Agricultural and Forest Meteorology 181 (2013) 133–142 Contents lists available at ScienceDirect Agricultural and Forest Meteorology jou rn al hom ep age: www.elsevier.com/locate/agrformet Energy/water budgets and productivity of the typical croplands irrigated with groundwater and surface water in the North China Plain Yanjun Shen a , Yucui Zhang a,∗ , Bridget R. Scanlon b , Huimin Lei c , Dawen Yang c , Fan Yang a,d a Key Laboratory of Agricultural Water Resources, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang 050021, China b Bureau of Economic Geology, The University of Texas at Austin, Austin, TX, USA c Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China d Hebei Seismological Bureau, Shijiazhuang 050021, China a r t i c l e i n f o Article history: Received 29 September 2012 Received in revised form 8 July 2013 Accepted 24 July 2013 Keywords: Energy and water balance Carbon budget Evapotranspiration Water use efficiency Cropping system North China Plain a b s t r a c t Although irrigation has markedly increased agricultural productivity in the North China Plain, it has reduced groundwater levels by up to 0.8 m yr -1 and dried up the Yellow River for extended times since the 1970s. The objective of this study was to compare water, energy, and carbon fluxes in regions irrigated with groundwater and surface water (Yellow River) using almost four years of eddy covariance data from agricultural stations in Luancheng (water table depth: ∼42 m) and Weishan (near Yellow River, water table depth: 1–3 m). Irrigation is mostly restricted to winter wheat as summer maize grows during the rainy season. Mean annual ET was 693 mm yr -1 for Luancheng site, which is higher than Weishan site (648 mm, ignore partial years). About ∼390–480 mm of ET occurred during the wheat season (from early October to next early June, about 247 days), 230–300 mm in the maize season (from early June to late September, about 107 days). Annual crop yields were ∼6864 kg/ha in the two regions. Annual water use efficiencies ranged from 4 to 6 g CO 2 kg -1 H 2 O. Water use efficiencies were higher for maize than for wheat. Annual cropland carbon budget (CCB) was 230–280 g C m -2 yr -1 at the two sites and suggested a weak carbon sink. Irrigation compensated for seasonal and inter-annual variability in precipitation. Shifting the cropping pattern from wheat–maize double crops to a single crop of maize could significantly reduce water withdrawal and lead to a more sustainable use of water resource in this region. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Irrigation plays a key role in increasing crop productivity and accounts for 20% of cropland and 40% of food production glob- ally (Rockstrom and Falkenmark, 2000). Most irrigation is derived from either surface water or groundwater, with the fraction from groundwater increasing during the past few decades (Giordano, 2009). Siebert et al. (2010) estimate that ∼40% of the areas equipped for irrigation are based on groundwater, with the remaining 60% from surface water or other sources. Although irrigation is highly beneficial for food production, there are many negative environ- mental impacts of irrigation, including depletion of surface water and groundwater resources and pollution (Pereira et al., 2002; Zektser et al., 2005). Irrigation derived from surface water has been responsible for flow reduction in streams and depletion in lakes (e.g. Yellow River, Tarim Basin, and Aral Sea) as well as soil ∗ Corresponding author. Tel.: +86 311 8587 2248; fax: +86 311 85815093. E-mail addresses: yjshen@sjziam.ac.cn (Y. Shen), yczhang@sjziam.ac.cn (Y. Zhang). salinization from rising water tables related to enhanced ground- water recharge from irrigation return flow (Singh and Singh, 1995; Khan et al., 2006; van Weert et al., 2009). Groundwater-fed irrigation has caused many of the hotspots of groundwater deple- tion globally (Wada et al., 2010) and indirectly impacted stream flow by reducing groundwater flow to streams. The North China Plain (NCP, 140,000 km 2 area, Fig. 1) provides an excellent field laboratory to assess many of the issues related to irrigation. The irrigated area represented ∼75% of cropland in 2008. Grain production in the NCP accounts for ∼10% of total grain pro- duction in China (Fig. 1, 2010 China Statistical Yearbook). Irrigation has played an integral role in the almost eight fold increase in grain yield in the NCP from 0.64 t ha -1 in 1950 to ∼5.00 t ha -1 in 2009 (Zhou et al., 2007). Grain yield relies largely on irrigation because precipitation amount (400–600 mm) and timing (mostly during summer monsoons) are insufficient to support the double crop- ping system of winter wheat and summer maize. Irrigation water is sourced from groundwater in most cropland in the Hebei province (∼75% of the total irrigated land) and from surface water reservoirs (∼25% of total irrigation land) in the Piedmont region of Taihang Moutain (Liu et al., 2010; Sun et al., 2010). In the Piedmont region, 0168-1923/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.agrformet.2013.07.013