Sunday, September 23, 2012

Mixed plantations

On my trips in Xishuangbanna, I came across a large variety of crops, from family gardens to industrial bananas, there is a lot to see in Southern Yunnan. In the surroundings of Jingmai mountain, an interesting field caught my eye:

One row of rubber trees (hevea brasiliensis) inter-cropped with four rows of tea trees (Camellia Sinensis var Assamica). This kind of setting contrasts with the usual vast mono-cultures.

According to several papers (here, here and here), inter-cropping rubber with tea would be advantageous on several aspects such as:

-increased carbon sequestration, leading to a richer soil on the long term.

-reduced run-off and soil erosion, rubber trees are infamously known in Yunnan for affecting the local climate, it is indirectly related to water retention capacity. Rubber tree tends to make the soil impermeable, during heavy rain, water will tend to flow down the slope instead of binding to the soil.

-increased revenues because of a more efficient usage of the field, if you wanted to have the same amount of rubber trees and tea trees in mono-culture, you would need more ground.

-increased stability because the price of rubber and tea leaves are not related.

Are we going to see rubber trees growing around Mahei, Lao Banzhang or Banpo Laozhai? Probably not, because the studies undertaken were aiming at lowland fields. As altitude increase, the price of tea increases and the yield of rubber trees decreases, hence, it would probably not be economical for the famous tea mountains to choose rubber trees as inter-crops.

However, many tea gardens require shade trees and natural tea gardens have room for other crops to be planted, maybe in the future, we could see a more advanced management of tea gardens, using nitrogen fixing plants to increase the soil nutrients and using specific predator hosts in order to keep pest away.

There is a lot of research being done on inter-cropping and tea, rubber, cocoa, coffee, banana, palm oil and other long term crops will be the first beneficiaries of these advancements. Because of the expected population increase (10 billion people in 2050), mankind must launch a ''doubly green revolution'' which implies a production increase as well as a reduction of the environmental impact. Let us hope there will be enough tea for everybody!


  1. Did you already harvest the rubber tree? If yes you probably know how it smell... Do you think it have a good impact on tea?

    Do you thing that an intensive double-culture, without any real biodiversity is really much more better than a classic mono-culture?

    Is it what you called "doubly green revolution"??

  2. Dear Anonymous,

    I did harvest rubber trees with a friend, in the north of Menghai. What you point out is interesting, maybe a strong outer smell could have an influence on the taste of tea. I remember reading a paper about fumigation of tea plants for pest control and they say it did influence the tea aroma. Another issue regarding rubber-tea inter-cropping is that rubber trees are usually sprayed in early spring with sulfur powder to protect them from fungi, this would very probably influence the taste of tea, but I guess they found a solution to that.

    The interest of inter-cropping is that you can exploit the ground and the sunlight at a better potential. For example, a tea plant does not need a direct exposition to grow leaves, the leaves do not exploit fully the energy given by the sun. If you put another layer of leaves (the rubber trees), a larger part of sunlight will be used for photosynthesis. Biodiversity can be increased, some species like to live in tall trees while others prefer to live in bushes or on the ground. Each crop have positive and negative impact on the local environment: some attract a lot of insects, some have deep roots which fixes the ground, some have an extensive foliage which lowers temperature and increase humidity... By combining two crops (or more)that fit well together, you can get an advantage.

    Intensive and ecological should not be opposite terms, this is what advanced farming try to achieve: a system with high output and few negative impacts on the environment. In the past, during the green revolution, we concentrated on increasing the yield, because we needed more food and didn't understand the consequences of a degraded environment. Now, the second agricultural revolution is called 'doubly green' because we must increase the yield even more while reducing the impact on the environment.


  3. Hi William,

    Maybe I don't understand anything about your advanced farming technology but I don't really get what is "green" in this plantation?

    According to your images I see 2 crops culture together... without forest or any other real biodiversity...

    You also wrote that rubber tree was sprayed with chemical... which have obviously a bad impact on the tea tree which are just next to the rubber tree...

    So... all of that for what?

    You said that "we need more food"... but is rubber a food, and do we really "need" more rubber?
    And what about puerh tea? Do we really "need" more and more (low quality) puerh tea and for what?

    I really think all of that is a mistake which is going to drive Yunnan ecology and tea economy to his loss..

    Steven (from Jinghong)

  4. Hi Steven,

    I did not mean that what you see in picture is an ideal ecological plantation, but it is certainly better than simple hevea mono-culture as you can see in the East of Xishuangbanna.
    Certainly, you will find more biodiversity in a tropical primary forest (as you can find in a part of Bulang Shan or in the North-West of Menglun) and in a ideal world, we would find only beautiful wild forests. But as far as agriculture is concerned, biodiversity for its own sake is not enough, it must give a benefit to the farmer.

    I was just passing by when I took the picture (it's on the road from Mengman to Huimin), I don't know how they intended to build their agroecosystem. But on the pictures, you can see small paddy fields, if they put fertilizer on the tea/hevea field, the run-off will fertilize the paddy fields and will be caught by the plants instead of ending up in the rivers. I can see that the paddy fields are divided into small parcels, maybe it's intended to avoid soil erosion, the banana trees'root system give some structure to the ground. The big tree on the second and third picture might hold beneficial species, for example predators (spiders, praying mantis...) that would repel invaders. On the last picture, you can notice that the soil is covered with tiny green plants, they host a whole micro-organisms that fix nitrogen (an important nutrient for plants). Looking at the fauna on the soil is important: ants, earthworms, spiders... All those things constitute biodiversity, they are not necessarily obvious things but they do have an impact on the health of an area.

    I agree with you that Yunnan countryside is developing too intensively, but there is a difference between this field and the large mono-culture plantations that you can find in more and more areas of Pu Er and Xishuangbanna. I also feel that most of the people are conscious of this issue, the most obvious change is the rarefaction of mist around Jinghong, you can ask any local about this. But on the other side, you have poor Yunnan farmers vs the world market. Rubber is getting more and more expensive (its price is correlated to oil price) and, as you probably know, tea is following the same path.

    Do we need more low quality Pu-erh? Well, as long as the demand is high, there is a pressure for planting more tea trees, now, better them to be of high quality because the customers become more picky. But instead of burning natural forest to build new plantations, we could, for example, inter-crop them with existing plantations like rubber trees. As to the quality of tea, there must be ways to improve it while not decreasing the yields and that's what many tea research centers are trying to achieve by developing new cultivars, exploring new agronomic techniques, etc...