This document discusses fertilizer recommendations based on soil test values. It provides information on essential plant nutrients and their functions. It explains how soil testing helps determine nutrient deficiencies and excess in different areas. Based on the soil test results for nitrogen, phosphorus and potassium, fertilizer recommendations can be modified by increasing or decreasing the recommended doses depending on whether the soil nutrient levels are low, medium or high. The document also provides methods for analyzing different soil properties and interpreting the results.

2. FERTILIZER RECOMMENDATION BASED
ON SOIL TEST VALUES
PRESENTED BY
YALLANAGOUDA B M
UG13AGR1916
UNIVERSITY OF AGRICULTURAL SCIENCES,RAICHUR
COLLEGE OF AGRICULTURE, KALABURAGI

3. Soil
Soil is one of the most important natural
resource and play a major role in crop
production
Soil testing is the base for management
decisions about fertilizer requirements
Helps to prepare soil fertility map
Areas of sufficient and insufficient nutrients
are marked out and nutritional requirements
are determined

4. Fertilizers such as NPK, lime or gypsum are
recommended to improve soil fertility
Fertilizer addition, which is based on soil
testing, usually leads to an increase in yields
and profits by providing the correct amounts
of needed nutrients
 It also leads to uniform application of
nutrients in a field.
Regular soil testing also contributes to
environmental sustainability as the use of
excess fertilizers can be avoided

5. Essential Elements for Plants
 Primary nutrients:
Nitrogen, Phosphorus,
Potassium
 Secondary nutrients:
Calcium, Magnesium, Sulfur
 Micronutrients:
Zinc, Manganese, Iron, Copper,
Boron, Molybdenum, Chlorine &
Nickel
 Carbon, Hydrogen, and Oxygen

7. Nutrient deficiency symptoms.

8. Mineral nutrient Nutrient mobility
within plant
Plant organ where deficiency
symptoms appear
N, P, K, Mg High Old leaves
S Low Young leaves
Fe, Zn, Cu, Mo Very low Young leaves
B, Ca Extremely low Young leaves and terminal
Mobility of nutrients in plant

9. Mobility of nutrients in
soil
Mobile Less mobile Immobile
Nitrate
(mass flow)
Ammonia
( mass flow)
Phosphorus
(diffusion)
Sulphur
(mass flow)
Potassium
(diffusion)
Zinc (diffusion)
Boron
(mass flow)
Calcium (root
contact)
Chloride
(mass flow)
Magnesium
(root cot act)
Manganese
(diffusion)
Copper
(diffusion)

11. Ca
Fe
Cu
Mo
K
N
B
S
Mn
Zn
Mg
P
Mobile and immobile Nutrients

12. Element & Symbol Ion or Molecule Functions
Primary macro nutrients
Nitrogen (N) NH4
+ (ammonium)
NO3
- (nitrate)
Synthesis of Proteins,but
structurally it is also a part of the
chlorophyll molecule.
Many proteins are enzymes.
Synthesis of nucleic acids, early
root growth , energy
transformation, fruiting &
seeding.
Carbohydrate metabolism,
enzyme activation, efficient use
of water, nitrogen uptake and
protein synthesis and
translocation of
Sugars(assimilates), early
maturity, resistance against insect
and diseases and in improving
quality.
Phosphorous (P) H2PO4
2-
HPO4 (phosphates)
Potassium (K) K+

13. Secondary macro nutrients
Calcium (Ca) Ca2+ Cell-wall, good root system. It protects
the entery of pathogens into the cell
wall.
Essential component of the chlorophyll
molecule and sugar translocation.
Protein synthesis and in Oil formation.
Magnesium (Mg) Mg2+
Sulphur (S) SO4
2-
Micronutrients (trace elements)
Zinc (Zn) Zn2+ Involved in the activation of various
enzyme systems (Enzyme : It is made
up of amino acids (protein) and it helps
in the conversion of organic and
inorganic nutrients into available forms
without changing itself. Synthesis of
chlorophyll.
Iron (Fe) Fe2+ (ferrous)
Manganese (Mn) Mn2+
Molybdenum (MO) MoO4
2-
Copper (Cu) Cu2+
Boron (B0) H3BO3 (boric acid) Translocation of sugars
Sodium (Na+) and
Chlorine (Cl-)
Na+ and Cl-
(Chloride)
Electrolytes necessary for osmotic
pressure and acid-base balance and
activates the oxygen producing enzyme
of photosynthesis.

14. Other
Carbon (C) CO2 (mostly through leaves)
Hydrogen (H) HOH (hydrogen from water), H+
Oxygen (O) CO2 (mostly through leaves),H2O,O2
Few additional elements
Cobalt (CO) CO2+ : Legumes
Nickel (Ni) Ni2+ : -
Silicon (Si) Si (OH)4 (non-ionized) : Paddy (Silicon contributes
to the structure of cell walls, thereby imparting greater
disease resistance, stalk strength, and resistance to
lodging.
Sodium(Na) Na+ : Sugarbeet
Vanadium (V) VO3
- : Algae

15. Nutrient use efficiency in India
Nutrient Efficiency (%)
Nitrogen 30-50
Phosphorus 15-20
Potassium 70-80
Zinc 2-5
Iron 1-2
Copper 1-2

16. Effect of pH on Nutrient Availability
Ideal pH for maximum Nutrient Availability is 6.5- 7.5

17. Nutrient Content in Fertilizers

18. Sl.
No.
Fertilizer Formula Nutrient Content (%)
1. Ammonium Sulphate [(NH4)2SO4] 20.5 N, 24 S
2. Urea [CO(NH2)2] 46 N
3. Calcium Ammonium Nitrate [Ca(NH4NO3)2] 26 N
4. Ammonium Chloride [NH4Cl) 26 N
5. Ammonium Molybdata [(NH4)6MO7O24] 52 Mo
6. Ammonium Nitrate [NH4NO3] 17NH4, 17NO3
7. Sodium Nitrate [NaNO3] 15- 16 NO-
3
8. Ammonium Sulphate
Nitrate
[(NH4)2 SO4NH4NO3] 26 N, 6.5 NO3, 19.5
NH4
9. Ammonia (Aqueous Ammonia) 80 N
10. Ammonium Phosphate
Sulphate
16 N, 20 P2O515 S

19. 11. Mono Ammonium
Phosphate
[NH4. H2PO4] 48 P2O5, 11 N
12. Single Super Phosphate [Ca (H2PO4]2 16 P2O5, 12 S
13. Diammonium Phosphate [(NH4)2 HPO4] 46 P2O5, 18 N
14. Double Super Phosphate - 32 P2 O5
15. Triple Super Phosphate - 48 P2 O5
16. Nitro Phosphate - 20 N, 20 P2O5
17. Bonemeal - 22 P, 1-2 N
18. Basic Slag - 6-20 P2O5
19. Rock Phosphate [Ca3(PO4)2] 18-20 P2O5
20. Muraite of Potash KCl 60 K2O

20. 21. Sulphate of Potash K2SO4 50 K2O, 18 S
22. Calcium Sulphate [CaSO4. 2H2O] 16-19 Ca, 13 S
23. Mangesium Sulphate [MgSO4. 7H2O]
16 Mgo, 13 S
24. Elemental Sulphur -
85-100, 15 S
25. Phosphogypsum - 16 S
26. Zinc Sulphate [ZnSO4. 7H2)]
21 Zn, 12 S
27. Chelated Zinc (EDTA form)
12 Zn
28. Iron Sulphate [FeSO4. 7H2O] 19 Fe, 19 S
29. Chelated Iron (EDTA form) 12 Fe
30. Copper Sulphate CuSO4. 5H2O] 24 Cu, 13 S

21. 31. Zinc Sulphate Mono
Hydrate
- 33 Zn
32. Manganese Sulphate [MnSO4. H2O] 30.5 Mn. 15 S
33. Borax (Soil application) [Na2B4O7. 10H2O] H2BO3
-,
HBO3
10.5 B
34. Solubar (foliar spray) Na2B4O7.5H2O+Na2B10O16.1
0 H2O
19 B
35. Pyrite(Agric. Grade) 22 S, others Fe
36. Sodium Molybodate NaMoO4. 2H2O 41 Mo

22. Advantages of soil testing
• Helps to take advantage of nutrients already in
the soil
• To know the characteristics and fertility status of
soil
• Soil fertility status helps in selection suitable
and economical crops for specific fields and
farming situations
• Helps to Know the soil pH, EC, Organic carbon,
available nitrogen, phosphorous, potassium,
secondary and micronutrients present in the
soil

23. Advantages of soil testing
• Lime requirement of soils
• Gypsum requirement of soils
• Helps in making fertilizer recommendations
for specific crops and cropping systems
• Reduce fertilizer applications by applying
only what is needed
• Maximizes yield and lowers the cost towards
fertilizer

24. Methods of analysis of soil sample
Properties Extractant
Soil /
Extractant
ratio
Shakin
g time
Method
pH Distilled water 1:2.5 30 Potentiometric method
EC Distilled water 1:2.5 30 Conductometric method
Organic Carbon Walkley & Black’s
method
Avail. Nitrogen (N) Alkaline potassium
permanganate method
Avail. P2O5
 Bray’s
extractant for
acid soils
 Olsen’s
extractant for
neutral &
alkaline soils
1:10 for
Bray’s
Method (5 g
soil : 50 ml )
1:20 for
Olsen’s
method (2.5
g soil : 50 ml )
5
30
Colorimetric method
Colorimetric method
Avail. K2O N N Ammonium
acetate
1:5 (5 g soil
:25 ml)
5 Flame photometric
method

25. Analysis of secondary nutrients
Nutrients Extractant
Soil /
Extractant
ratio
Shaking
time
Method
Avail. Ca N N
Ammonium
acetate
1:5 (10 g
soil : 50
ml)
5 min
EDTA Titration
method
Avail. Mg N N
Ammonium
acetate
1:5 (10 g
soil : 50
ml)
5 min
EDTA Titration
method
Avail. S Mono Calcium
Phosphate/
0.15% CaCl2
1:2.5 (10 g
soil : 25
ml)
30 min
Turbid metric
method

26. Soil analysis for micronutrients
• Available iron (Fe)
• Available Manganese (Mn)
• Available Zinc (Zn)
• Available Copper (Cu)
• Available Boron (B) – Hot water (1:2 ratio & 5 minutes
boiling) and Azomethan-H method
• Available Molybdenum (Mo) – Ammonium oxalate extractant
(1:10 ratio & 10 hours shaking) and Colorimetric or AAS
• Available Chlorine (Cl) – water(1:5 ratio & 5 min) and Mohr’s
titration method
DTPA extractant (1:2 soil to extractant
ratio & 2 hrs shaking) & Atomic
absorption spectrophotometer (AAS)

27. Lime & Gypsum requirement of soils
• Lime requirement of an acid soil (pH < 6.5) is
determined by Shoemaker’s method
• Gypsum requirement of an alkali/ saline–alkali soils
using saturated solution of gypsum & EDTA method

28. Interpretation of results
• pH
1 2 3 4 5 6 7 8 9 10 11 12 13 14
6.3 8.3
Neutral
Normal soil
Acidic soil Alkali soil
Required lime Required gypsum

29. Electrical conductivity (EC)
EC values Interpretation
< 1 dS m-1 at 250 C Normal soil with respect to
soluble salts
1- 2 dS m-1 at 250 C Critical to crop growth
> 2 dS m-1 at 250 C Injurious to crops

30. Interpretation of NPK results
Nutrients Low Medium High
Organic carbon(%) < 0.5 0.5 – 0.75 > 0.75
Avail. N (kg ha-1) < 280 280 - 560 > 560
Avail. P2O5 (kg ha-1) < 22.5 22.5 – 55.00 > 55.00
Avail. K2O (kg ha-1) < 144 144 – 336 > 336

31. Interpretation of secondary nutrients
Nutrients Critical level
Exch. Ca (meq /100 g) 1.5
Exch. Mg (meq /100 g)
1.0
Avail. Sulphur (mg /kg)
< 10

32. Interpretation of micronutrients results
Micronutrient Extractant
Critical level in soil
(mg /kg)
Iron (Fe) DTPA 2.5-4.5
Manganese (Mn) DTPA 2.0 -3.0
Zinc (Zn) DTPA 0.6 – 1.2
Copper (Cu) DTPA 0.2-0.5
Boron (B) Hot water 0.33-1.0
Molybdenum
(Mo)
Ammonium
oxalate
0.04

33. N - fertilizers recommendation based on soil test results
Recommended
dose of N fertilizers
Low available N
status in soil
High N status in soil
< 50 kg ha-1 No change in the recommendation
51 - 100 kg ha-1 + 12.5 kg ha-1 - 12.5 kg ha-1
100 - 175 kg ha-1 + 25.0 kg ha-1 - 25.0 kg ha-1
175 - 250 kg ha-1 + 37.5 kg ha-1 - 37.5 kg ha-1
251 - 325 kg ha-1 + 50.0 kg ha-1 - 50.0 kg ha-1
For medium N status of soil – No modification in the fertilizers recommended

34. P & K fertilizers recommendations
based on the soil test results
Recommended P or K
fertilizers
Low status of P or K
in soil
High status of P or
K in soil
Phosphorus
<25 kg P2O5ha-1 No change in the recommendation
26 – 75 kg P2O5ha-1 + 12.5 kg P2O5ha-1 - 12.5 kg P2O5ha-1
> 75 kg P2O5ha-1 + 25.0 kg P2O5ha-1 - 25.0 kg P2O5ha-1
Potassium
<25 kg K2O ha-1 No change in the recommendation
26 – 50 kg K2O ha-1 + 12.5 kg K2O ha-1 - 12.5 kg K2O ha-1
51 – 100 kg K2O ha-1 + 25.0 kg K2O ha-1 - 25.0 kg K2O ha-1
101 - 175 kg K2O ha-1 + 37.5 kg K2O ha-1 - 37.5 kg K2O ha-1

35. For example:
pH 8.20
EC (dS/m at 250 C) 0.20
OC (%) 0.40
Avail. N (kg ha-1) 180
Avail. P2O5 (kg ha-1) 59.0
Avail. K2O (kg ha-1) 400
Soil test results
•Farmer wants to grow Pigeonpea & the
recommended dose of NPK for
Redgram is
25: 50: 0 kg, N2:P2O5:K2O /ha
Therefore modified recommendation
based on soil test values is
25:37.5:0 kg, N2:P2O5:K2O /ha
Therefore, apply 22 kg of Urea and 94 kg of
Single Superphosphate per acre

36. Integrated nutrient management

37. IPNMS for Desired Yield
• Balanced Fertilization
• Reverse the ill Effect of Soil Mining of Nutrients
• Promoting Tenets of Sustainable Agriculture
• Response of Fertilizers Declining due to
• Sub-optimal and Imbalance in Fertilizer Use

38. IPNMS for Desired Yield
• Inappropriate Methods and Time of
Application
• Lesser Use of Organic Manure
• IPNMS Must for the Desired Results
• IPNMS for Desired Yield

39. The Key Objectives of IPNMS
• To maintain or enhance soil productivity through balanced
use of fertilizers combined with organic and biological
sources of plant nutrients
• To improve the stock of plant nutrients in the soil
• To improve the efficiency of plant nutrients
• To improve physical conditions of soils

40. Organic manures
• Farm yard manure
• Compost, vermi-compost
• Sewage sludge
• Press mud
• Green manure
• Crop residues

41. AVERAGE NUTRIENT CONTENT OF SOME MANURES
Snl no manures N (%) P2O5 (%) K2O (%)
1 FYM 0.5 0.2 0.5
2 FARM COMPOST 0.5 0.15 0.5
3 TOWN COMPOST 1.4 1 1.4
4 NIGHT SOIL 5.5 4 2
5 SHEEP AND GOAT
MANURE
3 1 2
6 POULTRY MANURE 3 2.63 1.4
7 VERMI COMPOST 3 1 1.5

42. FYM /COMPOST /STUBBLES

43. Neem cake & N use efficiency
• Neem cake has good nitrification inhibition
capacity (35% of applied N is lost through
denitrification). When neem cake is mixed with
urea, the rate of inhibition increases with
increasing proportion of neem cake. Neem
cake retains ammonium N for longer period
and higher NH4
+ - N contents are noticed in soil
with neem coated urea application.

44. Neem cake & N use efficiency
(contd.)
• Application of neem cake along with
Sesbania rostrata incorporation resulted
in significant reduction in nitrification
and population of nitrifying bacteria in
soil.

45. Green manure crops
Sunnhemp

46. ALTERNATE STRATEGIES
• Use Organic manures
• Use soil microbes which can
1.Fix atmospheric nitrogen
2.Solubilize or mobilize “P” and other nutrients
3.Produce growth promoting substances
4.Produce siderophores, antifungal compounds, metabolites
and volatiles

47. ADVANTAGES OF USING BIO-FERTILIZERS
• Can replace 25-30 % of chemical ‘N’ and phosphatic fertilizers
• Bio-fertilizers being cheap provide highly cost effective
supplement of chemical fertilizers
• Increase farm productivity, 15 – 30 %
• Activates soil biologically thereby increasing natural fertility of
soil, which causes sustainable agriculture
• Help in stimulating plant growth in general and roots in particular
as they serve various growth promoting hormones like auxin,
gibberellins etc and vitamins.

48. ADVANTAGES OF USING BIO-FERTILIZERS
• They help in better nutrient uptake and increase tolerance towards
drought and moisture stress.
• Secrete some fungi static and antibiotic like substances, which reduce
the incidence of various soil borne diseases. It has got antagonistic
behaviour against pathogens.
• They help to proliferate and survival of other beneficial microorganisms
in soil.
• Help in decomposing plant residues in soil, thereby improving C/N ratio,
improving soil texture and structure. Also help in increasing water-
holding capacity.

49. BIOFERTILIZATION BENEFITS TO CROPS
Crop Average yield
increase (%)/ha
N saving (kg)
/ha
P saving
(kg)/ha
Rice 13.0 35.0 20.0
Wheat 9.0 35.0 20.0
Millets 10.0 30.0 6.0
Pulses 13.0 13.0 10.0
Oil seeds 14.0 26.0 10.0
Vegetable 10.0 40.0 10.0
(Bisoyi, 2001)

50. Nitrogen fixing micro-organisms
1.Rhizobium
2.Azolla
3.Azospirillum
4.Azotobacter

51. Formation of a Root Nodule

52. Phosphate solubilizing micro-organisms
• Indian soils are very poor in P content.
• Only about 10-15% of the applied P
becomes available to the crop and the
remaining part gets converted into
insoluble/unavailable forms.
• About 130 million tones of low grade P is
deposited (non-available) in our soil, but
plant can not utilize this P directly.

53. Potash mobilizing bacteria (contd.)
• Frateuria aurantia is capable of
mobilizing elementary or fixed K into a
usable form to the plants.
• Increase K availability level to the
magnitude of 5-60 kg/ha.
• Increase banana yield by 20%.

54. Arbuscular mycorrhizal fungi (AMF)
• AMF are obligate symbionts which develop
both intra and extra metrical hyphae that
extends to far areas away from the roots and
increases the absorptive surface area for P and
Zn by mycorrhizal root system.
• Helpful in the biological control of root
pathogens.
• Save P fertilizers by 50%.

55. Enhancing nutrient use efficiency
Method of application
• Soil application: Fertilizers should be
applied in active root zone.
• Foliar application: Fertilizers should
be sprayed on to new flush.

56. .......Thank you