Water Requirement and Water Productivity of Cowpea (Vigna unguiculata [L.] Walp.) Crop in Two Agro-ecological Zones of Sennar State, Sudan

Abstract

A field experiment was conducted in two agro-ecological zones
in Sennar State, Sudan during seasons2014/2015 and 2015/2016to
estimate crop water requirement and water productivity of cowpea (Vigna
unguiculata L. Walp) under three farming systems (conventional farming
(CF), conservation agriculture (CA) and Water Harvesting (WH).The
agro-ecological zones were semi-arid zone (Sennar Research Station
Farm) and semi-humid zone (Abu Naama Research Station Farm). The
Weather and crop data were collected during the study period.
CROPWAT 8.0software was used to compute reference
evapotranspiration (ETO), crop factor (Kc) and the crop water requirement
(ETC). The analysis showed that the average values of ETO
rangedbetween1.2 and5.0 mm/day in semi-arid zone, and
between1.56and4.86 mm/day in the semi-humid zone. The average Kc
values during the initial, development, mid-season and late-season stages
were 0.45, 0.79, 1.08and 0.84, respectively, while the average values of
cowpea water requirements during initial, development, mid-season and
late-season stages were 37.4, 71.3, 149.5 and 77.0 mm for the semi-arid
zone and 34.1, 65.8, 130.6 and 77.3 mm for the semi-humid zone. The

average water requirement was 3350 m
3
/ha and 3050 m
3
/ha in the semiarid and semi-humid zones, respectively. The water productivity for
cowpea crop in the semi-arid zone was 0.33 kg/m3
and 0.35 kg/m3
in
semi-humid zone. The WH and CA farming system gave better results
compared to the CF for cowpea production in dryland areas of Sennar
state.