Unit-3.ppt

CHE881: Chemistry and Industry
Unit 3: Plant Nutrients & Soil, Fertilizers and their effects

Soil Chemistry (Plant Nutrients and Fertilizers)
Soil is the top layer of the earth’s crust in which organic matter grows. There are
many components which determine a soil type such as pH, nutrient level and
organic content. These factors can vary depending on the type of plant or crop
which grows in the soil and also on geographic location.

pH of the soil
Can be modified by adding different chemicals.
Soil pH indicates how acid or alkaline the soil is.
The pH of a soil is crucial because crops grow best in a narrow pH range which can vary
among crops.
For example, blueberries and a few types of flowers grow best when the pH is 5.5 or less.
Potatoes, a more familiar crop, grow best with a soil pH range of 5.5 to 6.0. Most garden
vegetables, shrubs, trees and lawns grow best when the soil pH is over 6.0 or 6.5.
The range between 5.5 and 7.5 is favorable for two reasons. It allows sufficient
microorganisms to break down organic matter. It is also the best range for nutrient
availability.

Liming
Farmers needed a way to increase the pH of the soil to make it suitable for other
crops.
The pH of soil can be increased by liming.
This is why people sometimes spread white powder on their lawns or gardens.
This white powder is Lime.
Calcitic limestone (CaCO3) provides a good source of Calcium (Ca) and helps
neutralize soil acidity.
Limestone functions similarly but also adds Magnesium (Mg).

Buffering capacity
is the ability of the soil to resist change. In the case of acidity, it is the ability of
the soil to resist change in pH.
Chemistry to liming
Hydrogen ions (H+) are attracted to soil and organic material which have a negative
charge. When lime is applied, these hydrogen ions are exchanged for calcium or
magnesium(Ca2+ or Mg2+) ions which have a greater positive charge. This helps to
neutralize the acidity of the soil. The free hydrogen ions are taken out of solution. This
also helps to increase the pH.

Source of Nutrients
Two major Source
• Air/Water
• Soil

Essential Elements
• The 16 essential elements required by plants are
obtained from the soil, water and air.
• Thirteen of these elements must be supplied by the soil.
• Six of the soil elements required by plants are needed in
relatively large amounts and are usually added to the soil
through fertilizer or lime. These are called
macronutrients.
• The remaining 7 elements supplied by soil are required in
very small amounts and are termed micronutrients.

Macronutrients
• Macronutrients are
needed in relatively
large amounts by
plants.
Element Symbol Source
Oxygen O Air/Water
Hydrogen H Air/Water
Carbon C Air/Water
Nitrogen N Soil
Phosphorus P Soil
Sulfur S Soil
Potassium K Soil
Calcium Ca Soil
Magnesium Mg Soil

Macronutrients – Form Used By Plants
Nutrient Form Used
Carbon CO2
Oxygen H2O
Hydrogen H2O
Nitrogen NO3
-, NH4
+
Phosphorus H2PO4 & HPO4
2-
Potassium K+
Calcium Ca+2
Magnesium Mg2+
Sulfur SO4
--
Charge on the
molecule

Micronutrients
• Macronutrients are
needed in relatively
small amounts by
plants.
• They are usually
supplied by
fertilizers.
Element Symbol Source
Iron Fe Soil
Manganese Mn Soil
Boron B Soil
Molybdenum Mo Soil
Copper Cu Soil
Zinc Zn Soil
Chlorine Cl Soil

Micronutrients – Form Used By
Plants
Nutrient Form Used
Iron Fe2+
Manganese Mn2+
Boron H2B03
-
Molybdenum MoO4
2-
Copper Cu2+
Zinc Zn2+
Chlorine Cl-
Charge on the
molecule

Deficiency symptoms
• Symptom: is any traceable change in known structure,
appearance or function.
These include:
1. Yellowing (Chlorosis: Chlorosis is a condition in which leaves
produce insufficient chlorophyll. )
2. Death (Necrosis)
3. Lesions(any abnormality in the tissue of an organism )
4. Malformation(Irregular or abnormal structural development)
5. Reduced growth and yield
Nutrient Deficiency Symptoms
• Nutrient deficiency symptoms usually appear on the plant
when one or more nutrients are in short supply.
• In many cases, deficiency may occur because an added
nutrient is not in the form the plant can use.

Conditions for nutrient deficiency
a) Amount and concentration of nutrients in the soil.
b) Form of the soil.
c) The contents of the soil solutions.
d) Soil pH.
Nutrient concentration in plants: these vary with
a) Plant age
b) Plant part
c) Plant species
d) Soil type

Deficiency Symptoms - N
• General Chlorosis.
• Chlorosis progresses from
light green to yellow.
• Growth is immediately
restricted and plants soon
become weak and drop
older leaves.

Deficiency Symptoms - P
• Leaves appear dull, dark
green, blue green, or red-
purple, especially on the
underside, and especially at
the midrib and deposit.
• Petioles may also exhibit
purpling. Restriction in
growth may be noticed.

Deficiency Symptoms - K
• Leaf margins brown, dry as a
bone, or have necrotic spots
(may be small black spots).
• Margins become brown and
cup downward.
• Growth is restricted and die
back may occur.
• Mild symptoms appear first
on recently matured leaves.

Deficiency Symptoms - Ca
• Growing points usually
damaged or dead (die
back).
• Margins of leaves
developing from the
growing point are first to
turn brown.
http://hubcap.clemson.edu/~blpprt/acid_photos/Blossom
EndRot.JPG

Deficiency Symptoms - Mg
• Marginal chlorosis or chlorotic
spots which later merge.
• Younger leaves affected with
continued stress.
• Chlorotic areas may become
necrotic, brittle, and curl
upward.
• Symptoms usually occur late in
the growing season.
http://quorumsensing.ifas.ufl.edu/HCS200/images/deficien
cies/-Mgcq.jpg

Deficiency Symptoms - S
• Leaves uniformly light green, followed by yellowing
and poor growth.
• Uniform chlorosis does not occur

Deficiency Symptoms - Cu
• Leaves faded, become
chlorotic, then necrotic.
• drooping and necrosis are
not dominant symptoms.

Deficiency Symptoms - Fe
• Distinct yellow or white
areas appear between
veins, and veins
eventually become
chlorotic.
• Symptoms are rare on
mature leaves.

Deficiency Symptoms - Mn
• Chlorosis is less marked
near veins.
• Chlorotic areas eventually
become brown,
transparent, or necrotic.
• Symptoms may appear
later on older leaves.

Deficiency Symptoms - Zn
• Leaves may be abnormally small and necrotic.
• Internodes are shortened.

Deficiency Symptoms - B
• Young, expanding leaves
may be necrotic or
distorted followed by
death of growing points.
• Internodes may be short,
especially at shoot
terminals.
• Stems may be rough,
cracked, or split along the
vascular bundles.

Crops Highly Susceptible to Deficiencies
Element Crops
Mn Soybean, Small Grain & Peanuts
Cu Wheat & Corn
Zn Corn
Mo Soybeans & Cauliflower
B Apples, Peanuts, Tobacco & Tomatoes
Fe Fruit Trees, Soybeans & Some Grasses

Fertilizers
Fertilizers are those substances which must be added to the soil in
order to remove the deficiency of essential elements required for
plant growth.
OR
Fertilizer is any material of natural or synthetic origin added to
the soil to supply one or more plant nutrients.

Needs of Fertilizers:-
a) To supplement what has been eaten up by the plant
b) To supply them on additional tonic and good food, so that they
may grow more health and produce a better yield
c) To maintain the pH of the soil in the vicinity of 7-8 and thereby
facilitate optimum growth health.

Source of Fertilizers
Two major source of fertilizers are:-
1 Natural source
A) Natural Organic Fertilizers:-
a) Plant Matter:-Plant waste
b) Farmyard manures:- Ex-Cow dung, sheep dung, human excretions.
c) Animal Matter:-Animal waste
d) Guano:-Guano is a example of complete fertilizer and it is a mixture of
birds excrement, Fish refuse etc
B) Natural inorganic fertilizers:-
a) Rock phosphates
b) Potassium salts
c) Chile saltpetre (Sodium Nitrate, NaNO3)

Essential requirements for fertilizers:-
The chief requisites of a fertilizer are:-
1. The element present in the compound must be easily available to
the plant.
2. The substance must be soluble in water.
3. It should be stable, so that it may be available to the plants for a
long time.
4. It should not be very costly.
5. It should maintain the pH of the soil in the vicinity of 7-8.
6. It should not be poison for plants.

Classification of Fertilizers
1 On the basis of chemical nature Fertilizers can be classified as
A. Inorganic Fertilizers:-
B. Organic Fertilizers:-
Inorganic Fertilizers are classified on the basis of following:-
a) According to their role they play in soil chemistry.
b) The number and type of nutrient elements they contain.
c) Their physicochemical properties and in particular.
d) Their solubility in soil water.
e) Their physiological effect on the soil to which the fertilizers has
been applied.
f) Method used for manufacturing them.

2- According to their agrochemical nature fertilizers are classified as:
Direct Fertilizers:-
Fertilizers which contain the nutrient elements in the form of
compounds which are directly absorb by plants
On the basis of nutrient elements direct fertilizers further classified
as Phosphatic, Nitrogenous, Potash, Magnesium etc.
Indirect Fertilizers:-
Those substances which are added to the soil in order to improve its
chemical, mechanical or biological properties
Ex-Gypsum, Limestone.

3-On the basis of source
a) Natural Fertilizer
b) Artificial Fertilizers
4- According to the number of basic nutrient elements fertilizers are
classified as:
a) Simple :-Containing only one nutrient. Ex-Urea
b) Double:-Containing two Nutrient. Ex- Di ammonium Phosphate
c) Triple(Complete Fertilizers):- Containing three Nutrient, NPK
fertilizers
5- According to behavior with water:-
a) Water Soluble:- All nitrogenous and potash fertilizers are water
soluble
b) Soluble in soil acids:- Most of the Phosphate Fertilizers.

6- According to Physiological effect on the soil fertilizers are classified
as:
a) Physiologically acid
b) Physiologically Alkaline
c) Physiologically Neutral:-
7- According to Physical properties fertilizers are classified as:
a) Powder form
b) Granulated form
c) Lumps (Commercial fertilizer form)

8-On the Basis of use fertilizers can be classified as
Fertilizer

1. Straight fertilizers
Straight
fertilizers are those
which supply only one
primary plant nutrient,
namely nitrogen or
phosphorus or
potassium. E.g. Urea,
ammonium sulphate,
potassium chloride
and potassium
sulphate.
2. Complex fertilizers
Complex
fertilizers contain two or
three primary plant
nutrients of which two
primary nutrients are in
chemical combination.
These fertilizers
are usually produced in
granular form e.g.
Diammonium phosphate,
nitrophosphates and
ammonium phosphate.
3. Mixed fertilizers:
Physical
mixtures are straight
fertilizers. They
contain two or three
primary plant nutrients.
Mixed fertilizers are
made by thoroughly
mixing the ingredients
either mechanically or
manually.

Sources and Forms of Fertilizer
9-Fertilizers can also be classified based on physical form
Solid fertilizers
Liquid fertilizers

Urea prills Granulated urea
Ammonium sulphate
Solid fertilizers are in several forms:

Fertilizer
10-Classification of Artificial Fertilizers
Liquid fertilizers
Liquid form fertilizers are applied with irrigation water or for application.
Ease of handling, less labor requirement and possibility of mixing with
herbicides has made the liquid fertilizers more acceptable to farmers.

Ammoniacal Nitrate Ammoniacal and
Nitrate
Amide fertilizer
Ammonium
Sulphate
Ammonium chloride
Anhydrous
ammonia
Sodium Nitrate
Calcium Nitrate
Potassium Nitrate
Ammonium Nitrate
Calcium Ammonium Nitrate
Ammonium Sulphate Nitrate
Urea
Calcium Cynamide
A. Nitrogenous fertilizers
More than 80 per cent of the fertilizers used in this country are made up
of nitrogenous fertilizers, particularly urea.

The nitrogenous fertilizers can be further classified into:
1. Ammonical fertilizers:- Ammoniacal fertilizers contain the nutrient nitrogen in the form of
ammonium or ammonia.
a) Ammonium sulphate [(NH4)2 S04]
It is a white salt completely soluble in water
b) Ammonium chloride (NH4Cl)
• It is a white salt contains 26.0 per cent of nitrogen.
2. Nitrate Fertilizers
• Nitrate fertilizers contain the nitrogen in the form of NO3
•Continuous use of these fertilizers may reduce the soil acidity as these nitrogenous fertilizers are
basic in their residual effect on soils.
a) Calcium nitrate [Ca (NO3)2]
It is a white crystalline hygroscopic solid soluble in water
The calcium is useful for maintaining a desirable soil pH.
b) Potassium nitrate (KN03)
The nitrogen of the potassium nitrate has the same properties and value as that of the sodium nitrate.

3. Ammoniacal and nitrate fertilizers
These fertilizers contain nitrogen in both ammonium and nitrate forms. The nitrates are
useful for rapid utilization by crops and the ammonical is gradually available.
a) Ammonium nitrate (NH4N03)
• Contain 35 per cent nitrogen half as nitrate nitrogen and half in the ammonium form.
• In the ammonium form, it cannot be easily leached from the soil.
• This fertilizer is quick-acting, but highly hygroscopic and not fit for storage.
b) Calcium ammonium nitrate (CAN)
•Containing 26 per cent of nitrogen.
•It is almost neutral and can be safely applied even to acid soils.
•50% of its total nitrogen is in the ammoniacal form and another 50% is in nitrate form.
c) Ammonium sulphate nitrate [(NH4)2S04 NH4NO3]
• It is a mixture of ammonium nitrate and ammonium sulphate.
• It is readily converted to ammoniacal and nitrate forms in the soil.
• It is suitable for most crops and can be applied to all soils.

4. Amide fertilizers
Amide fertilizers are readily soluble in water and easily decomposable in the soil.
a) Urea [CO (NH2)2]
It is the most concentrated solid nitrogenous fertilizer, containing 46 per cent nitrogen. It is a white
crystalline substance readily soluble in water.
B. Phosphatic fertilizers
Phosphatic fertilizers are chemical substances that contain the nutrient phosphorus in absorbable form
(Phosphate anions) or that yield after conversion in the soil.
Ex-1-Super phosphate [Ca (H2PO4)2)
This is the most important phosphatic fertilizer in use.
It contains 16 percent P2O5 in available form.
Phosphatic fertilizer hardly moves in the soil and hence they are placed in the, root zone.
Ex-2-Triple super phosphate:[CaH4(PO4)2].10H2O
The concentrated super phosphate is called as Triple super phosphate and it contains 46 percent P2O5.
This fertilizer is suitable for all crops and all soils.
In acid soils, it should be used in conjunction with organic manure.
Ex-3-Ammonium Phosphate(NH4H2PO4):-

C. Potassic fertilizers
There are a limited number of fertilizer materials that can be used to
supply K when needed.
Common fertilizer sources of K
Material Chemical Formula K2O Contend(%)
Potassium chloride KCl 60
Potassium-magnesium sulfate K2SO4-2MgSO4 20
Potassium nitrate KNO3 44
Potassium sulfate K2SO4 50

D. Secondary major-nutrient fertilizers
a). Magnesium fertilizers
These are chemical substances containing the nutrient magnesium in the form of
magnesium cations (Mg2+).
a) Magnesium Sulphate (MgSO4)
The utilization rate of magnesium fertilizers decreases with increasing potassium
supplies.
b) Calcium fertilizers
These are the chemical substances containing the nutrient calcium in absorbable
calcium cations ('Ca2+) form.
The raw material of calcium fertilizers is lime found in nature.
Calcium Chloride (CaCl2 6H2O)
It contains at least 15 per cent calcium.
It is highly water soluble and can, therefore, be dissolved for application as a foliar
nutrient.

E. Micronutrient Fertilizers
The importance of fertilization of crops with micro-nutrients is increasing
mainly because of greater removal from the soil, intensive liming of soil,
intensive drainage of soil, higher use of nitrogenous, phosphatic and
potassic fertilizers etc. There are seven essential micronutrients required
by plants.
These are iron, manganese, zinc, copper, chlorine, boron and
molybdenum.

Ferrous sulphate
(FeSO4 7H2O)
It is a water soluble fertilizer containing 20 % Fe
Fe – Chelates
Fe-EDTA
Suitable for application as foliar nutrients
a. lron fertilizers
These are generally water soluble substances, predominantly sprayed as foliar
nutrients on the crops. Plants absorb iron in the form of Fe2+.
b. Manganese fertilizers
The manganese (Mn) fertilizers are as follows:
Manganous Sulphate
( MnSO4 .7H2O)
It is the well known water soluble Mn fertilizer.
It is pink salt containing 24 % Mn.
It dissolves in water and is suitable for foliar application.
Mn – chelates It contains 13 % Mn.
It plays an important role in the crop fertilization.

Zincsulphate
(ZnSO4 7H2O)
It is water soluble whitish salt containing 23 % Zn.
It is applied as foliar nutrient.
Its acidic action causes corrosion damage to plants
Zinc-oxide(ZnO) It contains 70 % Zn.
It is slightly soluble in water
It is used as slow acting foliar nutrient
c. Zinc fertilizers
Zinc (Zn) fertilizers play an important role in Zn deficient

e. Boron Fertilizers
Borax (Na2B4O 10H2O) It contains 11 % B
It is water soluble white salt
It can be applied as a soil dressing or foliar application
Boric acid (H3BO3) It contains 18 % B
It is a white crystalline powder
It is applied as a foliar nutrient
d. Copper Fertilizers
Copper fertilizers have been used to correct copper (Cu),deficiencies.
Copper sulphate (CuSO4 5H2O) – 25 % Cu
Copper sulphate (CuSO4 H2O) – 36 % Cu

f. Molybdenum Fertilizers
Sodium molybdate
(Na2MoO42.H2O)
It contains 40 % Mo
Ammonium molybdate
(NH4)6Mo7O24.4H2O)
It contains 54 % Mo

To Sum up
Fertilizers are available in both organic as well as inorganic forms.
They are classified as straight, complex and mixed fertilizers.
They can also be classified into solid and liquid fertilizers.
Fertilizers are applied to supply nutrients required by the crop that are
taken up from the soil.

Bioaccumulation
w
a
t
e
r
z
o
o
p
l
a
n
k
t
o
n
0
.
0
4
p
p
m
s
m
a
l
l
f
i
s
h
0
.
5
p
p
m
l
a
r
g
e
f
i
s
h
2
p
p
m
Example-Fertilizers

The process of Eutrophication cont.

Effect of fertilizers on Environment and their components
a) pH Effect
b) Loss of biodiversity
c) Soil Erosion
d) Deforestation
e) Desertification
f) Eutrophication
g) Bio-accumulation

Unit-3.ppt

Recommended

Recommended

More Related Content

Similar to Unit-3.ppt

Similar to Unit-3.ppt (20)

Recently uploaded

Recently uploaded (20)

Unit-3.ppt