水肥气耦合对温室番茄地土壤N2O排放及番茄产量的影响

为揭示水肥气耦合对温室番茄地土壤N₂O排放的影响,提出适宜的温室番茄增产减排措施,采用静态暗箱-气相色谱法监测土壤N₂O的排放,分析水肥气耦合条件下土壤温度、灌溉水利用效率(WFPS)、NO^-₃-N、O₂含量的变化规律以及N₂O排放的影响机制.加气条件下设两个灌水水平0.6 W和1.0 W(分别代表亏缺40%灌溉和充分灌溉,W代表充分灌水时的灌水量)和3个施氮水平(120、 180和240 kg·hm^-2,分别代表低、中和高氮,以50%F、 75%F和F表示,其中F为当地推荐施氮量),以不加气充分灌溉(O为加气灌溉,CK为常规滴灌)条件下3种施肥水平为对照,共9个处理.结果表明,充分灌溉(W2F1O、W2F2O和W2F3O)的N₂O累积排放量较亏缺灌溉(W1F1O、W1F2O和W1F3O)处理平均增加了55.7%(P<0.05);高氮条件下(W1F3O、W2F3O和W2F3CK)土壤N₂

Effect of Water-Fertilizer-Gas Coupling on Soil N2O Emission and Yield in Greenhouse Tomato

To reveal the effect of water, fertilizer, and gas coupling on soil N₂O emissions in greenhouse tomato soil and suggest appropriate measures for increasing yield and reducing N₂O emissions, static chamber-gas chromatography was used to study the effects of soil N₂O emissions. The variation laws of soil temperature, water-filled pore space (WFPS), NO₃^--N content, and O₂ content and the influence mechanism of N₂O emission under the condition of water-fertilizer-gas coupling were analyzed. Aerated conditions comprised two water levels, 0.6 W and 1.0 W (representing 40% deficit irrigation and full irrigation, W represents when sufficient irrigation water was available), and three nitrogen levels (120 kg·hm^-2, 180 kg·hm^-2, and 240 kg·hm^-2, representing low, medium, and high nitrogen, respectively, with 50% F, 75% F, and F, F is the recommended amount of nitrogen application locally). Three levels of fertilization were used as controlled unaerated full irrigation (O representing aeration, and CK representing conventional drip irrigation). Nine treatments were designed in the experiment. The results showed that the tomato field cumulative emission of N₂O under full irrigation (W2F1O, W2F2O, and W2F3O) increased by an average of 55.7% compared with the corresponding treatment at W1 level (P<0.05). The N₂O emissions of W1F3O, W2F3O, and W2F3CK fields significantly increased by 13.4% and 43.8% compared with medium nitrogen W1F2O, W2F2O, and W2F2CK and low nitrogen W1F1O, W2F1O, and W2F1CK treatments, respectively (P<0.05).Compared with the corresponding unaerated full irrigation, the emissions (W2F1O, W2F2O, and W2F3O) significantly increased by 11.2% (P<0.05). Aeration, the increase of nitrogen rate, and irrigation amount resulted in the increment of tomato yield and yield-scaled N₂O emissions. Compared with medium nitrogen, the yield and yield-scaled N₂O emission of high nitrogen treatment increased by 12.5% (P<0.05) and 3.9% (P>0.05), respectively. Compared with low nitrogen treatment, the yield and yield-scaled N₂O emission of high nitrogen treatment increased by 30.4% and 9.6% (P<0.05), respectively. The yield and yield-scaled N₂O emissions of aerated full irrigation significantly increased by 29.7% and 18.7%, respectively, compared with aerated deficient irrigation. Compared with unaerated irrigation treatment, the yield under aerated treatment increased by 10.4% (P<0.05), and the yield-scaled N₂O emission increased by 3.9% (P>0.05). Under the conditions of increasing irrigation water, decreasing fertilizer application, and aeration, partial factor productivity, and irrigation water use efficiency (IWUE) can be significantly increased. After comprehensive consideration of cumulative N₂O emissions, tomato production, nitrogen fertilizer utilization efficiency, IWUE, and yield-scaled N₂O emission, it can be concluded that aerated low nitrogen full irrigation is an optimal management mode. The results provide reference for increasing yield and reducing emissions of greenhouse tomato.