Oat, pea, and canola intercropping: An investigation of the agronomic benefits and underlying biological mechanisms of a multi-crop forage system

Abstract

Oat, pea, and canola intercropping can provide benefits in terms of beef cattle forage as it can provide stable biomass and nutritional yield. Two underlying mechanisms were examined as potential explanations to its stability: 1) plant water use efficiency, and 2) arbuscular mycorrhizal fungi (AMF) community composition. This two-year project was a two-factor complete block design located at the Peace Country Beef and Forage Association research farm (Fairview, Alberta), where forage biomass, nutritive indicators, normalized difference vegetation index (NDVI), photosystem II photosynthetic efficiency (P[II]), water use, and mycorrhizal communities were sampled yearly. The two factors present in this project are intercropping systems and nitrogen (N) fertilizer addition. In Chapter 1, basic concepts that pertain to this project are revisited through previous studies with similar experimental designs. Chapter 2 provides insights to forage biomass and quality obtained from the project as a study of the benefits of intercropping as beef cattle forage. In general, intercropping was found have very stable biomass yield, as well as forage quality. The effect of N fertilizer depended heavily on the cropping system. Pea-canola intercropping performs better than pea alone or canola alone in terms of crude protein and certain mineral contents. Chapter 3 provides insights to water use efficiency (WUE) and water uptake, where pea-canola intercropping demonstrated promising increase in WUE. These results also showed that increased water uptake does not consistently translate to improved WUE. Additionally, the effects of N fertilizer were only significant in a wetter growing season. In Chapter 4, AMF communities were observed to increase in diversity when intercropping oat and pea, and the effects of N fertilizer was present in the drier year when the difference in AMF abundance was significantly different. Key genera were identified for the intercropping system examined and provided insight to how it could be further studied. Chapter 5 summarizes the project and provides potential directions to further the results found in this project.