The document discusses biofertilizers, which are preparations containing living microorganisms that help crop plants uptake nutrients. It describes various types of biofertilizers like nitrogen fixing bacteria, phosphate solubilizers, potassium solubilizers, mycorrhizal fungi, and their mechanisms and benefits. The document also discusses mass production and application of biofertilizers for organic farming to ensure food security while protecting the environment.

1. BIOFERTILIZERS
Likhith K
BiSEP - 2021
Dept of Biotechnology
St Aloysius College,
Mangaluru, Karnataka,

2. Contents
Introduction
Types of biofertilizers
Nitrogen fixing bacteria
Phosphate solubilizers
Potassium solubilizers
Mycorrhizal Fungi
Zinc solubilizers
Iron sequestration
Silicon solubilizing bacteria
Plant Growth Promoting Bacteria
Mass production of biofertilizers
Carrier materials
Categories of carrier materials
Preparation of innocum packets
Specification of polythene bags
Biofertilizer application

3. Caution
Advantages
Disadvantages
Conclusion
Reference

4. Introduction
Organic farming plays a major role in feeding the increasing population of
humans which has also resulted in growing dependency on agrochemicals. By
contaminating air, water and soil indiscriminate use of agrochemicals pose a
great threat to nature.
Since plants cannot take up these toxic chemicals, they begin to accumulate
in the ground water and some of which may also result in eutrophication of
water bodies. Such chemicals have a detrimental effect on soil by depleting its
water holding capacity, soil fertility, increase salinity and soil nutrient
disparity.
These chemicals adversely affect soil in terms of depletion of water holding
capacity, soil fertility, increased salinity, and disparity in soil nutrients. The
results of use of excess chemical inputs have made crops more susceptible to
diseases and reduced fertility of soil.
Organic farming is one among the strategies that not only ensures food
security but also contributes to soil biodiversity. The supplemental benefits of
organic agriculture includes longer shelf life that does not harm the
environment.

5. Eutrophication

6. Organic farming is largely reliant on soil’s natural microflora including all types
of beneficial bacteria and fungi like arbuscular mycorrhiza fungi (AMF) known as
plant growth promoting rhizobacteria (PGPR).
Biofertilizers is one such component of organic farming that keep the soil
environment rich in all kinds of micro- and macro-nutrients via nitrogen fixation,
phosphate and potassium solubilisation or mineralization, release of plant growth
regulating substances, production of antibiotics and biodegradation of organic
matter in the soil.
When biofertilizers are applied as seed or soil inoculants, they multiply and
participate in nutrient cycling and benefit crop productivity. In general, 60% to
90% of the total applied fertilizer is lost and the remaining 10% to 40% is
taken up by plants.
Biofertilizers improve soil fertility by fixing the atmospheric nitrogen and
solubilising insoluble phosphates and produce plant growth-promoting substances
in the soil.

7. These are preparations containing living cells or latent cells of efficient strains of
microorganisms that help crop plants uptake of nutrients by their interactions in
the rhizosphere when applied through seed or soil.
They accelerate certain microbial processes in the soil which augment the extent
of availability of nutrients in a form easily assimilated by plants.
The use of biofertilizers has proven effective in promoting growth of crop plants
such as rice, pulses, millets, cotton, sugarcane, and vegetables crops.

8. Types of Biofertilizer
Nitrogen Fixing Bacteria(NFB)
Phosphate Solubilizers
Potassium Solubilizers
Mycorrhizal Fungi
Zinc Solubilizers
Iron sequestration
Silicon Solubilizing Bacteria(SiSB)
Plant Growth Promoting Bacteria(PGPB)

10. Bacteria:
Symbiotic nitrogen fixers.
Rhizobium, Azospirillum spp
Free living nitrogen fixers.
Azotobacter, Klebsiella etc.,
Algal biofertilizers:
Blue green alga in association withAzolla
Anabena, Nostoc, Ocillatoria
Phosphate solubilising bacteria:
Pseudomonas, Bacillus megaterium
Fungal biofertilizer:
Vesicular-arbuscular mycorrhiza (VAM)
Earthworms
European lumbricids, Eisenia fetida, Eudrilus eugeniae; Perionyx
excavatus

11. 1. Nitrogen fixing biofertilizer (NBF)
Nitrogen (N) is one of the most essential nutrients for growth and productivity in
plants. Although it is present in the atmosphere at 78%, it remains unavailable for
plant use.
 Nitrogen must be converted to ammonia in order to use the atmospheric
Nitrogen, which can be readily assimilated by plants via the biological Nitrogen
fixation process (NFB).
 Nitogen-fixing micro organisms use an enzymatic complex known as
Nitrogenase to convert atmospheric nitrogen into ammonia.
Nitrogen fixers are classified as symbiotic and non symbiotic. The members of
family Rhizobiaceae that establish symbiotic relationships with leguminous plants
are types of symbiotic organisms .
On the other hand, free-living and endophytic forms of microorganisms such as
Cyanobacteria, Azospirillum, Azotobacter etc are types of non-symbiotic
microorganisms.

12. The N2-fixation process is accomplished through the nitrogenase enzyme complex
(Dinitrogenase reductase and dinitrogenase). Dinitrogenase reductase supplies the
electrons, while dinitrogenase uses these electrons to reduce N2 to NH3. Enzymes
bind to oxygen, rendering them inactive.
Rhizobium Medium
Rhizobium Medium is used for cultivation and isolation of Rhizobium species.
Composition Ingredients Gms / Litre
Mannitol 10.000
Dipotassium phosphate 0.500
Magnesium sulphate 0.200
Yeast extract 1.000
Sodium chloride 0.100
Agar 20.000
Final pH (at 25°C) 6.8±0.2

13. Yeast Extract Mannitol Agar (YEMA) is used for cultivation, isolation and
enumeration of soil microorganisms like Rhizobium species.
Composition Ingredients Gms / Litre
Yeast extract 1.000
Mannitol 10.000
Dipotassium phosphate 0.500
Magnesium sulphate 0.200
Sodium chloride 0.100
Calcium carbonate 1.000
Agar 15.000
Final pH ( at 25°C) 6.8±0.2
Rhizobium culture

14. 2. Phosphorus solubilizers
 The second key mineral nutrient required in substantial quantities by
plants is Phosphorus (P).There is a large amount of P present in the soil,
but it is normally fixed (i.e. P-fixation) at the point of application and
thus, becomes insoluble and unavailable to plants.
 The phosphorus that is insoluble is present as inorganic substances such
as apatite or as one of many organic forms including inositol phosphate
(soil phytate), phosphomonoesters, and phosphotriesters.
 Furthermore, soon after it is added to the field, much of the soluble
inorganic phosphorus used as chemical fertilisers becomes immobilized.
It thus becomes inaccessible to plants and is therefore wasted.
 The application of Phosphorus solubilising biofertilizer (PSB) is used to
help remedy and make P more bioavailable and bioaccessible to
promote growth and development of plants.

15.  For example, PSB includes phospho-bacterin, which helps to solubilize
insoluble phosphates (e.g. di- and tri-calcium phosphates,
hydroxyapatites, and rock phosphates) and makes them more accessible
to plants.
 The solubilisation effect is achieved by the phospho-bacterin synthesis
of organic acids that decreases the soil pH leading to the breakdown of
phosphate compounds and the release of ample P for plant use.
 The low molecular weight organic acids such as gluconic and citric
acids synthesized by these bacteria are characterized by hydroxyl and
carboxyl groups that can chelate phosphate-bound cations.
 This results in the conversion of insoluble forms of P to soluble ones.
The examples of bacteria with the capacity to solubilize and mobilize P
include Pseudomonas, Bacillus, Rhizobium, Burkholderia,
Achromobacter, Agrobacterium, Microccoccus, Aerobacter,
Flavobacterium, Aspergillus, and Erwinia

16. Pikovskaya’s Agar is recommended for detection of phosphate-solubilizing soil
microorganisms.
Composition Ingredients Gms / Litre
Yeast extract 0.500
Dextrose 10.000
Calcium phosphate 5.000
Ammonium sulphate 0.500
Potassium chloride 0.200
Magnesium sulphate 0.100
Manganese sulphate 0.0001
Ferrous sulphate 0.0001
Agar 15.000
Phosphate solubilising bacteria

17. 3. Potassium solubilizers
 Potassium is one of the key macronutrients that the plant requires to improve its
biological processes besides N and P. The availability of total K in the soil is
high, but only limited quantities are available for use by plants.
 There exists three forms of Potassium at the same time in the soil system;
namely, unavailable, slowly available, and readily available forms.
 The application of biofertilizers can help remediate this situation by solubilizing
the unavailable K and thereby furnishing it in available forms for plant uptake.
 For example, bacteria like Frateuria aurantia can mobilize and solubilize
unavailable K for the growth of plants. The examples of Potassium-solubilizing
microorganisms (KSM) are Aspergillus, Bacillus, Clostridium, Azotobacter,
Azospirillum, Phosphobacteria and Rhizobacteria.
 The Co-inoculation of Azospirillum brasilense and Rhizobium meliloti has a
beneficial effect on the yield of grains and the content of N, P and K in Triticum
aestivum

18. Aleksandrow Agar
Recommended for isolation and detection of Potassium solubilizing bacteria from
soil samples.
Composition Ingredients Gms / Litre
Magnesium sulphate 0.500
Calcium carbonate 0.100
Potassium alumino silicate 2.000
Dextrose (Glucose) 5.000
Ferric chloride 0.005
Calcium phosphate 2.000
Agar 20.000
Final pH at 25°C) 7.2±0.2
Potassium solubilizing bacteria

19. 4. Mycorrhizal Fungi
The term mycorrhiza describes a symbiotic association between plant roots and
certain fungi. In the mycorrhiza association, the fungi colonize the plant root
either intracellularly or extracellularly, depending on the type of plant and
fungus involved in this association.
In a simple view, the relationship that occurs between a host plant and fungus
may be described as mutual in the sense that the fungus is supplied with
carbohydrates needed for its metabolic activities by the host plant, and, in
exchange, the host plant is supplied with nutrients and water needed for its
growth by the fungus. Thus, the association between the fungus and the host
plant is a mutually beneficial symbiotic association .
Mycorrhizal fungi play a key role in enhancing the uptake of water and
nutrients, such as phosphorus from the soil, which is needed for plant growth
and productivity. Similarly, the inorganic phosphate transporter (Pi) in
mycorrhiza Glomus versiformis hyphae was reported to enhance the absorption
of phosphate from the soil to the host plant. Mycorrhizal fungi may also
facilitate the detoxification of both organic and inorganic soil pollutants that may
harm plant productivity.

20. Mycorrhizal fungi are classified into two major types: endomycorrhiza is
common to more than 86% of plant species, where the hyphae penetrate plant
root cortical cells forming intracellular arbuscules; and ectomycorrhiza
characteristic of trees and shrubs, where hyphae do not penetrate plant root
cells.
Mycorrhizal fungi in PDA

21. 5. Zinc Solubilizers
 Zinc forms an important part of many organic complexes and DNA-protein.
It also plays a key role in the synthesis of proteins, production of growth
hormones and development of seeds.
 The plant uses just 1- 4% of total available Zn in submerged conditions
while 75% of the zinc will undergo fixation rendering it inaccessible for use
by plants be fixed (i.e. crystalline iron oxide bound and residual Zn,
respectively).
 The availability of zinc declines due to changes in pH and the subsequent
formation of insoluble Zn compound both in flooded and submerged
conditions. Zn can be made available and accessible for use by plants via
biofertilizer application.
 For instance, the solubilisation of zinc from the compounds such as zinc
oxide (ZnO), zinc carbonate (ZnCO3) and zinc sulfide (ZnS) into the forms
used by plant like Zn2+ cation which is the dominant form taken up by
plants is enhanced bythe application of B. subtilis, Thiobacillust hioxidans,
and Saccharomyces sp. as biofertilizers.

22. Zinc Solubilising Agar
Zinc Solubilising agar is recommended for isolation and detection of zinc
solubilising soil microorganisms.
Composition Ingredients Gms / Litre
Dextrose (Glucose) 10.000
Ammonium sulphate 1.000
Potassium chloride 0.200
Dipotassium hydrogen phosphate 0.100
Magnesium sulphate, heptahydrate 0.200
Zinc oxide 1.000
Agar 15.000
Zinc solubilising bacteria

23. 6. Iron sequestration
Iron (Fe), an essential micronutrient, plays vital role in chlorophyll formation,
photosynthesis, respiration and various enzymatic reactions. Iron is absorbed by
plants either Fe2+ (ferrous cation) or Fe3+ (ferric cation) forms.
All living beings need Fe. Under anaerobic conditions, it forms insoluble
hydroxides and oxyhydroxides and predominantly occurs as Fe3+. Most of the Fe
is unavailable to both bacteria and plants.
In general, bacteria obtain Fe by producing iron chelators known as siderophores.
Majority of the siderophores both intracellular and extracellular siderophores have
low molecular weights, soluble in water and high affinity for complex.
Fe3+ is converted into Fe2+ in the bacterial membrane by both Gram-positive
and Gram negative bacteria. Siderophores then releases Fe2+ molecules into the
cell through a gating channel that connects the inner and outer membranes.
Consequently, under limiting conditions siderophores may also act as Fe
solubilising agents.

24.  There are different mechanisms of Fe assimilation by plant from bacterial
siderophores namely:
(i) chelating and releasing Fe;
(ii) direct uptake of siderophores-Fe complexes; and/or
(iii) by a ligand exchange reaction.
 In addition to Fe assimilation, bacterial siderophores also help host plant to
alleviate plant stress resulting from the accumulation of heavy metals in the
soil. Siderophores bind to heavy metals and reduce the concentration of
soluble metals in the soil.
 Media and dyes
 Pikovskaya's medium, Reyes's basal medium, and a modified basal medium
(sucrose, 10 g; NaCI, 0.1 g ; MgS04 , 0.5 g; yeast extract, 0.2 g; NH4CL 0.5 g;
MnS04 o Hp, 0.1 g; FeP04 2 g or AlP04 , 5 g as P sources) were used.
 Two pH indicator dyes, bromo phenol blue (BPB) and bromo cresol green
(BCG) were used in the modification of the media. A stock solution of 0.5% of
each dye was prepared in 70% ethanol and the pH was adjusted to 6.5 using 1
N. KOH.
 A 0.5 mL aliquot of the stock solution from each dye was added to 100 rnL of
Pikovskaya's agar, Reyes's basal agar and modified basal agar media,
autoclaved, and plated.

25. Iron oxidising bacteria

26. 7. Silicate-solubiliszing bacteria
Silicon (Si) is one of the major soil constituents. It is mainly absorbed by the
plant roots in the form of mono silicic acid Si(OH)4 from soil water.
Si plays an important role in alleviating different abiotic stresses like drought,
high temperature, freezing, lodging, radiation and ultraviolet and various composite
stresses like metal toxicity, salt tolerance and nutrient imbalance.
It imparts drought resistance by maintaining the rate of photosynthesis, leaf
erection, water balance and xylem vessels structure during higher transpiration
rates which mainly results from high temperature and moisture deficiency.
 There are many microorganisms present in the soil, but only few can solubilize
silicon. Micro organisms including Bacillus caldolyticus, Pseudomonas, Proteus
mirabilis and Bacillus mucilaginosus var. siliceous were found to be the most
appropriate for the solubilisation of Si from natural silicates

27.  These silicon solubilising bacteria can decompose silicates, mainly Al2SiO5.
During the growth period, these microbes synthesize many organic
substances that aid in weathering of minerals and also freeing K from K-
containing minerals.
 The microbes aided silica solubilisation is considered as good source for
supplying silicon to crops. These microorganisms promote the growth
characteristics, filled grains, 1000-grain weight and biological yield of paddy
crop.

28. NBRISSM Medium
 In order to develop a defined medium for screening of Si-solubilizing
microbes, insoluble sources of silicon viz, magnesium trisilicate, talc, and
feldspar were amended to the NBRIP medium.
 Organic acid production being the common mechanism for P and Si
solubilization raise the need to make the appropriate choice of phosphate
source.
 Therefore, tri-Calcium phosphate (TCP) was replaced by different P sources
such as hydroxyapatite (inorganic) and sodium phytate (organic), whereas,
potassium di-hydrogen phosphate (KH2PO4) served as positive control.
 After the selection of silicon and phosphate sources selection of appropriate
carbon (C) source was targeted. Different nine primary and secondary carbon
sources viz. glucose, sucrose, lactose, mannitol, L-arabinose, sorbitol, sodium
citrate, sodium acetate, and sodium benzoate were tested by replacing glucose
from NBRIP medium for better silicon solubilization.

29.  Ammonium sulfate, the nitrogen source of the NBRIP medium was replaced by
ammonium nitrate, ammonium sulfate, ammonium chloride, ammonium ferric
citrate, ammonium tartrate, and aluminum ammonium sulfate.
 For selection of better salt combinations to be used in medium, 15 different
salts of magnesium, potassium, calcium, and sodium were checked for better Si
solubilisation.
 In order to define the medium composition, the quantity of all components was
determined after taking one higher and one lower concentration of that
component used in NBRIP medium to get maximum Si and minimum P
interference.
 The basal medium NBRIP contained l−1: 10 g glucose; 5 g Ca3(PO4)2; 5 g
MgCl2.6H2O; 0.25 g MgSO4.7H2O; 0.2 g KCl; and 0.1 g (NH4)2SO4, whereas,
the developed silicon-solubilizing media (NBRISSM) contains l−1: 2.5 g
glucose; 2.5 g hydroxyapatite; 1.25 g MgNO3; 1.25 g CaCl2; 0.1 g (NH4)2SO4;
0.1 g Mg2O8Si3; 0.025g.

30. The above discussed amendments enlisted viz. various silicon, phosphate,
carbon, nitrogen, and salt sources were repeated thrice to design NBRISSM
medium.
Qualitative screening was performed as color change from blue to
purple/yellow which persists until fifth or seventh day of inoculation, where
bromo cresol purple (BCP) was used as pH indicator.
Different concentrations of BCP, i.e. 0.00125%, 0.0025%, 0.005% and 0.01%
was used and spectrophotometrically scanned to determine the shift in optical
density for qualitative differentiation of silicon-solubilizing bacterial strains.
The pH of the medium was adjusted to 7.0 before autoclaving.

31. Silicon solubilising bacteria

32. 8. Plant Growth Promoting Rhizobacteria (PGPR)
Kloepper was the first to define Plant Growth Promoting Rhizobacteria (PGPR)
as those soil bacteria that colonize plant roots after seed inoculation and enhance
growth of plants.
These PGPR include Actinoplanes, Agrobacterium, Alcaligenes,
Amorphosporangium, Arthrobacter, Azotobacter, Bacillus, Cellulomonas,
Enterobacter, Erwinia, Flavobacterium, Pseudomonas, Rhizobium,
Bradyrhizobium, Streptomyces and Xanthomonas.
The inoculation of these microorganisms enhance the growth of plants through
various mechanisms including plant disease suppression (bioprotectants),
improved acquisition of nutrients (biofertilizers) and production of
phytohormones (biostimulants).
These PGPR strains produce growth promoting hormones like IAA, gibberellins
and cytokinins thereby acting as biostimulants and enhance plant growth by
increasing the surface of absorption for the uptake of nutrients and water.

33. Mass production of biofertilizers
 Isolated bacterial cultures were subculture in to nutrient broth.
 The cultures were grown under shaking condition at 30±2°C for a day.
 The culture was incubated until it reaches maximum cell population of
10¹º to 10¹¹.
 The culture obtained in the flask is called Starter culture
 For large scale production , inoculum from starter culture is transferred
in to large flasks / fermentor and grown until required level of cell
count is reached.
 Carrier preparation
 Green house and field validation
 Packing and storage
 Marketing

35. Carrier material
The use of ideal carrier material is necessary for the production of good
quality of biofertilizer
Peat soil, lignite, vermiculture, charcoal, press mud, farmyard manure
and soil mixture are used as a carrier materials
Neutralized peat soil/lignite are found to be better carrier materials
Ideal carrier material should be
 Cheaper in cost
 Locally available
 High organic matter content
 No toxic chemical
 Water holding capacity of more than 50%
 Easy to process

36. Categories of Carrier Material
Natural materials Peat, lignite, coal, clay, and organic soil
Inert materials Talc, vermiculite, perlite kaolin, bentonite, silicate, rock
phosphate, calcium sulfate, and zeolite
Synthetic polymers Polyacrylamide, polystyrene, and polyurethane
Natural polymers Xanthan gum, carrageenan, agar agar, and agarose
Organic materials Charcoal, biochar, composts, farmyard manure,
sawdust, maize straw, vermicompost, cow dung, corn cob, and wheat husk
Agro-industry by-product Sludge ash, jagerry

37. Preparation of inoculants packet
 Neutralized and sterilized carrier material is spread in a clean, dry,
sterile metallic or plastic
 Bacterial culture drawn from the fermentor is added to the sterilized
carrier and mixed well by manual or mechanical mixer
 Inoculants are packed in a polythene bags sealed with electric sealer

38. Specification of the polythene bags
 Polythene bags should be of low density grade
 Thickness of bag should be around 50-75 micron
 Packet should be marked with the
 Name of the manufacture
 Name of the product
 Strain number
 The crops to which recommended
 Method of inoculation
 Date of manufacture
 Batch number
 Date of expiry
 Price
 Full address
 storage instruction

40. Biofertilizers application methods
There are three ways of using these N-fixing/P.S Bacteria/K.S Bacetria .
Seed treatment
Root dipping
Soil applications

41. Seed treatment is a most common method adopted for all types of
inoculant.
The seed treatment is effective and economic.
Seed treatment with Rhizobium, Azotobacter, Azospirillum along with
P.S.M and K.S.M.
Seed treatment can be done with any of two or more bacteria.
No side effect.
Important things to be remembered is the seeds must be coated first with
Rhizobium or Azotobacter or Azospirillum when each seeds get a layer of
above bacteria then the P.S.M. / K.S.M inoculant has to be treated on outer
layer of the seeds.
This method will provide maximum number of population of each
bacteria required for better results.
Mixing the any of two bacteria and the treatment of seed will not
provide maximum number of bacteria of individuals.

42. Seed treatment

43.  Root dipping
 Application of azospirillum with the paddy/vegetable plants this method
is needed.
 The required quantity of azospirillum has to be mixed with 5-10 ltr of
water at one corner of the field and all the plants have to kept for minimum
½ an hour before sowing.

44. Soil application
P.S.M. has to be used as a soil application use 2 kgs of P.S.M. per
acre.
Mix P.S.M. with 400 to 600 kgs of Cowdung along with ½ bag of rock
phosphate if available.
The mixture of P.S.M., Cowdung and rock phosphate have to be kept
under any tree shade or celling for over night and maintain 50% moisture.
Use the mixture as a soil application in rows or during levelling of soil.

45. Soil application

46. CAUTIONS
Store biofertilizer packets in cool and dry place away from direct
sunlight and heat.
Use right combination of biofertilizers
Rhizobium is crop specific, so use in specified crop
Do not mix with chemicals
Use the packet before expiry, only on the specified crop, by the
recommended method.

47. Advantages
 Renewable source of nutrients
 Sustain soil health
 Replace 25-30% chemical fertilizers
 Increase the grain yields by 10-40%.
 Decompose plant residues, and stabilize C:N ratio of soil
 Improve soil texture, structure and water holding capacity
 No adverse effect on plant growth and soil fertility.
 Eco-friendly, non-pollutants and cost effective method
 Secrete fungistatic and antibiotic like substances
 Solubilise and mobilize nutrients
 Stimulates plant growth by secreting growth

48. Disadvantages
Biofertilizers require special care for long-term storage
because they are alive.
Must be used before their expiry date.
If other microorganisms contaminate the carrier medium or if
growers use the wrong strain, they are not as effective.
Biofertilizers lose their effectiveness if the soil is too hot or dry.

49. Conclusion
 The use of microbial biofertilizers as a key to modern agriculture is
fundamental, based on its renewable, low cost, and eco-friendly potential
in ensuring sustainable agriculture. Importantly, the application of
biofertilizer as an integral component of agricultural practice in
promoting plant yield has gained more traction recently in meeting the
demand of food production of the world populace.
 Employing mycorrhizal fungi and PGPR in the production of
biofertilizers for rhizosphere management has recorded success in some
developing countries and will continue to grow with time.
 Moreover, the new technology which involves the amendment of plant
growth-promoting microorganisms with nanoparticles made from
organic and inorganic material will continue to gain more attention with
time. In conclusion, overdependence on the use of chemical fertilizers
has encouraged industries to produce chemicals that are toxic to human
health.

50. Thus, causing ecological imbalances. These drawbacks are
combined with a high cost of production that is beyond the means
of many farmers in the developing world. The application of
biofertilizers is eco-friendly, relatively inexpensive, nontoxic, and
possesses the significant potential to increase plant yield.
Thus, the function of plant growth-promoting microorganisms
and the application of biofertilizer made from viable microbial
strains to the field bodes well for successful management of the
rhizosphere for sustainable agriculture.

51. Reference
 Mahdi, S. S., Hassan, G. I., Samoon, Dar. S. A. (2010). Bio-fertilizers in
organic agriculture. Journal of Phytology 2 (10): 42–54.
 Mahdi, S. S., Talat, M. A., Hussain, D. M. et al., (2012). Soil phosphorus
fixation chemistry and role of phosphate solubilizing bacteria in enhancing
its efficiency for sustainable cropping-A review. Journal of Pure and
Applied Microbiology 66(4):1905-1911
 Yadav, A.N.; Verma, P.; Singh, B.; Chauhan, V.; Suman, A.; Saxena, A.K.
Plant growth promoting bacteria: Biodiversity and multifunctional attributes
for sustainable agriculture. Adv. Biotechnol. Microbiol. 2017, 5, 1–16.
 Pervaiz, Z.H.; Contreras, J.; Hupp, B.M.; Lindenberger, J.H.; Chen, D.;
Zhang, Q.; Wang, C.; Twigg, P.; Saleem, M. Root microbiome changes with
root branching order and root chemistry in peach rhizosphere soil.
Rhizosphere 2020, 16, 100249.

52.  Meena, V.S.; Maurya, B.R.; Verma, J.P.; Meena, R.S. Potassium
Solubilizing Microorganisms for Sustainable Agriculture; Springer:
Berlin/Heidelberg, Germany, 2016; p. 338.
 Kumar, A.; Singh, R.; Adholeya, A. Biotechnological advancements in
industrial production of arbuscular mycorrhizal fungi: Achievements,
challenges, and future prospects. In Developments in Fungal Biology and
Applied Mycology; Springer: Berlin/Heidelberg, Germany, 2017; pp. 413–
431.

53. Go green!
Thank you