THE SCIENTIFIC BASIS FOR USING "NUTRIENT LOADED SUPERTREE SEEDLINGS"
The November/December 2001 issue
of “Tree Lines”, a bimonthly newsletter of the Nurseries & Orchards Group
of International Paper Company, introduced a new product called “Nutrient Loaded
SuperTree Seedlings.” It stated, “When
handled and planted properly, they should provide you with improved performance
the very first year…We are conducting ongoing research on nutrient loaded
seedlings in plantings across the South.”
For nearly ten years our
scientific advisor on such matters has been Dr. David B. South, Professor of
Forestry, Auburn University who works with the Southern Forest Nursery
Management Cooperative, so we asked for his opinion on this product. He replied, “I think this has merit. I have argued for some time that our
seedlings have been underfertilized with nitrogen (N) in the nursery. As a result, their nitrogen status IMPROVES
after outplanting, i.e., N% in foliage increases. The really nice thing is this treatment is very inexpensive. Potential benefit/cost ratio is great.”
“Benefits are not as great as
those obtained from low-density seedlings, but on some sites, the boost in
first-year height growth may be 7% to 15% more than regular seedlings. Researchers at the University of Florida
found that when survival of control seedlings was less than 85%, survival was
improved by 10% or more by fall N fertilization.” South has summarized some of the studies on a web page: http://www.forestry.auburn.edu/sfnmc/class/outplanting/sld001.htm.
He also cited these published studies:
Blake, J. I. And D. B. South.1990
Extra nitrogen in pine nursery boosts forest wood growth. Ala. Agr. Exp. Sta.
Highlights Agr. Res. 37(2):13 http://www.forestry.auburn.edu/sfnmc/pubs/manuscri/highlights/extra.html
(Note that figures 1 and 2 are printed side by side. To view figure 2 showing difference in height growth, you must
scroll to the right.)
Irwin, K., M.L. Duryea, and E.L.
Stone. 1999. Fall-applied nitrogen improves performance of 1-0 slash pine
nursery seedlings after outplanting. Southern Journal of Applied Forestry.
22:111-116.
Sung, S.S., C.C., Black, T.L.
Kormanik, S.J. Zarnoch, P.P. Kormanik and P.A. Counce. 1997.
Fall nitrogen fertilization and
the biology of Pinus taeda seedling development. Canadian Journal of Forest
Research. 27:1406-1412.
Williams, H. M. and D. B. South.
1992. Effects of fall fertilizer applications on mitotic index and bud dormancy
of loblolly pine seedlings. Forest
Science 38:336-349
The study by Blake and South
states, “Applying extra nitrogen fertilizer in the nursery also resulted in
increased growth in the field, even when comparing seedlings with the same
needle mass, figure 2. Thus, seedling
nutrition appears to benefit growth in ways other than simply increasing
seedling size. This results from an
increase in the rates of photosynthesis of plants with the same amount of
needles…Subsequent observations indicate that the early effects of improved
nitrogen on growth will continue to affect yields as the plantation
develops.”
IPCO may discover other benefits in its research, but
because of the compounding effect of tree growth, the small improvement
reported above will increase harvest a significant amount in 20+ years. We urge you to use them, but stress that
they must be “handled and planted properly.”
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