Soil degradation of the spoil ground generated during the construction of expressways is a serious concern, which affects the surrounding ecological environment. In this study, the combination of vetiver grass cultivation and fertilization was used to repair the soil in spoil ground. Therefore, 12 treatments were set up to evaluate the effects of ecological restoration, including no fertilization (CK), nitrogen fertilizer only (N1:150 kg/ha, N2:300 kg/ha, and N3:450 kg/ha), phosphorus fertilizer only (P1:350 kg/ha and P2:700 kg/ha), and a chemical fertilizer combination (NP: N1P1, N2P1, N3P1, N1P2, N2P2, N3P2). Compared with the CK, the fertilization treatments significantly increased the contents of soil ammonia nitrogen, soil total nitrogen, soil total phosphorus, and soil available phosphorus in rhizosphere soil increased by 6.91–48.49%, 1.36–153.81%, 63.40–333.44%, and 3.22–138.12%, respectively; the activity of β-xylosidase and N-acetyl-glucosaminidase increased significantly by 41.25–119.84% and 13.54–128.45%, respectively; and the Chao1 and observed species microbial diversity indices increased by 19.98–55.62% and 16.49–53.29%, respectively. In addition, NP treatment had a higher path coefficient for plant traits [NP (0.897) > P (0.767) > N (0.373)] and enzyme activities [NP (0.807) > N (0.703) > P (− 0.993)]. Furthermore, N2P2 had the highest comprehensive score (34), indicating that N2P2 could be used as an effective fertilizer combination. These results indicate that combined fertilization treatment (NP) improved the path coefficient of soil physicochemical properties to plant traits and soil enzyme activities, and thus better restored the habitats of spoil ground.

高速公路建设过程中产生的弃土场土壤退化问题严重，影响周边生态环境。本研究采用香根草种植与施肥相结合的方式修复弃土场土壤。因此，设置12个处理评价生态恢复效果，包括不施肥（CK）、单施氮肥（N1：150 kg/ha、N2：300 kg/ha、N3：450 kg/ha）、磷肥。仅化肥（P1：350 千克/公顷和 P2：700 千克/公顷）和化肥组合（NP：N1P1、N2P1、N3P1、N1P2、N2P2、N3P2）。与CK相比,施肥处理显着提高了根际土壤氨氮、土壤全氮、土壤全磷、速效磷含量,分别增加了6.91%~48.49%、1.36%~153.81%、63.40%~333.44%、分别为 3.22–138.12%；β-木糖苷酶和N-乙酰氨基葡萄糖苷酶的活性分别显着增加41.25-119.84%和13.54-128.45%；Chao1和观测物种微生物多样性指数分别增加了19.98-55.62%和16.49-53.29%。此外，NP处理具有较高的植物性状通径系数[NP (0.897) > P (0.767) > N (0.373)]和酶活性[NP (0.807) > N (0.703) > P (− 0.993)]。此外，N2P2的综合得分最高（34），表明N2P2可以作为有效的肥料组合。这些结果表明，联合施肥处理（NP）改善了土壤理化性质对植物性状和土壤酶活性的通径系数，从而更好地恢复了弃土场的生境。