Optimizing the role of pulses in crop rotation: biological nitrogen fixation

Non-Peer ReviewedThe Pulse Research Network is a national research network aimed at optimizing the benefits of pulses in rotation. The network is funded through Agriculture Agrifood Canada (AAFC) through the Agriculture Bioproducts Initiative program (ABIP). A group of scientists in the Department of Soil Science at the University of Saskatchewan and Agriculture Agrifood Canada – Saskatoon are involved in the “Cropping Systems Module”. Research streams in this module are focused on maximizing 1) the N‐benefits, 2) the environmental benefits (i.e., carbon benefits), and 3) identifying best management strategies to optimize the beneficial role of pulses in crop rotations. While the role of biological nitrogen fixation (BNF) in supplying N to the pulse is generally well understood, the benefit of the pulse to the subsequent crops in rotation is less clear. A particular focus of the research is to quantify root N and rhizosphere N contributions to the soil N pools. The general approach taken in the research is to label plants with stable isotopes (15N and 13C) and quantify contributions to soil N and C fractions. A key component to maximizing the role of pulses in rotations is to determine how often a pulse should be included to achieve maximum benefit. As a part of this objective, a study was initiated to determine if frequency of inclusion affected BNF in the pulse year of the rotation. Results from this study are reported here