Sierra Leone Encyclopedia--updated yearly

Excellent information on both basics and details of many aspects of Sierra Leone development.  A core project of the Sierra Leone Information System, which is supported by the United Nations Development Program.

http://www.daco-sl.org/encyclopedia/  

"Gateway to Land and Water Information" - Sierra Leone.  Land, water, and plant-nutrient resources. http://www.fao.org/ag/aGL/
swlwpnr/reports/y_sf/z_sl/sl.htm  

"Traditional agro-forestry systems: Prospects for development"  A 1980s journal article from a Nigerian agricultural research center about bush-fallow and other crop rotation systems in tropical areas.  http://www.unu.edu/unupress/unupbooks/80364e
/80364E06.htm  

University of Pennsylvania Sierra Leone Page and Search Engine   Links to the CIA World Factbook, maps, travel, language information, etc. Created by Julie Sisskind, now maintained by Ali Dinar. UPenn has a search facility.  http://www.sas.upenn.edu/African_
Studies/Country_Specific/S_Leone.html

See also on Google, "bush fallow system" and "bush fallow system Sierra Leone."