Forestneeds

Typical annual stem diametre increments of around 10mm dont bode well for totara’s success as a commercial forestry crop. At a recent Northland Totara Working Group field day. Randal Austen told of annual stem diametre increments of 20mm after (non-targeted) application of superphosphate. We might ask what gains could come from targeted nutrient application; or even what proportions of what elements the tree uses. I suspect that certain factors in how totara has come to fill its ecological or evolutionary niche, means that it has higher resource needs than some other trees. The essential oils it produces also puts it in a high durability class, with perhaps similar needs as the durable cypresses or eucalypts. However, if nutrient availability is low, growth might also be low and tree form and health may be inferior. Open grown totara typically has lots of big branches and often is multi-leadered. The generally accepted theory is that having tightly spaced totara trees is the main foctor in producing clear stems. Sure, inter-tree competion and both light and wind sheltering are important in tree form, as is genetics. as is nutrition. My own observations around the North Island of New Zealand are that in at least some districts totara health and/or form is less than optimal, with multiple leaders and a predominance of high angled branches even on closely grown forest stands; foliage yellower or bronzier and sparser than need be; and I am left with a suspicion concerning insufficient rooting extent. This leads me to believe that intelligent additions of nutrients are part of the answer to impovement in health and form . Knowing what the tree is up to would be a big help in planning nutrient delivery. However, there has been no published studies on totara physiological processes; nor data on nutrient use within the tree. So, I got Hills Laboratories in Hamilton to analyse my trees and soil. It is an argicultural testing lab, so the soil test is for available nutrients rather than total element amounts within the sample. I will be getting another lab to tell me the totals; and plan to have samples from some more vigorous totara from elsewhere analysed.The stem sample was from the darkest pinky brown, 50mm from the centre of the trunks, the closest that I could get to true heartwood. The ‘foliage included the last 12 months branchlet growth as well as the needles, so it probably also represented a sapwood mix.It may have been bettter to have stripped the needles off the branchlets and had the 2 samples analysed separately. I also havent yet had an analysis of heartwood; that should be on the list of to dos. In the mean time the data below is a start and may help a little in understanding what totara is up to with resource allocation. I have a tentative opinion, however, I’d prefer to see some other comments before I do.

Soil

pH …………………5.3
Olsen P (mg/L)… 5
K (me/100g) …….0.52
Ca (me/100g)…… 2.1
Mg (me/100g)……2.34
Na (me/100g)…… 0.25
CEC 15
Base saturation K 3.5 Ca 14 Mg 15.8 Na 1.7
B (mg/kg) ………………1.2
P (Melich3) (mg/L) …..5
Fe (Melich3) (mg/L) 283
Mn (Melich3) (mg/L) 14.1
Zn (Melich3) (mg/L)… 0.81
Cu (Melich3) (mg/L)… 0.5
B (Melich3) (mg/L) …<0.5
Co (Melich3) (mg/L) 0,1

Al (Melich3)……….1480

Foliage ………………………………………………………………………Stem
N…. 0.9 %……………………………………………………………………… 0.2 %
P…. 0.1 %………………………………………………………………………. 0.02 %
K ….1.1 % ……………………………………………………………………….0.1 %
S…. 0.09 %…………………………………………………………………….. 0.02 %
Ca… 1.71 % ……………………………………………………………………..0.17 %
Mg.. 0.15 %…………………………………………………………………….. 0.02 %
Na.. 0.04 %……………………………………………………………………… 0.01 %

Fe (mg/kg) …74 …………………………………………………………….196
Mn (mg/kg) 130……………………………………………………………….. 9
Zn (mg/kg) …13……………………………………………………………….. 7
Cu (mg/kg)      3………………………………………………………………. 4
B (mg/kg) …..17 ……………………………………………………………….3
Mo (mg/kg) ….0.08…………………………………………………………… 0.07
Co (mg/kg)….. 0.22 ……………………………………………………………0.25
Se (mg/kg)…… 0.04…………………………………………………………… 0.01
Al(mg/kg) ….100 ……………………………………………………………/287