Abstract
Agricultural irrigation depends heavily on freshwater resources. Under the context of increasingly severe water shortages, studying the relationship among crop water requirements (ETc), actual crop evapotranspiration (ETa), irrigation water requirements (Ir), yield, and water use efficiency (WUE) would be beneficial to improve the agricultural application of irrigation water. Based on the daily data of 26 meteorological stations in Heilongjiang Province from 1960 to 2015, this study used the calibrated AquaCrop model to calculate the ETc, ETa, Ir, and yield of maize (Zea mays L.) in different hydrological years (extremely dry years, dry years, normal years, and wet years) along with WUE to evaluate the mass of yield produced per unit mass of crop evapotranspiration (ET) under rainfed and irrigated scenarios. The results showed that ETc and ETa decreased first and then increased from the west to the east during the four types of hydrological years. Ir exhibited a decreasing trend from the west to the east. Compared with the irrigation scenario, the rainfed scenario’s average yield only decreased by 2.18, 0.55, 0.03, and 0.05 ton/ha, while the WUE increased by 0.32, 0.4, 0.33, and 0.21 kg/m3 in the extremely dry years, dry years, normal years, and wet years, respectively. The results indicated that in the normal and wet years, the WUE was high in the central regions, and irrigation did not significantly increase yield; further, we determined that irrigation should not be considered in these two hydrological years in Heilongjiang Province. In the extremely dry and dry years, irrigation was necessary because it increased the yield, even though the WUE decreased. This study provides a theoretical basis for studying the regional irrigation schedule in Heilongjiang Province.
Highlights
Introduction distributed under the terms andAt present, the shortage of freshwater is regarded as one of the most critical global problems by scientists, policymakers, and even the general public [1]
We developed two scenarios to explore the changes in irrigation water supply and the requirements and yield of maize in Heilongjiang Province: 1
water use efficiency (WUE) refers to the amount of assimilated matter produced per unit of water consumed during crop production, reflecting the relationship between the yield water consumed during crop production, reflecting the relationship between the yield and andofET
Summary
The shortage of freshwater is regarded as one of the most critical global problems by scientists, policymakers, and even the general public [1]. In eastern China, especially during dry years with little precipitation, rainfed farming provides insufficient water to crops, and irrigation is needed to reduce yield loss [27]. Due to time, funding, and resource constraints, it is not feasible to evaluate large combinations of various crop management options under field scenarios in many different regions and environmental contexts To solve this issue, AquaCrop, as a fully tested, calibrated, and validated crop model, can be used to evaluate factors affecting maize yield and WUE [28]. It is necessary to quantify the ETc and Ir of maize, clarify the temporal and spatial changes and trends of ETc and Ir , and determine the irrigation management methods necessary for different places and hydrological years This assessment will provide essential information for irrigation strategies and sustainable water management to adapt to climate change in the region. (2) clarify the temporal and spatial distribution of ETc and ETa in the growing seasons of maize; (3) determine the temporal and spatial variations in yield and WUE under irrigation and rainfed scenarios; and (4) further reveal the effects of rainfed and irrigated scenarios on the Ir and WUE of maize
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