Table 3.
Yield metrics and yield gap calculation in wheat, barley, and canola.
| Measures | Definition and limiting factors | Data used | Yield gaps |
|---|---|---|---|
| Actual farm yield (Yf) | Average yield of selected cultivars (>1.0%) under rainfed conditions achieved by farmers† Limiting: Moisture, Genetics, Crop management, etc. |
Regional statistics (Agriculture Financial Services Corporation [AFSC], 2015; Statistics Canada, 2015) | – |
| Attainable yield or water limited yield (Ya) | Average yield for selected (>1.0%) cultivars under rainfed and optimal management conditions, a measure of the benefit of proper crop management† Limiting: Moisture, Genetics |
On-farm experiments (Alberta Agriculture and Rural Development [AARD], 2014) |
Management Gap: Ya–Yf (Fischer et al., 2009; Van Ittersum et al., 2013) |
| Max. attainable yield (Ym) | Average yield of the top performing cultivar under rainfed and optimal management conditions, a measure of the benefit of genetic selection and optimal crop management† Limiting: Moisture |
On-farm experiments (Alberta Agriculture and Rural Development [AARD], 2014) |
Genetic Gap: Ym–Ya Total Gap: Ym–Yf (Lobell et al., 2009) |
| Irrigated yield (Yi) | Average yield for selected (>1.0%) cultivars under irrigated condition, a measure of the benefit of adequate moisture† Limiting: Other Factors (e.g., CO${}_{2}$, radiation, temperature)‡ |
Regional Statistics (Agriculture Financial Services Corporation [AFSC], 2015) | Moisture Gap: Yi–Yf (Evans, 1993; Van Ittersum and Rabbinge, 1997) |
| Highest yield (Yh) | Highest yield recorded during study period | Anbessa et al., 2009; Harker et al., 2012; Alberta Agriculture and Rural Development [AARD], 2014 |
†All measurement were made for the same regions within Alberta, over the same 10-years period.
‡These limiting factors apply to all measurements.