Theory and application of no-tillage reseeding in degraded grasslands

There are 400 million hectares of grasslands in China, accounting for about 40.7% of the Chinese territory, which provide fundamental ecological and economic benefits. However, more than 90% of this grassland ecosystem is threatened by degradation. This leads to the loss of biodiversity and a decrease in ecosystem functions, such as productivity, soil preservation and pest control. Currently, restoration of degraded grasslands is the most urgent task for grassland ecological management in China. No-tillage reseeding is one of the best practical technologies for grassland vegetation regeneration, because of the significant opportunity to improve productivity and plant diversity through establishing suitable species with minimum disturbance of the soil. Here we present a conceptual framework, which integrates plant-soil feedbacks, gap principles, and subclimax management models to guide our understanding of no-tillage reseeding. The key components of no-tillage reseeding in degraded grasslands consist of the selection of reseeding species, reseeding technology and reseeded grassland management. Native plants can affect the success of establishing species in revegetation due to competition for light, nutrients and water, and revegetation species with neutral or positive plant-soil feedbacks must be selected that can establish under these conditions. Our previous studies show that small light gaps can increase the performance of reseeded legumes, while larger light and soil gaps are needed for grass reseeding. Therefore, we predict that small gaps for legumes and large gaps for grasses will benefit these species respectively in no-tillage reseeding. According to the subclimax management model, suitable grassland management, for instance, mowing, grazing and fertilization, can maintain plant community composition, productivity and biodiversity, when the target species were successfully established. On the basis of this conceptual framework, no-tillage reseeding technology has been invented and applied in the semi-arid and semihumid degraded grassland, and the plan for degraded grassland restoration nation-wide is proposed. We invented the T and V slot opener, which will result in minimal disturbance and help to maintain soil moisture after no-tillage reseeding. Given that plants differ in their ability to use soil nutrients; phosphorus, boron and molybdenum fertilization is recommended for legume reseeding and maintenance, while nitrogen fertilization can be applied to improve the performance of grasses. In summary, our study presents the scientific hypotheses and a framework for no-tillage reseeding technology, which will advance our understanding of successful grassland restoration and play an important role in sustainable grassland development in China.