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27
December 2014
ON FARM LEVEL
Conservation agriculture
t
his article is the tenth in a series of articles highlighting a
specific pasture crop species that can play an imperative role
in CA-based crop-pasture rotations. Besides improving the
physical, chemical, hydrological and biological properties of
the soil, such species, including annual or perennial cover
crops, can successfully be used as animal feed.
Livestock production systems are in many ways dependant on the
utilisation of pasture species, in this case as a pasture ley crop, and
can therefore become an integral component of CA-based crop-
pasture rotations. It is imperative however to identify a pasture
species fulfilling the requirements of a dual purpose crop, i.e. for
livestock fodder and soil restoration.
This article focuses on an annual pasture crop commonly used in a
short, one summer season rotation as a cover crop, either succeed-
ing a winter annual species cover crop with green manuring proper-
ties or being succeeded by the latter crop mentioned.
Pennisetum glaucum
(Pearl millet/
babala
)
Annual fodder cops are sometimes classified as expensive, because
of the annual seedbed preparation and establishment. The higher
production and palatability of newer Pearl millet cultivars might op-
pose this statement. Gerber
et al
. (2006) and Robertson
et al
. (2009)
reported that the production, palatability and quality of newer an-
nual summer cultivars make it popular crops for intensive animal
production systems.
Agro-ecological distribution
Pearl millet was introduced in the 1850s as forage used in the Gulf
Coast states. It originated in central Africa and is also found in the
drier tropics and parts of India. In South Africa, Pearl millet is pro-
duced in the Free State, Limpopo and KwaZulu-Natal. Common cul-
tivars used locally include Milkstar, Hypearl millet, common babala,
Nutrifeed and Speedfeed.
This species is known to grow in areas with a rainfall of anything
between 200 mm - 1 400 mm, but more often in areas receiving
250 mm - 750 mm of rain per year.
Even though this species is often known for its drought resistance, a
uniformly distributed rainfall during the growing season is desired.
With regards to too much rain during the reproductive stage of the
plant, crop failure is most likely possible.
Pearl millet is sensitive to low temperatures especially at critical
physiological growth stages such as seedling and reproductive
(flowering) stages. High temperatures are needed for the grain of
this species to mature. When seeded, Pearl millet germinates well
at soil temperatures of 18°C - 29°C and emergence can occur in two
to six days in favourable climatic conditions. Planting in cooler soils
can cause problems with reduced emergence and greater competi-
tion from weeds.
Pearl millet grows best in light, well-drained loamy soils. This spe-
cies has the ability to tolerate poor and infertile soils. It does not
necessarily grow well on clay soils that are prone to waterlogging. It
also has the ability to tolerate acidic (pH 4 - 5) subsoils that have high
aluminium contents.
Management and utilisation
Pearl millet does not have any difficulty with establishment. It is
common practice to either sow this species in a broadcast fashion
or plant it in rows. Planting in rows is recommended for areas that
receive less than 700 mm of rain. Recommended seeding rates for
rows (0,9 m): 5 kg/ha - 15 kg/ha, 15 kg/ha - 25 kg/ha for broadcasting
and as high as 30 kg/ha under irrigation.
As Pearl millet is adapted to a variety of soils, it is important to en-
sure a moderate level of phosphorus (P) and potassium (K) for good
production. Top dressing with nitrogen (N) (± 40 kg - 70 kg N/ha) tak-
ing rainfall and growth stage into account, can result in great yields
of good quality.
In a high rainfall season (± 1 200 mm/year) Pearl millet can produce
as much as 12,9 tons/ha when it is defoliated frequently (every four
weeks). The highest producers under these conditions were Milkstar,
Speedfeed, Hypearl millet and even common babala.
The regrowth distribution during a wet growing season differs be-
tween cultivars. Milkstar and common babala grow faster in Decem-
ber and January than in February and March (early season cultivars).
Speedfeed and Nutrifeed do not have specific production peaks;
however a gradual decline in production over time (full-season cul-
tivars) is expected. Hypearl millet starts slow, but production peaks
late February and March (late season cultivar). Pearl millet grown
out to the soft dough stage can be cut for hay, ensiled or grown out
for foggage.
WAYNE TRUTER,
University of Pretoria,
CHRIS DANNHAUSER,
Grass SA,
HENDRIK SMITH,
Grain SA and
GERRIE TRYTSMAN,
ARC-Animal Production Institute
Integrated crop and pasture-based
livestock production systems
– Part 10
AGRICULTURE
Conservat ion
Series