The Global Yield Gap Atlas

Farmers in parts of northern India only achieve a tenth of the rainfed maize yield production compared to the potential of the area, which suggest a yield gap of up to 90%. The yield of many crops is far from optimal in a lot of countries, but it is not easy to choose the right approach to close these yield gaps. All kinds of local factors play a role, such as nutrients, water and weeds.

In 2011, researchers of Wageningen University & Research (WUR) and the University of Nebraska-Lincoln (UNL), based in the USA, founded the Global Yield Gap Atlas (GYGA), an agronomic database that offers locally-relevant and high-quality data on yield gap and potential, as well as other indicators such as water productivity and nutrient requirement. Currently, GYGA contains comprehensive data sets of more than 70 countries and 13 crops. In the future data on more countries and more crops will be added.

Approximately 30,000 datasets have been downloaded from the GYGA website by companies, governments and non-profit organisations since GYGA was founded. What is the impact of making these data available to the world? Priska Prasetya, business developer at Plant Sciences Group, explains.

What was the reason for bringing together all these global data on local crop production?

“The GYGA founders Martin van Ittersum, professor at Plant Production Systems, Sander Janssen, researcher at Earth Informatics, and colleagues at University of Nebraska-Lincoln including Ken Casman and Patricio Grassini noticed that something was missing from existing global databases on yield gaps. In those databases the whole world and also a range of different crops are modelled behind a desk, without a great deal of local validation. But not only every crop, but also every region is different. That’s why they initiated developing the GYGA database more than a decade ago.

We work country by country and crop by crop with local validation in cooperation with local agronomists. That means we take into account the local soil data and weather data. So the data we produce are more locally relevant instead of the usual data that tend to be more general.”

Why do we need such specific data about the yield gap?

“We believe that it’s only possible to move towards global food security if we keep working on optimising the yield of agricultural land. At the same time we shouldn’t cause too much environmental impact, because using more land will affect the climate. And if we want to feed ten billion people in the future without expanding the land too much, we must narrow the gaps between farmers’ actual yields and potential yields. We need local data about crops and the environment to reduce these yield gaps. GYGA helps us to focus on sustainable intensification.”

What kind of insights does GYGA provide?

“We can calculate and then compare the actual farmers’ yield as a percentage of the potential yield of, for example, Ethiopia, the Philippines and the Netherlands (from low-yielding agriculture to intensive agriculture). The potential yield is determined by radiation, temperature, carbon dioxide, and also by water supply and soil type for rainfed conditions. The actual yield of farmers is by definition lower than the potential, and in some countries much lower. The yield gap for wheat and barley for Ethiopia is up to 75 percent of the potential yield. By contrast, the yield gap in the Netherlands is much smaller, but still at 30 percent of the potential yield.

Graphs can be used to visualise the causes of the yield gap. For example, a low efficiency of inputs being applied such as nitrogen or water, can be a cause. Or there’s a lack of resources, like labour or nitrogen, or a lack of technology. The causes of the yield gap vary per country and per crop. In this way we can obtain understanding of the causes of a specific yield gap and determine the local actions.”

Is the goal to close the gap completely, including in the Netherlands?

“No, GYGA does not necessarily recommend that farmers should close the yield gap and target 100 percent of the potential yield. Typically what we find is that closing the gap up to 70 or 80 percent of the potential yield already maximises the profits and minimises the environmental footprint per kilogramme of product.”

Can users also look at the past and the future?

“The platform includes data from the past 10 to 20 years, so users can see whether the yield gap has reduced or increased over time. This has already been an important feature for the UN Sustainable Development Solutions Network. In 2019 this UN organisation created a yield gap closure indicator, which has been used to monitor the performance of the Sustainable Development Goals. The indicator is directly derived from GYGA.

GYGA has also been used to undertake impact assessments of certain interventions. Financial agencies utilise the data to assess potential risks regarding yield stability. And we are now estimating the impact of climate change on the yield gaps. With that it will be possible to show the expected trends in yield gaps until 2050 while taking into account the changing climate.”

Who else uses GYGA, besides the UN?

“We have a lot of subscribers from the private sector, such as fertiliser and biostimulant companies, consultants and renewable energy companies. For example, companies want to see regions in South America that still have a potential for additional yield. So, they use this information for a market development strategy. Fertiliser companies would like to know the minimum nutrient requirements and the required fertilisers for given target yields of crops and for future crop production in target areas.

We are still growing as a platform, with the help of our individual licence and paying sponsorship subscribers. It’s a dynamic process and stakeholders are increasingly seeing the Global Yield Gap Atlas as a global reference for guiding strategic decision-making about the capacity of agriculture to satisfy the global demand for food, while taking into account environmental impact and resource use.”