优化施肥方式对黄土高原新增耕地土壤有机质含量和团聚体特性的影响

[目的] 研究优化施肥对黄土高原地区新增耕地土壤质量和作物产量的影响，为新增耕地土壤建立合理的优化施肥处理和区域新造土地的健康可持续发展提供理论依据。[方法] 通过盆栽种植试验，评估有机肥处理（OF）、有机肥配施化肥处理（NP）、常规施肥处理（CF）对新增耕地土壤团聚体数量、结构稳定性、有机质含量和玉米产量的改良效应。[结果] CF处理下新整治耕地土壤有机质含量最低为7.08 g/kg，土壤水稳性大团聚含量低，结构稳定性差。与CF处理相比，优化施肥方式下的OF和NP处理显著提高了新增耕地土壤有机质含量和玉米产量（p<0.05），>0.25 mm粒级大团聚体含量和团聚体稳定性显著提升，其中OF处理对新整治耕地土壤团聚体数量和稳定性的改善效果最佳。在0—10 cm土层，OF和NP处理下土壤有机质含量分别为12.67，11.79 g/kg，比CF处理分别提高了46.2%和36.1%。OF处理下水稳性团聚体MWD，GMD，R_0.25值分别比CF处理高了62.5%，21.4%和148.3%，分形维数比CF处理降低了1.7%；NP处理下水稳性团聚体MWD，GMD，R_0.25值分别比CF处理高了18.8%，3.6%和40.9%，分形维数比CF处理降低了0.4%。在10—20 cm土层，OF和NP处理下土壤有机质含量、团聚体数量和结构稳定性也得到一定的提升。土壤有机质含量与团聚体平均重量直径（MWD）、几何平均直径（GMD）呈显著正相关关系（p<0.001）。[结论] 优化施肥是有利于提升新整治耕地土壤结构稳定性、保肥特性和土地生产力的有效措施。

Effects of Optimized Fertilization Treatments on Soil Aggregate Characteristics and Organic Matter Content of Newly Reclaimed Cultivated Land in Loess Plateau

[Objective] The effects of optimizing fertilization on improving soil quality and crop yield of newly cultivated land were studied in order to provide a theoretical basis for the establishment of reasonable optimized fertilization recommendations and the sustainable development of newly reclaimed cultivated land in the Loess Plateau.[Methods] The improvement effects of organic fertilizer (OF), organic fertilizer combined with chemical fertilizer (NP), and conventional fertilization (CF) on soil organic matter (SOM), soil aggregate distribution, structure stability, and corn yield in newly reclaimed cultivated land were evaluated using pot experiments.[Results] SOM content of newly reclaimed cultivated land was the lowest (7.08 g/kg) under CF, with low aggregate content and poor structural stability. OF and NP significantly increased SOM content of the newly reclaimed cultivated land (p<0.05) compared with CF. The particle size>0.25 mm aggregate concentration (R_0.25) and aggregate stability were also significantly improved. The OF treatment had the greatest effect on improving the quantity and stability of soil aggregates. In the 0-10 cm soil layer, the SOM content under OF and NP treatments was 12.67 g/kg and 11.79 g/kg, respectively, which was 46.2% and 36.1% higher than SOM under CF. Moreover, the mean weight diameter (MWD), geometric mean diameter (GMD) and R_0.25 values of water-stable aggregates under OF were 62.5%, 21.4%, and 148.3% higher, respectively, than those values under CF, and the fractal dimension (D) was 1.7% lower than under CF. Meanwhile, the MWD, GMD, and R_0.25 values under NP were 18.8%, 3.6%, and 40.9% higher, respectively, than those values under CF, and the D value was 0.4% lower than under CF. In the 10-20 cm soil layer, the SOM content and the quantity and structural stability of soil aggregates under OF and NP were also increased to a certain extent. The MWD, GMD, and the SOM content showed significant positive correlations (p<0.001).[Conclusion] Optimizing fertilization is an effective measure for improving soil structure stability, fertility retention characteristics, and land productivity in newly reclaimed cultivated land.