Columbia subject headings:
Harvard subject headings:
Agricultural ecology--Africa--Congresses.
Crops and climate--Africa--Congresses.
Land capability for agriculture--Africa--Congresses.
Multiple cropping--Africa--Congresses.
Soils--Africa--Congresses.
Princeton subject headings:
Agricultural conservation--Congresses.
Agricultural productivity--Congresses.
Agricultural resources--Congresses.
Population forecasting--Congresses.