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[Objective] The study aimed to investigate the effects of nitrogen application rate on soil inorganic nitrogen content, cotton yield, nutrient absorption and utilization in cotton field in Southern Xinjiang. [Method] Taken Xinluzao 66 as the material, five nitrogen application treatments ( 0, 150, 225, 300, 450 kg N/hm2, respectively expressed as NO, N150, N225, N300, N450) were set, and field tests in Shaya county, Aksu Prefecture, Xinjiang in 2021 were conducted. The content of nitrate nitrogen, ammonium nitrogen, dry matter quality, nitrogen accumulation and yield of cotton in 0 - 60 cm soil layer were measured. [Result] ( i) The content of nitrate nitrogen and anunonium nitrogen in soil of each treatment decreased with soil deepening. With the increase of nitrogen application level, the contents of nitrate nitrogen and ammonium nitrogen in 0 - 60 cm soil layers were significantly increased. The nitrate nitrogen in 0 - 20 cm soil layers at bud stage was significantly different ( P < 0. 05, the same as below), and the fertilization treatment increased I. 54 - 2. 47 times compared with NO; There was no significant difference in ammonium nitrogen content between N225 and N300 treatments in 0 - 20 cm soil layer at seedling stage ( P >0. 05, the same as below), and N450 treatment significantly increased 57% -140% compared with other treatments. The anunonium nitrogen content was abundant at the seedling stage, but it was obviously lacking in the peak bell stage. The nitrate nitrogen content was lacking in the seedling stage and abundant at the peak bell stage. (ii) The dry matter quality, nitrogen content, lint yield, nitrogen fertilizer utilization rate and agronomic utilization rate of cotton all increased first and then decreased with the increase of fertilization amount, and reached the maximum under N300 treatment. The maximum dry matter accumulation of cotton roots, stems, leaves, buds, flowers and bolls under N300 treatment were 4. 16, 20. 33, 7. 47 and 10. 84 g/ plant, respectively; The nitrogen accumulation amount of cotton at N300 treatment was 304. 00 kg/hm2, and the nitrogen accumulation amount of the boll at N300 treatment was 32.17%, which increased by 3. 95% - 5. 27% compared to other treatments; The lint yield at N300 treatment reached 6574. 8 kg/hm2, which increased by 21. 23% -67. 54% compared to other treatments, the nitrogen fertilizer utilization rate increased by 6. 85 % - 20. 88 %, and the agronomic utilization rate 2. 86% -6. 66%. [ Conclusion] The best amount of nitrogen fertilizer is 300 kg/hm² . When the nitrogen application rate exceeds 300 kg/ hm², the dry matter quality and nitrogen accumulation of cotton decrease, the soil nitrate nitrogen ammonium nitrogen content is higher, the nitrogen use efficiency decreases, and the yield increase effect is not obvious. [ABSTRACT FROM AUTHOR]

The aim of the present study was to explore the effects of dicyandiamide（DCD）and surfactant on the form and content of nitro⁃ gen in digested slurry, using a laboratory simulation experiment with different combinations of application of the treatments. Six treatments were used：single application of digested slurry, digested slurry+8%DCD, digested slurry+16%DCD, digested slurry+surfactant, digested slurry+8%DCD+surfactant, and digested slurry+16%DCD+sufactant. The total nitrogen（TN）, total Kjeldahl nitrogen（TKN）, ammonium ni⁃ trogen（NH4+-N）, and nitrate nitrogen（NO3--N）content of digested slurry were measured at 10, 30 min, and 1, 3, 10, 24, 48 h. The results revealed that, in the digested slurry+8%DCD and digested slurry+16%DCD treatments, the concentrations of NH4+-N, TKN, and NO3--N in⁃ creased by 0.74%~8.96%, 24.67~59.70 mg·L-1, 13.42~145.88 times, respectively, and the concentrations of all three increased with the quantity of DCD. The addition of surfactant had little effect on the form and concentration of nitrogen in digested slurry. [ABSTRACT FROM AUTHOR]