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April 2015
t
his article is the 14th in a series of articles highlighting a spe-
cific 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, the species under discussion can also 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/or soil restoration.
This article focuses on an annual legume pasture crop commonly
used in the winter season as a green manure crop to improve
soil conditions and to provide cover in the winter months of a sum-
mer rainfall region. This annual legume crop could possibly suc-
ceed a perennial grass pasture prior to planting a grain crop the
next season.
With the rising cost of fertilisers and the objective of sustained soil
fertility and soil health improvement, this green manuring option
can provide an opportunity.
Ornithopus species
(Seradella)
Seradella is a winter growing, annual legume that has a semi-erect
to erect growth nature, but can also form stolons/creepers. This
species has a deep root system and can form creepers as long as
1 m. It is indigenous to north Western Europe and the Mediterra-
nean. It has the ability to grow on soils that are poor and not suitable
for other forage crops.
There are two common cultivars of Seradella, i.e. the French or pink
flowered
Ornithopus sativus
and the yellow flowered
Ornithopus
compressus
.
Agro-ecological distribution
Seradella’s growing season stretches from autumn to spring, and
it can grow at altitudes as high as 1 500 m above sea level with a
rainfall of between 300 mm to 700 mm rain per annum. Pink Se-
radella is not frost tolerant and is moderately drought-tolerant. As
mentioned, dry conditions are overcome by deep root systems
that are able to access deeper sources of soil water. It is known
that yellow Seradella can tolerate deep, sandy, acidic soils. This
species is also very susceptible to waterlogged conditions and not
suited to alkaline soils. This illustrates the potential of this species,
especially the earlier flowering varieties, to grow in lower winter
rainfall areas, as low as 350 mm per annum.
Supplemental irrigation can play an important role in increased
production. The hard seeded and deep root system characteristics
of the species, facilitates the establishment and persistence of this
species in soils with low fertility.
Soft seeded pink Seradella shows very similar growth properties as
a fodder plant on more infertile sandy soils. Pink Seradella is often
used a nurse crop for yellow Seradella, improving its establishment.
These species tend to do best on well-drained and fertile soils.
Management and utilisation
Good soil preparation is imperative for the successful establishment
of Seradella. It is recommended that the seedbed be as fine, firm
and weed free as possible to avoid unnecessary plant competition.
Seradella can be planted with a nurse crop, such as oats, for either
hay or silage purposes. It is then advisable to use 10 kg/ha - 20 kg/ha
of seed (depending on climatic and soil conditions) in mixture with
the oats seed. It is important that the seed be inoculated with the
correct strain of
Rhizobium
bacteria.
Seradella has a small seed and it is important that the seed is planted
shallow (10 mm - 15 mm) and rolled firmly to facilitate good estab-
lishment. It is advised that seed rather be drilled into the soil rather
than broadcast, as this will ensure the best seed soil contact re-
quired for optimal germination.
The seed is known to have a very low germination potential, how-
ever, dehulled seed seems to have a much better germination per-
centage. The peak growth period is generally in spring, followed by
a drying off of plants in summer.
Soil nutrient requirements for legumes are normally high levels
of potassium, calcium and particularly higher levels of phosphate
as well as micro nutrients such as copper, zinc and molybdenum.
It is advisable to raise the soil nutrient statuses to 30 mg/kg P and
120 mg/kg K.
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 14
AGRICULTURE
Conservat ion
Series
ON FARM LEVEL
Conservation agriculture