Abstract: Artificial grasslands are crucial for the sustainable and high-quality development of animal husbandry in China. The application of organic fertilizer in artificial grasslands is an indispensable management to achieve high yield and sustainable soil fertility. We examined the application of organic fertilizer (18000 kg·hm^-2) on artificial grasslands with each of four species, Trifolium repens, Cichorium intybus, Dactylis glomerata, and Plantago asiatica. We assessed the changes in biomass of the four artificial grasslands and soil physicochemical properties including soil organic carbon, moisture content, pH, total nitrogen, total phosphorus, and available phosphorus. The results showed that organic fertilizer application increased aboveground biomass by 11.0%-38.8% in the four artificial grasslands. Meanwhile, organic fertilizer application improved soil organic carbon content and soil water content. Specifically, soil organic carbon contents of Dactylis glomerata, Trifolium repens, Cichorium intybus, and Plantago asiatica were significantly increased by 40.3%, 25.7%, 17.5%, and 11.1%, respectively. Soil water contents were significantly increased by 11.1%, 8.4%, 8.1%, and 3.7%, respectively. However, other physicochemical factors such as ammonium, nitrate, total phosphorus, and available phosphorus content exhibited greater variability across grasslands with different plant species. Furthermore, correlation analysis and structural equation modeling revealed that the primary growth drivers differed among the four artificial grasslands. Trifolium repens and Dactylis glomerata were mainly influenced by total phosphorus and soil organic carbon contents, while Cichorium intybus and Plantago asiatica were primarily affected by soil organic carbon and water contents. In conclusion, organic fertilizer application enhanced grassland biomass by affecting soil nutrients, but the underlying mechanisms differed across grass species. These findings provide a scientific basis for the sustainable utilization and high-quality establishment of artificial grasslands in southern China.

Key words: artificial grassland, organic fertilizer application, biomass, soil property, driving factor