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t
his article is the 18th in a series of articles highlighting a
specific pasture crop species that can play an imperative role
in conservation agriculture (CA) based crop-pasture rota-
tions. Besides improving the physical, chemical, hydrological
and biological properties of the soil, such species, includ-
ing 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 to identify a pasture species fulfilling the require-
ments of a dual purpose crop, i.e. for livestock fodder and/or soil
restoration. This article focuses on an annual leguminous pasture
crop commonly used to improve soil conditions and to provide a
good grazing for ruminants.
Vicia
spp., vetches or
wieke
Vetches are annual legumes that have either a creeping or rank-
ing growth habit. They are a winter growing species and are thin
stemmed and have predominantly purple flowers. Currently the
most common vetch types cultivated in South Africa include pur-
ple vetch (
perswieke
or
Vicia purpurea/Vicia benghalensis
), grazing
vetch (
weiwieke
or
Vicia dasycarpa
), common vetch (gewone wieke
or
Vicia sativa
) and hairy vetch (
harige wieke
or
Vicia villosa
).
These vetch types can be used for silage, hay and grazing. Other
vetches that do not belong to the genus
Vicia
i.e. Litjieswieke
(
Aesochynomene
spp.), milk vetch (
melk wieke
or
Astragalus cicier
)
and crown vetch (
kroon wieke
or
Coronilla varia
) will not be dis-
cussed in this article.
Even though these species are commonly used in South Africa,
very little production data is available for our environmental condi-
tions and agricultural production systems.
Agro-ecological distribution
Vetches are commonly grown in dryland wheat production areas.
These species are well-adapted to a variety of soil types, but do not
particularly tolerate waterlogged conditions. The best time to sow
vetch is from December to March. This species is particularly sensi-
tive to acid soils, so it is advised that soil be limed properly prior
to planting. Purple vetch is mostly grown in winter rainfall condi-
tions and used specifically for silage or hay and is not suitable for
grazing purposes.
Grazing vetch however, is more tolerant of cold winters than
other vetches and more suited for grazing. It develops quickly and
is most adapted to poor and acid soils. It also has the potential to
reseed itself.
Common vetch is most commonly used for hay and silage too. This
vetch produces pods that are commonly grazed by sheep. Hairy
vetch is more common for fodder production in both winter and
summer rainfall regions.
It is sown in January and will provide good fodder late in winter.
Most vetch species require between 350 mm - 550 mm rainfall
per annum and if managed well, can provide a good quality animal
feed in winter months.
Management and utilisation
It is often recommended that vetch species are sown (mixed) with
winter cereal crops, especially oats, into summer grain crops like
maize, as a cover- or intercrop in order to provide fodder at a later
stage after grain has been harvested.
This mixture is usually planted in February; it can be grazed in
winter and spring and also makes good silage. Seeding rates for
vetches in mixtures range from about 20 kg vetch/ha - 30 kg vetch/ha
and 25 kg oats/ha.
When grazing or hairy vetch is sown on its own, a sowing density
of 35 kg/ha is recommended. Where this species is sown with grain,
it is essential to ensure that sufficient fertiliser is provided at estab-
lishment; with phosphorus (P) being the most important since it
is essential for legume growth. The best time to make hay is when
the first pods are well-formed. From a grazing perspective, it is es-
sential to graze the vetch just before the pods will start to mature.
Soil conservation and health benefits
Since vetch species are leguminous, nitrogen (N) is fixed and will
help meet the needs of the following crop, protect the soil from ero-
sion and improve soil tilth creating a loose and friable soil structure.
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 18
AGRICULTURE
Conservat ion
Series
September 2015
98
ON FARM LEVEL
Conservation agriculture