New shoots of Tea trees in China's subtropical tea-producing areas generally start growing around March and continue until they stop in September to October, after which the above-ground parts of the tea trees enter a dormant period. The temperatures in September to October are still within the suitable range for root growth, and the tea tree roots still have strong nutrient absorption capacity. By January, as temperatures continue to drop and root growth ceases, the tea tree roots still have strong nitrogen absorption ability and can transport it to the above-ground parts. The absorbed nitrogen is stored in the roots, branches, and mature leaves of the tea trees, ready for redistribution and utilization during the spring growth of new shoots. This storage and reuse of nitrogen is a key reason for the particularly high quality of early Spring Tea. Therefore, scientific fertilization of tea trees in autumn and winter is of great significance for the yield and quality of the following year's spring tea.

The Tea Nutrition and Nutrient Management Technology Innovation Team at the Tea Research Institute of the Chinese Academy of Agricultural Sciences, based on the fertilizer needs of tea trees in autumn and winter, formulated scientific fertilization recommendations for tea trees in autumn and winter based on scientific research results and combined with scientific fertilization models across different regions.

I. Fertilization Principles

In response to issues such as inadequate organic fertilizer input leading to poor soil fertility and water retention capacity, excessive fertilizer use and imbalanced phosphorus-potassium ratios in some tea gardens, and deficiencies in medium and micronutrients like magnesium, sulfur, and boron, the following fertilization principles are proposed:

1. Increase the application of organic fertilizers and combine them with inorganic fertilizers. Establish reasonable timing and amounts for fertilization, applying fertilizers deeply (15-20 centimeters).

2. Based on soil fertility conditions and yield levels, appropriately reduce nitrogen fertilizer usage and strengthen the combined use of phosphorus, potassium, and magnesium fertilizers, paying attention to supplementing sulfur, boron, and other nutrients.

3. For severely acidified tea gardens (soil pH

4. Combine with green, high-yield, and efficient cultivation techniques.

II. Fertilization Recommendations

1. For general production tea gardens, apply 20-30 kilograms per mu of nitrogen (N), 4-6 kilograms per mu of phosphorus (P₂O₅), and 4-8 kilograms per mu of potassium (K₂O). These amounts include the nutrients from organic fertilizers.

2. For magnesium-, zinc-, and boron-deficient tea gardens, apply 2-3 kilograms per mu of magnesium oxide (MgO), 0.7-1 kilogram per mu of zinc sulfate (ZnSO₄•7H₂O), and 1 kilogram per mu of borax (Na₂B₄O₇•10H₂O) to the soil.

3. For sulfur-deficient tea gardens, choose sulfur-containing fertilizers such as ammonium sulfate, potassium sulfate, or superphosphate. In terms of annual fertilization strategies, organic fertilizers, phosphorus, potassium, and magnesium should primarily be applied as base fertilizers in autumn and winter, while nitrogen fertilizers should be applied in divided doses. The base fertilizer should include all organic fertilizers, phosphorus, potassium, magnesium, microelement fertilizers, and 30-40% of the annual nitrogen requirement. The appropriate time for applying base fertilizer is between late September and late October after the end of the tea season, combined with deep plowing to a depth of about 20 centimeters. Topdressing is generally nitrogen-based and the timing depends on the growth and harvesting of the tea plants. The sprouting-promoting topdressing should be applied 30-40 days before the spring tea harvest, accounting for 30-40% of the annual nitrogen requirement. Summer tea topdressing should be applied before the summer tea begins to grow, usually in mid-to-late May, with an amount of approximately 20% of the annual total. Autumn Tea topdressing should be applied after the summer tea harvest, typically in mid-to-late July, with an amount of approximately 20% of the annual total. For tea gardens that only harvest spring tea and not summer or autumn teas, the nitrogen requirement should be reduced accordingly, and the lower limit of the recommended fertilization amounts can be used. Adjust the annual fertilization strategy by applying 20% of the annual nitrogen requirement as topdressing before deep pruning after the spring tea harvest, and then applying another 20% of the annual nitrogen requirement in late July.

4. Recommend a formula of 18-8-12-2 (N-P₂O₅-K₂O-MgO) or similar. Apply this formula fertilizer during the base fertilization period, with a recommended application rate of 50 kilograms per mu, along with 100 kilograms per mu of cake meal or 200 kilograms per mu of commercial organic fertilizer. Supplement appropriate amounts of nitrogen fertilizer through topdressing according to the type of tea produced and the amount harvested. Specifically, for high-quality green tea gardens that only harvest spring tea, supplement 6-8 kilograms per mu of nitrogen (N); for green tea gardens that harvest throughout the year, supplement 12-16 kilograms per mu of nitrogen (N); for Oolong Tea gardens, supplement 9-10 kilograms per mu of nitrogen (N); and for Black Tea gardens, supplement 6-8 kilograms per mu of nitrogen (N).