Cultivation method for renewal, crown replacement, quality improvement and yield increase of old tea tree

The invention discloses a cultivation method for renewal, crown replacement, quality improvement and yield increase of an old tea tree. The cultivation method comprises the following operation steps: (1) vertically and obliquely forming fertilizing grooves on both sides of the tea tree in winter in sequence, and flattening and cutting off all thick, old and big roots to form a new root cultivation area; (2) spraying a diluted agent mixed by low-concentration rooting powder, sodium naphthylacetate and potassium permanganate to the surface soil of the side surfaces of the fertilizing grooves once, and ensuring that the soil on the side surfaces is moist without dropping water; (3) backfilling fertile soil which is mixed with decomposed and fermented sheep manure and inorganic phosphorus and potassium and is 3-5 cm higher than the original soil surface, and spraying sufficient water; (4) in spring of the second year, carrying out deep pruning on the tea tree, and removing soil and exposing roots at the base part