July 02, 2018
Researchers from Nebraska, France, Australia and The Netherlands reveal a need for regional estimates of water productivity and uncover water-related and non-water-related options to mitigate water productivity gaps
LINCOLN, Nebraska, July 2, 2018 – Calculating gaps between potential and actual water productivity at local to regional scales can help agricultural producers improve crop production. In June, the international Journal of Agricultural and Forest Meteorology published a multi-country study that establishes a first-of-its-kind protocol for estimating water productivity gaps across these spatial scales. In addition, the study confirmed water productivity variations among regions with different soils and climates, and it revealed that non-water-related factors, such as nutrient deficiencies, pests and diseases often limit crop yield more than water supply.
The study was conducted by researchers from the United States, France, Australia and The Netherlands and supported by the Bill and Melinda Gates Foundation, the Daugherty Water for Food Global Institute at the University of Nebraska (DWFI), Wageningen University & Research, and the CGIAR research program on Climate Change, Agriculture, and Food Security (CCAFS). Researchers proposed an estimation approach based on information in the Global Yield Gap and Water Productivity Atlas (GYGA; www.yieldgap.org) developed by a team at the University of Nebraska-Lincoln (UNL) to quantify potential and actual water productivity and associated gaps.
The approach introduced in the study has the potential to help agricultural producers, researchers, and policy makers across the globe more accurately formulate benchmarks for monitoring and mitigating water productivity gaps and improving crop yields within defined geographic areas.
“It’s exciting to be able to confirm some foundational aspects of water productivity with this study,” said Patricio Grassini, PhD, UNL assistant professor and DWFI Faculty Fellow. “The unique method we used successfully estimated potential water productivity as compared to actual productivity. We found that water productivity varied widely depending on a region’s soil and climate, which means we should not use generic water productivity benchmarks to analyze local and regional crop production.” According to Grassini, the water productivity gap across all regions studied was, on average, 47% of potential water productivity for maize (corn) and 51% for wheat.
Grassini said the researchers do not know of another protocol for estimating potential and actual water productivity that is applicable across diverse cropping environments with a local-to-global relevance.
The study examined local weather, soil, and agronomic data and used spatial crop modeling to analyze rainfed maize and wheat cropping systems in 18 major grain-producing countries. The cropping systems varied from intensive, high-yield maize in North America and wheat in Western Europe to low-input, low-yield maize systems in sub-Saharan Africa and South Asia.
According to the article, two-thirds of the variations in water productivity among the areas studied were explained by differences in evaporative demand, crop evapotranspiration after flowering, soil evaporation, and intensity of water stress around flowering. “Non-water-related factors in about half of the areas covered in the study constrained crop yield more than water supply did. Those factors, including poorly implemented crop management operations, biotic and abiotic stresses, and their interactions, add support to the need for local/regional analysis,” said Juan Ignacio Rattalino Edreira, UNL research assistant professor and first author of the article.
Existence of both water-related and non-water-related factors highlights specific opportunities to improve practices and produce more food with the same amount of water. The journal article lists three essential protocol elements: (1) an accurate description of the local cropping system context (e.g., weather, soil, crop sequence, and sowing dates), (2) a robust spatial framework to upscale estimated water productivity from a local to a regional level, and (3) a tool to reliably estimate potential yield and water available for crop transpiration during the growing season (this study used the GYGA as an estimation tool).
“This approach gives producers a much-needed, accurate spatial method for quantifying water productivity and estimating gaps locally and regionally,” Grassini said. “That’s a necessary first step to figuring out what factors influence an area’s ability to produce more food with a limited water supply. Once the gaps are estimated for any given area and we understand what’s causing them, we can discover the best ways to close the gaps.”
Authors of the article include:
- Juan I. Rattalino Edreira, Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, Nebr., USA
- Nicolas Guilpart, AgroParisTech, UMR Agronomie AgroParisTech INRA Université Paris-Saclay
- Victor Sadras, South Australian Research and Development Institute, Australia
- Kenneth G. Cassman, Department of Agronomy and Horticulture, University of Nebraska-Lincoln
- Martin K. van Ittersum, Plant Production Systems Group, Wageningen University, Wageningen, The Netherlands
- René L.M. Schils, Plant Production Systems Group, Wageningen University
- Patricio Grassini, Department of Agronomy and Horticulture, University of Nebraska-Lincoln
Find the full article in https://doi.org/10.1016/j.agrformet.2018.05.019
About the Robert B. Daugherty Water for Food Global Institute at the University of Nebraska
The Robert B. Daugherty Water for Food Global Institute at the University of Nebraska was founded in 2010 to address the global challenge of achieving food security with less stress on water resources through improved water management in agricultural and food systems. We are committed to ensuring a water and food secure world while maintaining the use of water for other human and environmental needs.
The University of Nebraska has invested in four interdisciplinary, University-wide institutes — including the Robert B. Daugherty Water for Food Global Institute — that leverage talent and research-based expertise from across the University of Nebraska system to focus on complex state, national and global challenges.
Learn more at waterforfood.nebraska.edu/.