Nitrogen Fertilization of No-Till Winter Wheat and Rye. I. Yield and Agronomic Responses
- D. B. Fowler ,
- J. Brydon and
- R. J. Baker
Winter wheat (Triticum aestivum L.) and rye (Secale cereale L.) can be grown successfully in most parts of western Canada if sown directly into standing stubble. However, soil N is usually limiting under this production system. Consequently, 40 field trials were conducted over a range of soil types and environmental conditions to determine yield and other agronomic responses of no-till winter wheat and rye to N fertilizer applied in the spring. Each trial consisted of three to 12 replications with N rates of 0 to 303 kg ha−1. Nitrogen fertilizer had little effect on days to heading, days to maturity, test weight, and seed weight. Increased N resulted in height increases of up to 25 cm in wheat and 8 cm in rye in some trials, and decreases of up to 9 cm in both wheat and rye in other trials. Winter rye demonstrated a greater N use efficiency and yield potential than winter wheat. The relationships between grain yield (Y) and total available N were best described by modified inverse polynomials, Y = (1 − N/903) uN/(N + u/65.8) for wheat, and Y = (1 − N/800) uN/(N + u/88.5) for rye, where u represents the upper limit of yield when N is not limiting. These curves accounted for 99.3 and 98.7% of the observed variation in grain yield of wheat and rye, respectively. Maximum yields were related to moisture status during the growing season and were achieved at different rates of N fertilization.
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