A meta-analysis of global crop water productivity of three leading world crops (wheat, corn, and rice) in the irrigated areas over three decades

Abstract

The overarching goal of this study was to perform a comprehensive metaanalysis of irrigated agricultural Crop Water Productivity (CWP) of the world's three leading crops: wheat, corn, and rice based on three decades of remote sensing and non-remote sensing-based studies. Overall, CWP data from 148 crop growing study sites (60 wheat, 43 corn, and 45 rice) spread across the world were gathered from published articles spanning 31 different countries. There was overwhelming evidence of a significant increase in CWP with an increase in latitude for predominately northern hemisphere datasets. For example, corn grown in latitude 40-50°had much higher mean CWP (2.45 kg/m³) compared to mean CWP of corn grown in other latitudes such as 30-40°(1.67 kg/ m³) or 20-30°(0.94 kg/m³). The same trend existed for wheat and rice as well. For soils, none of the CWP values, for any of the three crops, were statistically different. However, mean CWP in higher latitudes for the same soil was significantly higher than the mean CWP for the same soil in lower latitudes. This applied for all three crops studied. For wheat, the global CWP categories were low (≤0.75 kg/m³), medium (>0.75 to <1.10 kg/m³), and high CWP (≥1.10 kg/m³). For corn the global CWP categories were low (≤1.25 kg/m³), medium (>1.25 to ≤1.75 kg/m³), and high (>1.75 kg/m³). For rice the global CWP categories were low (≤0.70 kg/m³), medium (>0.70 to ≤1.25 kg/m³), and high (>1.25 kg/m³). USA and China are the only two countries that have consistently high CWP for wheat, corn, and rice. Australia and India have medium CWP for wheat and rice. India's corn, however, has low CWP. Egypt, Turkey, Netherlands, Mexico, and Israel have high CWP for wheat. Romania, Argentina, and Hungary have high CWP for corn, and Philippines has high CWP for rice. All other countries have either low or medium CWP for all three crops. Based on data in this study, the highest consumers of water for crop production also have the most potential for water savings. These countries are USA, India, and China for wheat; USA, China, and Brazil for corn; India, China, and Pakistan for rice. For example, even just a 10% increase in CWP of wheat grown in India can save 6974 billion liters of water. This is equivalent to creating 6974 lakes each of 100 m³ in volume that leads to many benefits such as acting as 'water ARTICLE HISTORY

Long-term water productivity of maize (Zea mays L.) from limited Irrigation conditions under moderate semi-arid environment

“…Preceding studies showed that maize yield is a linear function of seasonal evapotranspiration (Gilley et al, 1980;Payero et al, 2006;Klocke et al, 2004;Stone, 2003). Also, the linear relationship between relative crop yield (Ya/Ym) and relative maize evapotranspiration (ETa/ETm) as the following relation developed by Doorenbos and Kassam (1979) for the first time.…”

“…Deficit irrigation method is one of the common strategies for producing crops under water deficit and limitation conditions in the arid and semi-arid environments over of the world. Deficit irrigation efficiency in crop production is evaluated by an index known as water productivity (WP) that is crop yield from applying 1 m 3 of irrigation water (Foley et al, 2020;Katerji et al, 2013). This index was considerably applied in crop irrigation researches in irrigated farms (Abadi et al, 2010;Bramley et al, 2013;Du et al, 2010;Fang et al, 2010;Guo et al, 2010;Li et al, 2010;Zhang et al, 2010;Nasseri and Bahramloo, 2009;Nasseri and Fallahi, 2007;Zamani and Nasseri, 2008).…”

“…This index was considerably applied in crop irrigation researches in irrigated farms (Abadi et al, 2010;Bramley et al, 2013;Du et al, 2010;Fang et al, 2010;Guo et al, 2010;Li et al, 2010;Zhang et al, 2010;Nasseri and Bahramloo, 2009;Nasseri and Fallahi, 2007;Zamani and Nasseri, 2008). This index is defined the as the ratio of crop yield to the crop evapotranspiration or water used in crop production (Nasseri and Fallahi, 2007;Ezenne et al, 2019;Foley et al, 2020). According to the report of Hamdy et al (2003), increasing WP is an essential priorities in the agricultural production systems under both conditions of irrigated and rainfed production systems.…”

“…Davis and Hagood (1961) found that the highest water productivity in maize production were attained with an actual evapotranspiration (ETa) lower than the potential rate (ETp) and, the highest water productivity was consequently obtained at 90% of the potential yield (Yp). Foley et al (2020) reported that enhancing crop yield without application of more water, and/or decreasing irrigation water with sustaining yields are methods to improve water productivity.…”

“…While, relation between crop production and actual evapotranspiration known as crop water production function (Kipkorir et al, 2002). Previous studies showed that maize yield is a linear function of irrigation water or seasonal evapotranspiration (Gilley et al, 1980;Payero et al, 2006;Klocke et al, 2004;Stone, 2003). According to the Kipkorir et al (2002) in full and with non-deficit irrigation conditions, water production function in non-linear (a second or third order polynomial) indicating that some of the irrigation water was lost as deep percolation from crop root zone.…”