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 /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 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 = in 2011 and in 2012) in mean yield among the tillage methods. No significant differences (p = in 2011 & 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 kg/ha in TRF – kg/ha in ARF to kg/ha in AMP to kg/ha in TDH irrespective of mulch max yields were 5362 kg/ha in TRF kg/ha in ARF 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 plants per ha as compared to 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.