The purpose of the present study was to determine the long-term benefits of adding compost compost during restoration of brownfield sites, especially from the perspective of carbon stored as organic matter. In 2007 five brownfield sites in NE England were amended with PAS100 green waste compost prior to planting with four energy crops – SRC willow, Miscanthus, switchgrass and reed canarygrass. At the Rainton Bridge site near Sunderland the resulting 1 hectare trial included perpendicular strips where 250, 500 or 750 t.ha-1 of compost were spread and incorporated into the upper c 10 cm surface of subsoil placed over a clay cap. Soils at this site were resampled in 2017-18 to determine if the effects of different rates of compost addition were still discernible. Tests included total and available nutrients, residual contaminants and in particular the resultant soil organic carbon levels.
Soils are a very important store of carbon For example the annual emissions of carbon as carbon dioxide gas from burning fossil fuels are equal to just four tenths of one percent of the carbon currently stored in the earth's soils. So taking care to add the right amount of organic material when restoring derelict sites could help add soil carbon to reduce net greenhouse gas emissions, as well as greening-up the sites for leisure purposes or nature conservation.
The project has shown that important differences can still be detected in brownfield soils 10 years after adding different amounts of green waste compost. An academic publication is in preparation to describe these in detail, which will be made publicly available here when it is published.
The British Land Reclamation Society is thanked for funding from the BLRS Legacy Investment Initiative that allowed the 10 year resampling of the BioReGen trial site
10-year carbon storage & nutrient status of compost-amended brownfield soils
|Short title||British Land Resclamation Society Legacy Investment|
|Effective start/end date||1/10/17 → 30/11/18|