Soil degradation and water scarcity constitute critical impediments to crop production in arid regions. The innovation of efficient resource utilization technology is necessary for agricultural development in arid regions. While biochar application's effects on enhancing soil quality and promoting crop growth have been well documented, the mechanism of biochar application under mulching drip irrigation in cotton field to improve soil hydrothermal environment and then to promote cotton production is unclear. To explore the effects of different amounts of biochar application on soil hydrothermal characteristics, cotton yield, and water-nitrogen utilization efficiency in cotton field under mulched drip irrigation. The experiment encompassed five rates of biochar applications: B1 (20 Mg ha⁻¹), B2 (40 Mg ha⁻¹), B3 (60 Mg ha⁻¹), B4 (80 Mg ha⁻¹) and CK (0 Mg ha⁻¹). Compared to CK, the application of biochar could increase soil water storage, soil accumulated active temperature and soil inorganic nitrogen in the top 40 cm of soil. The crop water productivity, crop N uptake, nitrogen partial factor productivity and cotton yield increased by 2.4913.39 %, 2.6615.30 %, 3.4312.00 % and 3.4111.98 % in treatments with biochar applications, respectively. Besides, the crop N uptake was closely related to cotton yield, which was stemmed from the improvement of soil water storage and soil active accumulated temperature by biochar application, and therefore an increase of the soil inorganic nitrogen content. According to the dual-objective regression analysis of cotton water productivity and cotton N uptake, the optimal biochar application rate was 42.42 Mg ha⁻¹. The results highlighted that further increasing water and fertilizer use efficiency is feasible under optimized biochar application rate to promote agriculture development in arid regions.

中文翻译：

---

生物炭提高干旱地区覆盖滴灌棉花的水氮利用效率


土壤退化和水资源短缺是干旱地区作物生产的关键障碍。资源高效利用技术创新是干旱地区农业发展的必要条件。虽然生物炭施用对提高土壤质量和促进作物生长的作用已得到充分证明，但棉田覆盖滴灌下施用生物炭改善土壤水热环境进而促进棉花生产的机制尚不清楚。探讨覆盖滴灌下不同生物炭施用量对棉田土壤热质特性、棉花产量和水氮利用效率的影响。该实验包括五种生物炭施用率：B1 （20 Mg ^ha-1）、B2 （40 Mg ^ha-1）、B3 （60 Mg ^ha-1）、B4 （80 Mg ^ha-1） 和 CK （0 Mg ^ha-1）。与CK相比，施用生物炭可以提高土壤储水量、土壤积累活性温度和土壤顶部40 cm土壤无机氮。生物炭施用处理作物水分生产力、作物氮吸收、氮素偏生产力和棉花产量分别提高了 2.49 13.39 %、2.66 15.30 %、3.43 12.00 % 和 3.41 11.98 %。此外，作物氮素吸收与棉花产量密切相关，这是由于施用生物炭提高了土壤储水和土壤活性积温，从而提高了土壤无机氮含量。根据棉花水分生产力和棉花氮吸收的双目标回归分析，生物炭的最佳施用量为 42.42 Mg ha⁻¹。 结果表明，在优化生物炭施用量下，进一步提高水肥利用效率促进干旱区农业发展是可行的。