The following article is an English translation of Zhou Zhonglin's publication on 茶业复兴 (Chá yè fùxīng, Tea Renaissance), dated 22/04/2020. Any references to figures and images are part of the original Chinese text.

Droughts persist in the tea area: is it natural catastrophe or human disaster?

After severe droughts, on April 13 Menghai finally experienced the first heavy rain of the year. However, on April 20, the Xishuangbanna Meteorological Observatory issued an orange drought warning: this means that droughts in Xishuangbanna will persist for the next few days, and the drought index will reach its peak in the next weeks.

According to the website of the China Meteorological Administration, from January to mid-March 2020, the average precipitation in Xishuangbanna was 78.3% less than in the same period of the previous year.

Drought is still the main theme of this year's spring harvest.

What consequences does this situation have on tea?
Tea buds germinate on average 10-14 days later than last year; and the picking cycle is less than 30 days, one third less than in previous years. The amount of tea picked is almost insufficient, and ancient tea trees in some areas do not germinate at all. It is expected that this year’s harvest output will be reduced by another 20-30% with respect to last year.

This situation may seem mysterious and inexplicable if we think that Xishuangbanna is clearly a tropical region. It would be reasonable to argue that it is an area with excellent water and heat conditions and abundant vegetation. Nevertheless, it does suffer from drought. In fact, because of the special geographical condition of Yunnan, there is little rain in winter and spring, while in summer and autumn rain is the daily routine. Yunnan is influenced by the strongest East Asian and Indian monsoons, forming a three-dimensional climate with distinct dry and wet seasons. With its special climate and geographical location, Yunnan has become one of the areas with the highest frequency of droughts every year from October to April. From 1950 to 2012, a total of 59 drought years occurred in Yunnan Province, and nearly half of them were classified as severe droughts. Since 2009, Yunnan has suffered 4 consecutive years of drought.

A large part of the precipitation in Yunnan comes from the intersection of cold and warm air. After the outbreak of the southwest monsoon in spring and summer, a large amount of water vapor was transported to Yunnan after passing through the Bay of Bengal. Once the cold air and warm air converge, large-scale precipitation forms. However, due to the high altitude, the warm and humid airflow is easily blocked by the mountains. The high altitude is mostly westerly, which is warm and dry, resulting in high temperature and little precipitation. Strong ultraviolet rays at high altitudes also intensify the evaporation of water. 

In general, spring drought is a characteristic of the Xishuangbanna tea area. Because of the spring drought, it is possible to sun-dry the tea leaves, ensuring perfect aging of the tea cakes. It can even be said that it is this climatic feature that has shaped the unique quality of Pu'er tea. If there is an excess of rain in spring, the tea farmers will also be worried.

But this is not to say that spring drought is good. Heavy spring drought has a great influence on the growth of tea trees, and in recent years, severe spring drought has become more and more serious.

THE IMPACT OF DROUGHT ON TEA TREES:

The tea tree is a plant that likes moisture and waterlogging, but in order to survive, it has a certain ability to resist drought. At the beginning of the drought, the tea tree will actively accumulate some regulators, such as soluble sugar, to improve the cell's ability to retain water. The high content of soluble sugar increases cell concentration and prevents water loss, to protect the cell structure and thus resist the damage caused by drought stress. In addition, at this stage, the growth rate of the tea tree slows down, and more nutrients can be accumulated, which is why many people say that the quality of tea leaves is improved under drought conditions.

However, when the tea tree's water content is in an imbalanced state for a long time, it will cause water deficit in the plant, metabolic activities will be negatively affected, and growth and development will be inhibited. Not only the leaves but even the most important nutrient organ for the growth of the tea tree, the root system, will also be greatly affected. At this time, the leaves of the tea tree will scorch and fall off. With the prolongation of severe drought, the whole tea tree will die.

 IN THE FUTURE, THERE WILL BE MORE DROUGHTS:

According to Nature ’s report, in a study called “China may have more sudden dryness in the future”, from 1979 to 2010 the number of sudden droughts in China has more than doubled. The study also pointed out that artificial warming may increase China's sudden drought in the coming decades.

 For some ancient tea trees whose nutritional status is greatly affected, can we consider artificial water supply? At the same time, the demand for breeding drought-resistant tea varieties is becoming increasingly urgent.

One point worth paying attention to is that the market is slowly recognizing that ancient tea trees grow strong even without chemical fertilization. In fact, organic fertilizers, and weeding are a greener and better solution, with significant effects on the growth of ancient tea trees. Especially in the case of extremely high picking frequency of recent years, tea trees will gradually increase the nutrient absorption of the roots in order to continue to grow. If the absorption rate exceeds the growth rate of soil fertility, it will cause the quality of tea to decline and the drought resistance capacity to weaken. In order to better protect ancient tea trees, it is necessary to resort to greener solutions.
For drought-damaged tea trees, after the drought, they must be deeply pruned and re-trimmed according to the dryness of the branches. Then, one must apply enough fertilizer, plant green manure, or lay grass between the rows, so that the damaged tea trees can quickly recover their vitality and promote the germination of new shoots.

Since the epidemic, we have experienced events that have not happened in hundreds of years. We thought everything was so strong, but the economy was fragile, international relations were fragile, and the natural environment was even more fragile. Whether you are a tea maker or a tea drinker, if we want to continue to enjoy the tea we love, we should make a difference and be brave enough to pass on the right ideas and do the right things.