Again Dr Srivastava, you are raising imminent questions. I would say that your question pool could be relevant for a whole book on "microbial role in agriculture in a changing climate".

I'm feeling at ease with using compost as a medium of balanced microbial inoculum. Using  one or more strains could be also interesting but rather in plant protection than in a fertilizing strategy. Soil types, irrigation mode, water quality, crops...all are factors that would affect the efficacy of your treatment. During the last 6-7 years, this issue is being largely studied and we will continue to study it as far as factors are multiple and situations are diverse both in-vitro and in-vivo (pot experiment).

Thanks Dr Anil Kumar for your inaugural response , which is indeed very impressive. That's a good point of discussion  , whether or not microbes could play any pivotal role in intensive agriculture ?. I do agree about the utility of native microbes.

Microbes have very strong role to pay not only in plant nutrition but reduce the load  in chemical fertilizers. However it remains to be seen, about the role microbes in fulfilling total nutrient requirement?

Again Dr Srivastava, you are raising imminent questions. I would say that your question pool could be relevant for a whole book on "microbial role in agriculture in a changing climate".

I'm feeling at ease with using compost as a medium of balanced microbial inoculum. Using  one or more strains could be also interesting but rather in plant protection than in a fertilizing strategy. Soil types, irrigation mode, water quality, crops...all are factors that would affect the efficacy of your treatment. During the last 6-7 years, this issue is being largely studied and we will continue to study it as far as factors are multiple and situations are diverse both in-vitro and in-vivo (pot experiment).

Khalid , don't you think , evaluating the response of microbial inoculation in-vitro is altogether a different  ball game compared to  in-vivo evaluation. Another point strikes to my mind, whether the concentration of microbial inoculation( in terms of cfu count ) is dependent on the soil microbial population to be inoculated ? 

Thanks Barabara, but unfortunately , the predominant role of microorganisms in cutting down the fertilizer requirement of a given crop  is not so heavily recognized?

Thanks Pierlorenzo for your thoughtful response . the rate of  microbial mineralization and immobilization is largely governed by C:N ratio of the soil and of feedstock ?your last sentence carries lot of meaning . Do you mean , in a nutrient deficient  soil , response of  microbial inoculation would be in a depleted from ?

Yes, microbes will behave vastly different in field than pot experiment or controlled conditions.

as far as I know, the microbial organisms have a very big role in increasing productivity of crop under long term and now a days developing countries like ours are using this technique for increasing productivity.

however it have some what a negative role on plant defense system as after inoculating it with  microbes there are much pests attack.

http://download.springer.com/static/pdf/882/art%253A10.1007%252Fs13593-015-0323-0.pdf?originUrl=http%3A%2F%2Flink.springer.com%2Farticle%2F10.1007%2Fs13593-015-0323-0&token2=exp=1460526275~acl=%2Fstatic%2Fpdf%2F882%2Fart%25253A10.1007%25252Fs13593-015-0323-0.pdf%3ForiginUrl%3Dhttp%253A%252F%252Flink.springer.com%252Farticle%252F10.1007%252Fs13593-015-0323-0*~hmac=e3270f20d71adf6f69e25bb017245fb38aa6fa0c064a53646af218981d8dbce7

Thanks Husain , that's  a very interesting piece of information , reporting 26% reduction in insect predatory diversity in corn plants upon inoculation with effective microorganisms. But , when non-inoculated control corn plants were set upon by caterpillars of the herbivore insect Spodoptera littoralis, plants increased the production of defensive organic volatiles by as high as 272% (Sergio Rasmann, 2015 , Agron. Suatain. Dev. 35: 1511-1519). The link is already provided by Husain Ahmad  , appreciate it for interesting link .

Complements to Dr Anoop for the question, which in my view includes the answer.

Multiple inoculation is responsive, but finally it's the natural soil ecosystem that'd regulate effective diversity of the microbes.

As has been pointed out in the question, integration of nutrient sources is important. Regarding suitable crops,  mixed cropping system would always have a positive impact.

By blending with organic manure (microbe-inoculated) we could reduce 50% of recommended chemical fertilizer in crops in upland ecosystems. But it's quite reverse in wetlands, which need to be researched in details

Thanks Nilay  for the response. Whats your opinion  about the contribution of microbial inoculation in cutting down the nutrient requirement of a crop , when tested without organic manures blend? 

Pierlorenzo , ok very good point put into perspective , like soil testing -based microbial  inoculation . Wonderful , I agree with you . This is where , you need to exploit upon plant -specific rhizosphere microbial diversity ?

Let me add some literature showing saving on inorganic fertilizers with multi-inoculants in different crops.

PDF enclosed:Comparative performance of Azotobacter chroococcum, Glucanobacter diazotrophicus tested both at 50 per cent and 75 percent recommended N showed that Glucanobacter diazotrophicus was more effective than Azotobacter chroococcum in improving the tuber yield and nutrient uptake. The total tuber yield per plot (8.53 kg), per hectare (38.61 tons) and nutrient uptake in plants (135.14-N, 28.96-P, 49.04-K, kg/ha) was maximum in combined inoculation of microbial inoculants viz., Azotobacter chroococcum, Glucanobacter diazotrophicus, Bacillus megaterium and Trichoderma harzianum, with 75 per cent N, P with full dose of K compared to control plants ( FYM alone T14). The combined effect of microbial inoculants helps in better uptake of nutrients, improved yields and also saves 25% of application of recommended dose of chemical fertilizers(Kumar et al . 2014 , Curr. Agri. J. 2:123-130).

PDF enclosed: The response of non-symbiotic microbial inoculants on growth, yield and quality of fennel (Foeniculum vulgare) grown in partially reclaimed sodic soils was studied at Lucknow (Uttar Pradesh). The results revealed that inoculation of phosphate solubilizing bacteria or in combination with Azotobacter chroococcum was superior resulting in 14%–15% increase in seed yield. Application of fertilizers (80 kg ha-1 N + 25 kg ha-1 P) with inoculants had an additive effect on plant growth. An increase in availability of soil P (41%–44%) and essential oil content (10%–14%) was also noticed( Garg 2007, J.Spices Arom. Crops. 16: 93-98).

PDF enclosed: Inoculation increased maize yield in 66 of the 92 small and 295 of the 369 large field trials (within the small plots, yield increased significantly at the 95% confidence level, by 0·17 ± 0·044 t/ha or 1·8%, while in the larger plots, yield increases were higher and less variable (i.e., 0·33 ± 0·026 t/ha or 3·5%). There was considerable inter-annual variability in maize yield response attributed to inoculation compared to the un-inoculated control, with yield increases varying from 0·7 ± 0·75 up to 3·7 ± 0·73%. N(Leggett et al. 2015, J. Agri. Sci., 153:1464-1478).

Hope , these will be of some use  in the context of further discussion .

Can anyone throw some light as how to develop microbial load of higher concentration from lower concentration of colony forming units.

What concentration of a microbe will be effective as soil inoculant and could throw response on plant growth?

Anoop Sir,

I endorse the statement of Bringoli sir.  Microbes can only fulfill nutrient requirement of the crop to the tune of 10%.  More-over bacterial population will decrease if the nutrient status is high in soil and if the pH is acidic.  Actinomycetes die if the soil is wet.   Fungi population will decrease if the soil pH is alkaline.  Multiple microbial consortium will definately promote the crop growth provided  INM has to be taken-up along with SSNM.

Thank you prof for your appreciation. I hope to learn more from the field specialists. Thanks again.

Prof the literature you shared with us is worth sharing and have very useful information. I have taken a good help in this regard. Thanks for sharing.

Thanks Dr. Swaroop for invitation.

What kind of microbes should preferably be the part of multiple microbial inoculation strategy?

Microbial population in soil is highly dynamic in nature. Externally added  (high dose) microbial inoculation of single or multiple inoculation will deteriorate native population of targeted organism. Addition of inoculations mainly for to keep the optimum population and activate the native population. Multi inoculations may suppress each others mechanism and too we are not sure about their sustainability in soil. Metagenoimcs might be the answer for your query sir. Analyse the targeted soil for their biodiversity, and absence or minimal population microbes can be delivered thorough single inoculations. And too availability of multi inoculations is impractical to to produce and to access. 

This to be more examined and discussed in this forum.

Thanks once again sir.

Inoculations can do wonders many wonders in sterilised soils in laboratory studies, but that is hard to rely on in natural soils where the relevant organisms often will be present in one form or another.  It is usually most important to inoculate with some types of nitrogen-fixing organism to some nitrogen-fixing plants with specific requirements, make sure that roots of e.g. grass can help supplying arbuscular mycorrhiza at least if transplanting with small root systems.  A few types of trees need specific ectomycorrhiza -incl. conifers. Cyanobacteria may be useful introducing in recently irrigated desserts with rice (N W India).  Rock-phosphate can benefit from adding sulphur and sulphuric acid producing bacteria if needed. 

Only N-fixation add nutrients from outside, and some market fake products even for that.  

Some N-fixing legumes can help providing organic matter and improve uptake of most / all nutrients from less available forms.  See my article on inoculation of Calliandra etc.

Hi all, here is a chapter recently published that deal with the topic of this question

Chapter Efficacy of Biofertilizers: Challenges to Improve Crop Production

So sorry , lots of discussion have taken place within a day , let me respond to all of them one by one , all of them are very informative and totally thoughtful.

Dr Rajakumar , Dr Hani , I do agree , it is next to impossible replace the inorganic fertilizers , with microbial inoculation , irrespective of how many and what diversity of microbes , you take for inoculation . But , fertilizers  saving on microbes , I have seen going beyond 40% , if  not more. I can understand the limitation of microbes , where from , such nutrients will come , its soil only having immobilized form of nutrients like P,S, Fe, Mn, Zn etc , except N that could be added through both asymbiotic and symbiotic nitrogen fixation .

Dr Rajan rasied a very good point ,. infact , these microbes , especially the thermophillic  microbes  act as blanket to orchard floor , disallowing soil temperature to be lethal to soil micorbes?

Dr Rajendran , this is  the reason , we keep insisting , identify the crop specific rhizocompetent microbes , then inoculate into the rhizosphere so that you are able to  give the required fillip to the indigenous population of soil microbes , and they perform multi-tasks, including the ecological services. Probably , the same response goes to response of Dr Mondal , wonders of microbial inoculation can only be witnessed , if inoculated microbes are competent with the natural inhabiting population of rhizosphere of a given plant .

Thanks Prof Antoun for appreciating . I have two cardinal points to toss up to you . Do you feel ,  a soil rich  in plant available supply of nutrients will be equally good in term of soil microbial load ; and two , do you feel , we will have better microbial diversity within the rhizosphere only when a sequence of crops ( comprising legumes , vegetable , fruits , cereals etc) is raised  as against monoculture ?

Do you feel that externally microbial inoculation will reduce the native microbial population in soil. If so how do you get crop growth response then  Dr Rajendran and other colleagues. 

I do not think so , otherwise , why should you inoculate the microbes into the soil . I agree with you , you will get the response of microbial inoculation only when inoculated microbes are accepted by the soil .

I think that multiple microbial inoculation may be of extent useful unless it based on scientific study for microbial state of the soil (types , population),soil pH.and environmental conditions as well as soil type.Furthermore bio-fertilizer may provide plants with many (not)needed nutrients.

Sir,

I am not saying that native population will be deteriorate, possibility of depletion will be encountered. Once u added a inoculation, competition will exist among the population whether it may be beneficial or harmful microbes. We encounter the response only form deficient or low population soil. That's why scientist are suggest the farmers to apply inoculations in Indian soil bcz our soil having a low population microbes (rainfed conditions). 

By meta genomics or biodiversity analysis, we can get a clear picture of biodiversity of particular soil. 

This is i want convey in this forum. 

Thanks  Dr Ali, the dynamism of  multiple inoculation or in form of microbial consortium would impose a different dynamics on growth of  plants compared to single or dual inoculation , the response data as of now , on these aspects are still miniscule. How does such microbial inoculations activate the plants metabolically that inoculated plants  are  transformed  so competitive to withstand most of the abiotic  stresses , to say the least ? 

Thanks Dr Rajendran for your response . once you inoculate the soil  any microbe( Preferably native microbes, that should be the thumb rule) , there will be fierce competition with indigenous microbial   population of soil . And , inoculated microbial population could go down  initially , but later overpowers such reactions ,finally becomes a part of the indigenous population .  But , your discussion has put forth  some very interesting points. Can we propose threshold levels of soil microbial population where there will be definite response of inoculation ?. Secondly , what is that critical level of soil organic carbon , should be considered threshold limit for response of microbial inoculation ?. Are  these  further influenced by the nature of crop ?

Friends, how do microbes communicates with each other. Is there different physiological signals according to different microbial communities. Any work done on these aspects. Do you feel better communication between microbes and host plant ensures better crop responses?

Friends , we have been talking quite substantially about the liquid-based  microbial consortium as single mode of inoculation using multiple microbes . Another distinct advantage of such microbial consortium is the compatibility with irrigation water to enhance their effectiveness by injecting them directly into the rhizosphere soil. Here is one excellent review by Pindi and Satyanarayana(2012) for further reading on this very important issue(PDF enclosed). Hope , you like this review.

a very informative discussion.

Thanks Husain . However , discussion is still incomplete . I feel so .

How do you regulate the microbial load , from initial population of say (For example ) 103 to 108 cfu/ml of liquid broth.  At this microbial load , if i want  to develop a microbial population.  Can anyone can throw some  light , what is the latest procedure to increase the microbial load ?

Shall we inoculate seed or growing medium to get better response of microbial inoculation?

Interesting response Dr Broxmeyer , liked it . We direly  need to unravel the biochemistry and physiology of synergies involving nutrient -microbe interaction or rhizocompetent microbe-crop interaction . The metabolic signals need to de decoded to understand the functioning of microbes at cellular/subcellular level.  Just imagine the comparison of Trichoderma  as fungi   and Pseudomonas bacteria, both are strong phosphate solubilizers , is there any mode of action , common to both of such diversified microbes , despite two belong to so different microbial communities , their function is so similar ? 

Indeed very useful discussions. Regarding enhancing the microbe population it can be done to a certain limit. A natural equilibrium in microbial intensity and diversity seems to be maintained in soil. We observed an immediate decline in population of specific bacteria with application of herbicides, without accompanied decrease in MBC. Does it indicate the rise of other (tolerant) species!! Then with continuous use of the chemical the population of the bacteria revived near to the initial magnitude. These are just observations, which need to be studied for further conclusion.

I am not sure if the following article may be of any guidance to the discussion:

http://www.annualreviews.org/doi/full/10.1146/annurev.ecolsys.38.091206.095740

Thanks Dr Anoop and all for initiating and participating such an important discussion

Thanks Dr Borah  for kind words . From the on-going discussion , it is still not clear , when should we decide about the necessity of microbial inoculation in  a given soil ?. Is there any guideline(s) about dos and donts for soil  microbial inoculation?

Do you feel,  microbes present in plant rhizosphere have the capacity to enter through root and act like plant endophytes ?

Very good counter -question Dr Deka. Couple of weeks back , we had a thorough discussion on plant endophytes on RG itself. You can have peep into the whole discussion , but surely , your point is well taken . It could be both ways . some of the studies have advocated , it is the same microbial  strain , initially active as soil microorganism , and later acted like an effective plant endophytes . And , with the result , few stress upon , there is no microorganism like endophytes . Other colleagues can add on it further please .

Yes. I agree with you Dr Srivastava. How does microbial diversity of soil differ from microbial diversity of plant as endophytes, can any one throw some light ?

Thanks Dr Shirgure for nice feedback on some newer issue . this si for sure, plant rhizosphere has far more greater microbial diversity than endophytic microbes?

I Dear Dr. Srivastava, 

Microbial inoculation alone cannot fulfill the nutritional requirement of crops with present and future levels of production and productivity. If you go through the rice production manual of irri 1967, it reveals that time with single rice crop, Soil Fertility was maintained by various microbes at that low level of productivity. 

However, we must pay huge attention towards Microbial management to have a living soil for better productivity with organics and inorganics  in combination. 

M

Thanks Dr Mahapatra for your informative response. That's the reason , we always say, lets use multiple inoculation , or alternatively the microbe sin consortium mode , considering the cropping intensity in present day context. You are right , better dividends can be harvested through  combined use of crop residues, inorganic fertilizers , organic manures/composts.

Frankly speaking, most of the microbiology in agricultural perspective still laboratory based. We need to simulate soil microbiology and fields. That will give new dimensions of research needed to harvest the millions of microbes for not only for crop production but also sound soil ecology and the environment. 

If we look into forest, microbes playing a huge role. We need to bring that role for crop production. The former is a long term effect. However, for crop production we need to go out and out activities to harvest the benefits of microbiology. We all know that after photosynthesis, BNF the most important biochemical rection carried out by microbes only. 

Good points Dr Mahapatra. Whats your take on plant endophytes versus rhizocompetent microbes?. Is there any possibility of tailoring the inoculation of different microbes according to critical growth stages vis-à-vis nutrient requirement ?. Let it be an imagination , scientifically , how  does it sound? 

Thanks Dr  Broxmeyer for two excellent links. I wonder , how could you get such  fascinating piece of information .Both the links are worth appreciating and equally worth reading . In the light of these discussion , if a rhizocompetent microbe is having  growth promoting ability  , possibly it will have some antagonistic property to take control of some pathogens to be able to  throw out the optimum crop performance?.

Friends , we often claim , addition of inorganic chemical fertilizers reduces the productivity potential of soil by cutting microbial load of the rhizosphere . On the contrary , there are ample reports stating that , as long as balanced fertilization is adopted , there is hardly any significant reduction in biological properties of the soil , which can cascade their cumulative  effect on productivity of the soil.  We have enough evidence to claim , that a microbe designated as rhizocompetent has the capacity tomcat bas nutrient sink , and later release the same quantum of nutrients in a much value added form (Assimilable form) into the rhizosphere . There is a scientific basis of nutrient-microbe synergy with respect to crop and with respect to soil as well. I am enclosing a PDF of a  review highlighting these issues, with hope to get back your feedback .  

Yes, Dr. Kumar, balanced fertilizer coupled with irrigation of good quality water and careful use of pesticides and weedicides do not affect microbial population. The population is only disturbed when agronomic practices enhance a stress. 

No. All nutrient requirements can not be fulfilled by microbial inoculation. Only N can be fixed symbiotically by microbes- others facilitate availability of nutrients.

Thanks Dr Biswas for the feedback on the issue. That's a good point . Let it be any number of microbial inoculations , microbes alone will not be able to supplement the entire nutrient requirement of the crop , unless combined with organic manures or inorganic fertilizers or all the three  plus crop residue addition /cover crops raising etc. to harness upon the multiple functions of microbes .

Yes, I totally agree to Dr. Kumar's view point.

 Total nutrient requirements of crops cannot be fulfilled by microbial inoculation in cold and temperate climatic conditions, because soil microorganisms are inactive during long winter and early spring season. But early spring is an important period, when all crops are especially needed in mineral nutrition. 

Elena ,  You have given a nice twist to  the whole discussion . My next quarry comes out with regard to time of inoculation . how should we schedule the time of inoculation ?. Shall we synchronise with critical growth stages or with seasonality of the different microbes to be inoculated ?

Inoculation at critical growth stages my be the right practice but we have to conduct a few trials before going into a recommendation.

Hi Dr. Anoop kumar,

Indeed a very good question and informative discussion.

Surely, just inoculations can not fulfill the the complete nutrient requirement. Addressing the right cause is important. A through examination/analysis of nutritional status, micro and macro fauna of soil can only suggest about external inoculations. Just inoculating single/consortium will led to disturbing the biodiversity. surely the needed can be applied.  

Thanks Dr Nazir. Sometimes , question is often asked , whether or not one time  inoculation is sufficient ? . This could be the case in annual crops , but in perennial crops , one time inoculation probably may not be sufficient . Where multiple inoculations are  involved , which microbe and what growth stage , shall we apply , is a matter of thorough investigation .  Do you feel , inoculation schedule similar to fertilizer is a call of the day ?

Yes, I agree to your view point. One time inoculation may not be sufficient, especially under stressed situations. Sometimes bacterial count significantly decrease due to hard situations e.g. after weedicide and pesticide sprays. I will suggest microbial tests after such agronomic operations and re-inoculation if count is found lesser than the standard one. Similarly, different growth stages of various crops can be addressed through inoculation. I totally agree that just one inoculation before sowing of long duration crops of 7-9 months (in tropics). Yes, it will be exactly true in case of perennial crops and fruit plants. 

Thanks Dr Waseem for your response. Its a good point , but this si the reason , we keep saying to add microbial consortium to be developed by exploiting the microbial diversity of the same crop , which it likes  using native isolates , so that natural diversity existing  within a crops rhizosphere is not unduly disturbed. 

Dr Nazir , thanks again .  I am taking your response to  further discussion . Why dont we have some yardsticks to define a particular soil microbially rich or poor?. Why dont we have  such guidelines similar to soil fertility standards ?. i can understand , microbial population is most sensitive to inputs of any kind , including the cultural practices , but diagnostic norms are distinctly missing .  

Yes, Dr. Kumar we need to set microbial standards like fertility statandards.

Biofertilizer program in our country was launched long back.  Couldn't get the harvest of that due to impractical attitude taken. Not given to indigenous components. I will again emphasize that the microbes in general cannot be ignored further for future soil sustainability and crop nutrition and productivity. As we have lost lot of time, the integration of organics with Biofertilizer is the need of the hour along with chemical fertilizers or other synthetics.

Taking the discussion further where Dr Nazir left with a nice food form thought . Whats your opinion friends , do we need to develop soil microbial community -based standards to define the soil health more precisely ?. I strongly feel in favour of it . 

Thanks Dr Mahapatra  for adding some icing on the whole issue . i totally agree with you . But where are we failing , we keep crying and i find umpteen number of M.Sc/Ph.D  thesis addressing this issue , but without any plausible solution at th e farmers level.  Whta is your opinion Dr Mahapatra , What kind of schedule , shall we adopt  in field to harness the maximum synergy  from the syndicate existing between three diversified sources of nutrients like microbial inoculants , organic manures and inorganic fertilizers. 

Multiple microbial inoculation is to be studied with respect to release of immobilized nutrients in soil besides replacing the amount of chemical fertilizers. AMFs must find a due place in such studies. 

Dr. Srivastava, the irony of the facts are as follows: 1. People decides treatments and combinations as per their reach. 2. Soils and crops are not taken into consideration 3. If you see some classical reference, eg rice production manual of IRRI in seventies, the role of biofertilizers including BGA highlighted huge, though that time it was mono Cropping with traditional rices.

Now it's high time to redefine the role of microbial inoculation in Soils and plants for sustainability of the Ecology and Productivity. 

Syndicating is the need of the hour. 

Organic and microbial application not only helps in nutrients availability but also favorably changes physical chemical and biological behavior for betterment. 

Dr Mahapatra,  i am in full agreement of your response . Long back , i raised this issue , we get our soils tested , how do we recommend fertilizers , unless we know the preferential requirement of different nutrients ..? Can we prescribe fertilizers  for two or three alternative crops , based on soil test report ...?.  And , there is hardly   any quality standards for manure quality with respect to microbial load ?

Dr. Srivastava,

Heterotrophic microbe(s) can only extract nutrient if there is enough and energetically economical substrate for the microbes to work on.

In other words, not every possible amount of nutrient element is extractable from soil using microbes.

If the amount goes below a certain level in soil/substrate microbes can not work whatever their population be.

In that stage, changing the type of microbe may help but soon a plateau would arrive.

Regards,

MKD

Thanks  Dr Dabi  . Effectiveness of any  rhizocompetent  microbe  is hugely dependent on the soil organic matter availability , besides the population of other compatible  microbes , so that if one microbe fails , the others are there in value added form to comprehend the further nutrient availability on sustained basis . These microbes also  later add in release of immobilised nutrients  depending upon the status of susbstrate left in soil .

As Dr. Srivastava prompted me, I am sharing here some thoughts closely related to the topic here and to his other discussion of nutritient solubilizing bacteria (https://www.researchgate.net/post/Why_dont_we_talk_about_microbial_solubilization_of_micronutrients2). 

As far as I gather from the popular lectures of Dr. Elaine Ingham about the soil foodweb, provided adequate climatic conditions, there is no soil on this planet that lacks the nutrients to grow plants. Once you have the right set of microorganisms to extract the nutrients, she says, you do not need, any additional fertilizers, pesticides and so on. In fact, she argues that inorganic fertilizers are detrimental for a good soil web and that in the long run inorganic fertilizers actually reduce fertility. She also argues that plants are best in determining what they need. I wrote about this in your discussion on solubilizing bacteria, plants, says she, release exudates to foster the growth of the particular solubilizing bacteria they need - if they need Zn, release certain type of exudate to foster growth of Zn solubilizers (as far as I understand from her talks on youtube).

Ingham's methodology and practical advice to farmers is to use microscopes to determine the soil foodweb structure in your soil. Take the microscope and investigate the current situation of your soil foodweb. Is it fungal or bacterially dominated? Do you have a well balanced food web? Do you have only bacteria and no fungi. Do you have any predators (bacterial feeding nematodes, protozoa, etc.) to control the populations of the lower trophic levels. I am not well acquainted with her methods, but the bottomline is that with some training a farmer can answer basic questions about his soil health and knowing the requirements of his crop, he can prepare an appropriate inocculum (in mundane tongue: good aerobic compost).

There is evidence that different succession stages are related to different bacterial to fungal biomass ratios. Following this thread, Ingham advises to use different types of composts (composts with diferent ratios of fungal to bacterial mass) based on the requirements of your crop. Maybe for wheat put in the compost more bacterial foods, so you can get a more bacterially dominated compost for inoculation. Or for conifers it would be a more fungal compost. (Check another discussion we started with Dr. Srivastava - https://www.researchgate.net/post/What_are_the_optimal_fungal_to_bacterial_biomass_ratios_for_different_crops). 

This is a very strong claim, if we say that we do not need any fertilizers, can you imagine what revolution this will be for agriculture? Just determine the best F/B ratios make adequate compost and you don't need any fertilizers! 

Can we eliminate fertilizers just by improving the soil food web? Is this overstating? Is this a hoax? Or is it true? Or is this something for the distant future? After all who sprays fertilizer in forests? Is it the fairies!? Do you know of any additional research that can support these claims - no fertilizers needed, only the adequate set of microorganisms, a good soil foodweb and a low perennial cover crop to sustain the biology in strip till. 

Please, check this article of Dr. Ingham, it is impossible to grasp what she is talking about without delving into the intricacies of the soil foodweb - http://www.rain.org/~sals/ingham.html

and this is her website - http://www.soilfoodweb.com/ .

Friends , this is one of the best feedbacks , i have so far received  in relation to on-going discussion . It  is full of insightfulness to think over and pamper all of you to think through out of  your avialable tool box . I am waiting for your feedbacks colleagues.....

Dr Christopher Joseph, its a fantastic feedback urging our friends to rethink some newer hypothesis.

Very good out of box response from Dr Christopher. Such innovative ideas are needed to rethink our conventional style of thinking on various scientific issues. I appreciate the interest of colleague like Dr Christopher. 

Yes Dr Shirgure , i also agree , but i am waiting for some interaction from our other colleagues. Hope to get some feedback very soon ...

We should address different nutrients instead of nitrogen and phosphorous. Nutrients like potassium, zinc, iron should be next agenda.

Let me raise the issue of exacting roles of different microbes/microbial inoculants , if your soils is biologically active to soil potential , you really do not need any fertilizers to be externally added , since the nutrient cycling in field conditions , is so efficient that can easily preclude the application of outside source of nutrients .  At the most , addition of some amount of microbially rich organic composts will do the job..?This is what my friend Christoper-Joseph raised  . How do you feel friend about this beautiful convincing logic ....

Dr Deka , you are right , microbes able to solubilise these  nutrients  will surely do the world of good to any crop..?

I am floating a another question to my colleagues, to what an extent multiple microbial inoculation can replace the inororganic fertilizers ?  

As the world is recovering from some of the adverse effect of negative exploitation of earths mineral resources it is a clear fact unless we get back to ecofriendly mean and methods of all process we will continue to bear the unprecedented reversal effects. example is the conventional use of legume crop as a the supplier of sufficient nitrogen and other minerals to the soil

Most important of all is , perhaps , the  ways and means to develop the  required synergy between legumes as a part of cropping sequence  and  cover crops , nutrient cycling  through residue management , microbial diversity evaluated from time to time , as function of nutrient turnover  ...In this context , comments of  Dr Ibrahim and Dr Shirgure hold importance .

As a co worker in a experiment conducted in gladiolus we reported that application of 75 % Nitrogen and phosphorous with Azotobacter and PSB each at 5 g per kg corms yields maximum spikes and corms. So Shirgure sir from our findings using 20 to 25 % nutrients through biofertilizers may fulfill the crop nutrient demand.

Vikas, can we go for multiple inoculation, how much chemical fertilizers we can save. I appreciate your response. 

We need to change our approach. Multiple microbial inoculation in long run going to be hugely beneficial for our production system. Intensive production system will always ask for supplemental nutrition, but with multiple inoculation, dependency level for brought in inputs will certainly be reduced. 

Good point ,  from both of you my dear friends , Dr Shirgure and Dr Mahapatra , you have raised , and i agree with you . But , most important is our preparedness with regard to soil organic matter content to be enough to harvest the effect of  such  multiple microbial inoculations. 

Multiple microbial inoculation will certainly not fulfill the total nutrient requirement of a crop, but it will supplement a major share of nutrients.

Thanks Dr Biswas, unfortunately the work on microbial  consortium is miniscule in terms of product outcome. 

Dr Srivastava and other colleagues, what are the pre-soil conditions for deriving the maximum benefit from microbial consortium ?

Available soil carbon and pH play an important role, off-course favorable temperature and moisture must be there. 

Bacterial inocularion is not suficient if the soil lacks some nutrients. You mut add them.

Rightly said. We can not observe the favorable response of microbial inoculation unless there is minimum soil fertility level observed in soil.

Luis ,Sikha, Dr Biswas,  i agree with the statements from all  of you three  . Microbial inoculation , whether single or multiple in nature , need to derive the food for their proliferation from soil only , where organic matter content of soil is of utmost importance , besides bare minimum nutrient supply level of  soil .  

Dr Srivastava you are very right, soil organic matter and pH are two most important soil properties to improve the response of microbial inoculation. What are the other ways to improve the response of microbial inoculation ? 

I think , the  comments of Dr Biswas are very valid, in the light of on-going discussion.

Yes, I agree with you Dr Srivastava, comments of Dr Biswas are well taken. 

We are discussing the issue for long. We must take note of the following: 1. Which microbial strains we are going to have. 2. Whether those are already exists in the field. 3. If so, microbial inoculation as such not going to be of practical importance. 4. The inoculation must be soil friendly. 5. Most of the cases, rhizobium has responded for legumes. 6. For other microbes, there will be beneficial effects rather than nutritional fulfillment of crops. 5. In long run, some of the nutrient like P application may be avoided, some micronutrients availability may be increased. 

Dr Mahapatra , some very pertinent points , making the discussion more useful. If a soil microbial species already exists in the soil , you inoculate with  the same species from other sources  , there could  still be a possibility of crop response , you never know that species , whether or not effective or not in terms of crop response? . You never know , whether or not that species is rhizocompetent or not ..?

Can you please spell out beneficial effects than nutritional effects ..?

Appreciate your discussion ...

Beneficial microbes might be present already, but the population density is not enough to make beneficial contribution to the plants. So, population build up through inoculation is required.