[Digestion] Digestate as fertilizer.

Wed Jul 6 00:09:18 CDT 2011

Dear Jean-Luc,
applying cellulosic (leafy) biomass to the soil is the thing that has
been happening in nature since the plants occupied land 500 million
years ago. The plant parts (leaves, flower petals, bark, branches,
fruits etc) fall on the ground and the soil microbes use them as
carbon source. Green manuring of crops has been an age old practice.
Just don't worry about the composition of the micro-organisms in the
soil. It changes from soil to soil, from climate to climate and from
season to season. My hypothesis is that the microbes, when provided
with organic carbon, multiply their numbers, and in that process they
take up minerals from the soil. When they die, they release the
minerals into the soil, which become available to plants. You can just
apply green leaves to the crop at the rate of about 125 kg per ha,,
once every three months, and get high yield even in the case of
sugarcane. 125 kg green matter per ha can just be the weight of the
weeds that one removes from a ha of land. Plants themselves apply
sugar to the soil, as was demonstrated in the case of sorghum.
Practically all agricultural crop species harbour aphids. Not a single
plant species, even the wild ones, has developed resistance to aphids.
This is because a plant affected by aphids drops sugar on the ground
below its canopy.  It seems that the aphids help plants in obtaining
their mineral nutrition by feeding the microbes in the soil.
Yours
A.D.Karve

On Tue, Jul 5, 2011 at 10:45 PM, Jean-Luc Sallustro
<jean-luc.sallustro at eventure-international.com> wrote:
> Dear Anand,
>
> I shall stress on the fact that we, in Mauritius and elsewhere in Africa,
> are fighting against this abusive use of chemical fertilizers. This battle
> is at a point that one of our subsidiary is totally devoted to a project
> which aims at producing organo-mineral fertilizer providing that we are
> supplied with compost and digestats issuing from several composting and
> biodigester plants we are builidng (treatment of poultry waste, sugar
> factory waste and ethanol distillery effluents, hostels organic waste ...)
> Then I totally agree with your assessment regarding the fact there is no
> inescapable need for chemical fertilizer.
> Now, my question was on the use of raw sugar not on the soundness of a
> biofertilization strategy. Once again I would like to stress on the fact
> that "sugar fertilization"  seems to be a very interesting alternative to
> CMS for example.
> Let me rise again the point related to the comparison you make between sugar
> (as a low level polymerised carbonaceous compound) and cellulosis and
> hemicellulosis. For my understanding the very question is here to define
> what we call "organic matter", not in absolute terms of calorific value but
> through an ecological point of view then taking into account the complex
> interaction of microbial strains, macro decomposers, chemical role of water
> as a solvant, chemical role of clay as a substrat for H+ ions exchanges etc
> ... We all know a bit about NPK export from soils solutions to plants but it
> seems to me that we are not enough aware about organic matter, and worst
> about biomass in soils. As an example I have raised the fact that sugar will
> feed a particular class of microbes (and maybe other macro biotypes) and
> that will maybe imply that a lot of other bacterial strains will disappear
> or be weakened (celullosis decompostion ones). Do you have some observation
> to share on this point ?
> Best regards
> jean-luc
>
>
> Le mardi 05 juillet 2011 à 11:02 +0800, Anand Karve a écrit :
>
> Dear Jean-Luc,
> on dry weight basis, green leaves have the same nutritional calorific
> value as sugar. Therefore, when farmers apply green manure to crops,
> they are also feeding the soil microbes. It is recommended by many
> sugar factories in India to grow a green manure crop between the rows
> of sugarcane, at the time of planting sugarcane, and then to plough
> the green manure into the soil at two month stage of the crop.
> Analysis of soils before and after this operation showed an almost
> doubling of N,P and K in the soil. This increase in NPK did not come
> directly from the green matter incorporated into the soil but through
> the microbes, which multipled their numbers when they fed on the green
> matter and took up minerals directly from the soil. We acknowledge the
> fact that the top 10 to 15 cm layer of soil in a field is very
> fertile, but we do not call it humus, because the organic content in
> our soils is always very low. The fertility of this layer is
> contributed by the fact that leaves, animal dung, and other organic
> residues fall on top of the soil, where they are decomposed by aerobic
> micro-organisms. As I stated above, the microbes multiply their
> numbers when provided with any source of organic carbon. In the
> process of multiplication, they take up the minerals directly from the
> capillary water in the soil. Soil contains an infinite variety of
> microbes, and those which are best adapted to that particular soil
> condition multiply. If the soil is phosphate deficient, the phosphate
> solubilizing bacteria would multiply. If the soil were nitrogen
> deficient, the N-fixing microbes would be better able to survive than
> the non-fixing ones, and if the soil were saline, the halophytic
> microbes would have the upper hand over others. It is plain "survival
> of the fittest". After the microbes have exhausted the food, they die
> of starvation and release the organo-mineral compounds into the soil,
> increasing thereby the soil fertility. The organo-mineral complexes,
> such as proteins, enzymes and co-enzymes are soluble in water and they
> can be readily taken up by plants. The plants don't care from which
> category of microbes they get their minerals. There is no need to
> apply chemical fertilizers to the soil. And there is also no need to
> apply any special kinds of bacterial cultures to the soil.
> Yours
> A.D.Karve
> On Mon, Jul 4, 2011 at 3:05 PM, Jean-Luc Sallustro
> <jean-luc.sallustro at eventure-international.com> wrote:
>> Dear Anand,
>>
>> I am really interested by this vision of sugar nutrient cycle.
>> 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)
>> 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.
>> Soils macro decomposers such as colemboles or worms alternatively or
>> complementary play a role within this decomposition stage of cellulose and
>> hemicellulosis.
>> 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).
>> 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 ?
>> 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 ?"
>> All the best
>> Jean-Luc
>>
>> Le lundi 04 juillet 2011 à 12:11 +0800, Anand Karve a écrit :
>>
>> 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
>> <jean-luc.sallustro at eventure-international.com> 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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-- 
***
Dr. A.D. Karve
President, Appropriate Rural Technology Institute (ARTI)

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