Abstract:
A field study was carried out for 2 seasons
(November to February 1999 and April to
August 2000) to investigate the influence of
irrigation on maize growth, nitrogen uptake and yield. The experimental design was
randomized complete block design laid out as
split plot with water regime as main plots
(irrigated, rainfed), and factorial
combinations of N (0, 50, 100 kg N/ha) and P
(0, 25 kg P20S) as subplots. Data collected
included leaf area index (LAI),
photosynthetically active radiation (PAR)
interception, total dry matter (TDM), nitrogen
uptake and maize grain yield. Phosphorus had
no effect on, growth and yield, so the data
were pooled [0{ P. In the wet (350 mm
rainfall) Short Rains, 1999 (SR99), irrigation
had no effect on LAl and fractional PAR
interception but significantly increased total
N uptake, TDM and grain yield by 50 to
100%. Under low rainfall (143 mm) in the
Long Rains 2000 (LROO), irrigation increased
LAI and PAE. interception by 50 to 100% and
N-uptake, TDM and grain yield by 10, 10 and
34 fold respectively. However there was no
significant response to N fertiliser application
without supplemental irrigation. Nitrogen
application above 50 kg!ha did not improve
maize growth and yield in both seasons.
Supplementary irrigation can therefore
increase maize yield even at low fertiliser
input level in semi-arid Kenya.
