Balancing sustainability and profitability: the role of crop varieties and crop rotations

As one of the largest grain exporters, Canada requires increasing grain production to meet the global food demands. Grain producers have been seeking effective approaches to increase crop yields, improve resource use efficiencies or minimize input costs, enhance agroecosystem resiliency and the whole-farm economics, and decrease the negative impact of farming on the environment while protecting the soil resource.

To achieve those multiple goals simultaneously, a systems approach must be taken where Best Management Practices (BMPs) are integrated together into the cropping systems. This project will evaluate six (6) carefully designed cropping systems at seven major Canadian prairie ecosites. Six sets of scientific data will be collected to achieve the following four objectives:

1. Increase crop yield and improve whole-farm economic outcomes.
2. Enhance the system resiliency (i.e., reducing risks to abiotic and biotic stresses or having a rapid recovery from stress-induced damages).
3. Improve soil nutrients supplying power and soil health.
4. Decrease the environmental footprint.

In Beaverlodge and Lacombe, a rotation sequence of canola - malt barley – canola - canola was a market-driven rotation. As canola requires a large amount of nitrogen, the market-driven system in those locations had the largest amount of N inputs compared to other systems. Rotation systems with legumes, on the other hand, require less N fertilizer as legumes fix their required N from the atmosphere.

Any rotation systems with legume crops are high in nitrogen fertilizer use efficiency. Legumes fix N for their growth; thus, low or no N fertilizer is required for legume phases. However, this does not automatically link to economic return. For example, green manure systems have high nitrogen fertilizer use efficiency; green manure normally provides enough revenue.

This rotational study is still underway, and additional data analyses, including soil nutrient efficiency, precipitation use efficiency, radiation use efficiency, weed, and disease management, soil organic matter, soil microbial community, and whole-farm economic analyses, are necessary to understand the full picture.

Market-driven system (canola – malting barley – canola - canola) seems to have a high yield and is relatively stable in Lacombe, while the conventional system (CWRS - Pea- CWRS -Canola) is better in Beaverlodge. However, no other specific data analysis has been included yet, and we have to have a comprehensive assessment of cropping systems to evaluate cropping system sustainability properly. A long-term crop rotation study is recommended to understand the unseen impact of rotation systems and make an appropriate cropping system recommendation.