1. Ahring R M, Banks D J and Springer T L 1987 Peanut seedling responses to root temperature controlled by a thermogradient sand box. Proc. Am. Peanut Res. Educ. Soc. 19, 39.
2. Atkinson D 1974 Some observations on the distribution of root activity in apple trees. Plant and Soil 40, 333?342.
3. British Ecological Society Special Publications;D Atkinson,1985
4. Atkinson D and Mackie-Dawson L A 1991 Root growth: methods of measurement. In Soil Analysis: Physical Methods. Eds. ASmith and C EMullins, pp 447?509. Marcel Dekker, New York.
5. Billing D W 1978 Chitedze Agricultural Research Station Detailed Soil Survey. Ministry of Agriculture and Natural Resources, Soil Survey Section, Lilongwe, Malawi.