PEARL MILLET’S ROOT LENGTHS
AND YIELDS UNDER CONVENTIONAL
AND CONSERVATION TILLAGE
METHODS IN OGONGO, NAMIBIA.
Mudamburi B, Ogunmokun A & Kachigunda B
INTRODUCTION
 More
than 70% of Namibia’s 2 mill people depend
on agriculture for their livelihood. (Tjaronda, 2009).
 Pearl millet (Pennisetum glaucum) widely grown by
small holder farmers in Northern Namibia and is
also staple food.
 Yields of pearl millet on smallholder farms are at
about 400 kg/ha (Davis & Lenhardt, 2009; Mahangu
and Sorghum Task Team (MSTT), 2009).
 Crop residues (stover) removed, either by livestock
or for domestic use, lots of mono-cropping of pearl
millet leading to deterioration of the farm’s ecology
and declining yields (Contill 2009).

INTRODUCTION CONT..
 Conventional
tillage and the preparation of a fine
seedbed are still considered characteristics of good
farming practice in Namibia (Mudamburi &
Namalambo, 2010).
 Study
conducted to compare the effects of 4 tillage
methods (two for Conventional Tillage (CV) and two
for Conservation tillage (CT) used by farmers in
Ogongo conditions of Namibia on root development
and yield of pearl millet.
METHODOLOGY
 Experiment
carried out at Ogongo Campus in the
North of Namibia during 2010/2011 and 2011/2012
cropping seasons.
 Ogongo lies in semi-arid region, mean annual
rainfall between 300 & 500 mm (Kuvare et al.,
2008).
 Soils at the site are sandy.
 Animal drawn mouldboard plough and a tractor disc
harrow used for CV & animal drawn ripper furrower
and a tractor ripper furrower were for CT.
 Planting done by dropping and covering seeds into
ripped and ploughed plots.
METHODOLOGY CONT..
 Split
plot design i.e. 5 treatments, & 2 mulch rates
(no mulch and mulch) with 4 replications totalling 40
plots.
 Treatments: (1) animal drawn mouldboard plough
(AMP), (2) Animal drawn ripper furrow (ARF), (3)
tractor disc harrow (TDH), (4) tractor ripper furrower
(TRF), and (5) Control- No tillage No crop (NTNC).
 Plots were 10 x 10m, with 5m borders between
blocks and 2m between plots
 Trained operators and animals used in test runs and
then in the experimental plots.
 Well designed harnesses also used for the animals.
METHODOLOGY CONT..
 Plant
population of 80 000/ha of pearl millet
 Seed rates of Okashana1 at 3 to 4 kg/ha.
 1m inter-row and 25 cm in-row spacing
 Crops for 1st yr trial planted in Jan 2011 and 2nd yr
in Jan 2012.
 Fertiliser applied at 150kg /ha of Mono ammonium
phosphate for all treatments.
 Goat manure at 5t /ha at planting stations.
DATA ANALYSIS
5
random samples of roots measured with a ruler in
cm.
 5 random samples of yields in kg per plot also
measured after harvesting using a scale.
 All random samples taken from the two middle rows.
 Whole plot yields also measured at the end to
compare since there was bird damage in some plots.
 Genstat statistical package used to analyse the data.
 Analysis of variance used to test for any significant
differences among the root length and yield means of
all tillage methods at a confidence level of 95%
(p=0.05).
ROOT LENGTH RESULTS
 Figure
1 shows mean pearl millet root length
in cm.
 No significant differences in mean root length
among the tillage methods in 2011 season
(p=0.120) but they were significantly different
in 2012 (p<0.005).
 No
significant differences in mean root lengths
between mulched and un-mulched plots.
 Abundance
of rain resulted in adequate soil
moisture even with un-mulched plots.
FIG1:MEAN PEARL MILLET ROOT LENGTH
IN CM.
PEARL MILLET YIELD RESULTS
 Fig
2 shows the mean pearl millet yield per
ha.
 No
significant differences (p = 0.410 in 2011
and 0.078 in 2012) in mean yield among the
tillage methods.
 No
significant differences (p = 0.758 in 2011
& 0.348 in 2012) between the mean yields
of the mulched and un-mulched plots.
MEAN PEARL MILLET YIELD IN
KG/HA.
YIELD RESULTS CONT..
 Yields
from the trials for 2011 ranged from
980 to 2 056 kg/ha in TRF
 1 163.8 – 1 811.3 kg/ha in ARF
 1 163.6 to 1 706.3 kg/ha in AMP
 1 435 to 1 723.8 kg/ha in TDH irrespective of mulch.

 2012
max yields were 5362 kg/ha in TRF
4 981 kg/ha in ARF
 4434.3 kg/ha in AMP
 4587 kg/ha in TDH irrespective of mulch.

CONCLUSIONS
 Vast
improvement in the yields in all the tillage
methods particularly in the 2nd year.
 Other factors contributed to the increase in yield.
 The increases in yields in the second year in line
with the studies from Zimbabwe that showed that
nutrients like nitrogen from manure become more
available to crops in the second season
(Nyamangara et al., 2003).
 Plant population of 80 000 plants per ha as
compared to 40 000 that extension normally
recommends to farmers.
CONCLUSIONS
Putting
manure and fertiliser at more or less the same
place in the furrows.
The
study showed that yield and root length were not
significantly influenced by CT.
In
good rainfall years, there may be no noticeable
differences in CT and CV in an arid area like Namibia.
In
both 2011 and 2012, TRF achieved the highest mean
root length and high yields overall.
The
increase in yields on TRF can greatly improve the
Namibian farmers’ pearl millet yields through the use of CA
practices.