2. SUBMITTED TO:
Dr. LAKSHMIPATHI
DEPT OF MICROBIOLOGY
SUBMITTED BY:
PRABHAKARA REDDY A V
I BSC SERI
ID NO.SLC3031
COLLEGE OF SERICULTURE,
CHINTAMANI

4. INTRODUCTION
Phosphorous is one of the essential
nutrient which is required for energy
storage and transfer system in the plant.
P is a component of building blocks of
genes and chromosomes.
P increases the root growth, enhances
crop maturity improves development of
reproductive parts.

5. DEFICIENCY OF ‘P’
 Shown by stunted growth of plants,
becomes
dark green colour of leaves, then changes
to grey and then to purple colour
because accumulation of sugars. This
sugar reacts with anthocyanin pigment
and forms purple colour (or) bronzing.

6.  Phosphorous is mobile in plants and relatively
immobile in soils.P is less in soils compared to N and
K.It varies between 0.005% to 0.15%.The total
phosphorous present in the soil includes both
organic and inorganic phosphorous.
Organic ‘ P ‘ comes from organic components like
enositol phospholipids, nucleic acids and
nucleoproteins.
Inorganic ‘ P’ comes from minerals, fertilisers,
Appetite has the highest amount of ‘P’ followed by
granite,gneiss,limestone,mica.
The inorganic ‘P’present in soil in different pools i.e
present in 3 forms ‘P’ bound to alluminium,’P’
bound to iron,’P’ bound to calcium.

7. IMPORTANCE OF ‘P’.
 study of p-cycle is essential to know the various p-
transformations occurring in the soil when any ‘P’
fertilizer (or)organic manure are applied.
1.The p-cycle is shown by simple reaction as follows
Soil solution P labile P non-labile P.
2.Depletion of labile P some non-labile P becomes
labile at a very slow rate in order to buffer both org-p
and inorg-p the primary and secondary P-minerals
dissolved to resupply these 2 ionic form in solution.
3.The inorg-P gets adsorbed on the clay surfaces as
H2Po4- and HPo4-- so this get desorbed and helps
in buffering the soil solution P.

8. Continue….
4.The soil mo’s digest the plant residues
containing P mineralized and supplies the
available form to the soil solution.
5.By this 2 reactions-mineralization,
adsorption and desorption,P concentration
in the solution is maintained (or)referred as
P intensity. The amount of P present in
inorganic form referred as quantity.
6.The P-nutrition depends on quantity and
intensity factor.
7.The ratio of quantity and intensity is defined
as buffering capacity.

9. P-fixation
 Thomas way(1850) observed P-fixation
in neutral, alkaline and acidic soil.
 Ca(H2PO4)2 + 2CaCO3------
Ca3(PO4)2+2Co2+2H2O
 Al+3+H2PO4- +2H2O------2H+ Al(OH)2H2PO4
 Fe+3 +H2PO4-+2H2O-------
2H+Fe(OH)2H2PO4-Fe3PO4

10. FACTORS AFFECTING P-
FIXATION.
1.Soil temperature
2.PH
3.Organic matter.
4.Liming.
5.Nature and amount of soil component.

11. P-management in soil-PUE
 PUE=Amo.of P taken up by DM/Amo.of
fertilizers applied.
 PUE is approximately 20-30%.
 To increase PUE
1.Timely application.
2.Method of application.
3.Liming of acidic soil.
4.Treatment of plant material.
5.Use of Bio-fertilizers.