Agriculture Reference
In-Depth Information
derived from discussion with farmers and colleagues that have used the
implements.
Inter-row cultivators: shovels and sweeps,rolling cultivators,
and rotary tillers
Tools designed to work between crop rows can dig moderately deeply
(typically 5 to 10 cm) without harming the crop. Consequently, complete
destruction of even large weeds is often possible during inter-row cultivation.
However, unless precautions are taken, vigorous soil movement can bury
young crop plants, and deep digging can damage the roots of larger crops. To
avoid crop damage, these tools usually work only 50% to 70% of the soil
surface, leaving weeds in the crop row unharmed. However, Melander &
Hartvig (1997) have shown that safe cultivation within 2.5 cm of the row is
possible if the crop is small and protected with shields and a good cultivator
guidance system.At later stages of crop growth,sweeps may be used to hill-up
soil in the crop row to bury small weed seedlings.
Sweeps and shovels are the most commonly used cultivation tools.They are
simple and durable.They vary greatly in width,shape,and pitch (Figure 4.11).
Generally, soil movement away from the shank increases with width and
pitch, and decreases as the angle between the leading edges increases.
“Goosefoot” style shovels (Figure 4.11c) move less soil than standard shovels
and sweeps (Figure 4.11b, e). S-shaped (Danish) shanks vibrate more, which
brings weeds to the surface and helps shake soil loose from weed roots, but
they are less robust than C-shaped shanks.
Multiple shanks provide flexibility. For example, Mohler, Frisch & Mt.
Pleasant (1997) used 2.5 cm spikes (Figure 4.11d, top) nearest the row when
maize was young to reduce soil movement toward the row, but changed to 10
cm sweeps to throw soil into the row at the last cultivation. However,
minimum-tillage cultivators designed to operate in high crop residue usually
have one shank with a single broad sweep per inter-row. This design presents
less metal at the ground level to snag debris. Also, these cultivators have a
coulter in front of each shank to cut residue so it can flow past the shank. In
minimum-tillage machines, hilling up around the crop is accomplished with
wing attachments that increase the lateral displacement of soil, or with disk
hillers (see below).
The usual tooling on a rolling cultivator consists of gangs of wheels with
stout, curved tines that cut and dig out weeds as they roll over the ground.
Alternatively, disk gangs can be used for cultivation in high residue. In either
case, each gang is mounted on a separate tube, with two gangs per inter-row.
Adjusting the angle relative to the direction of travel controls aggressiveness
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