为评价沙质土地区耕地整治中土壤团聚体的稳定性,在陕北榆林靖边县残次林地整治耕地项目区中设立试验田,采用正交试验方案[L9(3⁴)],分析不同肥料类型及施用量对土壤团聚体的影响。结果表明:与不施肥的农田土壤相比,N肥和有机肥配施可以提高水稳性大团聚体的含量,其中,当施用尿素421.34 kg·hm^-2,不施P肥,氯化钾125 kg·hm^-2,有机肥7.5 t·hm^-2(T7)时,>2 mm的水稳性大团聚体含量分别高于T1(不施N、P、K肥及有机肥)、T2(不施N肥、施用过磷酸钙333.33 kg·hm^-2、氯化钾62 kg·hm^-2、有机肥7.5 t·hm^-2)、T3(不施N肥、施用过磷酸钙675 kg·hm^-2、氯化钾125 kg·hm^-2、有机肥15 t·hm^-2)470.15%、360.24%和210.57%;对其数量分布、土壤团聚体累计含量为10%、30%、60%时所对应的团聚体直径D₁₀、D₃₀、D₆₀、平均重量直径(MWD)、几何平均直径(GMD)和土壤结构系数等有显著影响,其中对0.25~2 mm和>2 mm的水稳性大团聚体有着明显的促进作用,处理T3、T4(尿素198.28 kg·hm^-2、不施P肥、氯化钾62 kg·hm^-2、有机肥15 t·hm^-2)、T5(尿素198.28 kg·hm^-2、过磷酸钙333.33 kg·hm^-2、氯化钾125 kg·hm^-2、不施有机肥)、T6(尿素198.28 kg·hm^-2、过磷酸钙675 kg·hm^-2、不施K肥、有机肥7.5 t·hm^-2)、T7和T8(尿素421.34 kg·hm^-2、过磷酸钙333.33 kg·hm^-2、不施K肥、有机肥15 t·hm^-2)的土壤结构系数(Kctp)1.5~0.67,土壤结构良好。综上,说明N肥和有机肥配施,尤其是当尿素施用量421.34 kg·hm^-2(基施60%、追施40%)、氯化钾施用量125 kg·hm^-2、有机肥施用量7.5 t·hm^-2时能改善残次林地新增耕地土壤团聚体的结构,增强土壤团聚体的抗水分侵蚀能力。

To evaluate the stability of soil aggregates in cultivated land improvements in sandy soil areas, an experimental field was set up in the remnant forest land improvement project area of Jingbian County, Yulin, northern Shaanxi, China. The orthogonal experiment scheme [L9(3⁴)] was used to analyze the effects of different fertilizer types and application rates on soil aggregates. The results showed that compared to non-fertilized farmland soil, the combined application of N fertilizer and organic fertilizer can increase the content of water-stable macro-aggregates. Among them, the content of water-stable macro-aggregates larger than 2 mm was relatively higher when applying the T7 treatment (421.34 kg·hm^-2 urea, no P fertilizer, 125 kg·hm^-2 potassium chloride, and 7.5 t·hm^-2 organic fertilizer) than T1 (no N, P, or K fertilizer, and organic fertilizer), T2 (no N fertilizer, 333.33 kg·hm^-2 superphosphate, 62 kg·hm^-2 potassium chloride, 7.5 t·hm^-2 organic fertilizer), and T3 (no N fertilizer, 675 kg·hm^-2 superphosphate, 125 kg·hm^-2 potassium chloride, 15 t·hm^-2 organic fertilizer). The contents of macro-aggregates over 2 mm were 470.15%, 360.24% and 210.57%, respectively. The quantity distributions when the cumulative content of soil aggregates were 10%, 30%, 60% were D₁₀, D₃₀, D₆₀, respectively. The mean weight diameter, geometric mean diameter, and the soil structure coefficient all had a significant influence, with water-stable large aggregates >2 mm and 0.25-2 mm having obvious promoting effects. The soil structure coefficient (Kctp) of T3, T4 (198.28 kg·hm ^-2 urea, no P fertilizer, 62 kg·hm^-2 potassium chloride, and 15 t·hm^-2 organic fertilizer), T5 (198.28 kg·hm^-2 urea, 333.33 kg·hm^-2 super phosphate, 125 kg·hm^-2 potassium chloride, no organic fertilizer), T6 (198.28 kg·hm^-2 urea, 675 kg·hm^-2 superphosphate, no K fertilizer, 7.5 t·hm^-2 organic fertilizer), T7 and T8 (421.34 kg·hm^-2 urea, 333.33 kg·hm^-2 superphosphate, no K fertilizer, and 15 t·hm^-2 organic fertilizer) were between 1.5 and 0.67, with a good soil structure. In summary, the combined application of N fertilizer and organic fertilizer, especially with the urea application rate of 421.34 kg·hm^-2 (basic application 60%, topdressing 40%), the potassium chloride application rate of 125 kg·hm^-2, and the organic fertilizer application rate of 7.5 t·hm^-2 can improve newly added forest land. The structure of arable soil aggregates enhances the resistance of soil aggregates to water erosion.