About the Field: Timing of Fertilizer Application

This article is written by Hiroki A.

Fertilization management is a crucial factor in producing high-quality tea. While fertilization management essentially involves applying fertilizer, the key lies in determining what type of fertilizer to use, when to apply it, and in what quantity. This is because these factors influence the total amount of nutrients that the plants can absorb.

There are three fundamental principles of fertilization management: applying the necessary nutrients, at the necessary time, and in the necessary amount. These principles apply to many crops, and failing to adhere to them can negatively impact the harvest. For example, in tomato cultivation, excessive fertilization can lead to the spread of diseases or hinder fruit development. However, the tea industry is somewhat unique in that the amount of fertilizer applied (particularly nitrogen) has a directly positive correlation with tea quality. Simply put, the more fertilizer is applied, the higher the quality of the tea produced. Of course, excessive fertilization beyond a reasonable limit can be harmful, but within practical bounds, many tea farmers believe that increased fertilization leads to better-tasting tea.

Since tea quality directly affects its market price, fertilization in tea cultivation is often viewed not just as a management practice but as an investment. This shift in perspective has driven the need for more efficient and rational fertilization planning. In summary, producing high-quality tea requires a sufficient supply of nutrients, and fertilization plans must be designed to maximize this supply.

For effective fertilization of tea plants, split applications and proper timing are essential. Split application refers to dividing fertilizer applications into multiple rounds to minimize nutrient loss. Fertilization is mainly carried out during periods outside of the harvest season, typically from summer to autumn and in early spring. This timing not only avoids the busy harvest period but also ensures that the tea plants can absorb nutrients more efficiently. Since tea plant roots become less active in colder temperatures, it is preferable to apply fertilizer during relatively warm periods. Research has shown that the fertilization conducted in early spring has the greatest impact on the quality of the first flush tea. Therefore, tea fertilization management involves multiple split applications, with a particular emphasis on early spring when root activity is at its peak.

Our tea plantation follows this fertilization management approach, but recently, we have been considering increasing the proportion of fertilization applied in early spring to further improve efficiency and quality.