Abstract:
On-farm experiments were designed to investigate the response of maize establishment
and grain yield to variation in tillage systems. The tillage treatments included arara
ploughing followed by zig-zag harrowing and arara ridging (T1); emcot ploughing followed
by zig-zag harrowing and emcot ridging (T2); mouldboard ploughing followed by
disc harrowing and mouldboard ridging (T3); disc ploughing followed by disc harrowing
and disc ridging (T4); manual ridging (T5). Generally, shallow (0-15.0 cm) tilled plots of
T1 showed lower root lengths and root length densities than deep (0.28.0 cm) tilled plots
of T4. However, there was higher soil penetration resistance (PR) in T1 than in T4. Increased
PR in the range of 4.0 – 4.5 MPa decreased plant height (Hp), leaf area index
(LAI), and maize grain yield (Yg). Reductions in Yg in the range of 35 – 50% can be expected
for a reduction in soil moisture contents from 24.2 – 15.7%, w/w. Tillage treatment
significantly (P<0.01) affected Yg. However, there were no significant differences at
P<0.05 in the emergence rate index (ERI), LAI and Yg for the interactions of nitrogen
levels × planting methods × tillage treatments.
