Wednesday, March 25, 2015

For a fertile soil...

For a long time, soil has been seen as a simple support. The philosophy of conventional agriculture is to give each problem its solution: if there isn't enough nutrient, you add fertilizer, if there isn't enough water, you add irrigation and if there's a pest attack, you spray pesticides. In conventional farming, the soil is adapted to the crop by using a variety of inputs. 

Agroceology takes a different approach. The soil is the most important part of the field because many ecological processes occur in it. Changing your agricultural practices will affect those natural processes which will change your soil and create a positive or negative dynamics. Conventional agriculture focuses on the present and neglects those long-term evolutions, this is why soil degradation occurs in many place: because of a poor management of the ecological processes, the soil was kept in a vicious circle for years. The yield was not affected because the loss in soil quality was compensated by extra inputs added. Farming on a degraded soil is possible but it requires an intensive management because everything has to be brought. 

Irrigated and heavily pruned tea trees
A good soil can store nutrients and water, the main things plants need to grow. One of our teacher says "soil is to water what the fridge in your house is to you, and you prefer it big and full of good stuff". Some soils are better than others naturally, because of their texture. Soil has particles of different size, from big chunks of sand to tiny pieces of clay. The smaller the particles, the better the soil can keep things in it, therefore, a clay soil is generally preferred to a sandy soil. The soil texture cannot be changed by agriculture, it would mean bringing tons of new material and it is very unpractical.

However, the structure of the soil is very dependent on what people do on the soil. The structure means how the particles are organised. You want the soil to be bulky enough so that it won't fly away with wind and but not too compacted in order to offer a maximum surface contact between the soil particles and the air. That way, you can store much more nutrients and water : the fridge gets bigger.

The soil is so loose in some parts of Jingmai mountain that heavy rains give that hilly shape to the surface.

In agriculture, the main problem is compaction : it occurs when you use tractors or when you and your cows walk on the field. It is possible to loosen the soil by digging it, but this is hard manual labor. Small dudes can do the job for free : worms. As worms crawl through the soil, they dig galleries that will loosen the soil and therefore improve its structure. This is one of the main reasons why soil life is important.

Ants contribute to the soil structure

With a good structure, plants will grow roots easily and a special kind of fungi called mycorrhiza will fix on the roots and grow a network of filaments that will help the plants catch nutrients. In exchange, the fungi can take carbon from the plant to feed itself. This is one of the great mutualistic relationships known in Nature. It is believed that without mycorrhizae, the nutrient catching capacity of many plants would be severely reduced.

We should think about the soil first, and the crop second. A fertile soil is the guarantee of good yields on the long run. By improving soil life, we can improve the soil structure and therefore increase its fertility. 

Manual weeding as part of an experiment in Jingmai natural tea gardens


  1. Hi William,

    Thank you for posting these details of tea soil details. It is indeed a much healthier living style than in the middle of a big city.

    When you have a moment please have a look at the photos of the following link. This must have been one more reason why you liked Yunnan:

    Looking forward to your next post.


  2. Hi Rui,

    Thanks for the link, the pictures are really beautiful, I have never been to the areas mentioned, but i can see another time that Yunnan has many jewels hidden in the countryside. In every trip I make, I am rewarded with mindblowing landscapes. You can stay for years in Yunnan and still be amazed at each mountain top .