Deep storage irrigation can recharge farmland deep soil moisture and sustain production of summer maize (Zea mays L.) through flood resources utilization in irrigation districts of northern China

The irrigation districts of northern China face issues such as water scarcity, inability to effectively utilize flood resources, and groundwater overexploitation. In view of these challenges, this study proposes a new concept of deep storage irrigation through flood resources utilization. However, whether deep storage irrigation can recharge deep soil moisture and sustain crop production still requires further study. A two-year field experiment was conducted on summer maize in the Guanzhong Plain with five soil wetting layer depths (T1: 60 cm; T2: 90 cm; T3: 120 cm; T4: 150 cm; T5: 180 cm) and soil saturation moisture content as the irrigation upper limit. The results presented that the ranges of deep soil moisture recharge in the 100–200 cm soil profile (SMS_100–200) was 73.34–267.42 and 0–150.03 mm in 2021 (wet season) and 2022 (normal season). When the effective precipitation and irrigation exceeded 390 mm, the SMS_100–200 began to linearly increase. The highest grain yield (GY) were observed at T2 and T3 treatments in 2021 (11.44 t ha^-1) and 2022 (11.25 t ha^-1), respectively. The maize GY of T4 in 2021 and T5 in 2022 were only 3.9 and 5.7% lower than the maximize GY, respectively. However, the SMS_100–200 for T4 and T5 were 2.4 and 5.0 times that of T2 and T3 treatments in 2021 and 2022, respectively. Overall, the further increase in irrigation amounts induced only a slight decrease in grain yield, but it significantly increased deep soil moisture recharge. Therefore, the deep storage irrigation breaks through the traditional idea of water-saving irrigation with limited water resources, which can be utilized as an effective alternative to address the issues of water scarcity, low flood resources utilization, and groundwater level declines in the irrigation districts of northern China.