TY - JOUR
T1 - Water productivity of rainfed maize and wheat
T2 - A local to global perspective
AU - Rattalino Edreira, Juan I.
AU - Guilpart, Nicolas
AU - Sadras, Victor
AU - Cassman, Kenneth G.
AU - van Ittersum, Martin K.
AU - Schils, René L.M.
AU - Grassini, Patricio
N1 - Funding Information:
This study was supported by the Bill and Melinda Gates Foundation , the Daugherty Water for Food Global Institute at University of Nebraska-Lincoln (UNL) , Wageningen University & Research , and the CGIAR research program on Climate Change, Agriculture, and Food Security (CCAFS) . We thank Juan P. Monzon, Fernando Aramburu Merlos, Zvi Hochman, Marloes van Loon, and Haishun Yang for providing crop simulations results and weather data.
Publisher Copyright:
© 2018 The Authors
PY - 2018/9/15
Y1 - 2018/9/15
N2 - Water productivity (WP) is a robust benchmark for crop production in relation to available water supply across spatial scales. Quantifying water-limited potential (WPw) and actual on-farm (WPa) WP to estimate WP gaps is an essential first step to identify the most sensitive factors influencing production capacity with limited water supply. This study combines local weather, soil, and agronomic data, and crop modeling in a spatial framework to determine WPw and WPa at local and regional levels for rainfed cropping systems in 17 (maize) and 18 (wheat) major grain-producing countries representing a wide range of cropping systems, from intensive, high-yield maize in north America and wheat in west Europe to low-input, low-yield maize systems in sub-Saharan Africa and south Asia. WP was calculated as the quotient of either water-limited yield potential or actual yield, and simulated crop evapotranspiration. Estimated WPw upper limits compared well with maximum WP reported for field-grown crops. However, there was large WPw variation across regions with different climate and soil (CV = 29% for maize and 27% for wheat), which cautions against the use of generic WPw benchmarks and highlights the need for region-specific WPw. Differences in simulated evaporative demand, crop evapotranspiration after flowering, soil evaporation, and intensity of water stress around flowering collectively explained two thirds of the variation in WPw. Average WP gaps were 13 (maize) and 10 (wheat) kg ha−1 mm−1, equivalent to about half of their respective WPw. We found that non-water related factors (i.e., management deficiencies, biotic and abiotic stresses, and their interactions) constrained yield more than water supply in ca. half of the regions. These findings highlight the opportunity to produce more food with same amount of water, provided limiting factors other than water supply can be identified and alleviated with improved management practices. Our study provides a consistent protocol for estimating WP at local to regional scale, which can be used to understand WP gaps and their mitigation.
AB - Water productivity (WP) is a robust benchmark for crop production in relation to available water supply across spatial scales. Quantifying water-limited potential (WPw) and actual on-farm (WPa) WP to estimate WP gaps is an essential first step to identify the most sensitive factors influencing production capacity with limited water supply. This study combines local weather, soil, and agronomic data, and crop modeling in a spatial framework to determine WPw and WPa at local and regional levels for rainfed cropping systems in 17 (maize) and 18 (wheat) major grain-producing countries representing a wide range of cropping systems, from intensive, high-yield maize in north America and wheat in west Europe to low-input, low-yield maize systems in sub-Saharan Africa and south Asia. WP was calculated as the quotient of either water-limited yield potential or actual yield, and simulated crop evapotranspiration. Estimated WPw upper limits compared well with maximum WP reported for field-grown crops. However, there was large WPw variation across regions with different climate and soil (CV = 29% for maize and 27% for wheat), which cautions against the use of generic WPw benchmarks and highlights the need for region-specific WPw. Differences in simulated evaporative demand, crop evapotranspiration after flowering, soil evaporation, and intensity of water stress around flowering collectively explained two thirds of the variation in WPw. Average WP gaps were 13 (maize) and 10 (wheat) kg ha−1 mm−1, equivalent to about half of their respective WPw. We found that non-water related factors (i.e., management deficiencies, biotic and abiotic stresses, and their interactions) constrained yield more than water supply in ca. half of the regions. These findings highlight the opportunity to produce more food with same amount of water, provided limiting factors other than water supply can be identified and alleviated with improved management practices. Our study provides a consistent protocol for estimating WP at local to regional scale, which can be used to understand WP gaps and their mitigation.
KW - Maize
KW - Management
KW - Spatial framework
KW - Water productivity
KW - Wheat
KW - Yield
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U2 - 10.1016/j.agrformet.2018.05.019
DO - 10.1016/j.agrformet.2018.05.019
M3 - Article
C2 - 30224833
AN - SCOPUS:85048170922
SN - 0168-1923
VL - 259
SP - 364
EP - 373
JO - Agricultural and Forest Meteorology
JF - Agricultural and Forest Meteorology
ER -