Total Pageviews

Wednesday, July 15, 2009

Terra Preta - how does it work

Some of the following article on why Terra Preta works is speculation. Connecting some dots if you wish so take it with a grain of salt until someone does some definitive research on the subject.

Fairly recently fertile zones along the Amazon river were discovered. These are places which are rich in charred organic material and are fertile zones in an area of very poor soils. The depth of black soil is typically half a metre. In case this sounds strange to you; that the soils of the amazon jungle are poor, perhaps some explanation is in order.

You would think at first glance that the soils of the Amazon must be very rich to support such a large biomass of such rich flora and fauna; a veritable jungle. Apparently not so. If you cut down the jungle or burn a patch of it, you can plant some crops and if you are lucky you will get a couple of crops before you have to move to a new location.

If you do the same thing in the forests of Eastern North America as the Europeans did when they arrived, you could plant crop after crop in the rich deep dark soil before you have to start to fertilize. So what is the explanation for the incredible quantity and richness of flora and fauna in the jungle.

 The explanation is partially in the ability of the trees and plants to recycle all the nutrients that fall on the soil. Animals and plants die, Animals defecate and urinate on the forest floor and with the high rainfall, humidity and temperature. all this material is mineralized (changed back into phosphates, nitrates and all the other ates) and is taken up by the roots of the growing flora. So why isn't there an accumulation of rich dark soil as there is in temperate zones.

The answer apparently is in the relative temperatures of the two areas.

When the temperature of the soil is above 25degrees centigrade, in the presence of moisture, humus breaks down. Humus is the refractory material that is left in temperate soil when organic material breaks down. The humus is the part that doesn't break down.

 It is physically sticky and helps in the  formation of the crumb structure (peds) of soil which allows paths for aeration and water penetration. It holds large quantities of water which plants can draw upon. Of great interest, it chealates (binds loosely) a variety of plant nutrients. If there is a source of nutrients coming from, for instance the breakdown of plants or animals, the humus will hold these nutrients in the upper layers of the soil and keep them from being washed into the subsoil.

Humus is a little like the haemoglobin in our red blood cells. Haemoglobin can hold a lot of Oxygen but not very strongly. In the lungs where the Oxygen concentration is high, it absorbs oxygen and in the body where the oxygen partial pressure is low, it releases it. Humus does the same with water and nutrients. below 25 degrees, humus is very stable.Link

So now we come to Terra preta and why it works. Terra preta has been formed by generations of humans charring organic material and incorporating it into the soil. Along the Amazon, where these soils exist, the black layer is often about half a metre deep. Any of you who have done organic chemistry know how charcoal is used to remove odours and colours from liquids. Charcoal is very good at absorbing molecules on to its surface and releasing them. This is apparently the explanation for why all this char makes the soil so rich.

 It is not that it has much in the way of nutrients itself but it can hold nutrients just as humus does. If the farmers along the Amazon, for instance, net a bunch of fish and dig them into their terra preta, they will break down and the nutrients will be held by the soil instead of being leached out by the rain. And charcoal is very stable at high temperatures unlike humus. One wonders how they arrived at the idea. Perhaps they observed good growth of their yams or whatever in a place where there had been a fire that was put out by the rain. It could be that char also has some of the other properties of humus such as water retention or improvement of soil structure. Some careful work is necessary to tease out the finer details of how charcoal works in warm soils. In a way, char (charcoal) is the humus of the tropics.

Thursday, July 2, 2009

The Luddites had a point

The Luddites had a point. They were a group of artisans who wove cloth and socks in home industries in the early 1800's. When the mechanized loom was invented which could produce far more cloth with unskilled labour, the artisans formed the Luddite movement and went around destroying the mechanical looms. It became a hanging offence to do this and hence the name Luddite was apparently not the name of their leader although that was what the authorities assumed. Clearly it was not healthy to let the authorities find out who you were. Notably, they only destroyed looms of factories that undercut their prices. Factories that kept prices up to a level that allowed the artisans to compete were left alone. At present the word Luddite is applied perjoritively and rather unjustly to anyone who is against progress of any kind.

So now most of our cars are mainly constructed by robots, any plastic utensil is made by a huge machine with one operator and turns out thousands of items per hour and even the pieces of wooden furniture are to a large extent produced by machine and at the most, assembled by humans. On our road to utopia goods are produced more and more cheaply making them more affordable for us all but.....................

We still need money to buy them. Where do we get the money if none of us has jobs and for that matter, if we can get the money somehow, what are we going to be doing to the environment if everything is cheap. We will be (are) cutting down more and more trees to make furniture that we can all afford, mining more and more irreplacable minerals to produce cheap cars, extracting more oil to burn in our cars and to make our plastics, mining more rare earth metals for our electronics and so forth.

What has actually happened is that most of us have become employed in the service industries. Everyone is servicing everyone else while capital is making the big money. Services include everyone in the tourism business, politicians, writers, sex workers, most government employees soldiers and a raft of others. All of this still leaves a lot of people unemployed or under employeed. What do we do with them. We still have to get money into their hand somehow so that they can buy the products produced by capital and keep the whole system operating.

Some we put some on welfare. They get a dole-out from the state which has got it's money by taxing income from wage earners and from the earnings of capital. From, say, the sale of plastic collanders that have been produced by their tens of thousands from a single maching with a single operator.

Some we put in the army. This is especially valuable to a capital intensive country which can produce far more than they use and produce it very cheaply. The army produces nothing of value, burns up fuel, destroys vehicles and blows up munitions. It keeps the taxes flowing from the government into salaries and back into factories which can continue to produce as the government uses up their production. It necessitates mining more minerals, extracting more oil, carring out research and many more activities to keep the army operating. Of course an army has to have a war from time to time to use up all this excess production and make room for producing more. I have read an estimate that one in every ten dollars in America is earned providing something for the armed services. Imagine if there was no army airforce or navy. Unemployment in America would be huge. Of course an army has the slight dissadvantage that it kills people in far away countries who, with a complete lack of appreciation of the way the world works, object to being killed. They fight back and kill our good old boys both in their country and in ours which is most unfair. Of course this provides employment for a raft of other services such as undertakers, spys, security guards, and the manufacturers of a host of metal and explosive detectors. Full employment for all.