Review of the improvement techniques and equipment development for degraded grasslands

More than 90% of grasslands in China are in a state of degradation or ongoing degradation. Some difficulties have posed on the sustainable supply and feed of animal husbandry. At the same time, the ever-increasing degree of ecological environment damage has seriously threatened sustainable animal husbandry and ecological environment. Therefore, it is crucial to improve the degraded grasslands at present. However, there is a great research gap among scientific theory, practice, technology, and machinery of grassland improvement in China. The overall promotion can be limited in the grassland improvement. In this review, 24 common technologies were summarized and then classified for grassland improvement. The characteristics and applicable conditions were given for the different technologies. A systematic analysis was implemented on the grassland improvement techniques. A classification framework was then established for a comprehensive process pipeline of grassland improvement. Four types of degraded grassland improvement were proposed, including less damage and improvement (improvement type I), the optimal growth environment of forage (improvement type II), the promoting development and improvement of forage (improvement type III), and the changing biological community and improvement (improvement type IV). The improvement techniques, processes, and machinery were analyzed within the framework of the four types of grassland improvement. The research and development direction of machinery and equipment were proposed after that. Four aspects were further determined in grassland improvement, including the intensive protection of grassland, the mechanized process of degraded grasslands, the new types of improvement machinery, as well as decision-making on grassland protection and improvement. The synergistic effect of these four aspects can bring positive promotion to the improvement of degraded grasslands. Since the current situation of grassland degradation cannot be fully curbed, the following work should be focused on the future grassland protection and mechanized improvement of degraded grasslands. 1) To strengthen grassland protection, the prevention of grassland degradation in the path of combining grass and land. 2) In grassland improvement, the existing no-till live broadcast can be optimized to develop compound machinery. 3) In grassland mechanization, the fundamental research should be strengthened for the technical improvement machinery, in order to fully leverage the technological advantages. 4) Grassland protection and improvement policies support and technical guidance to grassroots should be strengthened to enhance their enthusiasm for grassland protection and improvement. The technology schemes of degraded grassland improvement, machinery selection, and relevant policies can provide a strong reference for the research and development of grassland improvement machinery and equipment.