No. 22 Poplars and willows for drought fodder
NEW ZEALAND FARM FORESTRY ASSOCIATION INFORMATION LEAFLET
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Part of John Prebble’s
poplar drought fodder operation.
Electric break fence shown in background in front of standing trees.Photo:
John Prebble
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Poplars
Willows
Poplars
After the 1988-89 drought I decided to plant an area in poplars with
the specific intention of using them solely for stock fodder in the
next drought. I planted about 500 wands 5 x 5m spacing and this covered
just over 1ha.
The first lesson I learnt was that poplars are quite site-selective.
The planting site included a small flat and two hollows, and poplars
planted off the valley floor did very poorly, some not surviving. In
future plantings I will use rooted cuttings instead of wands which,
although starting well, seemed to root shallowly into the surface layer
of soil making them liable to die in the first summer in a dry spell.
The variety ‘Flevo’ was used with a few ‘Tasman’ spread through the
planting, and some ‘Kawa’ were added in gaps some 3 to 4 years later.
Future plantings will be of ‘Flevo’ because its leaf yield was superior
to that of Tasman. The dry knobs of the block that was just on 2ha
overall were planted in radiata
pine.
The whole block was shut up for the first three years and some light
grazing has been taken from then on. The block has been monitored
regularly and stock removed if any bark damage occurred.
Dry sheep proved to be the best animals for grazing, causing the least
damage. In contrast, the flock rams were put in one hot summer to give
them the benefit of the shade and plentiful pasture, but in one night
they decided to have a mainly bark diet and were quickly removed!
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Good utilisation of the felled poplar, including all the bark
on the
trunk!
Photo: John Prebble |
In the autumn of 1998, with the drought starting to become severe, I
decided that the time had come to use the poplars, with the best of
them now being over 10m tall.
There was stock water in the flat area so with a single electric wire,
I fenced off one row of trees, felled part of the row and introduced
thirty-three 18-month steers and heifers. The question was, how many
trees were needed to feed the cattle? Eight to ten trees were cut each
day, with numbers increased if the trees were smaller.
The trees were cut about 1m above the ground, a good height to safely
operate a chainsaw and not require any climbing. It also meant
that the job could be done quite quickly. Using this method and
shifting the electric wire as necessary, the block of just over 1 ha
lasted 30 days, with the 33
cattle gaining weight. Before the cattle were put into the poplars, all
the killable cattle from the herd had been drafted, and on removal from
the poplars, another 12 were drafted, showing that the cattle grew as
fast on poplars as they would have on grass at this time of the year.
From my experience:
- Poplars are very site-selective and to get good yields of leaves,
loamy valley soils are best.
- Poplar leaves are equivalent in feed value to good lucerne hay.
- Poplar leaves have a high dry-matter content and a greater
variety of
minerals and trace elements brought up from the deeper subsoil that
normal pasture can’t source. This may account for the shiny coats of
the cattle after about two weeks browsing on poplars.
- Cutting trees 1m above the ground is simple and fast, requiring
minimum daily time, and leaves plenty of stump area for coppice
regrowth. Shoots appeared about 6 weeks after the trees were cut.
- Cut stumps were painted to reduce the risk of fungal infection.
I estimate that the next crop from this block will be ready for feeding
in about five years, and I will select 3 to 4 shoots to grow on each
stump. Some further fine tuning is needed to estimate the yield of
leaves from the trees to help with determining how much feed is
required for each animal each day. Poplars have proven to be a good
source of fodder in drought times on my property, and with this
success, I will be looking at planting other suitable small areas into
poplars for feeding to livestock to cope with future droughts.
(top)
Willows
Like many areas of the East Coast of New Zealand in 1998, our normally
summer-safe part of Hawkes Bay was severely affected by drought. In
past dry spells we have cut both willow and poplar for emergency feed
for cattle and sheep, but the seriousness of the drought meant that
this year willow
especially became an integral part of our supplementary feed
regime.
We began cutting in mid-February to help eke out the remaining pasture,
but as it became apparent that there was going to be little or no
autumn rain, cutting began in earnest, to be fed along with bought-in
oat balage. As we worked our way through the various blocks (planted
for erosion control, rather than specialist fodder), it became obvious
that more thought needed to be given as to how the trees were cut.
In the past we had tried to make the job as neat as possible, with
branches cut flush with the trunk, leaving trees looking either like
pollarded avenue specimens, or some sort of pruned butt. On the second
rotation however, these trees proved very difficult to work with, if
not downright dangerous. The remaining branches were too big and too
far off the ground to be safely dealt with, or the pollarded crowns
weren’t big enough to confidently stand in without a high risk of the
branches giving way under your weight. It is very easy to drive around
in the ute and talk about dropping a few branches for the cows, but far
less so when it comes to standing underneath a 12yr old tree, and
working out how it can be done without endangering lives, limbs and
equipment!
It also became obvious that the bigger the branch did not necessarily
mean more dry matter per time and risk spent cutting it. Bigger is not
best. Regrowth from earlier cutting proved to have far more luxurious
growth, thus more dry matter per branch. From all this we deduced that
for optimum fodder production regular cutting is preferable (every 5 or
6 years), and that leaving a large and somewhat ugly crown makes for a
safer platform to work in.
Willows are extremely dangerous to work with. Seemingly innocuous
branches will split and kick-back without warning, jamming saws and
causing many adrenalin rushes. It is imperative to have a spare saw and
a second person handy should problems arise. Having said that, the
willow we have planted has proved to be a very valuable
drought management tool, providing good food from foliage,
small twigs, and bark.
(top)
The article on poplars by John Prebble, appeared with
photos in the May
1998 issue of the New
Zealand
Tree Grower, while the article on willows by Michael
Halliday appeared with photos in the August 1998 issue of the New Zealand Tree
Grower.
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