What is new here?

Our approach has a strong agronomic foundation. It gives preference to best available sources of weather, soil, and management data, well-validated crop simulation models to estimate potential yield and water productivity, and expert opinion to provide scientifically robust, transparent, and reproducible yield gap assessments. Results are upscaled from location to climate zone and country following a novel bottom-up approach.

How are potential and water-limited yields estimated?

These variables are estimated for a given location using crop growth simulation models and local weather, crop management and soil data as input for these models. These location-specific estimates are upscaled following a novel bottom-up approach. See Glossary for definitions of potential and water-limited yield and GYGA protocol page for more details.

How is crop water productivity estimated?

Potential crop water productivity is estimated as the ratio of water-limited yield potential to crop water availability while actual crop water productivity is calculated as the ratio of actual yield to crop water availability. In both cases, crop water availability is estimated from the simulated crop evapotranspiration, which accounts for the stored soil moisture in the rootable soil depth at sowing, rainfall during the growing season, soil moisture left in the rootable soil depth after harvesting and other unavoidable field-level water loses through deep percolation and surface runoff. Crop water productivity is only estimated for rainfed crops. See Glossary for definitions of crop water productivity and GYGA protocol page for more details.

Why are simulated yields and water productivity always higher than actual yields and water productivity?

The ideal conditions that allow full expression of crop yield potential and most efficient use of water resources rarely occur in producer fields. That is why, even in intensive high-yield cropping systems, actual yields do not reach yield potential. See the Glossary for definitions of potential and water-limited yield potential.

Which countries and crops are covered by the Atlas?

We focus on countries that produce major staple food crops. Please see this link for an overview of the countries and crops currently covered in the Atlas.

How can I contribute to the Atlas?

We always welcome new partners. Please contact us by email as indicated below.

How do I cite the Atlas?

The Atlas can be cited as follows:  Global Yield Gap and Water Productivity Atlas. Available URL: www.yieldgap.org (accessed on: month, day, year)