2. SOIL FERTILITY & SOIL
PRODUCTIVITY
2
Inherent capacity of the soil to supply all
essential plant nutrients in available forms and
in suitable proportions (SOIL
FERTILITY)
Ability of the soil to yield crop produce or
capacity of the soil to produce more per unit
area
(SOIL
PRODUCTIVITY)
3. NUTRIENT
3
Is a mineral element.
Considered to be essential for plant
growth and development,
If
The element is involved in plant metabolic
functions.
Includes in plant nutrition either as constituent
of molecules or for the reaction of enzymes.
Plant cannot complete its life cycle without
that element.
4. Arnon’s criteria of essentiality (1954)
4
Plant must be unable to grow normally or
complete its life cycle in the absence of that
element. If absent, shows deficiency
symptoms.
The element is specific (in action & in
symptoms) and cannot be replaced by
another.
The element plays a direct role in plant
metabolism.
5. Nicholo’s Criteria (1961)
5
The term “Functional Element” or “Metabolic
Nutrient” be used to include any mineral element
that functions in plant metabolism whether or not its
action is specific.
Arnon’s may be more exact but the definition
of Nicholos is more practical.
6. Limitations to Arnon’s
Criteria
6
• Possibilities to replace one element by another to do the
same activity.
Ex. Br for Cl, Ru for K, St for Ca, V for Mo
In such cases the essentiallity of K, Ru, Ca, St, V or Mo
can’t be decided.
7. 7
Primary / Major nutrients- nutrients which are required by plants in large amounts for its
growth and development – N, P and K.
Secondary nutrients – moderate amount and given secondary importance in its supply and
management.-Ca, Mg and S
Micronutrients – utilised by the plants in small quantities –Fe,Cu,Zn , B, Mo, Cl and Ni
Metals- K,Ca,Mg, Fe, Mn, Zn and Cu
Non-metals – C,H,O,N, P, S , Cl
Non metal
nutrients
Macronutrients Micronutrients
primary secondary By all
plants
some
C,H,O N,P,K Ca.Mg. , S Fe,Mn.
Zn ,Cu,
B, Cl,
Mo
Na,Co,
Va,Ni ,
Si
8. Essential Elements – Plant
nutrition
8
Previously 16 elements
C, H, O - Primary elements
N, P, K - Major Nutrients
Ca, Mg, S - Secondary Nutrients
Fe, Mn, Zn, Cu, Mo, B and Cl - Micro Nutrients
Subsequently 4 more added
Co, V, Na and Si
Beneficial or Potential micronutrient under specific
conditions
Co, V, Na, Si, Ni, Al, I, Se, Ga etc.
Macro Nutrients
9. FORMS OF ELEMRNTS IN MINERAL SOIL
9
Nutrients Mineral / solid Cations Soil solution as ions
N Organic compounds and
aminoacids
NH4 NH4, NO2, NO3
P Organic compounds, nucleic
acids and inorganic compounds
- H2PO4, HPO4
K Feldspar, mica ,silicate clays K K
Ca
Mg
S
Feldspar , hornblende,
limestone
Mica, hornblende , limestone
Organic sources-protein,
aminoacids
Inorganic sources-gypsum
Ca
Mg
-
-
Ca
Mg
SO3
SO4
10. FORMS OF ELEMRNTS ABSORBED BY PLANTS
10
Nutrients forms Nutrients forms
C Mainly
through
leaves
K, Ca , Mg
Zn , Co , Na
K, Ca, Mg
Zn, Co, Na
H H2O Fe Fe2+, Fe 3+
O H2O
Atmosphere
Mn Mn 2+, Mn4+
N NH4, NO3 Cu
P
Cl
B
Mo
Si
Cu+, Cu 2+
H2PO4, HPO4
Cl-
H3BO3, H2BO3
MoO4
Si ( OH) 4
11. Elements accepted as essential for
all plants
11
Eleme
nt
Established by Year
H
From time immemorial water is essential for all life
1800
O
C Priestly, Ingenhonz, Senebier and De Saucsure proved the
dependence of plant life on atmospheric CO2
N Theodre De Saussure 1804
P
C. Sprengel 1839
K
Mg
S
Fe E. Gris 1844
Mn J. S. Mc Hargue 1922
Zn A. L. Sommer & C. P Lipman 1926
12. Elements accepted as essential
12
Elemen
t
Established by Year
Cu A. L. Sommer & G. Mc Kinney 1931
Mo P. L. Arnon & P. R. Stout 1939
V P. F. Brownell & J. G. Wood 1957
Co S. Ahmed & H. J. Evans 1959
Elements accepted as essential for higher plants only
Ca C. Sprengel 1839
B K. Warington 1923
Cl T. C. Broyer, A. B. Carlton, C. M. Johnson & P. R. Stout 1954
13. Elements accepted as essential for
particular group/ Species of plants
13
Eleme
nt
Group/ Species of plants Established
by
V Scenedesmus obliquus (Legume) Arnon &
Wessel
Si Diatoms (Microscopic Organism) J. C. Lewis
I Polysiphonia L. Fries
Se Astrgalus sp S. F. Trelease
& H. M.
Tredase
Ga Aspergillus niger P. A.
Strenberg
Al Ferns K. Taubock
14. Carbon, Hydrogen and Oxygen
They are obtained from air, water and soil solids.
Plant growth is not seriously affected due to lack of
C, H and O as long as H2O is available, CO2 in the
atmosphere is plentiful.
About 95 to 99.5 % of fresh plant tissue is made up
of C, H and O.
Only 0.5 to 5 % remains as ash after burning.
14
16. ABOUT ELEMENTS IN PLANTS
113 elements discovered.
More than 60 elements have been detected
in plant tissues.
Only 20 have shown to be essential for
plants.
16
