Centre for Alternative Technology

Britain's major centre for environmental inspiration and courses.


Low carbon land use

CAT is situated in the uplands of Wales, surrounded by sheep farms and plantation forestry. CAT land management provides a reserve for biodiversity and a range of useful products. CAT gardeners grow vegetables, flowers and shrubs in abundance using organic principles (see our CAT gardens webpages). On the periphery of the gardens stand the woodlands, field and smallholding where we use sustainable techniques to research and enhance production.

four geese looking for food

The field is to be planted with nut trees, under which geese graze. This will provide us with eggs, nuts and timber. This is an example of Agroforestry, a practice that can maximise production and minimise negative environmental impacts (for more information on agroforestry see http://www.agroforestry.co.uk/agover.html). This method of land management also allows us to sequester (absorb into the terrestrial zone) more carbon from atmosphere. This carbon is locked up in the trees and soil. In another area of the smallholding we will be growing cereals to feed to the geese and chickens. This is an illustration of on-farm animal feed production. Providing organic, home grown feed reduces the environmental impact of transporting these products but also shows CAT visitors the total land area required to feed these animals, or the ‘indirect land use’.

We are currently researching biochar (http://www.biochar.org.uk/index.php) as a soil additive to increase productivity of food and to sequester carbon from the atmosphere. Carbon is absorbed by plant material as it grows. If you then turn this material into charcoal the carbon will not return to atmosphere through the rotting process but will be stored indefinitely in a stable form; char.  Biochar is also thought to have water retentive properties and act as a slow release fertiliser and habitat for beneficial microorganisms.


diagram of a charcoal retort


We make charcoal (or biochar) in a retort system.  This is a process that is quicker and produces fewer greenhouse gases than a traditional kiln. The charcoal is then crushed and is either mixed with urine, soaked with sewage effluent by using it as a trickle filter (shown below) or mixed with geese/chicken poo by using it as bedding. This char is then added to the soil using no dig  techniques  in order  to prevent carbon loss during digging and cereals are then planted.

a trickle filter

Biochar doesn’t have to be made of wood and in fact is more sustainable if made from waste organic matter. Our charcoal is made out of a whole host of materials including cut reeds from the reedbeds, wood and brambles.

CAT once had goats on the land here but decided to replace them with non-ruminants in order to illustrate to visitors that despite the sheep grazing surrounding CAT there are other options that are sometimes more sustainable. Although there are circumstances where ruminants play an important part in land management and production, they can be an inefficient way to extract calorific value from the land, and the methane they produce globally contributes  to a significant proportion of greenhouse gas emissions. Our report, Zero Carbon Britain, explains more about land use and livestock.