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Table 1 Concepts and definitions of the yield levels and yield gaps estimated in this manuscript

From: Wheat yield gaps across smallholder farming systems in Ethiopia

Notation Concept Definition and reference
Yield levels
Ya Actual yield Yield observed in farmers’ fields as a result of growth-limiting and -reducing factors (van Ittersum et al. 2013a);
YTEx Technical efficient yield Maximum yield that can be achieved for a given input level (Silva et al. 2017);
YHF Highest farmers’ yield Average yield across top 10th percentile of actual yields (van Ittersum et al. 2013a);
Ye Economic yield Maximum yield with available technology and best-practice management in which marginal costs equal marginal revenue (van Dijk et al. 2017);
Yf Feasible yield Maximum yield with available technology and best-practice management but no economic constraints (van Dijk et al. 2017);
Yw Water-limited yield Maximum yield of a given genotype when crop growth is limited by water supply (van Ittersum et al. 2013a).
Yield gaps
Yg Total yield gap Difference between water-limited yield (Yw) and actual yield (Ya);
Eff. Yg Efficiency yield gap Difference between technical efficient yield (YTEx) and actual yield (Ya);
Res. Yg Resource yield gap Difference between highest farmers’ (YHF) or feasible yield (Yf) and technical efficient yield (YTEx);
Alloc. Yg Allocative yield gap Difference between economic yield (Ye) and technical efficient yield (YTEx);
Econ. Yg Economic yield gap Difference between feasible yield (Yf) and economic yield (Ye);
Tech. Yg Technology yield gap Difference between water-limited yield (Yw) and highest farmers’ (YHF) or feasible yield (Yf).
  1. We note these yield levels and yield gaps are only meaningful, and therefore also defined, for a given genotype × environment combination