Continuous no‐tillage winter wheat response to nitrogen fertilizer by yield environment.

Maintaining crop residue through no‐tillage (NT) has allowed increased water storage and continuous cropping in dryland wheat (Triticum aestivum L.)‐based systems. However, there is little information regarding nitrogen (N) fertilizer rates for a continuous NT wheat cropping system across various yield environments. The main objective of this study was to determine agronomic optimum N rates for a continuous NT wheat in different yield environments. The study was conducted from 1981 through 2003 at the Kansas State University Agricultural Research Center near Hays, with six N fertilizer rate treatments (0, 22, 45, 67, 90, and 112 kg N ha−1). Experimental years were divided into four yield environments: very low yielding (VLY), low yielding (LY), high yielding (HY), and very high yielding (VHY). Results showed that LY environments required a relatively greater N amount (79–98 kg N ha−1) than HY to VHY environments (72–73 kg N ha−1) to attain optimal yields. The optimal yields at low‐yield environments were smaller (1184–1654 kg ha−1) than in high‐yield environments (2181–2733 kg ha−1). Protein yield increased by 120 g for 1 kg increase in grain yield. We concluded that the optimum N fertilizer rates for continuous NT wheat ranged from 70 to 100 kg N ha−1, but these rates should be adjusted based on yield environments. Core Ideas: Optimal N rate was greater in low‐yield (79–98 kg N ha−1) than high‐yield (72–73 kg N ha−1) environments.Yields at optimal N rate for low‐yield (1184–1654 kg ha−1) were less than high‐yield (2181–2733 kg ha−1) environments.Protein yield increased by 120 g for 1 kg increase in grain yield.No‐tillage N rates should be adjusted based on yield environments. [ABSTRACT FROM AUTHOR]