Conclusions
In this study planting of cowpea as early as 10th of March in 2009 and 20th of March 2010 produced sufficient
biomass of cowpea that was incorporated as green manure. Planting of maize one week after incorporation of the
green manure was found to be adequate under the present climate (with high moisture and temperature) as
compared with two weeks suggested in literatures. Incorporation of cowpea green manure led to a grain yield
increase of succeeding maize by 92 -131 % and 43-124 % in 2009 and 2010 respectively. It can be concluded
that the erratic rains that characterize the beginnings of the season could provide sufficient moisture for the
growth of cowpea green manure. This can be incorporated at the time of land preparations for arable crops. Thus
this period( as early as 10th – 20th March) can serve as a niche for growing green manure and enhancing the
fertility of the soil, without encroaching into or shortening the regular period available for arable crop
production. These findings will be of immense benefit to the resource poor farmers who are the major producer
of food crops in the derived savannah ecological zone of Nigeria and areas with similar climate world over. It
can also be concluded that growing of cowpea as green manure will extent the period of soil cover in a drought
condition and ameliorate the negative impact of climate change.