Abstract:

This study investigates the effects of reduced irrigation combined with biochar application on the stability of soil aggregates and the distribution of carbon and nitrogen within them in wheat fields of the Northern Xinjiang irrigation area, aiming to provide a theoretical basis for farmland soil improvement and water-saving irrigation in the region. A randomized block design was employed, featuring four biochar application rates (B0: 0 t·hm⁻²; B1: 10 t·hm⁻²; B2: 20 t·hm⁻²; B3: 30 t·hm⁻²) and two irrigation levels (W0: 4.50×10³ m³·hm⁻², conventional irrigation; W1: 4.05×10³ m³·hm⁻², reduced irrigation), resulting in a total of eight treatments. The study analyzed the changes in soil aggregates and their carbon and nitrogen contents across different soil layers (0-20 cm, 20-40 cm) under the various treatments. The results showed that soil aggregates under all treatments were predominantly in the 0.25-2 mm size class. The highest proportion of 0.25-2 mm aggregates in both soil layers was observed under the combination of reduced irrigation and 20 t·hm⁻² biochar application (B2W1), accounting for 46.4% in the 0-20 cm layer and 46.2% in the 20-40 cm layer. The application of 20 t·hm⁻² biochar significantly increased (p<0.01) the mean weight diameter, geometric mean diameter, and the content of >0.25 mm macro-aggregates in the 0-20 cm soil layer, with increases of 8.66%, 11.7%, and 2.91%, respectively, compared to the treatment without biochar. Furthermore, biochar application significantly increased the organic carbon and total nitrogen contents in all aggregate size classes, with higher contents observed under reduced irrigation compared to conventional irrigation. The carbon-to-nitrogen ratio of soil aggregates >2 mm was also affected. In conclusion, reduced irrigation combined with biochar application can effectively promote the formation of soil macro-aggregates and enhance their stability, while simultaneously improving soil fertility by regulating soil carbon and nitrogen levels. The optimal improvement effect was observed with the application of 20 t·hm⁻² of biochar. This study provides a theoretical basis and data support for the rational application of biochar and the implementation of water-saving irrigation in farmland within the Northern Xinjiang irrigation area.

Key words: biochar, reduce irrigation, soil aggregates, stability, carbon and nitrogen distribution

摘要：

探究减量灌水配施生物炭对北疆灌区麦田土壤团聚体稳定性及其碳氮分布的影响，为灌区农田土壤改良和节水灌溉提供理论依据。采用随机区组设计，设4个生物炭用量（B0：0 t·hm⁻²；B1：10 t·hm⁻²；B2：20 t·hm⁻²；B3：30 t·hm⁻²）和2个灌水量（W0：4.50×10³ m³·hm⁻²常规灌溉；W1：4.05×10³ m³·hm⁻²减量灌水），共8个处理，分析不同处理下不同土层（0－20 cm，20－40 cm）土壤团聚体及其碳氮含量变化。结果表明：各处理下土壤团聚体主要以0.25－2 mm团聚体为主，其中减量灌水配施生物炭20 t·hm⁻²时各土层土壤0.25－2 mm团聚体占比最高（B2W1），分别为46.4%（0－20 cm土层）和46.2%（20－40 cm）；施用生物炭20 t·hm⁻²显著提升了0－20 cm土层土壤团聚体平均质量直径、几何质量直径和>0.25 mm大团聚体含量（p<0.01），较不施生物炭处理分别增加8.66%、11.7%和2.91%；>2 mm粒级土壤团聚体的碳氮比。各粒级团聚体的有机碳和全氮含量均随生物炭施用量增加而显著增加，且减量灌水条件下的有机碳和全氮含量均高于常规灌溉。综上，减量灌水配施生物炭能够有效促进土壤大团聚体的形成并提高其稳定性，同时通过调控土壤碳氮水平进一步提升土壤肥力，当生物炭施用20 t·hm⁻²时具有最佳的改良效果。该研究可为北疆灌区农田合理施用生物炭以及节水灌溉提供理论依据和数据支撑。

关键词: 生物炭, 减量灌水, 土壤团聚体, 稳定性, 碳氮分布