Controlled-release urea for winter wheat in southern Alberta

• Published in: Canadian journal of soil science Vol. 87; no. 1; pp. 85 - 91
• Main Authors: McKenzie, R H, Bremer, E., Middleton, A B, Pfiffner, P G, Dowbenko, R E
• Format: Journal Article
• Language: English
• Published: 01.01.2007
• ISSN: 0008-4271; 1918-1841
• DOI: 10.4141/S06-055

The recent development of low-cost controlled-release urea (CRU) may provide additional options for N fertilization of winter wheat (Triticum aestivum L.). Two field experiments were conducted over 3 yr at three locations in southern Alberta to evaluate different options of applying CRU to winter wheat. In the first experiment, three N fertilizers (20-day CRU, 40-day CRU and urea) were seed-placed and side-banded at the time of seeding at 0, 30, 60, 90 and 120 kg N ha -1 . Stand densities were substantially reduced by seedrow application of urea at rates greater than 30 kg N ha -1 , but were unaffected by seedrow application of CRU, even at the highest rate of N application. When N fertilizer was sidebanded, stand densities were unaffected by fertilizer type or N rate. Yield gains due to N application were reduced by application of high rates of seed-placed urea, but similar for other treatments. Grain protein concentration and N uptake were also similar for CRU and seed-placed urea. In the second experiment, three N fertilizers (CRU, urea and ammonium nitrate) were broadcast at 30 kg N ha -1 in early spring on plots that had received 0, 30 or 60 kg N ha -1 of CRU at the time of seeding. Inadequate release of spring broadcast CRU was indicated by reduced grain protein concentrations relative to conventional N fertilizers. Under the conditions experienced in our study, CRU substantially increased the maximum safe rate of seed-placed urea, provided minimal benefits to N response relative to side-banded urea, and was less effective than conventional N fertilizers when broadcast in early spring. Key words: N fertilizer use efficiency, slow release, winter survival