Why This Matters ▼
Broadbalk intentionally updates cultivars to reflect British farming practice. In 1968, the field was redesigned: traditional long-straw varieties were replaced with semi-dwarf cultivars carrying Rht dwarfing genes.
Austin et al. (1980) showed total biomass hadn't changed — yield gain came entirely from harvest index. Mackay et al. (2011) showed 88% of post-1982 yield gain was genetic.
Full Yield Timeline with Cultivar Eras (Plot 08)
Plot 08 Yield (1852-2022) highlighting the impact of modern varieties.
Harvest Index Evolution
The fraction of total biomass allocated to grain
1988-1990 Head-to-Head Trial
Squarehead's Master (Traditional) vs. Brimstone (Modern) at varying N rates
Yield Ceiling by Era
Pre-1968 (Long-straw)
2 - 3 t/ha
1968-1985 (Early Dwarfs)
4 - 6 t/ha
1985-2000 (Mid-Modern)
7 - 9 t/ha
Post-2000 (Current)
10+ t/ha
Methodology & References ▼
- Austin et al. (1980) - Genetic improvements in winter wheat yields since 1900 and associated physiological changes.
- Mackay et al. (2011) - Reassessing the recent yield progress of winter wheat in the UK.
- Broadbalk Guide - Rothamsted Research.