Fertilizers and Environmental
Chapter 9
The principles of application fertilizers
Law of the
Minimum:the
crop’s yield is
restricted by the
lack of one
element,even
though there may
be sufficient
quantities of all the
other elements.
Law of Diminishing Return
报酬递减律
the response of a plant to
the addition of a growth will
become smaller and smaller as
the amount of the growth
factor increases
The principles of application fertilizers
Yield or growth cure
Fertilizer use and agricultural production
Year
Number of
people
supported by
one hectare
Grain yield
per hectare
Fertilizer
consumption
kg NPK per
hectare
1800 0.8 0.73 -
1875 1.3 1.20 3.1
1900 1.6 1.84 15.6
1925 2.1 2.28 43.9
1950 3.3 2.98 101.9
1975 4.6 4.43 233.5
1978 4.5 4.63 255.8
The major factors that control crop
quality are genetically controlled,but
environmental and nutritional factors
do have some influence.
Crop Quality and application fertilizer
80 kg N/ha
+40 kg N/ha
at flowering
stage
+60 kg N/ha
at flowering
stage
Yield
(tonnes/ha) 4.59 4.98 5.24
Protein
content % 11.9 12.7 13.3
Sedimentation
value 28.0 30.0 34.0
The additions of N at flowering increased grain yield and baking
quality,This may not be true in dry areas.
Crop Quality and application fertilizer
In potatoes,K increases the
translocation of
carbohydrates from the
leaves to the tubers resulting
in an increase in the starch
content of potatoes,
K also increases the content
of citric acid which reduces
the occurrence of black
spot in potatoes.
Crop Quality and application fertilizer
The quality of oil crops may be affected by N nutrition,
The oil content of canola seeds was reduced by high
levels of N,
Nitrogen
rate
Seed yield
(g/pot)
Seed wt
(mg/seed)
Oil content
% DM
Low 10.0 3.0 46.8
High 18.6 3.6 41.7
Crop Quality and application fertilizer
Vegetable and Fruit Quality
NO3- NO2- during storage and
processing of fruits and vegetables
NO3- NO2- in the stomach
NO2- may be further transformed
into cancer-causing chemicals in the
human body,Therefore NO3- in fruits
and vegetables is a health concern.
Crop Quality and application fertilizer
0
0.4
0.8
1.2
1.6
2
NO3 content
(% NO3-N in DM)
Low light High Light
Effect o f l i g ht a nd s o i l N O
3
-
o n the N O
3
-
co ntent o f s pi na ch
0 mg N/kg soil
100 mg N/kg soil
200 mg N/kg soil
As N levels in the soil increase,the NO3- content of
vegetables such as spinach will also increase,Light also
affects the level of NO3- in the plant,As light increases,
NO3- levels decrease,
The European
Union has set a
limit of 2500
mg NO3-/kg
fresh weight of
spinach,
Nutrition and Vitamin Content of Vegetables
As N supply goes up,
the carotene (胡萝卜素）
content of tomatoes
and carrots increases,
Carotene is converted
into Vitamin A in the
body,
It protects us from
disease and helps our
eyesight,
Crop Quality and application fertilizer
Nutrition and Vitamin Content of Vegetables
High levels of K generally increases
the Vitamin C content in vegetables,High
levels of N generally had the opposite
effect (reduced Vitamin C).
Vitamin C helps builds up connecting
tissue in our body,heals wounds,and may
strengthen our immune system,
Crop Quality and application fertilizer
Plant Nutrition and Fruit Quality
Fruit quality includes both taste
and appearance,Inadequate levels
of P and K may result in small
fruits that are poor in taste.
Over fertilization with N may
result in new shoot growth in
apple trees,Ca taken up by the
tree may move into the new shoots
instead of the fruit,or dilute the
Ca in fruit owing to bigger fruit,
resulting in a condition known as
“bitter pit”
Crop Quality and application fertilizer
Plant Nutrition and Fruit Quality
“Blossom end rot” occurs when Ca2+ levels are low,High levels
of NH4+,Mg2+,or K+ may interfere with Ca2+ uptake by the plant.
Crop Quality and application fertilizer
Fertilizer – A fertilizer is a chemical product either mined or
manufactured material containing one or more essential plant
nutrients that are immediately or potentially available in
sufficiently good amounts.
Soil amendment or conditioner 土壤调理剂 – material used
to alter the physical properties of the soil,Examples include,
?Lime (CaCO3) is used to raise the soil pH
?Gypsum (CaSO4?2H20) used to improve soils with a high
exchangeable Na content,
?Elemental sulfur (S) is used to lower the soil pH
Fertilizers and Fertilization Techniques
Synthetic fertilizer – fertilizers that are manufactured
by industrial processes.---mineral fertilizers
Natural fertilizers include at least two different categories:
?Naturally occurring minerals nitrate--- mineral
fertilizers
?Plant or animal derived fertilizers such as bone meal,
compost,FYM,fish meal etc,----organic fertilizers
Fertilizers and Fertilization Techniques
Fertilizers may be applied in either solid,liquid,or
gaseous forms,The use of anhydrous ammonia (NH3) is
very common in many parts of the U.S,The ammonia is
stored under pressure inside the tank so it is in liquid form,
but as when it enters into the soil,the pressure is released
and it changes into a gas.
Straight fertilizer – Straight Fertilizers supply single plant nutrient
either nitrogen (N),or phosphorus (P),or potassium (K),Example,
Urea supplies 46% N; Super phosphate provides 7% P or 16% P2O5.
Multinutrient (compound) fertilizer – contains two or more nutrients
Complex fertilizer is prepared by chemically combining two or
more nutrients,An example is diammonium phosphate (DAP,
(NH4)2HPO4)
Mixed fertilizer are physical mixture of two or more straight
and/or complex fertilizers to supply particular combination of plant
nutrients,
Example,one can buy DAP and Muriate of Potash and mix them
in a ratio to get a fertilizer mixture containing a grade of 12-32-16 of
N,P2O5,and K2O.
Fertilizers and Fertilization Techniques
What is fertilizer grade?
Fertilizer grade refers to the guaranteed content
(analysis) of plant nutrients in a fertilizer,That
is percentage of the major plant nutrients; NPK
in that order,present in a fertilizer reflects the
grade of that fertilizer,
Thus 14-14-14-fertilizer grade refers to the
fertilizer guaranteed to contain a minimum of
14% nitrogen (N),14% of phosphorus (P2O5)
and 14% of potassium (K2O),
Fertilizers and Fertilization Techniques
When other nutrients are included in the fertilizer,
they are represented as a fourth number in the fertilizer grade,
For example,10-0-2-6Mg contains 10%N,2% K20 and 6%Mg.
the Advantages of Complex Fertilizers
? The possibility of adulteration掺假 is
generally less.
? Each granule is homogenous in nutrient
content,
? Being granular,the drilling of fertilizer is
easy,
? They are concentrated,It is cheap to
transport and storage and application
? Phosphorus availability is not affected
(fixation is less) as the phosphorus in the
granules will have less contact with soil
particles,
Disadvantages with Complex Fertilizers
? The disadvantage with complex
Fertilizers is that the ratios of the
nutrients are fixed and the
? farmers may have to supplement
with straight fertilizers to meet the
crop requirements.
The advantages of Mixed Fertilizer
? There will be considerable saving in time and
labor in application to the crops,as all the
nutrients required are present in the same
packing,
? One can ensure balanced nutrient application
if suitable mixture is chosen,
? Micronutrients can also be included in the
mixtures,
The disadvantages with Mixed Fertilizers
? There is possibility for adulteration(掺
假 ) with inert material,
? Farmers themselves can mix the
fertilizers provided they are
knowledgeable about what fertilizers
cannot be mixed together,
Bulk blending
1,Fertilizers that are blended together must be
physically and chemically compatible
2,Chemical compatibility means that there are
no gaseous loses,no decrease in nutrient
content,no caking (sticking together),
Chemical compatibility
a) Hygroscopicity 吸湿性 – the property of absorbing
moisture (water)
b) Precipitation
Ca(H2PO4)2·H2O + CaO > 2CaHPO4 (low solubility)
+ H2O
2CaHPO4 +CaO > Ca3(PO4)2 (precipitates) + H2O
a) Volatilization
2NaNO3 + Ca(H2PO4)2·H 2O >
CaN2(HPO4)2 + N2O5 (↑) + 2H20
Physical compatibility
? Physically – the fertilizer granules
(small balls) must have a similar size
and hardness,or they will separate
during transport and spreading.
Mode of action
Quick acting fertilizers are water-soluble and immediately
available to the plant.
Slow-acting fertilizers or controlled release fertilizers are
in a form that delays its availability for plant uptake,For
example,the fertilizer may have an outer coating that must be
dissolved before the nutrients are released into the soil.
Liquid fertilizers (fluids)
The term,fluid” includes,liquids” in which the fertilizer is
completely dissolved and,suspensions” in which the
fertilizers is present in the form of suspension,
Fertilizers and Fertilization Techniques
1,Basal application (基肥）
2,Topdress or Sidedress application（追肥）
3,Broadcasting （撒施，或均匀施肥）
4,Banding （带状施肥）
5,Pop-up or starter（种肥）
6,Foliar spraying (叶面施肥）
7,Fertigation （肥灌）
Application Methods
Basal application – refers to the application of
fertilizer before or during the planting process.
Topdress or sidedress application – refers to the
application of fertilizer after planting (while the crop is
growing).
Application Methods
Broadcasting means
that the fertilizer is
uniformly distributed
on the soil surface,It
may remain on the
soil surface
(unincorporated) or it
may be mixed into the
soil by tillage
(incorporated).
Application Methods
Advantages of broadcast application
?Easy
?Results in uniform fertilizer distribution
?Doesn't need expensive application equipment
Disadvantages of broadcast application
?Allows weeds to take up nutrients easily.
?Fertilizer may become unavailable if the surface of the soil
becomes dry.
?The fertilizer (especially immobile P and K,but also N)
may become unavailable to the plants.
?NH4 volatilization in alkaline soil
Application Methods
If a fertilizer is banded,
it means that the
nutrients are placed in a
small area near to the
seeds or seedlings,The
fertilizer should be put
at least 5 cm away from
the seed to prevent
damage to the plant
Application Methods
Banding
Advantages of banding application
?Positions fertilizer where seedling root systems can easily
use them,The nutrients are more available to crops than to
weeds.
?Requires less fertilizer/ha compared to broadcasting,
Improves fertilizer use efficiency.
?Reduces the problem of P and K fixation by limiting the
surface area contact with the soil
Disadvantages of banding application
?Requires special equipment and may slow planting
?Increases N losses to leaching
Application Methods
If a pop-up fertilizer is used,it
means that a small amount of
fertilizer in direct contact with the
seed,The amount of fertilizer
must be very small or it can
damage the seedlings,
Pop-up fertilizer or starter
Advantages of starter or pop
?Places fertilizer where root systems of seedlings can easily
take them up.The fertilizer is more available to crops than
to weeds.
?Increases the rate growth when the plant is small,It is very
helpful when the soil is cold and wet.
Disadvantages
?If too much fertilizer is used,it may damage the seed or
seedling.
?Requires an additional application of fertilizer to meet the
full nutrient requirements of the plant..
Application Methods
Foliar Application
A foliar fertilizer is one that is applied to the the surface of
the plant,In order to be used by the plant,the nutrients must
pass through the plasma membrane of the leaf cells (just like
nutrients must pass through the plasma membrane of the root
cells).
Foliar application is used to supplement the nutritional needs
of the plant,It cannot replace the need for the application of
nutrients to the soil,
Application Methods
Advantages of foliar application
?Nutrients can be absorbed quickly
?Avoids the problem of nutrient fixation in the soil
?The effect can occur quickly
Disadvantages
?Rate of application is limited (if it is too high,the leaf will
be harmed.
?May require multiple applications – every week or two.
Application Methods
Seeds treat and foliar application
Because they are used in very small amounts,
micronutrient fertilizers may be applied in the
following ways:
?Seed coating
?Seed soaking
?Foliar sprays
Application Methods
? Fertigation means a combination of
irrigation and fertilizer application in which
plant nutrients are dissolved in the
irrigation water.
? Macrofertigation 大型肥灌
? Microfertigation 微型滴灌
? The advantages of microfertigation are the
adaptation of nutrients supply to the crop
demand at various growth stages and to weather
conditions,precise application and avoiding
excess of fertilizer.
Application Methods
Fertilizer application and the environment
? 1,Drinking water and fertilizers
? The main constituent of fertilizers which
has an undesirable effect on the quality
of drinking water is nitrate.
? Nitrate itself is not toxic,but nitrite
originating from the reduction of nitrate
induces methaemoglobinemia（高铁血红
蛋白血症） in infants,
? Nitrite and amines can react to form
nitroamines亚硝胺 which are
cancinogenic (致癌的）
Fertilizer application and the environment
? 2,Eutrophication(水体富营养化 ） and fertilizers
? Eutrophication is the process which promote the
growth of plants,animal and microorganism in lake
and rivers owing to nutrients concentration increase in
lakes or rivers,
? It results in a progressively increasing deficiency of
oxygen in the water,Thus anaerobic organism growth
quickly,but aerobic organism is limited,Under this
conditions organic material is not decomposed
completely to H2O and CO2,and methane,ethylene,
H2S,butyric acid and other low molecular weight
substances is increased,These compounds are large
toxic to the lakes and rives.
Fertilizer application and the environment
3,Greenhouse gas and the destruction of the
stratospheric ozone
Methane is one of the main greenhouse
gases,
Increasing mineral fertilizer(NH3) rates
depressed the methane oxidation potential
of soils,and farmyard manure application
had only a minor depressive effect,NO3-N
is virtually without influence,
Fertilizer application and the environment
? N2O is also a greenhouse gas and absorbs light
in the infrared region,In addition it is involved
in the destruction of ozone in the stratosphere,
Nitrous oxide has a long lifespan.
? N2O comes from nitrification and
denitrification,Both of it depends upon soil
moisture,At field capacity,nitrification and
denitrification overlap,N2O is formed in
maximum.
summary
? The theory of fertilization
? The effects of fertilizers on the crop
yield and quality
? The concept of fertilizer
? The methods of fertilization
? The fertilization and environmental
Chapter 9
The principles of application fertilizers
Law of the
Minimum:the
crop’s yield is
restricted by the
lack of one
element,even
though there may
be sufficient
quantities of all the
other elements.
Law of Diminishing Return
报酬递减律
the response of a plant to
the addition of a growth will
become smaller and smaller as
the amount of the growth
factor increases
The principles of application fertilizers
Yield or growth cure
Fertilizer use and agricultural production
Year
Number of
people
supported by
one hectare
Grain yield
per hectare
Fertilizer
consumption
kg NPK per
hectare
1800 0.8 0.73 -
1875 1.3 1.20 3.1
1900 1.6 1.84 15.6
1925 2.1 2.28 43.9
1950 3.3 2.98 101.9
1975 4.6 4.43 233.5
1978 4.5 4.63 255.8
The major factors that control crop
quality are genetically controlled,but
environmental and nutritional factors
do have some influence.
Crop Quality and application fertilizer
80 kg N/ha
+40 kg N/ha
at flowering
stage
+60 kg N/ha
at flowering
stage
Yield
(tonnes/ha) 4.59 4.98 5.24
Protein
content % 11.9 12.7 13.3
Sedimentation
value 28.0 30.0 34.0
The additions of N at flowering increased grain yield and baking
quality,This may not be true in dry areas.
Crop Quality and application fertilizer
In potatoes,K increases the
translocation of
carbohydrates from the
leaves to the tubers resulting
in an increase in the starch
content of potatoes,
K also increases the content
of citric acid which reduces
the occurrence of black
spot in potatoes.
Crop Quality and application fertilizer
The quality of oil crops may be affected by N nutrition,
The oil content of canola seeds was reduced by high
levels of N,
Nitrogen
rate
Seed yield
(g/pot)
Seed wt
(mg/seed)
Oil content
% DM
Low 10.0 3.0 46.8
High 18.6 3.6 41.7
Crop Quality and application fertilizer
Vegetable and Fruit Quality
NO3- NO2- during storage and
processing of fruits and vegetables
NO3- NO2- in the stomach
NO2- may be further transformed
into cancer-causing chemicals in the
human body,Therefore NO3- in fruits
and vegetables is a health concern.
Crop Quality and application fertilizer
0
0.4
0.8
1.2
1.6
2
NO3 content
(% NO3-N in DM)
Low light High Light
Effect o f l i g ht a nd s o i l N O
3
-
o n the N O
3
-
co ntent o f s pi na ch
0 mg N/kg soil
100 mg N/kg soil
200 mg N/kg soil
As N levels in the soil increase,the NO3- content of
vegetables such as spinach will also increase,Light also
affects the level of NO3- in the plant,As light increases,
NO3- levels decrease,
The European
Union has set a
limit of 2500
mg NO3-/kg
fresh weight of
spinach,
Nutrition and Vitamin Content of Vegetables
As N supply goes up,
the carotene (胡萝卜素）
content of tomatoes
and carrots increases,
Carotene is converted
into Vitamin A in the
body,
It protects us from
disease and helps our
eyesight,
Crop Quality and application fertilizer
Nutrition and Vitamin Content of Vegetables
High levels of K generally increases
the Vitamin C content in vegetables,High
levels of N generally had the opposite
effect (reduced Vitamin C).
Vitamin C helps builds up connecting
tissue in our body,heals wounds,and may
strengthen our immune system,
Crop Quality and application fertilizer
Plant Nutrition and Fruit Quality
Fruit quality includes both taste
and appearance,Inadequate levels
of P and K may result in small
fruits that are poor in taste.
Over fertilization with N may
result in new shoot growth in
apple trees,Ca taken up by the
tree may move into the new shoots
instead of the fruit,or dilute the
Ca in fruit owing to bigger fruit,
resulting in a condition known as
“bitter pit”
Crop Quality and application fertilizer
Plant Nutrition and Fruit Quality
“Blossom end rot” occurs when Ca2+ levels are low,High levels
of NH4+,Mg2+,or K+ may interfere with Ca2+ uptake by the plant.
Crop Quality and application fertilizer
Fertilizer – A fertilizer is a chemical product either mined or
manufactured material containing one or more essential plant
nutrients that are immediately or potentially available in
sufficiently good amounts.
Soil amendment or conditioner 土壤调理剂 – material used
to alter the physical properties of the soil,Examples include,
?Lime (CaCO3) is used to raise the soil pH
?Gypsum (CaSO4?2H20) used to improve soils with a high
exchangeable Na content,
?Elemental sulfur (S) is used to lower the soil pH
Fertilizers and Fertilization Techniques
Synthetic fertilizer – fertilizers that are manufactured
by industrial processes.---mineral fertilizers
Natural fertilizers include at least two different categories:
?Naturally occurring minerals nitrate--- mineral
fertilizers
?Plant or animal derived fertilizers such as bone meal,
compost,FYM,fish meal etc,----organic fertilizers
Fertilizers and Fertilization Techniques
Fertilizers may be applied in either solid,liquid,or
gaseous forms,The use of anhydrous ammonia (NH3) is
very common in many parts of the U.S,The ammonia is
stored under pressure inside the tank so it is in liquid form,
but as when it enters into the soil,the pressure is released
and it changes into a gas.
Straight fertilizer – Straight Fertilizers supply single plant nutrient
either nitrogen (N),or phosphorus (P),or potassium (K),Example,
Urea supplies 46% N; Super phosphate provides 7% P or 16% P2O5.
Multinutrient (compound) fertilizer – contains two or more nutrients
Complex fertilizer is prepared by chemically combining two or
more nutrients,An example is diammonium phosphate (DAP,
(NH4)2HPO4)
Mixed fertilizer are physical mixture of two or more straight
and/or complex fertilizers to supply particular combination of plant
nutrients,
Example,one can buy DAP and Muriate of Potash and mix them
in a ratio to get a fertilizer mixture containing a grade of 12-32-16 of
N,P2O5,and K2O.
Fertilizers and Fertilization Techniques
What is fertilizer grade?
Fertilizer grade refers to the guaranteed content
(analysis) of plant nutrients in a fertilizer,That
is percentage of the major plant nutrients; NPK
in that order,present in a fertilizer reflects the
grade of that fertilizer,
Thus 14-14-14-fertilizer grade refers to the
fertilizer guaranteed to contain a minimum of
14% nitrogen (N),14% of phosphorus (P2O5)
and 14% of potassium (K2O),
Fertilizers and Fertilization Techniques
When other nutrients are included in the fertilizer,
they are represented as a fourth number in the fertilizer grade,
For example,10-0-2-6Mg contains 10%N,2% K20 and 6%Mg.
the Advantages of Complex Fertilizers
? The possibility of adulteration掺假 is
generally less.
? Each granule is homogenous in nutrient
content,
? Being granular,the drilling of fertilizer is
easy,
? They are concentrated,It is cheap to
transport and storage and application
? Phosphorus availability is not affected
(fixation is less) as the phosphorus in the
granules will have less contact with soil
particles,
Disadvantages with Complex Fertilizers
? The disadvantage with complex
Fertilizers is that the ratios of the
nutrients are fixed and the
? farmers may have to supplement
with straight fertilizers to meet the
crop requirements.
The advantages of Mixed Fertilizer
? There will be considerable saving in time and
labor in application to the crops,as all the
nutrients required are present in the same
packing,
? One can ensure balanced nutrient application
if suitable mixture is chosen,
? Micronutrients can also be included in the
mixtures,
The disadvantages with Mixed Fertilizers
? There is possibility for adulteration(掺
假 ) with inert material,
? Farmers themselves can mix the
fertilizers provided they are
knowledgeable about what fertilizers
cannot be mixed together,
Bulk blending
1,Fertilizers that are blended together must be
physically and chemically compatible
2,Chemical compatibility means that there are
no gaseous loses,no decrease in nutrient
content,no caking (sticking together),
Chemical compatibility
a) Hygroscopicity 吸湿性 – the property of absorbing
moisture (water)
b) Precipitation
Ca(H2PO4)2·H2O + CaO > 2CaHPO4 (low solubility)
+ H2O
2CaHPO4 +CaO > Ca3(PO4)2 (precipitates) + H2O
a) Volatilization
2NaNO3 + Ca(H2PO4)2·H 2O >
CaN2(HPO4)2 + N2O5 (↑) + 2H20
Physical compatibility
? Physically – the fertilizer granules
(small balls) must have a similar size
and hardness,or they will separate
during transport and spreading.
Mode of action
Quick acting fertilizers are water-soluble and immediately
available to the plant.
Slow-acting fertilizers or controlled release fertilizers are
in a form that delays its availability for plant uptake,For
example,the fertilizer may have an outer coating that must be
dissolved before the nutrients are released into the soil.
Liquid fertilizers (fluids)
The term,fluid” includes,liquids” in which the fertilizer is
completely dissolved and,suspensions” in which the
fertilizers is present in the form of suspension,
Fertilizers and Fertilization Techniques
1,Basal application (基肥）
2,Topdress or Sidedress application（追肥）
3,Broadcasting （撒施，或均匀施肥）
4,Banding （带状施肥）
5,Pop-up or starter（种肥）
6,Foliar spraying (叶面施肥）
7,Fertigation （肥灌）
Application Methods
Basal application – refers to the application of
fertilizer before or during the planting process.
Topdress or sidedress application – refers to the
application of fertilizer after planting (while the crop is
growing).
Application Methods
Broadcasting means
that the fertilizer is
uniformly distributed
on the soil surface,It
may remain on the
soil surface
(unincorporated) or it
may be mixed into the
soil by tillage
(incorporated).
Application Methods
Advantages of broadcast application
?Easy
?Results in uniform fertilizer distribution
?Doesn't need expensive application equipment
Disadvantages of broadcast application
?Allows weeds to take up nutrients easily.
?Fertilizer may become unavailable if the surface of the soil
becomes dry.
?The fertilizer (especially immobile P and K,but also N)
may become unavailable to the plants.
?NH4 volatilization in alkaline soil
Application Methods
If a fertilizer is banded,
it means that the
nutrients are placed in a
small area near to the
seeds or seedlings,The
fertilizer should be put
at least 5 cm away from
the seed to prevent
damage to the plant
Application Methods
Banding
Advantages of banding application
?Positions fertilizer where seedling root systems can easily
use them,The nutrients are more available to crops than to
weeds.
?Requires less fertilizer/ha compared to broadcasting,
Improves fertilizer use efficiency.
?Reduces the problem of P and K fixation by limiting the
surface area contact with the soil
Disadvantages of banding application
?Requires special equipment and may slow planting
?Increases N losses to leaching
Application Methods
If a pop-up fertilizer is used,it
means that a small amount of
fertilizer in direct contact with the
seed,The amount of fertilizer
must be very small or it can
damage the seedlings,
Pop-up fertilizer or starter
Advantages of starter or pop
?Places fertilizer where root systems of seedlings can easily
take them up.The fertilizer is more available to crops than
to weeds.
?Increases the rate growth when the plant is small,It is very
helpful when the soil is cold and wet.
Disadvantages
?If too much fertilizer is used,it may damage the seed or
seedling.
?Requires an additional application of fertilizer to meet the
full nutrient requirements of the plant..
Application Methods
Foliar Application
A foliar fertilizer is one that is applied to the the surface of
the plant,In order to be used by the plant,the nutrients must
pass through the plasma membrane of the leaf cells (just like
nutrients must pass through the plasma membrane of the root
cells).
Foliar application is used to supplement the nutritional needs
of the plant,It cannot replace the need for the application of
nutrients to the soil,
Application Methods
Advantages of foliar application
?Nutrients can be absorbed quickly
?Avoids the problem of nutrient fixation in the soil
?The effect can occur quickly
Disadvantages
?Rate of application is limited (if it is too high,the leaf will
be harmed.
?May require multiple applications – every week or two.
Application Methods
Seeds treat and foliar application
Because they are used in very small amounts,
micronutrient fertilizers may be applied in the
following ways:
?Seed coating
?Seed soaking
?Foliar sprays
Application Methods
? Fertigation means a combination of
irrigation and fertilizer application in which
plant nutrients are dissolved in the
irrigation water.
? Macrofertigation 大型肥灌
? Microfertigation 微型滴灌
? The advantages of microfertigation are the
adaptation of nutrients supply to the crop
demand at various growth stages and to weather
conditions,precise application and avoiding
excess of fertilizer.
Application Methods
Fertilizer application and the environment
? 1,Drinking water and fertilizers
? The main constituent of fertilizers which
has an undesirable effect on the quality
of drinking water is nitrate.
? Nitrate itself is not toxic,but nitrite
originating from the reduction of nitrate
induces methaemoglobinemia（高铁血红
蛋白血症） in infants,
? Nitrite and amines can react to form
nitroamines亚硝胺 which are
cancinogenic (致癌的）
Fertilizer application and the environment
? 2,Eutrophication(水体富营养化 ） and fertilizers
? Eutrophication is the process which promote the
growth of plants,animal and microorganism in lake
and rivers owing to nutrients concentration increase in
lakes or rivers,
? It results in a progressively increasing deficiency of
oxygen in the water,Thus anaerobic organism growth
quickly,but aerobic organism is limited,Under this
conditions organic material is not decomposed
completely to H2O and CO2,and methane,ethylene,
H2S,butyric acid and other low molecular weight
substances is increased,These compounds are large
toxic to the lakes and rives.
Fertilizer application and the environment
3,Greenhouse gas and the destruction of the
stratospheric ozone
Methane is one of the main greenhouse
gases,
Increasing mineral fertilizer(NH3) rates
depressed the methane oxidation potential
of soils,and farmyard manure application
had only a minor depressive effect,NO3-N
is virtually without influence,
Fertilizer application and the environment
? N2O is also a greenhouse gas and absorbs light
in the infrared region,In addition it is involved
in the destruction of ozone in the stratosphere,
Nitrous oxide has a long lifespan.
? N2O comes from nitrification and
denitrification,Both of it depends upon soil
moisture,At field capacity,nitrification and
denitrification overlap,N2O is formed in
maximum.
summary
? The theory of fertilization
? The effects of fertilizers on the crop
yield and quality
? The concept of fertilizer
? The methods of fertilization
? The fertilization and environmental
