Objectives This study investigated the effects of soil water content during the flowering period of wheat on N accumulation and transfer and soil NO₃⁻-N leaching to provide a theoretical basis for water conservation to promote high wheat yield and efficient N use.

Methods Field experiments were conducted during 2018–2019 and 2019–2020 wheat-growing seasons using Jimai 22 as the test cultivar. Three water treatments were set up during the anthesis stage: no watering (W0), watering 0–40 cm soil depth to a relative moisture content of 70% (W1) and 85% (W2). The wheat N accumulation and translocation at anthesis and maturing stage were determined; wheat yield and N fertilizer efficiency were investigated at the maturing stage, and soil nitrate-nitrogen content in 0–200 cm soil depth was analyzed.

Results After anthesis, the average N transfer in the vegetative organ of W1 at maturity was 11.6% and 7.3% higher than W0 and W2, and the N transfer rate in W1 was 9.5% and 6.1% higher than W0 and W2. At the maturity stage, the grain N distribution in W1 was 22.5% and 12.9% higher than W0 and W2, but the N distribution in the leaf and spike axis and glume in W1 was (P < 0.05) lower than in W0 and W2, thus increasing N harvest index. Compared with W0 and W2, W1 treatment reduced NO₃⁻-N content in 60–120 cm soil depth, increased wheat N uptake by 11.4% and 6.5%. The apparent excess soil N in W1 treatment was 51.0% and 40.9% lower than W0 and W2, reducing the risk of NO₃⁻-N leaching into the deeper soil layer. W1 reduced the residual inorganic N in 0–200 cm soil layer and the apparent excess soil N, which benefited absorption and utilization by wheat roots. Compared with W0 and W2, a thousand-grain weight of W1 treatment was 11.0% and 5.4% higher, grain yield was 25.9% and 11.8% higher, and the water use efficiency was 17.0% and 12.7% higher in the two growing seasons. Similarly, N use efficiency was 13.0% and 4.9% higher in W1 than W0 and W2, and the N uptake efficiency was 11.4% and 6.5% higher on average.

Conclusions Irrigating 0–40 cm soil layer to a moisture content of 70% during the flowering period benefits N transfer from vegetative organs to grains in the middle and late grain filling stages and at maturity, thereby promoting grain N accumulation, yield, N harvest index, and water use efficiency. Irrigating to 70% of the soil water capacity at the flowering stage reduces the NO₃⁻-N content in 60–120 cm soil depth, thereby decreasing the risk of NO₃⁻-N leaching, which improves wheat N use efficiency and uptake for production. Excessive irrigation leads to excessive downward movement of NO₃⁻-N, which affects root absorption. Insufficient water, on the other hand, decreases the transport of N to the grains.