The productivity of rice, maize, cowpea and cassava cultivars was evaluated in mulched
plots in Igarape-Açu, Pará State, Brazil, in order to select adapted cultivars for areas with fire-
free land preparation in tropical fallow systems. In 1995, 8 rice, 21 cowpea, 11 maize and 5
cassava cultivars were tested; in 1997, a further 8 maize cultivars were tested. The
screening was carried out with and without the application of NPK fertilizer. Cassava alone
made use of the residual fertilizer from a preceding maize crop, increasing yield by 23 …

Forest fires in slash-and-burn agriculture rank high in the list of environmental concerns. The
objective of this study in Pará State, Brazil, was to evaluate fire-free alternatives to burning of
the slashed fallow vegetation for crop production in the humid tropics. Burning, mulching
and incorporation of fallow biomass were compared in two successive cropping periods with
rice, cowpea and cassava, with and without NPK fertilizer. In the traditional system, with
slash-and-burn technology and without fertilizer, the shortening of the fallow period from 10 …