Application of char products improves urban soil quality (Singapore)

This paper has appeared in Soil Use and Management, September 2012, 28, 329–336
Application of char products improves urban soil quality
Abstract
"Urban soils are a key component of the urban ecosystem but little research has considered their quality and management. The use of char or partially combusted char products as a soil amendment is becoming popular worldwide because of perceived benefits to fertility and the potential for increasing carbon sequestration. In this study, we assessed the effect of applying coarse and fine char material on the quality of four different types of soil-based root-zone mixes typically used for turfgrass and general landscaping in Singapore: clay loam soil, approved soil mix (ASM, 3 soil:2 compost:1 sand), 50:50 (sand ⁄soil) and 75:25 (sand ⁄soil). Char briquettes made from sawdust were mixed thoroughly at rates of 25, 50 and 75% by volume with the soil mixes. Results showed that addition of char (both coarse and fine) significantly enhanced the carbon content of the mixes, with the largest increase being associated with the 50% and 75% additions. Soil nutrients (total N, extractable P, K, Ca and Mg) and mean weight diameter of aggregates were also significantly increased following the application of char. The clay loam and the 50:50 and 75:25 soil mixes were more responsive to the addition of char than was ASM."

S. Ghosh(1,2), D.Yeo(3), B.Wilson(2,4) & L.F.Ow(1)
1 - Centre for Urban Greenery and Ecology, National Parks Board, Singapore 259569, Singapore,
2 - School of Environmental and Rural Sciences, University of New England, Armidale, NSW 2351, Australia,
3 - Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore, and
4 - Office of Environment and Heritage, University of New England, Armidale, NSW 2351, Australia