Growing Poplar and Willow Trees on Farms, National - FAO

The greater the area of trees, then the greater the costs that must be carried
each year. Hence, in non-drought years, the farm operating surplus is
decreased by the cost associated with having the trees. Based on current
costs <strong>and</strong> prices, for a 600 ha Otago farm, up to 4 ha (0.7% of farm area) of
pollarded poplars is profitable if the labour costs are not included. On a
North Isl<strong>and</strong> hill country farm, however, where there is a higher sheep
stocking rate, up to 2% of the farm area in pollarded poplars may be
profitable if labour costs are not included.
5.2 Browse willows for sheep grazing
The willow browse block is planted at 7,000 trees/ha. Often, an area is
chosen which is constantly waterlogged, <strong>and</strong> hence produces very little
pasture, especially during winter. The willows have the effect of drying the
soil, allowing more pasture to grow <strong>and</strong> be grazed throughout the year.
Hence this system can result in extra pasture production along with the tree
biomass, compared with similar areas without trees. On this basis, extra
stock are wintered on the browse block. The willow block has a high
establishment cost ($9,870/ha including labour, $7,320 without) due to the
high plant population. There is also a loss of grazing during the
establishment phase, but this is minimal due to the low initial pasture
production.
For a 500 ha Wairarapa case study farm, up to 2 ha (0.4% of farm area) of
browse willow was profitable if the labour costs were not counted. If the
willow tree crop lasts only ten years, then the establishment costs double
within a twenty-year period, <strong>and</strong> each crop provides fodder for only two
droughts. On this basis alone, the crop would be unprofitable, however, the
crop needs to be grazed each year, <strong>and</strong> as further information is gained, the
net benefit of annual grazings needs to be reviewed.
5.3 <strong>Willow</strong>s for dairy effluent uptake <strong>and</strong> forage
For the case study property at Clydevale, Otago, willow cuttings were
planted at 7,200/ha on 0.6 ha <strong>and</strong> a ‘K-Line’ irrigation system was installed
(new line only, the base infrastructure was already on the farm). The edible
yield in February 2006 was about 0.35 kg DM/tree from the trees planted as
cuttings. At about 90% tree survival (6,480 trees/ha), this equates to 2,268
kg DM/ha for the first 18 months. It has been projected that once
67