Gross N Cycling in Simple Rotations: Do Pulse Crops Make a Difference?.

Pulse crops in rotation improve the sustainability of cropping systems through biological N fixation, but the benefit of pulses is also proposed to extend beyond the year of pulse production. To quantify any additional benefits, soil processes and properties related to N and C cycling were examined in long-term crop rotations with and without pulse crops at two Agriculture and Agri-Food Canada Research Stations: Scott, SK (pea-wheat, canola-wheat, continuous wheat) and Swift Current, SK (lentil-wheat and continuous wheat). Stable ¹⁵N isotope dilution was used to quantify gross mineralization and nitrification rates for three years at Scott and two years at Swift Current. Measurements were completed annually at pre-seeding, anthesis and post-harvest. Results will be presented and related to additional measures of residue quantity and quality. Implications for crop rotations will be discussed.