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t
his article is the 26th and final of a series of articles high-
lighting 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 an-
nual 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, or pasture ley and cover crops (used
interchangeably in this article), and can therefore become an integral
component of CA-based crop-pasture rotations.
To qualify as a pasture ley crop, a plant species must fulfil the re-
quirements of a dual purpose crop, i.e. it must be functional for
livestock fodder and for soil restoration. This article concludes the
series and focuses on the way these different species can be incor-
porated into cropping systems as ‘pasture ley’ crops.
The term ‘pasture ley’ can include a variety of annual or perenni-
al species, legumes, grasses or root forage crops used in short or
long-term rotations. It is therefore important to distinguish be-
tween a short term and long term ley cropping system.
Integration of pasture leys with grain
crop systems
With the declining fertility and productive capacity of many South
African cropping soils, there is an increasing need to develop suc-
cessful ley pasture systems in grain producing regions. Ley pastures
in crop rotations have the ability to reverse declining soil health
and various properties, improve livestock productivity and reduce
rising environmental problems.
The past series of articles on different species have highlighted
the important benefits of such species as an integral part of crop-
livestock CA systems. These benefits include: Improved nutrient
cycling and soil biodiversity, reduced erosion, compaction and nu-
trient leaching, improved soil aeration and water conservation, in-
creased carbon sequestration and storage.
It is however important to understand the attributes of the different
ley pasture species, as the wrong combination of species can lead
to negative effects on succeeding crops. Legume pasture ley crops
are most commonly used for nitrogen contribution because of their
ability to fixate nitrogen to be used by a following crop. Grass ley
crops are more widely used to control soil erosion, to control weeds,
improve nutrient recycling and carbon sequestration and to improve
soil structure as a result of soil compaction.
Brassicas are used to reduce compaction and increase soil struc-
ture through increased levels of organic matter, recycle nutrients
and to suppress diseases and weeds.
Ley crop rotations and associations with
cash crops
The following section provides information about different ley or
cover crops grown during, in-between or after cash crops. Emphasis
is given to the summer rainfall area of South Africa. These crops
should preferably be planted as multi-species mixture and utilised
through mob grazing, or short-duration, high-intensity grazing. The
ideal is to have a diversity of living roots in the soil for the entire
year to boost soil health.
After maize or soybeans, or late in growing
season (as a winter cover crop or relay crop)
Cereal rye, annual ryegrass, wheat, oats or triticale as grasses can
be planted to accumulate soil organic matter, recycle nutrients, and
reduce soil compaction (see
Photo 1
).
Brassicas (oilseed or tillage radish or turnips) is used to recycle
nutrients, reduce compaction, and promote weed and disease
suppression. Vetch can be planted as a nitrogen source. Relay crop-
ping is the technique of seeding these winter cover crops into a
maize crop. The cover crops germinate and grow slowly under the
maize canopy (see
Photo 2a
and
Photo 2b
).
When the maize is harvested in the fall or winter, the cover crops
are already established and growth resumes, saving valuable time.
Generally, the relay crop will have far more growth throughout
the winter and spring, than will any cover crop seeded after maize
harvest.
Apart from the advantage for livestock integration, there are many
other economic and environmental benefits.
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 26
AGRICULTURE
Conservat ion
Series
ON FARM LEVEL
Conservation agriculture
Junie 2016
36