Yield gaps of cereals across Europe.

Abstract

To find proper compromises between land productivity, resource use efficiency and environmental impact, benchmarking of yields is a helpful starting point. Yield gaps are defined as the difference between potential or water-limited yield and actual yield. The GYGA project applies a consistent bottom-up approach to estimate yield gaps per country. Here we focus on the application for wheat, barley and maize in Europe. For each country, a climate zonation is overlaid with a crop area map. Within climate zones with important crop areas, weather stations are selected with at least 10 years of daily data. For the dominant soil types within a 100 km zone around the weather stations, the potential and water-limited yields are simulated with the WOFOST crop model, using location-specific knowledge on crop systems. Data from variety trials or other experiments, potential or water-limited yields, are used for validation and calibration of the model. Actual yields are taken from sub-national statistics. Yields and yield gaps are scaled up to climate zones and subsequently to countries. The average national simulated potential wheat yields under rainfed conditions varied from around 5 to 6 t/ha/year in the Mediterranean to nearly 12 t/ha/year on the British Isles and in the Low Countries. The average actual wheat yield varied from around 2 to 3 t/ha/year in the Mediterranean and some countries in East Europe to nearly 9 t/ha/year on the British Isles and in the Low Countries. The average relative yield gaps varied from around 10% to 30% in many countries in northwest Europe to around 50% to 70% in some countries in the Mediterranean and eastern Europe. For an initial understanding of yields and yield gaps, we assess differences between climate zones, soils and in relation to nitrogen input.