| Summary: | The experiments discussed in this thesis are part of a continuing research program testing the influences of chemical fertilizers on the survival, growth and cone production of Douglas fir in coastal British Columbia. This study was initiated in the early spring of 1963 by the Consolidated Mining and Smelting Company of Canada Limited, Trail, B. C, and the Faculty of Forestry of the University of British Columbia.
The thesis summarizes the influence of several chemical fertilizers on the survival and growth of planted Douglas fir seedlings from the beginning of the study to the present date.
During the first phase of this study, the responses of planted Douglas fir to chemical fertilization have been investigated by four experiments.
The first experiment, a trial of slowly soluble fertilizers, was initiated at the end of April, 1963, at three locations: U.B.C. Campus nursery, and TS 3 and TS 32b in the U.B.C. Research Forest. In a split plot design arrangement, Magamp, Urea, Aqua humus, Cxamide, Thiourea, Sludge and a bark product were dumped into or mixed with the soil in the holes made for the planting of four size classes of Douglas fir seedlings.
At the end of April, 1964, the trial of slowly soluble fertilizers was repeated on the same locations. This time, the response to three Magamp particle sizes (commercially distributed Magamp, Magamp -6+8, and Magamp -8+10) as well as Sludge, Uramite and Thiourea was tested. Additional information concerning survival of planted Douglas fir seedlings was obtained from the Tahsis Logging Company at Gold River, B. C, which,
in 1963, carried out a similar experiment with the same slowly soluble fertilizers.
In all cases, the use of more readily soluble sources of nitrogen resulted in excessive mortality.
The climate in 1963 and 1961; substantially influenced the survival and growth of the fertilized seedlings.
In the second experiment, the response of Douglas fir seedlings planted in 1953, 1956 and 1959 to ammonium nitrate was investigated in the U.B.C. Forest. Nitraprills was applied randomly at six levels (0 to 800 lb. of nitrogen par acre) to a total of 360 trees. Treatments
were applied in May of 1963 and 1964 at the time of flushing of vegetative buds. To date, the fertilization has improved neither height growth nor diameter increment and has had no influence on cone production.
The third experiment was initiated at the end of December, 1963, in the U.B.C. Campus greenhouse. A. six-factor experiment was designed to test the responses of 2+0 planted Douglas fir seedlings to Magamp and Mitraprills.
The fourth experiment was planned to compare the effects of Magamp and Nitraprills on 2+0 planted Douglas fir seedlings in the field in the U.B.C. Research Forest during the summer of 1964.
The results of the third and fourth experiments have proved that the slowly soluble Magamp is more advantageous to seedlings than is the rapidly soluble Nitraprills when both are applied at the time of planting. However,
these analyses have shown limited advantage to using either fertilizer
during planting. The studies of these fertilizers should be continued and extended to include other sources of slowly soluble nitrogen. === Forestry, Faculty of === Graduate
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