Abstract: Grassland degradation has become a key issue constraining the sustainable development of animal husbandry. The objective of this study was to investigate the effect of biochar on the ecological restoration in degraded grassland. In this study， we established a field experiment in the degraded cultivated grassland in Zhaotong， Yunnan， and designed the treatments with application of biochar （75 g·m^-2， 150 g·m^-2 and 300 g·m^-2） and biochar combined with chemical fertilizer （nitrogen at 4.00 g·m^-2+phosphate at 1.40 g·m^-2）. And the changes in biomass and soil nutrients in cultivated grassland were explored after two-year experiment. Our results showed that above-ground biomass increased by 66.15%~79.58% with biochar alone and 78.25%~118.29% with chemical fertilizer； below-ground biomass increased by 184.26%~290.63% with biochar alone and 303.83%~385.11% with biochar plus chemical fertilizer； and total biomass increased by 134.99%~184.93% with biochar alone and 229.35%~263.34% with chemical fertilizer. Meanwhile， the combination of biochar and chemical fertilizer increased soil nutrients， such as soil organic carbon， total nitrogen， total phosphorus， dissolved organic carbon， ammonium nitrogen and available phosphorus， as well as improved the soil bulk density， water content and pH. In addition， structural equation modeling analysis showed that soil phosphorus content was the main impact factors for vegetation recovery in degraded cultivated grassland in Zhaotong， Yunnan. In conclusion， our findings suggest that the addition of biochar， especially with chemical fertilizer， can significantly increase the biomass of grass and improve soil nutrients， thus effectively promoting the recovery of degraded grassland in the south. Our findings can provide a scientific basis for the sustainable use of grassland in southern China.

Key words: Biochar, Biomass, Soil nutrient, Degraded grassland, Grassland restoration, Soil phosphorus

摘要： 草地退化已成为制约畜牧业可持续发展的关键问题。本研究以云南昭通退化人工草地为对象，通过设置单施生物炭（75 g·m^-2，150 g·m^-2和300 g·m^-2）和生物炭配施化肥（氮4.00 g·m^-2、磷1.40 g·m^-2）的处理，探究生物炭在退化草地生态恢复过程中的作用。经过两年的处理，测定了人工草地生物量和土壤养分等指标。结果表明，单施生物炭处理下地上生物量增加66.15%~79.58%，配施化肥则增加78.25%~118.29%；单施生物炭处理下地下生物量增加184.26%~290.63%，配施化肥则增加303.83%~385.11%；单施生物炭处理下总生物量增加134.99%~184.93%，配施化肥则增加229.35%~263.34%。同时，生物炭和化肥配施能提高土壤有机碳、总氮、总磷等总养分含量，以及可溶性有机碳、铵态氮、速效磷等可利用养分的含量，并改善土壤容重、含水量和pH值。此外，结构方程模型分析表明土壤磷含量是云南昭通退化人工草地植被恢复的主要影响因子。综上，生物炭添加，尤其和化肥配施能显著提高草地生物量并改善土壤养分，进而有效促进南方退化草地恢复，研究结果可为南方草地的可持续利用提供科学依据。

关键词: 生物炭, 生物量, 土壤养分, 退化草地, 草地恢复, 土壤磷