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Abstract

Evaluating staple crops like maize's water footprint (WF) is essential for improving agricultural water use efficiency, particularly in areas with limited water resources. The twenty-year dynamics of the maize production WF in Qiqihar City, a crucial maize-producing region in China's semi-arid black soil region, were examined in this study from 2005 to 2024. We applied the FAO CROPWAT 8.0 model to determine the green and blue water footprints and investigated their responses to different hydrological year types, namely wet, normal, and deficit (Fig. 1). The principal findings are: (1) GWF constituted the largest portion of the total WF, between 53.5% and 100.0% (0.04–0.10 m³ kg⁻¹), emphasizing a primary dependence on rainfall. (2) BWF, ranging from 0.01 to 0.08 m³ kg⁻¹ and accounting for 2.13% to 46.45%, was present in only half of the years (10 years), showing a notable clustering effect during deficit and normal years. (3) The WF per unit yield showed a significant decreasing trend (R² = 0.63), indicating improved water use efficiency over the two decades, likely attributable to agricultural technological advancements. (4) Significant growth was observed in the cultivated area, peaking in 2015, and in the yield per unit area, peaking in 2012. The total WF showed a strong correlation with the planted area, described by a power function with an value of 0.79. This research highlights the importance of enhancing water resource management, especially by creating effective water-fertilizer strategies to lessen reliance on irrigation (BWF) during both dry and normal years, which is essential for ensuring high and stable maize yields and sustainable water use in Qiqihar. The findings from our research provide key data and a theoretical basis for establishing water-saving agricultural policies in this and similar semi-arid areas.

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