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Dear Anand,<BR>
<BR>
I am really interested by this vision of sugar nutrient cycle.<BR>
Let me say first that even if I am from Europe, (you are right on this point) my group is in Mauritius, and then involved with sugar cane agronomy (or other Poacae)<BR>
Sure that cellulose is a kind of sugar ... but strongly polymerized, at a point that the only bacterial strain enabling its degradation is aerobic and particularly thermophilic.<BR>
Soils macro decomposers such as colemboles or worms alternatively or complementary play a role within this decomposition stage of cellulose and hemicellulosis.<BR>
What seems to me of utmost interest in your assessment is that sugar (I assume you are considering raw sugar ?) provides for direct enhancement of soil fertility (when bring with organic N) for the reason that this immediately available energy positively stresses bacterial flora (but which strains in particular ?) and then allows the production of mineral nutrients to reach the plants depending on export demands (Poacae are C4 type and therefore strongly dependant from photocycles and water availability).<BR>
The way different +/- polymerized sugars reach the soil is a well known thing, but what's about humus role (even as thin it seems ... there is always an upper layer of biomass on the 0 to 15 cm depth of soils), and what is happening as an interaction between microbial activity in this superior soil level, sugar solution (rain fed context) and other N linked bacterial strains ?<BR>
My hypothesis was that there is a risk of demobilisation of these endemic bacterial strains, maybe one can put the question like this "when stopping "sugar feeding" what will happen with organic N, P and K availability ?"<BR>
All the best<BR>
Jean-Luc<BR>
<BR>
Le lundi 04 juillet 2011 à 12:11 +0800, Anand Karve a écrit :
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<PRE>
Dear Jean-Luc,
feeding sugar to the soil microbes is done by the plants themselves.
The water of guttation of sorghum and safflower contains sugar. All
the plants that are infested by aphids also drop sugar on the ground
below their canopy. The leaves that fall on the ground also contain a
type of sugar (cellulose), In the case of many trees, one finds a
carpet of fruits underneath their canopy. The fruits contain sugars.
Chickpea (Cicer arietinum) leaves exude organic acids, which too fall
on the ground to feed the soil microbes. In India, in the region where
I live, literally thousands of farmers have taken up the practice of
applying sugar to the field. For every hectare,they use a mixture of
25 kg sugar, 25 kg cattle dung and 25 litres cattle urine. It is
applied once every three months. In an earlier experiment, I got the
soil from a non-irrigated and non-fertilized field analysed
consecutively for 5 years and found that in spite of growing crops on
this soil, there was no change in the soil composition over this
period. In India, the agricultural yield is positively correlated with
the rainfall and not with any other factors like the sale of
fertilizers, pesticides, hybrid seed, etc. Humus is a typical topic
raised by European agricultural scientists. Nobody talks of it in
India, most probably because our soils do not have the humus layer
that European soils have.
Yours
A.D.Karve
On Sun, Jul 3, 2011 at 10:52 PM, Jean-Luc Sallustro
<<A HREF="mailto:jean-luc.sallustro@eventure-international.com">jean-luc.sallustro@eventure-international.com</A>> wrote:
> Dear A D Karve
>
> For my understanding microbes have an important role in the soil at a stage
> where endemic proto nutrient are made available for them within the humic
> clay complex.
> This deep stage of macro nutrient (organic NPK) evolution can be depleted
> for many reasons such as K sustainable sequestration, unavailability of
> macro nutrient, not enough water percolation (soil solubility) etc.
> Don't you think that one of the risks of depletion in N chain can be the
> demobilization of upper soil decomposers due to the fact that immedialty
> avalible nutrient are provided (sugar)
> Regards
> J-L Sallustro
>
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