The slow release fertilizers urea formaldehyde, sulphur coated urea (SCU), agriform 20-6-10, osmocote 18-6-12 and osmocote 18-5-11 were compared with ammonium sulphate (21-0-0) and ammonium phosphate (11-55-0) in the nursery. Fertilizers were banded into the bed below the seed, except for ammonium sulphate which was top dressed three times during the first year. The fertilizers were applied at rates supply 60 and 90 kg nitrogen (N) per ha, and a control treatment receiving no N was included.
The faster releasing osrnocote (18-6-12) and ammonium phosphate produced the largest 1-0 Douglas-fir. The advantage in dry matter content over ammonium sulphate was about 12%. Largest 1-0 white spruce seedlings were obtained with osmocote 18-5-11 and ammonium sulphate. Urea formaldehyde was also effective for this species. During the second year of growth the advantage of the 12-14 month release osmocote became more evident, with an increase in spruce dry matter content, over the ammonium sulphate treatment of 21% and over the control of 42%.
Since the same total amount of N was supplied by all treatments these differences must have largely been attributable to the rate of release, the form of the N, or the other nutrients which the fertilizer supplied. Both osmocote fertilizers and agriform contained K, for which no compensation was made, although the P supplied by each fertilizer was balanced, except in the case of ammonium phosphate. The ammonium phosphate treatment actually supplied about twice as much P as the other treatments. Ammonium phosphate was one of the three best fertilizers in producing large 1-0 Douglas-fir, but it was not particularly satisfactory for spruce. The other two effective fertilizers for Douglas-fir were osmocote 18-6-12, which contained P, and SCU, which contained no P. However it was also observed that uptake of P per seedling was highest for these three fertilizers (ammonium phosphate, SCU and osmocote 18-6-12) in 1-0 Douglas-fir. Thus P availability as well as N release rate may have been important for Douglas-fir.
Uptake efficiency of fertilizer N, at the 60 kg N per ha treatment level, averaged 35% for 1-0 Douglas-fir and 7.4% for white spruce. Uptake efficiency was relatively unaffected by level for the slow release fertilizers, but dropped sharply for ammonium sulphate with increase of level.
Slow release fertilizers have some potential for improving growth of seedlings in the nursery, but are expensive (Osmocote 18-5-11 costs about five times as much as ammonium sulphate). However the cost of fertilizer is not a large portion of the total cost of seedling production, but fertilizer may have a big effect on the final size, and possibly quality, of the seedling. Thus substantial increases in expenditure for purchase of slow release fertilizers may be justified.
For further information please contact:
R. van den Driessche
Senior Tree Physiologist
B.C. Ministry of Forests
[Abstract contains full text of memo.]
BC Forest Service - Research Division. 1980. E.P. 640.66 Growth of Douglas-fir and white spruce seedlings treated with slow release fertilizers in the nursery. British Columbia Ministry of Forests, Lands, Natural Resource Operations and Rural Development. Research Memo (FLNRORD). RM39
Topic: FLNRORD Research Program
Keywords: FLNRORD, Research Memo, British Columbia
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