TheImprovement ofTropical and Subtropical Rangelands

164 IMPROVEMENT 0' TROPICAL AND SUBTROPICAL RANGELANDS
spreader, as well as by aerial broadcasting, airstream, hand broadcasting,
or other methods that take into consideration range seeding
principles (Valentine, 1971).
Drill Seeding
Drilling is by far the moet effective method ofplanting seed where
site conditions permit. The seed is covered to the proper depth by the
drill control; distribution is uniform; the rate of seeding is positively
controlled; and compaction can be applied if needed. Several types
of drills are available (Larson, 1980).
Rangeland Drill This drill is a rugged seeder with high clearance
designed to work on rough sites (see figure 7-7). It has performed
well on rough seedbeds. It can be converted into a deep furrow implement
by removing the depth bands. The depth of the furrow is
controlled by adding or removing disk arm weights. Weights up to
30 kg can be used. The seed-metering device on this drill can be
adapted to handle a variety of leeds at widely varying rates.
PreIS Drill The press drill is designed for seeding on light, loose
soils. A heavy press-wheel packs the soil. The seed is placed in the
packed furrow and an adjustable drag covers it (figure 7-8). This drill
cannot be used on rocky or rough seedbeds. The feed on the drill
will not accommodate trashy seed unless it is especially designed for
this purpose.
Ordinar, Grain Drill. The drills in this group are designed and
built for use on cultivated fields. They are too lightly constructed for
rough rangeland seeding. Breakage is a problem, and often the seed
is not placed properly in the ground. For these reasons, they have
limited use for critical area seedings.
Truh, Seed Drill This drill is equipped with two types of seed
boxes, one for planting trashy seed, such as bufFelgrass (Cenchru
ciliam), and another for planting fine seeds, such as lovegrass or teff
(Eragrostu spp.). The boxes can be used together or separately. The
drill has a welded frame construction and uses rubber-tired wheels.
Broadcast Seeding
Broadcasting is any method that scatters the seed directly on the
soil without soil coverage. However spread, the seed must be covered