In view of the severe water shortage of resource-based irrigation areas in the west of the river oasis and the large amount and low utilisation of mulch and water and nitrogen inputs in crop production, the effects of no-tillage and two-year use of mulch on the water utilisation characteristics of subsequent crops under water and nitrogen reduction conditions were explored to provide a practical basis for the construction of water and nitrogen reduction and efficient water utilisation technologies in the trial area.

From 2019 to 2021, a three-factor split plot experiment was carried out, with two tillage methods of conventional tillage (CT) and no-tillage (NT), two irrigation levels of 20% reduced irrigation (I1, 1 920 m³·hm^-2) and conventional irrigation (I2, 2 400 m³·hm^-2), and three N levels of 40% reduced N application (N1, 135 kg·hm^-2), 20% reduced N application (N2, 180 kg·hm^-2) and conventional N application (N3, 225 kg·hm^-2), to study the evapotranspiration, evaporation and water use efficiency of different treatments.

The one film for two years can optimize the soil water environment before wheat sowing and reduce the ineffective water consumption during wheat growth period. Compared to CT, NT was beneficial to increase soil water content and water storage before wheat sowing, which increased by 16.9%-23.0% and 14.5%-16.5%, respectively; It can reduce the evapotranspiration (ET), total evaporation (E) and proportion of evaporation to evapotranspiration (E/ET) of wheat in the whole growth period by 3.5%-4.2%, 19.0%-20.2% and 16.8%-19.3%, respectively. With the reduction of irrigation and N application, the three indicators of evapotranspiration, evaporation and E/ET decreased. Compared with I2, the three indicators decreased by 6.1%-6.4%, 10.8%-11.1% and 5.5%-6.0%, respectively; Compared with N3, N2 and N1 decreased by 2.2%-3.9%, 4.2%-10.9% and 1.7%-7.2%, respectively; Under the interaction of tillage and irrigation, evapotranspiration and E/ET of NTI1 decreased by 0.6%-6.6% and 17.4%-17.6% respectively compared with CTI1; Integrated water and nitrogen reduction for two years with no tillage and one film to further optimize water consumption structure, the three indicators for NTI1N2 were reduced by 11.0%-12.9%, 28.3%-47.6% and 22.5%-26.4% respectively compared to CTI2N3. Compared with CT, NT significantly improved wheat grain yield and water use efficiency by 4.8%-6.3% and 9.0%-9.5% respectively. Under NT and CT conditions, there was no significant difference in grain yield and water use efficiency (WUE) between I1N2 and I2N3, I2N2 wheat. Comparing wheat grain yield and water use efficiency under different treatments, NTI1N2 was the highest, increasing grain yield and WUE by 5.1%-6.6% and 5.7%-6.2%, respectively, compared to the control CTI2N3.

In the Hexi irrigation area, no-tillage and one-film two-year rotation of maize for wheat, irrigation of 1 920 m³· hm^-2 and N application of 180 kg· hm^-2 in the whole growth period, is a production technology suitable for water and nitrogen conservation, high wheat yield and efficient water use in this area.