Intensification of common bean and maize production through rotations to improve food security for smallholder farmers.

A field experiment was conducted to understand whether non-formalized monocultures of maize could be substituted by the rotations with common bean on smallholder farms. This study was installed in the northern highlands of Tanzania along the slopes of the highest African peak of Mt. Kilimanjaro with the predominance of smallholder farmers. Cropping seasons (S), cropping systems (C), bean varieties (V), and their interactions were evaluated. Data collected were plant height, ground coverage, total biomass, number of pods per bean and seeds per pod, 100-seed weight, and grain yield. Results indicated that bean in long rainy seasons produced significantly larger grain yields as an effect of S (3.3 t ha-1) in 2015, C (3.4 t ha-1) in intercrop, V (2.7 t ha-1) in local bean, S × C (4.4 t ha-1) in 2015 in intercrop, S × V (3.4 t ha-1) in improved bean in 2015, C × V (4.6 t ha-1) in intercropped local bean, and S × C × V (5.0 t ha-1) in intercropped local bean in 2017. In a short rainy season, significantly larger bean grain yield (1.8 t ha-1) was recorded as an effect of C when sown subsquent to maize. The effects of V and/or C × V were not significant on bean grain yield during short rainy season. Maize in long rainy seasons produced significantly larger grain yields as an effect of C (2.9 t ha-1) but not for S and S × C in rotation with the local bean. In short rainy seasons, significantly larger maize grain yield was produced in 2015 (2.6 t ha-1) but the effects of C and S × C were not significant in 2015 and 2016. This study concluded that inclusion of intercrops (of maize and common bean) as part of a rotation with one of these crops significantly improved grain yields and hence provided promising grounds of the options for sustainable food production on smallholder farms.