Tagasaste management

Tagasaste management

Tagasaste is a leguminous, drought-tolerant fodder shrub which has made some of the poorest
sandy soils in Western Australia highly productive. On deep pale sands, tagasaste can
increase the annual carrying capacity from one to two DSE
under annual pastures to eight DSE with alleys of tagasaste. However, when it is poorly managed, then tagasaste can quickly grow
beyond the reach of the stock and, if not brought back
under control, there is the telltale legacy of large, out-of-control
tagasaste trees in the paddock. Who better to speak with
about managing tagasaste than Bob Wilson, the president
of Evergreen Farming. Bob has extensive experience
in managing tagasaste on his property near Lancelin, and also has a contract tagasaste
seeding and cutting business. We meet Bob at his property,
aptly named Tagasaste Farm. The farm itself
is around 2,000 hectares and…which about half of that,
about 1,000 hectares, is planted to tagasaste, with about another 400 hectares planted to subtropical
perennial grasses, and the rest is with
traditional annual pastures. Well, we are running all cattle
on the farm. We don’t have any sheep on here
at the moment. We say we’ve increased our carrying
capacity by two to three times with tagasaste. We’ve just finished weighing
some heifers that are putting on about
1.2 kilos per head, per day, over the last three months. That’s a fairly common
growth pattern over the sort of late winter/spring
period. That will slow down, and in summer,
especially with our cow/calf units, we tend to just maintain weight. If we have animals
that we need to put weight on over the summer period, that’s when we do the supplementing
with usually lupins as a supplement on the tagasaste
as well, to maintain growth rate. The main reason it seems that
the lupin supplement is a benefit on a high-protein diet,
which the tagasaste has, is the change in the acid base of the rumen itself. Well, tagasaste
is an evergreen shrub. So, basically,
it’s growing all year round. But in this climate we have
here in Western Australia, obviously, for the growing season, which is the six months of the year
when we get rain normally, that’s its main growth time. The six months dry period that
we normally have over summer, it stays green
but its growth rate slows down and as it goes under
more moisture stress, it also has some other problems
associated with that dry period. And that basically is the levels of phenolic compounds
in the leaves start to rise. And the phenolics, which basically
make the plant bitter, occur at two times of the year,
or two main times of the year. One is after the plant has flowered. And so our whole
management strategy is to try and stop the plant
from flowering, so we graze it
as hard as we can in spring to try and alleviate that flowering. But if it has flowered, it goes into its reproductive stage and the level of phenolic compounds
in the leaves go up as a defence mechanism. It doesn’t want to be eaten. The other time, of course, is during
the moisture stress, during summer, where again it comes under
that stress period and the plant’s defence mechanism
is to try and stop it from being eaten, so the level of phenolics go up again. I’m standing in a paddock
of tagasaste that was planted in 1987. So, it’s 25 years old now. The plantation was laid out
in a double row, two metres apart, with five metres
between the double rows. And the rows themselves are running
in a north-south trajectory. We did that, in the early days, because we were trying to alleviate
the potential wind erosion and most of our winds
either came from the east or the north-west or the south-west. So, we thought by running the rows
north and south, we’d be able to go across
most of those main wind directions. Now, the tagasaste here
has been cut and managed so that it’s under control,
as we call it. This was cut about… ..the final cut was done
about two months ago, and the paddock hadn’t been cut
for about four years before that. So, since that period of time, we’ve had some cattle in
just recently, into this paddock, and they have grazed this down, although it does need more grazing and we’ll put cattle in again
very soon. What we’re trying to do
with the tagasaste is maintain it at a height here
of a bit below a metre and try to keep the plants
in what we call a broccoli shape. Now, basically, that just means we want the new growth eaten down
as it grows. So, you can see
that the main area here has been chewed down fairly hard
by the animals and has new growth
coming up from underneath it. I have in my hand
a longer piece of tagasaste, which comes from another plant
that hasn’t been grazed. This is in need of grazing
very quickly. The cattle will graze what we call down to maybe pencil thickness
of the stem. But the, um… I think this is
not quite pencil thickness. But this needs grazing very quickly
to keep it under control. So, we’ll put 150 cows and calves
into this 20-hectare paddock and run them around fairly hard
for about a week, and then move them out, so that they’ll then
come back in again in about another three weeks
after that. Our main focus with
the management of the tagasaste is to try and stop the plants
from flowering. Now, we either do that by great
judicious grazing management or occasionally,
we have to cut the plants to get them back under control so that then the stock
can keep on top of it. So, you’ll notice here,
there’s the occasional flower, but that’s…in the main, we’ve cut most of
the older growth off and so it’s all new growth
that’s here now. So, this is now very tasty and the cattle will graze this happily
for the next two or three years before we may have to cut it again. What we’re looking at here
is a row of tagasaste that we’re starting to manage,
or cut and manage. Now, what we’ve done
is we’ve cut the centre out of the row of tagasaste – the big branches in the middle – about three to four months ago. We’re now allowing it to regrow
in the middle so that it gives some stability
to the tagasaste, and then we’ll come in
and cut the edges off very soon, which will bring the tagasaste plant
back to a good hedge row. Well, you look around this paddock and we’re looking at the height,
for one. This paddock was actually cut in the middle last year, so it’s not as high as it could be, but it’s getting out of control. We’re looking to get all this fresh
growth underneath exposed ’cause it’s just getting shaded out
as it is now, so we’ve got to open it up
and let it rejuvenate. We aim to cut
once every five years here, just to keep the plants rejuvenated
and fresh growth on it, because once it gets this old leaf, the stock just don’t want to touch it. So, you keep it fresh
and you don’t have any problems. Flat cut across the top for a start,
and that’ll open it up, and that’ll leave
the bush out like that, and then I’ll do an outside cut. Then I’ll reach over with the arm
and do an inside cut. And that’ll just expose
the whole bush then, and usually we would have stock,
if we have enough cattle… ..uh, they’d eat this stuff. It sweetens right up
after a couple of days and it’s really good fodder, actually. And then just
let the paddock rejuvenate. After about three months,
you’ll have stock back in here, all freshly growing and beautiful. Well, the thing with the tagasaste is that it’s being grown mainly
on some of the poorest sands in the West Midlands area or throughout Western Australia. And, obviously, these sands are deficient in every mineral
known to man. But tagasaste certainly has
a huge requirement for phosphate. It’s probably its main element
that it needs is superphosphate. But when we plant tagasaste
into a paddock, it’s not a monoculture. We have it planted in rows and
we have the inter-row in between. And the pastures that we grow
in the inter-row usually respond to potash as well. So, we use the normal system of trace elements,
super copper zinc, every sort of five or ten years, and super and potash every year. And in some of the poorest
of the sands, we also find that we’ve had
a manganese deficiency. Our main challenge here,
every now and then, is the wingless grasshoppers
over summer, which can affect the grazing
of the tagasaste. The wingless grasshoppers are
a problem that occurs on our farm. They don’t come from elsewhere because they don’t fly in,
like locusts do. But they can cause problems because they occur
around December, and the December period,
they’ll eat the leaf and even if they don’t
defoliate the plant, what the plant does, it actually reacts
to the grazing of the grasshopper and increases its levels of phenolics. So, two things occur. One is that the grasshoppers are
eating some of the new green leaf that the cattle should be eating. But the other thing is the plant reacts,
as a defence mechanism, and raises the level of phenolics
in the plant and so the stock
don’t eat as much anyway, because it’s become bitter. Here on Tagasaste Farm, we’ve planted all the tagasaste at… ..we have a double row,
two metres apart, and we have an inter-row of
six metres between the double row. Now, we started planting that
back in the late ’80s, when we knew very little about how the tagasaste plantation
should be set up. What we’ve discovered is that we probably planted
those rows too close and we tended to develop into
a little bit of a monoculture. Our aim now, in the sowings
that we do around the State, is probably a minimum of eight,
possibly ten metres, between the inter-row space. So, it allows for more of
a balanced pasture mix. Back behind me, in the paddock, about every 20th row I’ve decided to leave
a row of tagasaste to grow up to mature height, mainly just for shade
and shelter during summer. And it’s been great to be able to
come out here in the middle of summer,
when it’s 40 degrees, and see the cattle utilising the shade
from the tagasaste.

One thought on “Tagasaste management

  1. Hi team, I've been thinking about growing this tree for some time, but in drought now. Did you grow from seed and if so did you inoculate so it can fix nitrogen? Great presentation BTW

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