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When
commercial forest plantations are established in most Southern
Hemisphere countries, it is common practice to apply
fertilizer at the time of, or shortly after planting, The
objective is to enable the newly planted tree to take up
sufficient nutrients as soon as possible after planting for
rapid initial growth. Generally, 100 to 150g granular NPK
fertilizer is applied approximately 25 to 30 cm from the
plant. This distance is necessary to prevent root scorching.
However, by the time that the transplant roots have grown to
reach the fertilizer, much of the applied nutrients have
already been leached away. Therefore, fertilization is often
not cost effective.
It is hypothesized that by using Aqua-Soil instead of ordinary
fertilizer:
•
Less nutrients at a lower cost,
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can be applied closer to the roots with an almost instant
beneficial effect,
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which will be longer lasting because of reduced leaching.
With the already proven advantages of Stockosorb added to
these expected benefits, this new product could revolutionise
tree establishment practices.
Therefore, the following trial has been initiated by the
Department of Forest Science of the University of Stellenbosch,
South Africa:
On 7 July 2001, Pinus radiata seedlings, raised in standard
nursery containers, were transplanted into these
pots to simulate planting in the field. Six pots of each
of the nine above-mentioned treatments were placed in each two
growth cabinets set at 25°C/15°C, 16/8 hours day/nigh and 85%
relative humidity. The design is a complete randomized block
in each cabinet. Plants in the one cabinet are irrigated with
300ml water every 6th day vs. 150ml water every sixth day in
the other cabinet. These two treatments simulate a moist and
a relatively dry site respectively.
Weeds are removed regularly by hand. No additional fertilizer
will be applied.
After 3 months,
seedlings will be harvested and their roots gently washed
free of soil. Shoot length was measured immediately after planting
and will be measured again to determine shoot growth during
the trial period. Shoot and root mass will also be determined
when the trial is determined. Data will be subjected to analysis
of variance and if significant, differences among treatment
will be compared with Scheffe's test. |
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