in UK farm practice.

Dr Paul Burgess is Reader in Crop Ecology and Management at Cranfield University's Soil and Agrifood Institute, and Secretary of the Farm Woodland Forum: www.agroforestry.ac.uk. He is co-author of The Agroforestry Handbook, working alongside the Soil Association and the Woodland Trust, which can be downloaded from www.soilassociation.org