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t
his article is the eleventh in a series of articles highlighting
a specific pasture crop species that can play an imperative
role in conservation 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 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-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/or soil restoration.
This article focuses on an annual pasture crop commonly used in a
short one summer season rotation as a cover crop either succeeding
a winter annual species cover crop with green manuring properties
or either being succeeded by the latter crop mentioned.
Sorghum spp.
(forage sorghum)
Fodder crops are sometimes classified as expensive, because of
the annual seedbed preparation and establishment. However, the
higher production and palatability of forage sorghum cultivars
challenge this statement.
The value of forage sorghums are because they are easy to estab-
lish, fast growing and high yielding, palatable summer annual and
perennials. Forage sorghums are generally more palatable and nutri-
tious than babala. They have the ability to recover well from defolia-
tion and respond extremely well to fertilisers.
Annual forage sorghums
These are normally hybrids of crosses between different sorghum
types and/or Sudan grass. These hybrids can often have many char-
acteristics which make this species suitable for silage, grazing or
even hay.
The annual sorghum is the most commonly planted sorghum. There
are however numerous cultivars available each year commercially,
and it varies from year to year. This often makes it difficult for the
producer to select the most suitable cultivar for his requirements.
Perennial forage sorghums
These sorghum species can survive between three to five years, all
depending on the climate as well as the row spacing in which they
are planted. It is also known that the persistence of these species is
easily affected by incorrect management practices, especially in low
rainfall areas.
Agro-ecological distribution
Sorghums are well-adapted to regions that do not necessarily have
a high rainfall. It can be stated that a rainfall of between 400 mm
- 650 mm is more that acceptable for normal production of sor-
ghum. This however, does not restrict their use in higher rainfall
areas and/or irrigated land.
The species are very adaptable to a wide range of soil types, but
mostly cropped on lower potential soils and are very tolerable of
higher levels of salt or alkali. This emphasises their ability to adapt
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 11
AGRICULTURE
Conservat ion
Series
“
...this crop with its
high growth rate and
yield is indicative of a
significant amount of
organic matter returned
back to the soil through
root biomass.
“
ON FARM LEVEL
Conservation agriculture
Januarie 2015
20