Four rows of corn hybrid SC-704, with 1000-kernel
weight of 0.250 kg, emergence rating of 92% and purity
of 97% were planted in each plot with a single row
multi-purpose pneumatic row-crop planter. The planter
was equipped with double disc furrow opener which is
recommended by FMO (1981) for minimum tillage and
high residue conditions. The planter seeded at 0.75 m
row spacing and 0.10 m theoretical plant spacing (xref).
Planting operation speed was maintained at 7 km h1
for all treatments. For planting in each plot the relevant
planter attachment was fixed to the unit to realize the
desired planting operation.
The coulter was 0.47 m in diameter made from
0.035 m thick high-carbon steel and was sharpened to
148 (Fig. 1). The coulter assembly was designed in such
a way that the coulter could follow direction of machine
travel and avoid side forces. The coulter could cut the
trash and penetrate beds before furrow opener engage
soil. The coulter assembly was fixed so that the coulter
could work at a depth similar to that of furrow opener
discs. The row cleaner attachment was made up of two
0.16 m diameter free rotating tine wheels placed at 458
angle to each other (Fig. 2). Row cleaner assembly
24 h, and weighted to estimate surface residues after
planting. Subsurface residue was identified by cutting
off the upper 0.06 m of soil from the cores. Residues
were separated from the soil using water and sieves, and
finally washed and weighted. Similarly subsurface
residues were dried at 105 8C for 24 h, and weighted.