Seperating the agronomic effects of burning and biomass removal in a typical slash and burn rotation system in Southern Cameroon

Norgrove, L., Nkem, J.N. & Hauser, S. (2003). Separating the agronomic effects of burning and biomass removal in a typical slash and burn rotation system in Southern Cameroon. Biological Agriculture & Horticulture, 21(4), 367-381.

Little research on slash and burn systems has investigated whether effects of burning are due to the fire per se or to the removal of biomass from the soil surface. In this experiment, the aim was to assess the effects of burning versus no burning and mulching versus no mulching on maize yields, chlorophyll levels, nutrient uptake and soil properties in a short fallow ‘no external input’ system in two consecutive cropping seasons on an ultisol in southern Cameroon. In the second maize cropping season, treatments were not re-imposed so any effects would be residual. In the first cropping season, when mulch was retained, grain dry mass was 2.79 Mg ha-1, more than the 1.41 Mg ha-1 obtained without mulch. Soil bulk density was higher in non-mulched than in mulched treatments and both grain yield and maize aboveground biomass were strongly (both r2 = 0.50) and negatively associated with soil bulk density. Under such short fallow conditions, farmers should be encouraged to mulch rather than burn residues when cropping maize, as this leads to higher yields within the usual time frame of the cropping cycle.