1. The use of sesbania (Sesbania rostrata) and urea in lowland rice production in Sierra Leone;Bar;Agroforestry system,2000
2. Bera, A.K., 1994. Effect of tillage and rice straw on soil physical properties and energy requirement of wheat crop. M.Sc. Thesis. Division of Agricultural Physics, IARI, New Delhi, India.
3. Building up of organic matter status of the soil and its relation to soil physical properties;Biswas;Int. Symp. Soil Fert. Evaluation Proc.,1971
4. Carbon and nitrogen in soil organic matter;Biswas,1994
5. Bulk density;Blake,1965