Green manuring orchards and tea gardens: concept, effects, and application

Fruit orchards and tea gardens in China are often established in sites with poor field conditions, farmed by clean tillage, and are popularly and excessively reliant on chemical fertilizers, leading to severe soil and nutrient losses, as well as soil degradation and decline of fruit and tea quality. Utilizing green manures in fruit orchards and tea gardens not only provide a large amount of organic matter but also act as biological tillage and green cover, ensuring the steady production and quality improvement of fruits and tea. As the core supporting technology for high-quality orchards or gardens, green manuring should be the most preferred path for China to improve the quality and efficiency of fruit and tea industry in future. Here, we introduce the concept of “green manuring orchard, green manuring tea garden” that takes green manuring as a fundamental component in establishing orchards and tea gardens. Green manuring improves the stability of fruit and tea yields, increases soluble solids, vitamin C content, and the sugar/acidity ratio in fruits; improves the physical properties as well as organic matter and available nutrients in garden soils; enhances the suitability of soil temperature and humidity for fruit and tea trees, reduces the losses of water, soil and nutrients, and suppresses weeds and pests. The area of orchards and tea gardens in China is about 16.4 million hectares, in which only about 1.21 million hectares are currently managed by green manuring, accounting for only 7% of the total area of fruit tea gardens, and there is a vast space and potential for the promotion of green manure fruit tea gardens. The main practices for green manuring orchards and tea gardens in China include the multi-years’ coverage and recycling utilization method for northern deciduous orchards, and the winter coverage - no-tillage grass suppression method and the annual green manure coverage method for southern orchards and gardens. Deciduous orchards in the north China often choose leguminous crops with strong drought and cold resistance, such as hairy vetch and common vetch, as well as cruciferous plants like February orchid and rapeseed, or gramineous crops like Fescue grass and ryegrass. Fruit and tea gardens in southern China mainly select leguminous crops such as hairy vetch, smooth vetch, milk vetch, common vetch, and peavine as winter green manure. The technical and theoretical system for green manuring orchards and tea gardens is mainly expected as follows: the innovation of germplasms for green manure crops, the integrated management of soil, nutrients, and water for green manure together with trees, the quality evaluation indicator systems for fruit and tea products, and the industry pathways for "green manure +" fruit and tea.