Mixed Pastures and Organic Livestock
By David Musgrave
Waihi Bush Organic Farm, 21 RD,
Geraldine, New Zealand
My Background
 I
grew up on the 140 ha mixed cropping farm I now own at Woodbury, near
Geraldine. I spent 6 years at Lincoln University doing a Masters degree
in Agronomy and went on to spend 14 years working for MAF Research as
a scientist in the South Island High Country and the East Coast Hill Country.
Right through this time most of my work was focussed on the potential
for deeper rooting and more drought tolerant pasture species than the
traditional ryegrass/white clover pastures. I then become a plant breeder
for Dalgety AgResearch in Timaru, who held the marketing rights for some
of the key species I had previously been trialing. This gave me the opportunity
to get some of these species out onto farms and to develop mixtures that
worked in practice to give improved productivity and animal health. About
this time I started farming my own property using organic techniques and
consulting for other farmers, so during the last 15 years I have been
able to refine the recipes even further.
The following comments are my reasons for always using mixed pastures
on my own farm and in my recommendations to the clients I consult for.
Ryegrass and white clover based pastures are used almost universally
on New Zealand farms, for their quick establishment, cheap seed, and ease
of management and reasonable productivity. What is not generally recognised
is that such pastures have a number of inherent limitations that can affect
the whole farming system.
In this article I will focus on some of the shortcomings of ryegrass
based pastures, particularly in relation to Alpacas. This article also
discusses the attributes of other species that can be used in pasture
mixes to create more productive and persistent pastures.
Ryegrass Based Pastures?
Most scientific reviews on the subject of pasture mixes find there is
no consistent pattern of increased dry matter production from using mixed
pastures of other species. I am not aware of any farmlet studies comparing
animal performance on ryegrass versus mixed pastures, so the lack of a
dry matter response is usually taken to mean that the correct decision
for farmers is to continue using ryegrass-based pastures. There seems
to be a lack of awareness that ryegrass, as a species, has a number of
shortcomings which affect the whole farming system, which are not shared
by all grasses.
Productivity
Comparisons of productivity of ryegrass/white clover pastures and more
complex mixtures based on ryegrass do not generally show any increase
in productivity by the mixtures. However in recent years along the East
Coast of NZ there have been programs aimed at increasing the use of non
ryegrass, more drought tolerant species to improve productivity. Unfortunately
these have generally been simple one-grass/ one-legume mixtures. My experience
has been that this type of pasture does not confer the same benefits as
more complex mixtures. Where complex mixes based on deeper rooting species
have been trialed; data has shown that even under irrigation such mixes
are capable of producing more dry matter than ryegrass-based pastures.
Data on animal productivity on mixed pastures is very scarce. However
a trial in the Manawatu was able to show increases in beef meat output
of about 14% by use of a newly released red clover cultivar. '
This is particularly significant in organic systems reliant on clovers
to build soil nitrogen levels, as there is a strong correlation between
nitrogen fixation and productivity of clovers. To a large extent the productivity
of a mixed pasture depends on the suitability for the environment, management
regime and the compatibility of the species sown.
Animal Health
The alkaloid produced by the ryegrass endophyte fungus (which protects
ryegrass from damage by Argentine stem weevil) also acts as an antifeeding
agent for livestock. Thus it is very difficult to get young sheep to grow
any faster than 120-150 grams per day during their first autumn no matter
how lush the high endophyte ryegrass pasture.
On species such as timothy, tall fescue, Prairie grass or low endophyte
ryegrass growth rates of 200-240 grams per day are possible and on chicory,
lucerne or clovers growth rates in excess of 300 grams per day are possible.
This suggests that young stock grazing high endophyte ryegrass are under
considerable dietary stress. Such stress is likely to make them more susceptible
to internal parasites. My own experience on my farm has been that the
need for synthetic anthelmintics is substantially less when young stock
are grazed on mixed pastures free from ryegrass.
Alpacas are extremely susceptible to ryegrass staggers, so it is vital
to have endophyte free pastures available for alpacas. Alpacas are so
susceptible to ryegrass staggers that once exposed to endophyte poisoning,
the staggers will reoccur whenever the animals are stressed.
Having a range of species in a pasture is an accepted way to balance the
mineral status of the diet. Tall fescue tends to have low sodium content,
which can be a problem in simple mixtures, but is not in complex mixtures.
Including herbs, such as chicory (which is very high in zinc, potassium
and calcium) or plantain (which is high in magnesium and calcium) in the
pasture, is a particularly effective way increasing the mineral content
of the pasture, which can increase stock health.
Investigations in progress suggest that some plants, such as lucerne
and chicory, have substantially lower levels of infective larvae of internal
parasites in the zone harvested by grazing animals, which has potential
to reduce the need for anthelmintics. There is also growing evidence for
a degree of direct anthelmintic effect from including plantain in the
pasture.
Thus it is important for optimum livestock health and performance that
mixed pastures are used - it is not sufficient to plant endophyte free
ryegrass based pastures.
Weed Infestation
Ryegrass pastures are quite susceptible to weed invasion, particular
after a dry autumn or grassgrub/Porina damage. I established a fully randomised
grazing trial on my farm at Geraldine in 1987 to investigate grass mixtures
with Puna chicory. In the second year, after a very dry autumn, counts
of nodding thistle were made and after progressive invasion by Californian
thistle further counts were taken in year seven.
Thistle numbers recorded below illustrate the potential for other pasture
species to reduce weed invasion.
Generally the pattern was that those that form a complete sward with
good cover of the sown species, such as tall fescue, were best at preventing
the invasion of both Nodding and Californian thistle.
A really interesting result was that the numbers of chicory plants were
very low by the time the Californian thistle counts were taken. Yet wherever
chicory had been included in the original mixture the number of Californian
thistle plants were very low. There were clear, straight lines across
the paddock, thick Californian thistle on one side and nothing on the
other side where the chicory had been.
This and other observations suggest that the deep taproot of chicory
is breaking up compacted layers down the soil profile and making conditions
unfavourable for Californian thistle growth. If one digs a hole down to
the subsoil, one usually finds the Californian thistle rhizomes in the
compacted zone just below the cultivation zone.
Insect Damage
The numbers of grassgrub larvae in the soil are controlled into a cyclical
pattern by natural pathogens and predators. Unfortunately the level at
which grassgrub numbers usually start to crash is higher than the level
at which substantial damage starts to happen to ryegrass based pastures.
Two trials that measured the effects of a high population of grassgrub
larvae on grass productivity showed that of all the commonly used grasses,
ryegrass was by far the most sensitive. Species such as tall fescue and
cocksfoot were scarcely effected, while ryegrass production was dropped
by 50-60 %.
Since I started using mixed pastures on my own property, I have only
once noticed faints signs of grassgrub damage - when I sampled the affected
area I found over 600 grubs per square meter - an unusually high population
which would have completely destroyed a ryegrass based pasture.
Choice of Species
Tall fescue - has many desirable attributes for use in mixed pastures.
It is a deep rooting species that makes it one of the most drought tolerant
of the common temperate species. Some cultivars have excellent spring
growth - up to 25% more than ryegrass in the early spring, and because
they do not rehead after flowering, they have excellent yields of green
leaf over the summer.
A feature of tall fescue-based pastures is the excellent legume content
- my experience has been that the right cultivars of tall fescue form
an excellent base for very productive mixed pastures based on both lucerne
and clovers. I have many testimonials from very satisfied farmer clients
who have sown such pastures.
Prairie grass - has only been used in NZ pastures for about 25 years,
but in that time has gained a reputation for high productivity, particularly
over the autumn and winter. Unfortunately, it is almost universally recommended
to be sown only with clover as a special purpose pasture. Yet a long term
grazing trial in the Manawatu has shown that in more complex mixtures,
Matua has thrived under both cattle and sheep type managements for ten
years. My experience has been that in mixtures with tall fescue, both
Matua and Gala grazing brome contribute significantly to cool season growth
and will persist as long as the pastures are not set stocked for too long.
Cocksfoot - tends to be the most widely used of the other grasses. Cocksfoot
has many attributes in common with tall fescue - drought and insect tolerance,
and excellent summer autumn production. Unfortunately, a high level of
cocksfoot in a mixed pasture severely reduces both lucerne and clover
production compared to other grasses and cocksfoot is not particularly
palatable to livestock. Both problems are particularly significant in
organic systems, which reduces the usefulness of cocksfoot and I generally
recommend only small quantities of cocksfoot in a mix.
Phalaris - is unique in its ability to thrive in high nitrogen, heavily
grazed areas such as stock camps. Being a very hardy perennial, it competes
well with the barley grass, which also thrives in such areas and can greatly
reduce the barley grass problem. Phalaris is also totally resistant to
grass grub. Phalaris can be toxic to animals, but when used as a very
minor component of a mixture this has never been a problem and it is able
to persist in stock camps and high levels of grassgrub.
Red Clover - as I have already mentioned, red clover based pastures have
the potential to increase legume yield and hence fertility build up in
the soil. Although they are relatively short lived, they can still contribute
significantly to the productivity of an organic cropping system.
Lucerne - as a single species is an open invitation to weed invasion,
with high levels of soil nitrogen and bare ground during the cool season.
While most research fails to find any yield increase from including single
grass species in mixes with lucerne, I have experimented with various
lucerne based mixes on my own and clients farms and the results have been
very positive. If the right combinations are used the stands remain weed-free
and productive, with excellent animal health and they make very high quality
hay or silage.
Chicory - is the most important herb widely available at present. It
is a very important component of mixed pastures because its high productivity,
high quality and high mineral content promotes healthy animals. Its ability
to improve the soil structure and reduce weeds is also important.
Plantain - has recently received the attention of NZ plant breeders and
data is accumulating to show a reliable reduction in animal scouring and
some degree of vermicidal effect. It also has high mineral content and
the cultivar Tonic has excellent winter growth, which helps to counter
the generally lower levels of minerals in cool season herbage.
Sheeps Burnett - has been widely used in the past for its high mineral
content and good cool season growth. I have found it to reduce to a very
minor component on more fertile soils.
Some suggestions for mixtures:
For most situations a clover based mixed pasture will be easier to manage
and will give good performance even in a dry year. However, on lighter
soils or drier environments it is worth going to a lucerne-based pasture.
For such mixtures it is really critical to match the grass cultivars to
the lucerne cultivars, so that the growth rhythms are similar. If this
is not done you are likely to have either grass or lucerne dominating.
I have established a number of very successful examples of lucerne based
mixed pastures - including one on my own farm (800mm average rainfall)
which stayed as a very productive, well balanced, weed free pasture for
ten years.
Such lucerne-based pastures should include lucerne, chicory, timothy,
tall fescue, grazing brome, phalaris and cocksfoot.Clover based pastures
should include chicory, timothy, tall fescue, grazing brome, phalaris,
cocksfoot, red clover, white clover, plantain and yarrow.
Soil testing:
It is advisable to obtain a soil test before proceeding to resow new
pastures to check for the following:
- That calcium, magnesium, potassium and sodium levels are present
at close to the optimum ratios, which is important for plant and animal
health. It is the ratio that is important rather than the absolute level
and to calculate the ratios you need to know the Cation Exchange Capacity
of the soil.
- That phosphate and sulphur levels are present in close to the optimum
levels.
- That trace elements such as boron, cobalt, copper, selenium and zinc
are present in close to the optimum levels. Lack of any of these elements
can be particularly important for stock heath.
Not all soil-testing laboratories routinely test for all these parameters
- I personally use R J Hill Laboratories. If you want to farm organically
it is helpful to get your soil test done through an organic consultant
so that you get a fertiliser recommendation suitable for your system.
How to establish:
To establish new pasture you need to kill the existing sward by either
- Spraying with herbicides such as glyphosate, followed by direct drilling.
If there are lots of annual species such as barley grass or thistles
it may be necessary to spray in the autumn and again in the spring before
planting.
- Prepare a conventional seedbed to plant into by cultivation.
To ensure that you get the pasture balance you wanted (and sowed), it
is important to sow in early autumn (no later than early March) or early
spring. This is because some of the species used in mixed pastures vary
in their ability to establish at low temperature or are winter dormant
(eg chicory). Late planting will mean that such species are poorly represented
in the pasture.
It is important to drill at 2 -3 cm depth - deeper planting will mean
that some of the small seeds cultivars will not emerge. In dry conditions
this surface can very quickly become dried out and give patchy establishment.
I have found that heavy rolling immediately after drilling restores the
capillary action to the soil and helps to keep the surface moist - which
greatly enhances establishment. In windy areas, such rolling can increase
the risk of wind blow during the establishment phase.
Pasture management:
Planted at the right time, a mixed pasture will establish at about the
same speed as a ryegrass-based pasture. It is desirable to take the first
grazing when the pasture reaches about 10 - 15 cm height, as this will
remove any annual weed growth and encourage the pasture to thicken up.
All the mixtures I have suggested are designed for rotational grazing
rather than set stocking. This does not mean a fresh paddock is needed
every day, but it is desirable to have at least four paddocks your stock
can be rotated around. This pasture should not normally be grazed down
below about 8-10 cms.
Conclusions:
I have designed and trialed mixed pastures (or mixed herb leys) extensively
on farms on the summer dry East Coast areas. These pastures are based
around the species mentioned above, but can incorporate up to 10-12 species.
By addressing many of the inherent limitations of ryegrass-based pastures,
mixed pastures are able to have a considerable impact on the health and
productivity of Alpaca farming systems.
A well established herbal ley pasture in Loburn, North Canterbury, sown
three years ago. Previously this was dry stony riverbed supporting heavy
weed infestations of thistles, broom, storksbill. Wooly mullien. The ground
was repeatedly ploughed over the winter months, and the soil tested and
appropriately fertilised organically prior to sowing. No sprays were used.
The new pasture ("designed" by David Musgrave for the particular
soil types and climate) was quick to establish with no regrowth of the
previous weeds. Some amounts of fat hen appeared the first year which
disappeared after the following winter. No irrigation was available but
this pasture has shown immense ability to withstand extreme drought conditions
due to the deep rooted species used in the pasture mixture.
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