Nitrogen Fertilization of No‐Till Winter Wheat and Rye. I. Yield and Agronomic Responses

Abstract

AbstractWinter 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.