Abstract:
Performance evaluation of center pivot sprinkler irrigation system installed at Hiwot
Agricultural Mechanization farm was conducted. The existing irrigation system and
agricultural practices were studied and measurements of the water application uniformity
indicators were made and performance gaps were identified. HAM farm has 32 center pivot
machines, out of which only five center pivot machines were under operation at the time of
the present study. Radial measurements of water application along the CP sprinkler
irrigation system lateral line were made for the estimation of coefficient of uniformity,
distribution uniformity, and potential application efficiency of low quarter. Catch cans
were placed along the CP lateral at 3m spacing for collection of water application along the
lateral of center pivot. The measurement were made at five location s identified by the
number of CP irrigation machine, m4, m6, m7, m8, and m12. Three of the locations were
at upstream (m8, m12, and m4) and two located in middle (m6 and m7) of HAM farm. The
measurements at location m4 were made twice, day time (about 2 pm) and night time (about
9 p m), however, for the remaining locations measurements were made only during day
time. The measured value of water application rate for different locations along center pivot
lateral line varied widely, generally lower values at pivot and higher values at end of center
pivot lateral line. The Distribution uniformity, coefficient of uniformity and potential
application efficiency of low quarter were varied from 67% to 85%, 73% to 86%, and 66%
to 80% respectively. The highest value of DU was at night time measurement for location
m4 as compared with m4 at day time due to lower wind velocity during night time (1.5m/s)
and lowest value was for location m7. The highest value of CU was at location m7 whereas
the lowest value was for location m12. The application rate at all the location was higher
as compared to basic infiltration. The measured values of irrigation efficiency at different
locations varied from 60 % at location m7 to 69% at location m6. The highest value of crop
water requirement at location m6, m7 and m12 was 5.24 mm/day in September at mid stage
and for location m4 and m8 in October at mid stage equal to 4.99 mm/day. Whereas, the
lowest crop water requirement at location m6, m7 and m12 was 2.52 mm/day in July at
initial stage which was and for location m4 and m8 in august at initial stage equal to 2.08
mm/day
