Abstract:In order to study the effects of different nitrogen fertilizer synergist and water and nitrogen amount on the yield of winter wheat, a field experiment was carried out by using a split zone design. The main area had three water levels (W1:30mm, W2:60mm and W3:90mm), and subplot had three nitrogen levels (N1:75kg/hm2, N2:150kg/hm2 and N3:225kg/hm2). A non-nitrogen control was set under each main area (CK), and deputy vice district was treated with two kinds of nitrogen fertilizer synergists with urease inhibitor (NBPT) and double inhibitors (NBPT+DCD), using traditional fertilization (CO) as the control. The results showed that the yield of winter wheat was significantly affected by irrigation level, nitrogen application level and type of nitrogen synergist (P<0.01). The yield of winter wheat under three nitrogen fertilizer synergist was increased at first, and then decreased with the increase of irrigation water/nitrogen application rate. Compared with CO, the yield of NBPT and NBPT+DCD reached the maximum at 60mm of irrigation and 75kg/hm2 of nitrogen, which were 20.23% and 38.96%, respectively. Regression analysis and frequency analysis showed that NBPT could achieve higher yield of winter wheat in the range of 139~183kg/hm2 nitrogen application and 47~67mm irrigation. The yield reached the theoretical maximum of 7409kg/hm2 when nitrogen application was 162kg/hm2 and irrigation was 48mm. Under the treatment of NBPT+DCD, the yield of winter wheat was higher when nitrogen was applied at 149~185kg/hm2 and irrigation water was 50~65mm. Among them, the theoretical maximum yield was 8329kg/hm2 when nitrogen was applied at 158kg/hm2 and irrigation water was 51mm. When the maximum yield was obtained by CO treatment, the nitrogen application interval was 143~247kg/hm2, and the irrigation interval was 49~63mm, and the corresponding yield within this interval was 5912~6443kg/hm2. It can be seen that both NBPT and NBPT+DCD had obvious effect of increasing yield and saving fertilizer, and NBPT+DCD was better.