Saturday, 10 April 2010

First Terra preta experiments, chinampas, huglekulture and Montezuma method

I have had my allotment for 28 years now and still enjoying every minute of it. I completed digging this week and now the interesting part comes. Planting. I have planted Pentland Javelin and Kestrel potatoes breaking my rotation - something that I have never done before. I bought too many Pentland Javelin for the bed I had prepared for the potatoes so I had to put some of the kestrels in the bottom bed. That is the bed that the council replaced all the soil to a depth of 60cm because they found that it was contaminated with some foul chemical which I would be able to tell you the name of if I still had my original blog.

The new soil was completely unsuitable for allotment gardening and replaced some beautiful fibrous soil that had been built up over 27 years of continuous cultivation. Well, it has now been bashed into submission and is beginning to take on the resemblance of acceptable soil, however its fertility is suspect and I have just covered it, again, with about 4cm of well rotted cow muck.

Into this I have planted three rows of Kestrel. I am not expecting exhibition standard potatoes, although stranger things have happened. On the middle bed on the top half allotment I have planted four rows of sweet peas. I am hoping to grow some exhibition standard blooms again. I never show the sweet peas - I just like to show myself that I can do as well as the exhibitors. They are grown uncovered and open to all the elements. I will be growing them up canes and side shooting and detendrilling them as they grow.

I triple dug the onion bed during the winter mainly because I was taking down five silver birch in my garden. They had grown far too large for my small garden and were taking a lot of water and nutrients from the lawn. I needed to find somewhere to get rid of them and, as is my want; I like to bury anything that is or has been organic. So triple digging, and I think I will post the photographs to show what I did, allowed me to bury the five birches under about 1 metre of soil. I also buried about ten gooseberry bushes and an old Granny Smith apple tree which was not producing anything edible. Then I ran out of things to bury and I still had quite a bit of this bed to dig.
The allotment committee has allowed someone to dump laylandii shreddings in one of the bays near the gate. No one wanted to use them and one allotmenteer was heard to say that they were poisonous. Not a view that I subscribe to. Well if no one else wanted them, I thought, well why not put them under the subsoil because they cannot do much damage there.

Now there is madness in my method. I am becoming more and more fascinated by ancient South American Indian agriculture and horticulture. One of the things that the South American Indians did in the past was to stake out an area in a lake bed and fence it off. The farmers then layered it with mud, sediment and decaying vegetation until it was above water level. These were called Chinampas. When I first had my allotment there were about three springs on it. The allotment site is north facing at the top of a hill. So I have set about raising it in the same way that the Aztecs did in the past. I don't do raised beds - I do raised allotments. In order to keep the soil off the paths I have put upright paving slabs completely around the allotment. I will be doing this with the bottom half allotment too. So the allotment is about 2 foot higher than the surrounding paths.

However, I think that I overdid it a little with the laylandii shreddings on the onion bed and it is a little high now. Still it keeps the water flowing beneath my allotment and I do not sink into the soil to my hips like I used to do. I am not joking...  Still this is my Montezuma method and it is similar to huglekulture but I like to bury rather than putting brushwood on the surface and covering .  Burying high carbon organic material does not necessarily make your soil infertile, in my experience.

Trying to justify and research burying brushwood and logs, I found out a lot about South American agriculture and their methods of growing.

So what has all this to do with Terra Preta? Well as soon as it was brought to my attention that there were extensive farms and gardens along the Amazonian rivers and that they produced extremely fertile soil in an area that was thought to be extremely infertile my interest was aroused. It seems that these soils are very high in charcoal or what the Americans like to call biochar.

Some of these terra preta, manmade soils are over 2 metres deep and there is some evidence that they were being produced up to a thousand years ago. It seems that the Amazonian civilization was decimated soon after they were discovered by the Spanish, however their soils are still fertile to this day.

I, and several other allotmenteers, are trying to replicate these soils. I am using lump charcoal for barbecues, blood, fish and bone meal mixed in with comfrey tea. Now the science behind this could be very interesting and the adsorption of chemicals to the surface of charcoal may have something to do with it. I remain to be convinced. I am using this mixture along the planting lines for the sweet peas, onions, shallots, garlic and potatoes.

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