Abstract:To explore the impacts of irrigation, tillage, and nitrogen application on soil ecological stoichiometry characteristics in dryland, a field experiment was conducted using a split-split plot design with three replications from 2019 to 2023. There were two irrigation levels in the main plots: non-irrigation (I0) and one-off irrigation (I1), three tillage methods in the subplots: plowing tillage (PT), rotary tillage (RT), and sub-soiling (SS), and four nitrogen (N) application rates in the sub-subplots: 0 (N0), 120 (N120), 180 (N180), and 240 (N240) kg·hm-2. For I0, all N fertilizers were broadcast in the plot, while for I1, 50% of N fertilizer was broadcast in the plot and the other 50% N fertilizer was applied with irrigation. Soil samples were collected after wheat harvest in 2023 for analysis of soil total carbon (TC), total nitrogen (TN), total phosphorus (TP) contents, and their stoichiometric ratios at 0—100 cm soil depth. The results showed that: 1) For the whole profile of 0—100 cm soil depth, I1 decreased soil TC, TN, and TP contents by 35.1%, 15.0%, and 2.4%, and decreased soil C:N, C:P, and N: P ratios by 14.7%, 24.6%, and 10.5%, respectively, comparing with I0. Soil nutrients and their stoichiometric ratios, except for soil TN contents and N:P, showed significant differences among the three tillage practices. Additionally, soil TN contents and N: P increased with the increase of N application rates, while soil TC contents, TN contents, C:N, and C:P showed no significant differences among four N application rates. 2) Effects of irrigation, tillage, and nitrogen application on soil nutrients contents and their ecological stoichiometry characteristics varied with soil depths. I1 significantly decreased soil TC and TN contents at 0—20 cm, 20—40 cm, 40—60 cm, 60—80 cm and 80—100 cm soil depth, while decreased soil TP contents at 60—80 cm and 80—100 cm soil depths. Specifically, the variation of soil TC contents in each soil layer increased with soil depth. The variation of soil TN contents decreased first and then increased with soil depth. In the case of tillage, the SS increased soil TC and TP contents in each soil depth compared to RT and PT, and the variations decreased with soil depth. The irrigation and tillage had a markedly influence on soil C:N and C:P in each depth, while irrigation had significant effects on soil N:P for soils below 40 cm depth. The effect of N application rates on soil TN content decreased with soil depth, and N application had no markedly effect on soil nutrients and their ecological stoichiometry characteristics, except for soil TN contents and topsoil C:N. 3) The variation of soil nutrients and their ecological stoichiometry characteristics were significantly influenced by tillage and irrigation, which explain 59% and 19%, respectively. a Besides, irrigation could reduce the differences among three tillage practices. Overall, one-off irrigation decreased soil TC, TN, TP, and their ratios, which is not benefited to maintain soil nutrients, but its combination with SS and N180 can ensure soil fertility and achieve sustainable development of dryland.