last final thesis of umer

2.9. Maize-cowpea intercropping systems
Maize (Zea mays) and cowpea (Vigna unguiculata) are important components of traditional mixed
cropping system in the tropics because of the associated benefits; notable among which are
suppression of weeds, maintenance of soil fertility, protection of soil against soil erosion and soil
water losses, insurance against crop failure. Intercropping practice helps to increase profit margin
of the farmers, and usually suppress growth of weeds. It also controls pests and diseases occurrence
and guides against crop failure (Agbato, 2000).
Maize and cowpea exhibit complementary use of water and N resources in intercrop systems.
Cowpea in intercrop with maize has been found to supply up to 72% of its N needs through
biological N fixation, though this percentage is depressed under P limited conditions (Vesterager
et al., 2008). Maize cowpea intercrops have also been found to exhibit higher water use efficiency
than either crop in monocrop (Hulugalle and Lal, 1986).
In intercropping systems maize has been found to withdraw the majority of water under wet
conditions, while cowpea is capable of withdrawing soil water under conditions too dry for maize,
resulting in complementary water use (Adiku et al., 2001).
The productivity of maize in intercrop with cowpea relative to maize in monoculture may depend
on the fertility inputs applied to the system. Additive maize cowpea intercrops have been found to
produce maize yields that are equivalent to maize monocrops, while also producing cowpea, when
no N is added to the system (Ofori and Stern, 1987; Rusinamhodzi et al., 2012). However, under
fertilized conditions, maize yields in maize cowpea intercrops can be sharply depressed when
compared with maize monocrops (Ofori and Stern, 1987; Watiki et al., 1993) but see
15