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ŠUMARSKI LIST 3-4/1969 str. 21     <-- 21 -->        PDF

CHLOROSIS OF NORWAY SPRUCE IN
YOUNG CULTURES IN THE AREA OF HEATHER-SOILS


Summary


Outside its natural range Norway Spruce is cultivated in northern Croatia in
heather and bracken meadows. In young Spruce cultures the authors have established
a widespread phenomenon of needle chlorosis and poor rate of growth.
The chlorosis of needles lasts throughout the year. Preliminary investigations have
shown that the chlorotic Spruce plants cultivated on heath soils possess low concentrations
of nitrogen and phosphorus in the needles. In a typically chlorotic
culture near Plaški was laid out in the spring of 1967 a fertilizing trial aimining
at establishing whether the causes of the needle chlorosis and of the poor growth
lie in the edaphic conditions of plant nutrition. The culture is 4 + 6 years old with
a spacing of 2x2 m. According to data of the weather station Plaški lying at a distance
of 4 km. the mean temperatures of the seasons are: spring 9,2°, summer 18,2°,
autumn 11,1°, and winter 0,3* C.


The monthly rainfall amounts to: 127 (Jan.), 127 (Febr.), 108 (March), 106
(April), 142 (May), 112 (June), 87 (July), 78 (Aug.), 136 (Sept., 157 (Oct.), 156 (Nov.),
and 141 mm (Dec). The soil belongs to the type of the acid brown soil on relict
terra rossa. Below soil layers several metres deep there lie stratified Triassic dolomites.
The soils possess very favourabl physical properties (Tabs. 2 and 3).


— The experiment included the following variants of fertilization: O, NP, NK,
KP, NPK and NPKMg. Per one plant were applied 100 g. nitromoncal, 150 g. superphosphate,
100 g. potassium salts, and 133 g. sulphate of potash-magnesia. The
experiment was laid out according to the randomized block system with three
replications.
— Results of experiments: the fertilization reflected itself positively in an
increase of the height growth in all variants (Tab. 4).The highest effect was shown
in those variants to which nitrogen was applied, and specially the NPKMg-variant,
in which the volumes of terminal shoots in the second experimental year were
nearly ten times higher than in the control. Through the application of mineral
fertilizers were considerably increased the concentrations of N, Ca and P in the
needles (Tab. 5), and the Occurence of needle chlorosis disappeared completely,
except for the KP-variant. After fertilization the needles assumed a normal appearance,
their growth increased up to twofold, likewise the number of lateral shoots
and their size increased (Photo 1). In contrast to Norway Spruce in the investigated
area, Scots Pine and Eastern White Pine did not manifest any symptoms of
chlorosis and showed a good nutritional condition.