Relationships of soil fertility and stem borers damage to yield in maize-based cropping system in Cameroon

Field trials were designed to investigate the effect of direct nitrate fertilisation and mucuna fallow on maize yield and borer attacks in the humid forest zone of Cameroon. A traditional maizecassava-groundnut system (farmers' practice) was compared with a maize-cassava + 120 Kg N ha(-1), a rotation system in which maize-cassava followed a mucuna fallow as well as with a maize monocrop grown after mucuna fallow and with a maize monocrop grown with 120 Kg N ha(-1). Average egg batch densities of Busseola fusca (Lepidoptera: Noctuidae) were lower by 35-55% in inter- than monocrops but the effect of nitrogen on B. fusca oviposition was not different from that of mucuna fallow. Highest larval infestations were found in sole maize with nitrogen and sole maize after mucuna. Yield losses were 4-10 times higher in the farmers' practice compared to maize-cassava after mucuna and maize-cassava with nitrogen. Mixed cropping systems including farmers' practice yielded higher total gross and net benefits compared to sole maize crops. But, they were higher in maize-cassava intercrop + N than for farmer's practice.