@INBOOK {DVORAK:1993, title = {Characterizing system dynamics for soil management research in the humid tropics: studies in southeastern Nigeria}, author = {Dvorak, K. A. }, editor = {Dvorak, K. A. }, year = {1993}, type = {Social science research for agricultural technology development:spatial and temporal dimensions}, pages = {167--191}, publisher = {CAB International}, address = {Wallingford, Oxon, UK}, }