A.D. Karve is an active contributor to the terra preta list and is a botanist by training. His observations and experiments are well worth reviewing. I have extracted a number of his postings on the subject of biochar.
It may be too early to suggest that a consensus currently exists, but it is fair to say that opinion is converging on several key points.
1 Biochar and by inference terra preta is typically produced in the mid temperatures (plus and minus around 350 degrees Fahrenheit). Production at other higher temperatures is also officious with less residual. It is produced primarily from non woody plant waste in order to provide a fine carbon powder with maximum yield in the all critical surface area. Wood charcoal is just as useful after crushing but normally has a fuel market and is diverted.
2 The powdered charcoal acts as a catalytic sponge for free ions in the soil. The use of the word catalytic is a bit unfair since all we expect is that the receptor sites in the charcoal will grab a free ion and hold it until such time as a biological agent removes it. However, it does get the idea across and I am hardly the first to overuse this word. This mechanism retains nutrients in the working soil while preventing nutrient loss through leaching.
3 The evidence to date suggests that this goes far beyond a mere retention usage. It appears to facilitate the rapid reconstruction of a high quality soil base even in wasted lands and even hostile soils with little remaining organic content. This was unexpected but it appears that we are going there. It is now possible to suggest that it is possible to construct a rich fertile soil many inches deep starting in the middle of the desert in a time span of perhaps twenty years. This is an apparently wild claim but every thing that I have seen combined with our limited knowledge earned to date supports this conjecture.
4 This actually makes total sense. The retention of nutrients particularly nitrogen, allows organic material to be reduced with a limited loss into the atmosphere as CO2. The soil can then be manufactured swiftly.
5 To date every problem soil this has been tried on has eventually generated positive results including land ruined by excess salinity. That is the most important problem where irrigation has wreaked the soils over thousands of years. In fairness, we are still in early days. In fact the work cited here is as good as it gets to date. However, we are approaching the point were hundreds and thousands will start working with these precepts.
6 The char is easily produced by either an earthen kiln, not unlike that used for indigenous charcoal making with waste wood, or the simple expedient of a sheet metal drum set on a bed of sticks to provide limited air flow with a lid to control the fire started on top of the charge. None of this is elegant but is will produce a satisfactory yield while disposing of all the farm waste at little new cost.
7 It is very easy to wax enthusiastic on this subject when a five thousand year field trial conducted by the Indios in Brazil supported a civilization of millions on the worst tropical soils ever. The reason it never found its way into other areas was simply that these other areas never produced enough plant waste to make a noticeable difference. Today that is easily solvable. I have posted on corn stover and bagasse as feedstocks. And the wood chipper is also producing a viable feedstock for the satisfactory production of biochar. Modern equipment will allow us to use our ingenuity to reduce all agricultural and woodland waste to biochar without an excessive expense.
8 It is a reasonable conjecture that the application of powdered charcoal to soils will eliminate the majority of fertilizer wastage now producing oceanic dead zones. It will also quickly reduce the need for fertilizer to vastly lower levels.
9 Vast tracts of well watered tropical and semi tropical lands are very suitable for this technology as well as those lands already been exploited for agriculture. Thus before any effort is expended on more arid lands, it appears that we can expect a massive increase in agriculture in these areas. For starters, the multi year slash and burn cycle will disappear forever.
10 I have accepted a long soil gestation cycle as a reasonable assumption. In fact there is no evidence to suggest that is the case. The first application of biochar should establish good production if not immediately, certainly by the next season as the soil responds. Ten to twenty years of continuous cropping and biochar application should produce a thick rich soil that then requires no further biochar. Field trials may end this process a lot sooner. The remote fields of the Indios were named terra mulato because the charcoal content was present but visibly lower but still significant. I do not have a grade yet, but since one initial season of corn culture can produce respectable carbon content (one to two tons per acre) it is very possible that the direct manufacture of a remote field was a one time effort that paid off for years.
The one point that we should recognize is that all other soils will also need extensive field testing before the local advisory agencies can get fully behind its universal implementation. It is not that we already know the answers – we do – it is just that a field test establishes best local practice and any noteworthy anomalies. Even after all that is said, every farmer will want to run his own test plot in order to both see the results on his ground but also to learn methodology. The good news, is that we are now approaching this threshold of activity.
Dear List,
a former colleague of mine conducted a study of the slash and burn agriculture in the Western Ghats mountain range in India. The farmers generally cultivate a plot for about 5 years. Every year the yield is lower than in the previous year. The plot is abandoned after 5 years becasue the yield is down to unacceptably low level. Weeds, wild herbs and grasses take over the ababdoned land. Some woody plants also establish themselves in this plot of land. After a fallow period of about 10 years, the vegetation on the land is again destroyed by slashing and burning and the land is again brought under cultivation. My colleague conducted soil analysis before and after every crop, and he found that the soil analysis did not change over the five year period of cultivation, and yet the yield dropped every year. He explained this phenomenon by the fact that it was not the soil fertility that diminished over the years, but that the soil was washed away by heavy rains and also because the land sloped. Thus, at the end of the fifth year, hardly a couple of inches of soil was left in the field.
Yours
Dear List,
soil micro-organisms need the same elements as green plants. In soils that are phosphate deficient, the phosphate solubilizing bacteria have a distinct advantage over others because they have the ability to get phosphorus out of phosphatic compounds that are normally insoluble and therefore not available to organisms in the soil. Whenever one applies an organic nutrient compound to the soil, the soil micro-organisms multiply by feeding on the organic nutrient, which primarily provides them with carbon. The mineral ions and molecules are obtained by them from the soil solution. But if the soil solution is deficient in phosphorus, application of an organic nutrient to the soil would automatically lead to a selective increase in the population of phosphate solubilizing bacteria, because only the PSB have the ability to multiply in such soils. Two of my students are currently conducting experiments to test if this hypothesis is correct.
Yours
Dear Mr.Astrupgaard,
when I used the word carbon source, I meant food containing carbon. Please note that nobody can use charcoal as food. The green plants use carbon dioxide as their carbon source. The non-photosynthetic organisms use digestible organic substances like carbohydrates, organic acids etc. as their carbon source. So rotting vegetation and compost also form a part of their food. The nitrogen fixing bacteria need energy to fix nitrogen, to conduct their own metabolism and also to multiply. This energy comes from the carbon in the food that they consume. The carbon gets converted into carbon dioxide in this process. That is why they all, including all animals, need a carbon source in the form of an easily digestible organic compound. As long as they live, the N-fixing organisms do not give the nitrogen fixed by them to any other organism, but use it in their own metabolism and reproduction. The molecules and ions (nitrogen, phosphorus, potash, iron, boron, etc.) in their cells become available to other organisms only when they die. Animals generally need ready made proteins, fats, vitamins etc. for survival. The micro-organisms generally need only a good source of carbon like sugar or a polysaccharide. They can synthesize their own proteins, vitamins etc. using inorganic salts containing the essential minerals.
Yours
Dear Sean,
the azotobacter are free living bacteria and as long as they have a carbon source available to them, they go on multiplying and utilizing the fixed nitrogen for their own metabolism and reproduction They die when the carbohydrates and other sources of carbon available to them are exhausted. In fact that is the basis of my application of 25 kg sugar per ha to the soil once every three months. The sugar increases the number of micro-organisms in the soil, and when the sugar is exhausted, they die. The nutrients released from the dead cells become available to the green plants. The nitrogen fixing microbes do not provide nitrogen to others as long as they are living. The case of rhizobium is altogether different. They are held captive in the root nodules and work like a part of the plant itself. They are fed by the green plants and the green plants extract amino acids from them. In the case of cyanobacteria, the ntrogenous compounds are stored in special perennating organs called heterocysts. Even when the Cyanobacteria die, the heterocysts survive in the dry soil as propagules, from which the next generation of cyanobacteria arises the next year. I am not saying that phytohormones can substitute nitrogenous fertilizers. I was only trying to explain the 10 to 15 % higher yield that is recorded whenever the cyanobacteria are applied to rice fields and I also gave my interpretation of the ecological significance of why the Cyanobacteria promote the growth of rice. There are enough reports in literature of 10 to 15% yield increase caused by substances like triacontanol (a C30 alcohol), organophosphatic insecticides, etc. which have growth promoting effect. Even urea spreayed as 2% solution gives similar effect. It is not caused by the nitrogen in the urea but it is due to the growth stimulating effect of urea.
Yours
Dear List,
there is a school of thought that believes that the free living nitrogen fixing organisms do not give any nitrogen to other organisms, Fixing atmospheric notrogen requires huge expenditure of energy (e.g. look at Haber-Bosch process). When an organism spends that much energy on fixing atmospheric nitrogen, why should it give it to other organisms? In India, cyanobacteria are recommended to be applied to rice fields. There are enough data to show that this treatment causes about 10 to 15% yield increase in rice. Assuming that the cyanobacteria do not give nitrogen to rice, but that they promote growth of rice through plant growth promoting substances, I conducted experiments in which I germinated seeds of barley in a culture filtrate of cyanobacteria and demonstrated that such a filtrate did actually have plant growth promoting property. The plant growth promoting property of cyanobacteria was demonstrated by us even in the case of kidney beans and wheat. Most of the growth promoting substances work at concentrations of 5 to 10 p.p.m. Therefore, plant growth promoting substances are used in quantities that can be measured in grams per hectare, whereas nitrogen being a fertilizer chemical is required in kilogram quantities. So, if the soil micro-organisms want the green plants to grow more vigorously, it makes sense for them to exude phytohormones into their environment than lose to the environment the nitrogen fixed by them so laboriously. It costs them much less energy to produce phytohormones. The question now arises as to why the microbes should promote the growth of green plants. As far as the cyanobacteria in rice paddies are concerned, if the rice plants developed a thick canopy, the growth of green algae would be restricted, because the photosynthetically active radiation would be absorbed by the leaves of rice. Thus, by promoting the growth of rice, the cyanobacteria eliminate the competition from green algae. In the case of other plants, the bacteria may be getting more sugar or more root exudates if the green plants grew more vigorously.
Yours
Dear Martin,
I really do not know, how much char is to be applied per hectar. But I can tell you how to make char out of your burnable organic waste. The simplest device is a top-lit updraft kiln. It consists of a vertical cylinder, having relatively small holes near its base for primary air. You fill the cylindrical body of the kiln with the material to be charred and then light it from the top. Once the fire gets going, you place a lid on the cylinder. There is a chimney built into the lid. The lid does not sit flush on the kiln, but there is a gap between the lid and the kiln. The draft created by the chimney sucks secondary air into the chimney, where it gets mixed with the pyrolysis gas to burn it. The biomass burns downwards, leaving a layer of charcoal on top. As the primary air comes upwards, it meets the burning front which traverses downwards. The burning biomass utilises all the oxygen in the primary air, so that the air going up through the layer of char has only carbon dioxide, carbon monoxide, nitrogen and the pyrolysis gas left in it. As there is no oxygen left in the updraft air, it cannot burn the char that has formed above the burning biomass.The pyrolysis gas and carbon monoxide burn in the chimney, because of the secondary air that is sucked in through the gap between the chimney and the kiln. You have to find out by trial and error, how long it takes to char the material loaded in the kiln. After that much time is over, you remove the lid, and extinguish the fire by sprinkling water over the burning material. This particular device is portable and manually operated. There are larger charring kilns, based on the oven and retort process. Prof. Yuri Yudkevich, a Russian scientist, has made them for charring useless material generated by the timber industry in Russia. We are already using both types of kilns under field conditions in India for charring agricultural waste as also urban waste. We have a video CD that describes the kilns and you can fabricate them by watching the video CD. I have not used Prof. Antal's kiln and have absolutely no idea how it operates. Our web site
www.arti-india. org would show you how to get our CDs by paying us through Pay Pal.
Molasses do have some minerals in them, but the idea that I am propagating is, that one provides the soil microbes only with a carbon source and that they take up the rest of the minerals from the soil solution. I had mentioned in a previous communication, that the water of guttation of many plants contained sugar (e.g. sorghum) or organic acids (e.g. chickpea). Water of guttation is the water oozing out from the leaves during the night. I had already mentioned that the amount of minerals dissolved in the soil solution has a constant value depending upon the solubility of the concerned mineral. Therefore, when the micro-organisms remove the mineral molecules and ions from the soil solution, they are replaced by more of the molecules and ions getting dissolved in the soil solution in order to maintain the equilibrium. When the carbon source has been exhausted, the micro-organisms die, releasing the minerals sequestered in their cells. The green plants and the microbes need the same mineral elements. Therefore when the micro-organisms die, the minerals released from their cells become available to the plants. This symbiosis between the soil microbes and green plants evolved when the green plants came out of the sea and occupied land. Aphids seem to be a part of this symbiosis, because they suck out sugar from the green plants and exude it out of their bodies. The water of guttaion washes off this sugar and drops it on the ground. The fact that plants drop their leaves and flower petals on the ground can also be looked upon as a part of this symbiotic relationship, because these organs feed the soil micro-organisms. It is a known fact that most of the useful minerals are retracted by the plants from the leaves before they are shed. I am trying to mimic the behaviour of the plants in order to develop techniques of growing crops without using chemical fertilizers.
Yours
Dear Greg,
Most of the reactions on externally applied organic matter take place in the top layer of the soil and they are therefore aerobic. Alcohol is formed under anaerobic conditions. Sugar is directly ingested as food by most micro-organisms and it is used by them as carbon source. In the case of plants and also most micro-organisms in the soil, almost 95 per cent of the weight is constituted by carbon, hydrogen, oxygen and nitrogen, all of which are obtained from air. Only 5% come from minerals in the soil. These minerals are absorbed from the soil solution. Whenever an organinc substance with high nutritive value is applied to the soil it causes the number of micro-organisms in the soil to increase. When the carbon source has been exhausted, the microbes die, releasing the sequestered mineral ions and molecules back into the soil solution, making them available to the plants. This is of course just a hypothesis, on which I am working. Literally thousands of farmers are applying today unrefined raw sugar to their fields at the rate of 10 kg per acre or 25 kg per ha, once every 3 months. They are getting good yield from their crops. I am only trying to find out the scientific reason behind this phenomenon.
Yours
Dear Mr. Haard,
ploughing in green plants is called green manuring. It provides soil micro-organisms with high calorie nutrition. In the normal green manuring practice, the green crop is grown on the entire field and ploughed in, after about 45 days. Because of the availability of a carbon source in such abundance, the microbes multiply very fast and take up and bind all the minerals in the soil solution in their own cells. Then you wait for at least a month before planting your crop, becasue otherwise your crop would not get any mineral nutrients from the soil. After a month, a part of the microbes are dead and have released the mineral molecules back into the soil. You therefore lose about 45 days in growing the green cover and another month in allowing it to rot in the soil, Green manuring is therefore not popular with farmers, because they lose a complete season. Under rainfed cropping in India, it means losing the entire year. That is why I recommend applying just 125 kg green leaves per ha along with the seed. While the seedlings are growing, he microbes multiply their numbers by eating the leaves, but because the leaves have been applied in just a small quantity, the nutrition is exhausted very fast by the soil microbes and they start to die, releasing the nutrients sequestered in their cells. By this time, the crop plants have developed their own root system and they are ready to absorb these nutrients. This is just a hypothesis. All that I have observed is that I get high yield whenever I apply about 125 kg green leaves per ha to my crop, right at the beginning of the season. I am trying to find out how and why this practice works so beneficially.
Yours
Dear Mr. Haard,
this refers to your request about my reaction to the observations of Dr. Makoto Ogawa. I am a botanist who used to work as the Research Director of a seed company in India. I worked mainly in the fields of plant physiology and plant breeding. I am now 72 and I head a voluntary organization founded by me for rural development through application of science and technology. I was made aware of the topic of Terra Preta by Ron Larson and Tom Miles and so I became a member of the Terra Preta discussion group. I developed interest in this topic because I had developed some theories of my own about plant nutrition, and agriculture without the use of chemical fertilizers. In the course of my research I found that by feeding the soil bacteria with high calorie, non-composted organic matter such as sugar, starch or cellulose, one not only increased the number of the soil microbes but also the yield of the crops. Just to test my hunch, I applied just 125 kg green leaves to a hectare of land owned by me, and got higher yield from this land than I used to get by applying chemical fertilizers. Now I have started a series of pot experiments in which the pots containing 1 kg soil each received 500 mg sugar, no sugar and a dose of chemical fertilizers. The pots are kept in a randomized complete block design, so that the data can be statistically analysed. After I started talking to my colleagues about charcoal being added to soil, some of them applied char made from sugarcane leaves to plants raised in pots and they reported that the plants in pots with char grew better than the ones not receiving this treatment. These experiments were not conducted very scientifically and they should be treated as anecdotal evidence.
Realising, that I did not know anything about soil science, I recently purchased a book on this subject and have started reading it. Although this book makes reference neither to Terra Preta nor to plant nutrition, the knowledge about soil minerals, their genesis and their metamorphosis under different climatic conditions is helping me greatly in understanding many aspects of plant nutrition. I feel that this knowledge would eventually be useful to me also in understanding Terra Preta. When I gain an insight into this topic, I shall certainly share it with this group.
Yours
It may be too early to suggest that a consensus currently exists, but it is fair to say that opinion is converging on several key points.
1 Biochar and by inference terra preta is typically produced in the mid temperatures (plus and minus around 350 degrees Fahrenheit). Production at other higher temperatures is also officious with less residual. It is produced primarily from non woody plant waste in order to provide a fine carbon powder with maximum yield in the all critical surface area. Wood charcoal is just as useful after crushing but normally has a fuel market and is diverted.
2 The powdered charcoal acts as a catalytic sponge for free ions in the soil. The use of the word catalytic is a bit unfair since all we expect is that the receptor sites in the charcoal will grab a free ion and hold it until such time as a biological agent removes it. However, it does get the idea across and I am hardly the first to overuse this word. This mechanism retains nutrients in the working soil while preventing nutrient loss through leaching.
3 The evidence to date suggests that this goes far beyond a mere retention usage. It appears to facilitate the rapid reconstruction of a high quality soil base even in wasted lands and even hostile soils with little remaining organic content. This was unexpected but it appears that we are going there. It is now possible to suggest that it is possible to construct a rich fertile soil many inches deep starting in the middle of the desert in a time span of perhaps twenty years. This is an apparently wild claim but every thing that I have seen combined with our limited knowledge earned to date supports this conjecture.
4 This actually makes total sense. The retention of nutrients particularly nitrogen, allows organic material to be reduced with a limited loss into the atmosphere as CO2. The soil can then be manufactured swiftly.
5 To date every problem soil this has been tried on has eventually generated positive results including land ruined by excess salinity. That is the most important problem where irrigation has wreaked the soils over thousands of years. In fairness, we are still in early days. In fact the work cited here is as good as it gets to date. However, we are approaching the point were hundreds and thousands will start working with these precepts.
6 The char is easily produced by either an earthen kiln, not unlike that used for indigenous charcoal making with waste wood, or the simple expedient of a sheet metal drum set on a bed of sticks to provide limited air flow with a lid to control the fire started on top of the charge. None of this is elegant but is will produce a satisfactory yield while disposing of all the farm waste at little new cost.
7 It is very easy to wax enthusiastic on this subject when a five thousand year field trial conducted by the Indios in Brazil supported a civilization of millions on the worst tropical soils ever. The reason it never found its way into other areas was simply that these other areas never produced enough plant waste to make a noticeable difference. Today that is easily solvable. I have posted on corn stover and bagasse as feedstocks. And the wood chipper is also producing a viable feedstock for the satisfactory production of biochar. Modern equipment will allow us to use our ingenuity to reduce all agricultural and woodland waste to biochar without an excessive expense.
8 It is a reasonable conjecture that the application of powdered charcoal to soils will eliminate the majority of fertilizer wastage now producing oceanic dead zones. It will also quickly reduce the need for fertilizer to vastly lower levels.
9 Vast tracts of well watered tropical and semi tropical lands are very suitable for this technology as well as those lands already been exploited for agriculture. Thus before any effort is expended on more arid lands, it appears that we can expect a massive increase in agriculture in these areas. For starters, the multi year slash and burn cycle will disappear forever.
10 I have accepted a long soil gestation cycle as a reasonable assumption. In fact there is no evidence to suggest that is the case. The first application of biochar should establish good production if not immediately, certainly by the next season as the soil responds. Ten to twenty years of continuous cropping and biochar application should produce a thick rich soil that then requires no further biochar. Field trials may end this process a lot sooner. The remote fields of the Indios were named terra mulato because the charcoal content was present but visibly lower but still significant. I do not have a grade yet, but since one initial season of corn culture can produce respectable carbon content (one to two tons per acre) it is very possible that the direct manufacture of a remote field was a one time effort that paid off for years.
The one point that we should recognize is that all other soils will also need extensive field testing before the local advisory agencies can get fully behind its universal implementation. It is not that we already know the answers – we do – it is just that a field test establishes best local practice and any noteworthy anomalies. Even after all that is said, every farmer will want to run his own test plot in order to both see the results on his ground but also to learn methodology. The good news, is that we are now approaching this threshold of activity.
Dear List,
a former colleague of mine conducted a study of the slash and burn agriculture in the Western Ghats mountain range in India. The farmers generally cultivate a plot for about 5 years. Every year the yield is lower than in the previous year. The plot is abandoned after 5 years becasue the yield is down to unacceptably low level. Weeds, wild herbs and grasses take over the ababdoned land. Some woody plants also establish themselves in this plot of land. After a fallow period of about 10 years, the vegetation on the land is again destroyed by slashing and burning and the land is again brought under cultivation. My colleague conducted soil analysis before and after every crop, and he found that the soil analysis did not change over the five year period of cultivation, and yet the yield dropped every year. He explained this phenomenon by the fact that it was not the soil fertility that diminished over the years, but that the soil was washed away by heavy rains and also because the land sloped. Thus, at the end of the fifth year, hardly a couple of inches of soil was left in the field.
Yours
Dear List,
soil micro-organisms need the same elements as green plants. In soils that are phosphate deficient, the phosphate solubilizing bacteria have a distinct advantage over others because they have the ability to get phosphorus out of phosphatic compounds that are normally insoluble and therefore not available to organisms in the soil. Whenever one applies an organic nutrient compound to the soil, the soil micro-organisms multiply by feeding on the organic nutrient, which primarily provides them with carbon. The mineral ions and molecules are obtained by them from the soil solution. But if the soil solution is deficient in phosphorus, application of an organic nutrient to the soil would automatically lead to a selective increase in the population of phosphate solubilizing bacteria, because only the PSB have the ability to multiply in such soils. Two of my students are currently conducting experiments to test if this hypothesis is correct.
Yours
Dear Mr.Astrupgaard,
when I used the word carbon source, I meant food containing carbon. Please note that nobody can use charcoal as food. The green plants use carbon dioxide as their carbon source. The non-photosynthetic organisms use digestible organic substances like carbohydrates, organic acids etc. as their carbon source. So rotting vegetation and compost also form a part of their food. The nitrogen fixing bacteria need energy to fix nitrogen, to conduct their own metabolism and also to multiply. This energy comes from the carbon in the food that they consume. The carbon gets converted into carbon dioxide in this process. That is why they all, including all animals, need a carbon source in the form of an easily digestible organic compound. As long as they live, the N-fixing organisms do not give the nitrogen fixed by them to any other organism, but use it in their own metabolism and reproduction. The molecules and ions (nitrogen, phosphorus, potash, iron, boron, etc.) in their cells become available to other organisms only when they die. Animals generally need ready made proteins, fats, vitamins etc. for survival. The micro-organisms generally need only a good source of carbon like sugar or a polysaccharide. They can synthesize their own proteins, vitamins etc. using inorganic salts containing the essential minerals.
Yours
Dear Sean,
the azotobacter are free living bacteria and as long as they have a carbon source available to them, they go on multiplying and utilizing the fixed nitrogen for their own metabolism and reproduction They die when the carbohydrates and other sources of carbon available to them are exhausted. In fact that is the basis of my application of 25 kg sugar per ha to the soil once every three months. The sugar increases the number of micro-organisms in the soil, and when the sugar is exhausted, they die. The nutrients released from the dead cells become available to the green plants. The nitrogen fixing microbes do not provide nitrogen to others as long as they are living. The case of rhizobium is altogether different. They are held captive in the root nodules and work like a part of the plant itself. They are fed by the green plants and the green plants extract amino acids from them. In the case of cyanobacteria, the ntrogenous compounds are stored in special perennating organs called heterocysts. Even when the Cyanobacteria die, the heterocysts survive in the dry soil as propagules, from which the next generation of cyanobacteria arises the next year. I am not saying that phytohormones can substitute nitrogenous fertilizers. I was only trying to explain the 10 to 15 % higher yield that is recorded whenever the cyanobacteria are applied to rice fields and I also gave my interpretation of the ecological significance of why the Cyanobacteria promote the growth of rice. There are enough reports in literature of 10 to 15% yield increase caused by substances like triacontanol (a C30 alcohol), organophosphatic insecticides, etc. which have growth promoting effect. Even urea spreayed as 2% solution gives similar effect. It is not caused by the nitrogen in the urea but it is due to the growth stimulating effect of urea.
Yours
Dear List,
there is a school of thought that believes that the free living nitrogen fixing organisms do not give any nitrogen to other organisms, Fixing atmospheric notrogen requires huge expenditure of energy (e.g. look at Haber-Bosch process). When an organism spends that much energy on fixing atmospheric nitrogen, why should it give it to other organisms? In India, cyanobacteria are recommended to be applied to rice fields. There are enough data to show that this treatment causes about 10 to 15% yield increase in rice. Assuming that the cyanobacteria do not give nitrogen to rice, but that they promote growth of rice through plant growth promoting substances, I conducted experiments in which I germinated seeds of barley in a culture filtrate of cyanobacteria and demonstrated that such a filtrate did actually have plant growth promoting property. The plant growth promoting property of cyanobacteria was demonstrated by us even in the case of kidney beans and wheat. Most of the growth promoting substances work at concentrations of 5 to 10 p.p.m. Therefore, plant growth promoting substances are used in quantities that can be measured in grams per hectare, whereas nitrogen being a fertilizer chemical is required in kilogram quantities. So, if the soil micro-organisms want the green plants to grow more vigorously, it makes sense for them to exude phytohormones into their environment than lose to the environment the nitrogen fixed by them so laboriously. It costs them much less energy to produce phytohormones. The question now arises as to why the microbes should promote the growth of green plants. As far as the cyanobacteria in rice paddies are concerned, if the rice plants developed a thick canopy, the growth of green algae would be restricted, because the photosynthetically active radiation would be absorbed by the leaves of rice. Thus, by promoting the growth of rice, the cyanobacteria eliminate the competition from green algae. In the case of other plants, the bacteria may be getting more sugar or more root exudates if the green plants grew more vigorously.
Yours
Dear Martin,
I really do not know, how much char is to be applied per hectar. But I can tell you how to make char out of your burnable organic waste. The simplest device is a top-lit updraft kiln. It consists of a vertical cylinder, having relatively small holes near its base for primary air. You fill the cylindrical body of the kiln with the material to be charred and then light it from the top. Once the fire gets going, you place a lid on the cylinder. There is a chimney built into the lid. The lid does not sit flush on the kiln, but there is a gap between the lid and the kiln. The draft created by the chimney sucks secondary air into the chimney, where it gets mixed with the pyrolysis gas to burn it. The biomass burns downwards, leaving a layer of charcoal on top. As the primary air comes upwards, it meets the burning front which traverses downwards. The burning biomass utilises all the oxygen in the primary air, so that the air going up through the layer of char has only carbon dioxide, carbon monoxide, nitrogen and the pyrolysis gas left in it. As there is no oxygen left in the updraft air, it cannot burn the char that has formed above the burning biomass.The pyrolysis gas and carbon monoxide burn in the chimney, because of the secondary air that is sucked in through the gap between the chimney and the kiln. You have to find out by trial and error, how long it takes to char the material loaded in the kiln. After that much time is over, you remove the lid, and extinguish the fire by sprinkling water over the burning material. This particular device is portable and manually operated. There are larger charring kilns, based on the oven and retort process. Prof. Yuri Yudkevich, a Russian scientist, has made them for charring useless material generated by the timber industry in Russia. We are already using both types of kilns under field conditions in India for charring agricultural waste as also urban waste. We have a video CD that describes the kilns and you can fabricate them by watching the video CD. I have not used Prof. Antal's kiln and have absolutely no idea how it operates. Our web site
www.arti-india. org would show you how to get our CDs by paying us through Pay Pal.
Molasses do have some minerals in them, but the idea that I am propagating is, that one provides the soil microbes only with a carbon source and that they take up the rest of the minerals from the soil solution. I had mentioned in a previous communication, that the water of guttation of many plants contained sugar (e.g. sorghum) or organic acids (e.g. chickpea). Water of guttation is the water oozing out from the leaves during the night. I had already mentioned that the amount of minerals dissolved in the soil solution has a constant value depending upon the solubility of the concerned mineral. Therefore, when the micro-organisms remove the mineral molecules and ions from the soil solution, they are replaced by more of the molecules and ions getting dissolved in the soil solution in order to maintain the equilibrium. When the carbon source has been exhausted, the micro-organisms die, releasing the minerals sequestered in their cells. The green plants and the microbes need the same mineral elements. Therefore when the micro-organisms die, the minerals released from their cells become available to the plants. This symbiosis between the soil microbes and green plants evolved when the green plants came out of the sea and occupied land. Aphids seem to be a part of this symbiosis, because they suck out sugar from the green plants and exude it out of their bodies. The water of guttaion washes off this sugar and drops it on the ground. The fact that plants drop their leaves and flower petals on the ground can also be looked upon as a part of this symbiotic relationship, because these organs feed the soil micro-organisms. It is a known fact that most of the useful minerals are retracted by the plants from the leaves before they are shed. I am trying to mimic the behaviour of the plants in order to develop techniques of growing crops without using chemical fertilizers.
Yours
Dear Greg,
Most of the reactions on externally applied organic matter take place in the top layer of the soil and they are therefore aerobic. Alcohol is formed under anaerobic conditions. Sugar is directly ingested as food by most micro-organisms and it is used by them as carbon source. In the case of plants and also most micro-organisms in the soil, almost 95 per cent of the weight is constituted by carbon, hydrogen, oxygen and nitrogen, all of which are obtained from air. Only 5% come from minerals in the soil. These minerals are absorbed from the soil solution. Whenever an organinc substance with high nutritive value is applied to the soil it causes the number of micro-organisms in the soil to increase. When the carbon source has been exhausted, the microbes die, releasing the sequestered mineral ions and molecules back into the soil solution, making them available to the plants. This is of course just a hypothesis, on which I am working. Literally thousands of farmers are applying today unrefined raw sugar to their fields at the rate of 10 kg per acre or 25 kg per ha, once every 3 months. They are getting good yield from their crops. I am only trying to find out the scientific reason behind this phenomenon.
Yours
Dear Mr. Haard,
ploughing in green plants is called green manuring. It provides soil micro-organisms with high calorie nutrition. In the normal green manuring practice, the green crop is grown on the entire field and ploughed in, after about 45 days. Because of the availability of a carbon source in such abundance, the microbes multiply very fast and take up and bind all the minerals in the soil solution in their own cells. Then you wait for at least a month before planting your crop, becasue otherwise your crop would not get any mineral nutrients from the soil. After a month, a part of the microbes are dead and have released the mineral molecules back into the soil. You therefore lose about 45 days in growing the green cover and another month in allowing it to rot in the soil, Green manuring is therefore not popular with farmers, because they lose a complete season. Under rainfed cropping in India, it means losing the entire year. That is why I recommend applying just 125 kg green leaves per ha along with the seed. While the seedlings are growing, he microbes multiply their numbers by eating the leaves, but because the leaves have been applied in just a small quantity, the nutrition is exhausted very fast by the soil microbes and they start to die, releasing the nutrients sequestered in their cells. By this time, the crop plants have developed their own root system and they are ready to absorb these nutrients. This is just a hypothesis. All that I have observed is that I get high yield whenever I apply about 125 kg green leaves per ha to my crop, right at the beginning of the season. I am trying to find out how and why this practice works so beneficially.
Yours
Dear Mr. Haard,
this refers to your request about my reaction to the observations of Dr. Makoto Ogawa. I am a botanist who used to work as the Research Director of a seed company in India. I worked mainly in the fields of plant physiology and plant breeding. I am now 72 and I head a voluntary organization founded by me for rural development through application of science and technology. I was made aware of the topic of Terra Preta by Ron Larson and Tom Miles and so I became a member of the Terra Preta discussion group. I developed interest in this topic because I had developed some theories of my own about plant nutrition, and agriculture without the use of chemical fertilizers. In the course of my research I found that by feeding the soil bacteria with high calorie, non-composted organic matter such as sugar, starch or cellulose, one not only increased the number of the soil microbes but also the yield of the crops. Just to test my hunch, I applied just 125 kg green leaves to a hectare of land owned by me, and got higher yield from this land than I used to get by applying chemical fertilizers. Now I have started a series of pot experiments in which the pots containing 1 kg soil each received 500 mg sugar, no sugar and a dose of chemical fertilizers. The pots are kept in a randomized complete block design, so that the data can be statistically analysed. After I started talking to my colleagues about charcoal being added to soil, some of them applied char made from sugarcane leaves to plants raised in pots and they reported that the plants in pots with char grew better than the ones not receiving this treatment. These experiments were not conducted very scientifically and they should be treated as anecdotal evidence.
Realising, that I did not know anything about soil science, I recently purchased a book on this subject and have started reading it. Although this book makes reference neither to Terra Preta nor to plant nutrition, the knowledge about soil minerals, their genesis and their metamorphosis under different climatic conditions is helping me greatly in understanding many aspects of plant nutrition. I feel that this knowledge would eventually be useful to me also in understanding Terra Preta. When I gain an insight into this topic, I shall certainly share it with this group.
Yours
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