[Terrapreta] sugar usage

[adkarve]

I received many inquiries about sugar. I give below the thought processes
that led me to applying sugar to a field.
Sorghu,m, being highly drought resistant, is quite popular with farmers who
cannot irrigate their fields. Sorghum farmers drill the seed into the field
when the first showers of the monsoon have wetted the soil sufficiently to
assure germination of the seed. After that stage, if the rainfall is
adequate, the farmers harvest an average 2 tonnes of grain and about 4
tonnes (dry weight) of fodder per ha. If the rainfall is inadequate, they
lose the crop. Since the harvest is uncertain, the farmers do not apply any
inputs to the field. The grain is used as human  food and the stems and
leaves are fed to cattle. Only the roots are left in the field to rot.
 When one looks at the input and output of plant nutrients in the case of a
sorghum field, it becomes obvious that the soil loses more nutrients every
year than it receives. I therefore started looking for mechanisms that would
allow the soil to sustain such robbery of the nutrients. Although water,
carbon dioxide and perhaps even nitrogen are derived from the atmosphere,
the other nutrients have to come from the soil. This led me to search for
mechanisms that would generate water soluble nutrient ions every year anew
in the soil.
 As stated above, the roots of sorghum rot in situ. Like seeds, roots too to
contain plant nutrients.  If you cut a plant at soil level, it sprouts
again, using the food stored in the roots. Normally, when one applies only
composted organic matter to the field. Compost does not have much
nutritional value as far as the soil micro-organisms are concerned.
Therefore, although the agronomists recommend the application of compost to
the field as a source of food for the soil micro-organisms, the doses of
application of compost (25 to 40 tonnes per ha) are calculated on the basis
of its N,P and K content, and not on the basis of its nutritional calorific
value. The roots thus represent non-composted, high calorie source of
carbon. Because the micro-organisms need the same mineral nutrients that the
green plants need, I argued, that the soil micro-organisms utilize the
carbon and the energy in the roots to extract mineral ions from the normally
insoluble soil minerals.  When the roots have been completely consumed, the
micro-organisms too die, releasing the minerals in their cells for the next
crop of sorghum.
 I started experimenting with sugar, because it represented a high calorie
carbon source, that did not have any mineral components in its molecular
structure. Later on I learned that the water of guttation that falls every
night from the leaves of sorghum on the soil surface, also contains sugar.
When I started looking for similar phenomena, I found that water of
guttation of safflower also contained sugar. The water of guttation of
chickpea contains organic acids. It was clear that the plants were already
feeding the soil micro-organisms with  high calorie, noncomposted organic
matter, long before I thought of it.
 Therefore, it is not the quality of sugar or its composition that is
important. It has to be a high calorie, non-composted organic substance. At
least under Indian conditions, application of about 25 kg (dry weight) of
such a substance to a hectare, once every two or three months, gives very
good results.
 I got interested in terra preta because charcoal, with its highly porous
nature, offers a much increased surface area for the soil micro-organisms to
settle on. Application of charcoal, along with relatively small quantities
of high calorie, non-composted organic matter may evolve in future as the
new agronomic practice.
Yours
A.D.Karve