81
October 2014
ON FARM LEVEL
Conservationagriculture
t
his article is the eighth in a series of articles highlighting a
specificpasture crop species that canplay 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 successfullybeused 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 thereforebecomean integral component of CA-basedcrop-pas-
ture 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.
Medicago sativa
/Lucerne (
Lusern
)
Lucerne is a long-living, erect perennial legume with an extremely
deep taproot systemwithpurple flowers and spiral shapedpods. Its
growthpoints develop form the crown.
Lucerne is alsowell-known as the king of hay. Palatablewith a high
nutritional value, but causesbloat problemswhengrazeduncontrol-
lably. Of all the perennial species that can be used to provide good
quality grazing and have significant soil reclamation properties,
there is nobetter species than lucerne.
This species is most suitable to irrigated conditions, especially for
hay production, but there are cultivars that can be planted under
rainfed conditionsmore suited tograzing.
Agro-ecological distribution
Lucerne can be divided into nine different classes according to its
winter dormancy. It is adapted to a wide variety of situations, from
clay to sandy soils and cold to hot areas. It survives under rainfed
conditions of as low as 400mmper annum, especially in soilswith a
goodwater holding capacity.
As a result of its deep taproot system, it is a relatively drought toler-
ant species. This species is also sensitive to acid and waterlogged
soils. For practical purposes, the following threemain groups are of
importance:Winter dormant (dormancy 2 to5); non-winter dormant
(dormancy 7 to 8); highly non-dormant (dormancy 9 to 11).
Lucerne cultivars are classified according to their growth activity
duringwinter. The lower the dormancy class (e.g. Class 2), themore
winter dormant and the slower thewinter growthwill be.
Class 9 to 11 cultivars, on the other side of the spectrum, are not
winter dormant and will grow during winter. The utilisation of the
cultivars is also correlated with dormancy class. The lower classes
aremore suitable for grazing, classes 5 to8 canbe classified as dual
purpose, while classes 9 to 11 aremainly for hayproduction.
Management and utilisation
Winter dormant cultivars are best for grazing, the non-winter dor-
mant cultivars for grazingandhay, and thehighlynon-dormant culti-
vars for hay. Inoculated seed canbe planted for themost part of the
year (not inwinter).
Use 4 kg/ha seed under rainfed conditions (in the range of 500mm)
in rows of up to 18 kg/ha under irrigation.When seeding for grazing
purposes, 5 kg/ha - 20 kg/hacanbeplanted, all dependingon rainfall
and soil quality.
The best time of the year to plant is mainly autumn (February to
May), as weeds germinate and grow slower in this period and less
competition is expected, but it should be noted that lucerne smaller
than 100 mm tall are prone to frost damage. Alternatively, lucerne
canbeplanted inspring (August -September),which is thepreferred
planting timeon theHighveld.
When lucerne is planted in rows, it should be done at a spacing of
600mm - 900mm apart. On the Highveld, rows of 30 cm are often
usedwhen the pasture is grazed by sheep. This ensures that sheep
donot damage the crownof lucerne.
When planted under irrigated conditions, broadcast seeding is rec-
ommended if the seed isproperly consolidated (rolled). Under these
irrigated conditions, production in the summer rainfall regions is ap-
proximately 15 tons/ha, however 20 tons/ha has been reported. Of-
ten lucerne is planted inmixed pastures, and by planting it together
withother species in rows,makes it easier tograzewith lesschances
of bloat occurring.
Since lucerne is able to adapt tomany soil types (excluding alkaline,
brackish soils), it thrives best ondeep, sandy soils.
WAYNE TRUTER,
University of Pretoria,
CHRISDANNHAUSER,
Grass SA,
HENDRIKSMITH,
Grain SA and
GERRIE TRYTSMAN,
ARC-Animal Production Institute
Integrated cropandpasture-based
livestockproduction systems
–Part 8
AGRICULTURE
Conservat ion
Series
