| dc.description |
Productivity of maize–pigeonpea cropping systems is dependent on facilitative and competitive
interactive effects on resource availability. Controlling these interactions may benefit farmers through
increased productivity associated with optimized crop yields. Previous research on maize–pigeonpea
culture in Sub-Saharan Africa has focused on yield and soil fertility, but provided inadequate information
on the mechanisms of possible interspecific competition. We employed a factorial field experiment to
examine yield and nutritional responses of maize and pigeonpea to cropping systems (sole maize,
intercropping, and improved fallow), N and P fertilizer additions, and cattle manure additions in
Dodoma, Tanzania. The study objectives were to assess competition between crops and to determine
how manure or fertilizer inputs may mitigate such interactions to improve yields. Intercropping
enhanced maize yield over sole maize only when fertilized, reflecting probable nutrient competition.
Improved fallows alone or with fertilizers (1.2–1.6 Mg ha 1 ) increased maize yields over sole maize
(0.6 Mg ha 1 ). These increases were attributed to pigeonpea facilitation through soil nutrient
replenishment, reduced competition associated with sequential cropping arrangements, and added
nutrients from fertilization. Combined fertilizer and manure applications also improved maize and
pigeonpea yields. Plant nutrient diagnosis indicated primary and secondary P and Ca deficiencies,
respectively associated with P-fixation and leaching of cations due to high soil acidity and exchangeable
Al. Maize competed strongly in mixture suppressing biomass and grain yields of the unfertilized
pigeonpea by 60% and 33%, respectively due to limited soil nutrients and/or moisture. These yield
reductions suggest that the intercropped pigeonpea did not recover from competition after maize
harvesting that reduced competition. Optimizing yields of both maize and pigeonpea would require the
addition of prescribed fertilizer when intercropped, but applications can be reduced by half under the
improved fallow system due to alleviating interspecific competition. |
|