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Urea and Biuret Stimulate Growth of Douglas‐fir and Western Hemlock Seedlings
Author(s) -
Miller Richard E.,
Anderson Harry W.,
Young Donald C.
Publication year - 1988
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1988.03615995005200010045x
Subject(s) - biuret test , urea , tsuga , chemistry , dry weight , western hemlock , zoology , fertilizer , seedling , botany , horticulture , agronomy , biology , biochemistry
Two experiments were conducted in a greenhouse to test a theory that biuret in urea fertilizer reduces growth of Douglas‐fir [ Pseudotsuga menziesii (Mirb.) Franco] or western hemlock [ Tsuga heterophylla (Raf.) Sarg.]. Newly germinated seedlings in 2.5‐L pots were treated with 0, 0.224, 2.24, or 22.4 kg biuret ha −1 (40% N) in factorial combinations with 0, 84, or 168 kg N ha −1 as reagent‐grade urea (46% N). The biuret was applied as a solution to either the sandy loam soil or the foliage. Four of the eight replicates were harvested 203 d after treatment. For Exp. 2, the remaining seedlings were retreated as they were initially and harvested 305 d later. In both experiments, the two species responded strongly to urea; moreover, seedling dry weight increased with increasing biuret ( P = 0.003). Averaged over all other factors, weight of seedlings treated with the highest biuret dosage was 14% more than the weight of seedlings with no biuret. Unfertilized hemlock responded as much to 0.2 kg biuret ha −1 (0.08 kg N ha −1 ) as to 84 kg N ha −1 as urea; this suggests that biuret functions as a hormone. The results indicated that biuret is unlikely to reduce growth of seedlings of either species even when urea heavily contaminated with biuret is applied at high dosage.