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t
his article is the 24th of a series of articles highlighting a
specific crop species that can play an imperative role in con-
servation agriculture (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 dependent on the
utilisation of forage species, in this case as an annual cover crop,
and can therefore become an integral component of CA-based crop-
pasture rotations.
It is imperative to identify a plant species fulfilling the requirements
of a dual purpose crop, i.e. for livestock fodder and/or soil restora-
tion. This article focuses on an annual winter grass cover crop with
the potential to be used to improve soil conditions and to provide
high quality forage for ruminants.
Lolium multiflorum
L.
,
annual ryegrass
or
eenjarige raaigras
Annual ryegrass is a cool season (winter) evergreen tufted grass.
There are two varieties of annual ryegrass known by their common
names as Italian ryegrass (
Lolium multifolrum var. italicum
) and
Westerwolds ryegrass (
Lolium multiflorum var. westerwoldicum
).
Italian ryegrass varieties are generally more persistent than Wester-
wolds ryegrass varieties. Westerwolds ryegrass is a very rapid grow-
ing, leafy, extreme annual which was selected from Italian ryegrass.
Italian and Westerwolds ryegrasses are not easily distinguishable
from each other on the basis of their morphological characteristics.
Certain cultivars have the ability to persist into a second season and
be regarded as a biennial in moderate climatic regions.
These two groups of ryegrass cultivars can be divided further
into two more groups, namely diploids and tetraploids. Tetraploid
ryegrass cultivars have longer, broader leaves, less stems which are
much thicker and bigger seeds than diploid ryegrass cultivars.
There are a number of different cultivars available in South Africa, as
this species is most commonly used in the dairy industry because of
its high nutritional value. Annual ryegrass has a dense shallow root
system; however, this extensive root system tolerates compacted
soils and makes it an effective catch crop for excess nitrogen.
Agro ecological distribution
This species is adapted to temperate climates and is mostly cultivat-
ed in the high rainfall regions of South Africa. When produced under
dry land, rainfall in excess of 850 mm will be sufficient for optimal to
good production.
It is also grown very well under irrigation. Annual ryegrass has a
high requirement for fertility and moisture. The grass grows well on
a variety of soils but does extremely well on deep fertile soil with a
capacity to hold moisture.
Ryegrass seedlings are extremely sensitive to heat and drought,
because very high summer temperatures may have a detrimental
effect on the production and persistence of the species.
Management and utilisation
The best time to establish this grass is in autumn, from mid-Feb-
ruary to mid-April depending on the climatic region. Westerwolds
ryegrass cultivars can be sown earlier than Italian ryegrass cultivars.
Seeding rates for these different cultivar groups are based on their
seed size. Diploids can be planted at 20 kg/ha using a drill seeder,
but if seed is broadcasted 25 kg/ha is sufficient.
Tetraploids on the other hand, will require more seed, i.e. 25 kg/ha
(drill seeded) and 30 kg/ha (broadcast). A fine firm seedbed is re-
quired and consolidating (rolling) the seedbed before and after seed-
ing will promote a good stand.
If aerially seeded, increase seeding rates at least 30% compared to
broadcast seeding rate. You can overseed into maize at or later than
last cultivation or plant right after silage harvest. When seeding into
soybeans, overseed at leaf-yellowing stage or later. When overseed-
ing, it is an option to include an annual legume (e.g.
Vicia
spp.) if low
soil nitrogen (N) levels are expected.
Take note that certain residuals of herbicides used for grain crops
can kill ryegrass. If ryegrass is considered as a cover crop, make
sure the herbicides used in your grain cropping system are not det-
rimental.
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 24
AGRICULTURE
Conservat ion
Series
ON FARM LEVEL
Conservation agriculture
Maart 2016
76