Thursday, 18 June 2009
I went to look at the Chinampas project we manage the other day and it looks fantastic. Very beautiful soft sweeps of water filled with purple water hyacinth between raised banks edged in vertiver and young soto caballo trees. On the banks vegetables growing luxuriously from the water hyacinth mulch. A picture postcard.
Chinampas is a method of cultivation used in Mexico since the Aztecs. It has been credited as the reason why the Aztec population was able to grow so large and prosperous on what was basically swamp land and shallow lakes. Chinampas comes from the Nahua language and means square made of canes and refers to the method of constructing these 'floating fields'. In shallow lakes square areas would be marked out with canes and then woven cane walls would be fixed in place and the area inside would be filled with sludge taken from the floor of the bordering area. The 'island' would be built up of sludge, earth, plant matter and stones until it was higher than the surface of the water. Willow trees were often planted at the corners to help hold the land and protect against erosion. Vertivert and soto caballo (or relatives) which have strong wide reaching root systems were also planted to protect and secure edges. This small field would be planted with food crops and flowers, while the canals of water between were wide enough for a canoe to pass along and gave access to the farmer. Chinampas were used widely in swamps too: canals were dug into the swamp and the sludge dug was piled up on the adjoining land to create raised beds.
Free floating aquatic plants were allowed to grow in the canals and were harvested annually to use as mulch on the fields.
Last year the farmer went to Mexico to study the system and has brought it to this area. We manage a local chinampas project on what was once very swampy abandoned pastureland. Canals were dug to follow an old creek bed and the natural flow of the land. We had to wait for the driest time of the year to dig, and dig fast!This year we have continued with the digging as weather permits and the canal is slowly being extended throughout the length of the pasture. It winds its way between established trees and between the many fruit trees which have been planted. The canal is about 5 feet deep and 10 feet wide, and the sides are stabilised with vertivert and spaced soto caballo. We put water hyacinth into part of the canal and placed stakes in the water to keep the hyacinth constrained: when the hyacinth fills this area we harvest all but one or two plants (hyacinth can double its population in 2 weeks)and spread this on the land as mulch. The water hyacinth breaks down quickly and is a great source of nitrogen. The vegetables are loving the mulch and the fruit trees are also enjoying spreading their roots out to the canal for its fresh and tasty water and nutrients. All in all the project is thriving. We have been amazed and impressed by the abundance and rapidity of growth and by the beauty of the system.
When I first heard of the chinampas I thought of the farming system of the crofters I had seen in Scotland. Much of the land is peat bog and the farmer would dig shallow channels in the bog, piling the peat up on either side. These 'beds' were about a foot to two feet high and maybe 3 feet wide, and this is what the farmer's wife would grow the family's vegetables on. The chinampas seems the same idea on grander scale.