Nitrogen use in spring wheat affected by crop diversification, management, and tillage

Abstract

AbstractDryland wheat production potential in the northern Great Plains (NGP) often is limited by N availability affected by various management practices. A 4‐yr study was conducted in northeast Montana to relate spring wheat (Triticum aestivum L.) productivity and N utilization to management system (conventional and ecological), tillage (till and no‐till), and four crop rotations (continuous spring wheat, spring wheat–pea [Pisum sativum L.], spring wheat–hay barley [Hordeum vulgare L.]–pea, and spring wheat–hay barley–corn [Zea mays L.]–pea). Ecological management included greater seeding rates, delayed planting dates, banded N fertilizer, and increased stubble height compared with conventional management with standard seeding rates and planting dates, short stubble height, and broadcast N fertilizer. Continuous spring wheat showed the lowest grain yield, with the least efficient utilization of N compared with 2‐, 3‐, and 4‐yr rotations. Mineral nitrogen use efficiency was 37% lower for continuous wheat than for other rotations. Increasing the complexity of crop rotation had little impact on wheat production or N relationships. The delayed planting date associated with ecological management of spring wheat contributed to 33% less efficient use of N compared with an early planting date with conventional management. Overall, results indicated that crop rotation and management system often affected N relationships with wheat production, whereas the effects of tillage differed with year. Differences in yield and N use of spring wheat varied among years, underscoring the need to refine management systems given the highly variable precipitation patterns typical of the NGP.