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Chapter - 5
The Impact of Chemical Fertilizers on Our
Environment and Ecosystem
Authors
Chandini
M.Sc. (Ag) Agronomy, Banaras Hindu University, Varanasi,
Uttar Pradesh, India
Randeep Kumar
M.Sc. (Ag) Agricultural chemicals, G.B. Pant University of
Agriculture and Technology, Pantnagar, U.S. Nagar,
Uttarakhand, India
Ravendra Kumar
Asst. Prof., Dept. of Chemistry, G.B. Pant University of
Agriculture and Technology, Pantnagar, U.S. Nagar,
Uttarakhand, India
Om Prakash
Prof., Dept. of Chemistry, G.B. Pant University of Agriculture
and Technology, Pantnagar, U.S. Nagar, Uttarakhand, India
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Chapter - 5
The Impact of Chemical Fertilizers on our Environment
and Ecosystem
Chandini, Randeep kumar, Ravendra kumar and Om Prakash
Abstract
Though the chemical fertilizer increases the plant growth and vigour,
hence meets the food security of the world, but the plants grown in this way
does not develop good plant characters such as, good root system, shoot
system, nutritional characters and also will not get time to grow and mature
properly. Chemically produced plant will accumulate in the human body,
toxic chemicals, which are very dangerous. The deleterious effect of the
chemical fertilizers will itself start from the manufacturing of these
chemicals, whose products and byproducts are some toxic chemicals or
gases like NH4, CO2, CH4 etc. which will cause air pollution. And when the
wastes from the industries are disposed off untreated into nearby water
bodies it will cause water pollution. It also includes the most devastating
effect of chemical waste accumulation in the water bodies i.e., the water
eutrophication. And when added in soil, its continuous use degrades the soil
health and quality hence causing the soil pollution. Therefore, this is high
time to realize that this crop production input is depleting our environment
and ecosystem. Hence its continuous use without taking any remedial
measure to reduce or judicious use will deplete all the natural resources one
day and will threaten all the life from the earth. The adverse effect of these
synthetic chemicals on human health and environment can only be reduced
or eliminated by adopting new agricultural technological practices such as
shifting from chemical intensive agriculture which includes the use of
organic inputs such as manure, biofertilizers, biopesticides, slow release
fertilizer and nanofertilizers etc. which would improve the application
efficiency as well as use efficiency of the fertilizers. Opting organic farming
will create a healthy natural environment and ecosystem for the present as
well as future generation.
Keywords: Chemical fertilizers, environment and ecosystem, plant growth
and maturity, organic agriculture
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1. Introduction
The industrial revolution followed by the green revolution which
fulfilled the food demands of the growing population caused an increase in
yield per unit area in crop production, but they also increased the use of
synthetic fertilizers in agriculture. Less soil fertility is one of the most vital
constraints in improving the agricultural production [1]. But the intensive use
of inorganic fertilizer in agriculture worldwide for ensuring the world food
security caused so many health problems and unrecoverable environmental
pollution.
Total world consumption of nitrogen (N), phosphorus (P), and
potassium (K) in 1998/1999 was 81, 14, and 18 Tg/yr, respectively [2]. Fifty-
five per cent of the nutrients were used for cereal production, 12% for
oilseed crops, 11% for grassland, 11% for commodities (e.g., cotton, sugar,
and coffee), 6% for root cropps, and only 5% for fruit and vegetable
production. In 1950, fertilizers comprised only a small percentage of the
nutrients needed for grain production, most of the supply being provided by
the “natural fertility” of the soil and added manure [3]. By 2020, more than
70% of the grain yield will have to depend on fertilizers. The demand for
plant nutrients is expected to increase continuously with population growth
[4]. According to Keeney (1997), world population is expected to increase by
about 2.3 billion by 2020 and double by the year 2050. If meat and food
consumption in developed countries are matched by the rest of the world by
the mid-21st century, then grain and nutrient demand are expected to triple
[5]. Keeping in mind that the amount of land used for food production
changed very slightly over the past few decades [3], and may even have
decreased in parts of the world due to urbanization [5], the nutrient load per
unit area is steadily increasing. All this implies that food production will
have to be much more intensive and efficient than ever before.
Thus, to reduce and eliminate the adverse effects of Synthetic fertilizers
on human health and environment, nowadays a new agricultural practice has
been developed called as organic agriculture, sustainable agriculture or
ecological agriculture [6]. Organic fertilizers are primarily cost-effective,
easily available from locality products than chemical fertilizers [7]. Organic
matter is the basis of soil fertility [8]. Microbial fertilizers are distinctly
environment-friendly, non-bulky, cost-effective which plays a significant
role in plant nutrition [9]. On the other hand, inorganic fertilizers are known
for their high cost and their negative environmental effects if managed
poorly [10]. All these give rise to reduced crop yields as a result of soil
degradation and nutrients imbalance [11]. Some other technologies and
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management practices such as integrated nutrient management (INM), using
slow release fertilizer or Nano-fertilizers, conservation tillage, cover
cropping etc. can be adapted to supply balanced nutrients to plants.
Fertilizers are very important for the crop growth, yield, quality parameters,
even for soil health only when applied in optimum recommended dose or
when used judiciously. Fertilizer improves the nutrient status and quality of
soil by enriching it with nutrients which it lacks. Crop plants require
nitrogen, phosphorous and potassium to maintain the normal physiological
function of the cell. In a similar way according to [12] lack of nitrogen results
in poor growth and slow growth, but the excess use of nitrogen results in
delayed maturity and low quality of leaf [13]. However intensive fertilizer
application causes serious environmental problems, (for e.g. eutrophication
of waters, loss of biodiversity, global warming and stratospheric ozone
depletion), soil and plant health problems as some fertilizers also contains
heavy metals, excess use of which leads fertilizer to enter the food chain via
absorption from soil. Thus, fertilization leads to water, soil and air pollution.
2. Fertilizer Basics
A fertilizer is any material of natural or synthetic origin (other
than liming materials) that is applied to soils or to plant tissues to supply one
or more plant nutrients essential to the growth of plants or to overcome the
plant nutrient deficiency. Many sources of fertilizer exist, both natural and
industrially produced. Any natural or manufactured material that contains at
least 5% of one or more of the three primary nutrients – nitrogen (N),
phosphorous (P), or potassium (K) – can be considered a fertilizer.
Industrially manufactured fertilizers are sometimes referred to as
“mineral” fertilizers. Fertilizers contain varying proportions of plant
essential major (N, P, K, etc.) and minor (Zn, Mn, Fe, etc.) elements, as well
as impurities and other non-essential elements. This definition includes
both inorganic (mineral) and organic fertilizers and also soil conditioners,
such as lime and gypsum, which may promote plant growth by increasing
the availability of nutrients that are already in the soil or by changing the
soil's physical structure.
Fertilizers typically provide following nutrients in varying proportions:
Three Main/Primary Macronutrients
Nitrogen (N), is a major constituent of several of the most important
plant substances like chlorophyll hence causes leaf growth.
Phosphorus (P), is involved in many vital plant processes like
energy transfer, Development of roots, flowers, seeds, fruit.
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Potassium (K): serves as an activator of enzymes used in
photosynthesis and respiration, strong stem growth, movement of
water in plants, promotion of flowering and fruiting.
Three Secondary Macronutrients
Calcium (Ca), regulates the transport of other nutrients into the
plant and is also involved in the activation of certain plant enzymes,
is also involved in photosynthesis and plant structure.
Magnesium (Mg), in plant nutrition, is as a constituent of the
chlorophyll molecule. As a carrier, it is also involved in numerous
enzyme reactions as an effective activator.
Sulphur (S), is a structural component of some amino acids and
vitamins, and is essential for chloroplast growth and function; it is
found in the iron-sulfur complexes of the electron transport chains
in photosynthesis. It is needed for N2 fixation by legumes, and the
conversion of nitrate into amino acids and then into protein.
And Micronutrients
Copper (Cu), is important for photosynthesis, involved in the
manufacture of lignin (cell walls) and involved in grain production.
Iron (Fe), is necessary for photosynthesis and is present as an
enzyme cofactor in plants.
Manganese (Mn), is necessary for photosynthesis, including the
building of chloroplasts.
Molybdenum (Mo), is a cofactor to enzymes important in building
amino acids and is involved in nitrogen metabolism.
Zinc (Zn), is required in a large number of enzymes and plays an
essential role in DNA transcription.
Boron (B), has many functions within a plant: it affects flowering
and fruiting, pollen germination, cell division, and active salt
absorption.
Silicon (Si), strengthen cell walls, improve plant strength, health,
and productivity.
Cobalt (Co), essential for nitrogen fixation by the nitrogen-fixing
bacteria associated with legumes and other plants.
Vanadium (V), may be required by some plants, but at very low
concentrations. It may also be substituting for molybdenum.
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3. Fertilizers Classification
The term fertilizer is defined in the Act. No. 156/1998 Coll., as
amendment. So fertilizers are required and thus applied to replenish nutrients
taken away from the soil by crop harvest and so they are applied to
supplement more nutrients to boost crop yield [14]. Plant nutrients are
essential for the production of healthy crops for the world’s increasing
population. Plant nutrients are therefore a vital component of sustainable
agriculture. Increased crop production largely depends on the type of
fertilizers used for supplementing the essential plant nutrients [15]. The nature
and the function of nutrient released from inorganic, organic and
biofertilizers are different, also each type of fertilizer has its own advantages
and limitations with regard to crop growth and soil fertility. Thus a sound
fertilizer management must be done to ensure both an enhanced and
safeguarded environment; therefore, a balanced fertilization strategy that
combines the use of chemical, organic or biofertilizers must be developed
and evaluated [32]. Fertilizers can be classified in numerous ways, like for eg;
on the basis of a number of nutrient elements present, on the basis of the type
of essential nutrient present, etc. [17].
I. On the Basis of Its Nature
Types
Examples
Inorganic
fertilizer
These include industrially synthesized fertilizers. e.g., CO (NH2)2
(Urea) 45-46% nitrogen, chile saltpetre with 15% nitrogen.
Organic
fertilizer
Fertilizers derived from living or formerly living materials. e.g., animal
wastes, plant wastes from agriculture, compost, and treated sewage
sludge. Beyond manures, animal sources can include products from the
slaughter of animals-blood meal and bone meal.
Biofertilizers
Fuentes-Ramirez and Caballero-Mellado (2005) defined a biofertilizer
as “a product that contains living microorganisms, which exert direct or
indirect beneficial effect on plant growth and crop yield through
different mechanisms”. E.g., AM fungi, N-fixer, P solubilizer and K
solubilizer.
II. On the Basis of Form of the Fertilizer
Types
Examples
Solid
1. Powder (single superphosphate)
2. Crystals (ammonium sulphate)
3. Prills (urea, diammonium phosphate, superphosphate)
4. Granules (Holland granules)
5. Supergranules (urea supergranules)
6. Briquettes (urea briquettes)
Liquid
1. Liquid fertilizers are applied with irrigation water or for direct
application.
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2. Ease of handling, less labor requirement and possibility of mixing with
herbicides have made the liquid fertilizers more acceptable to farmers
III. On the Basis of Complexity of Fertilizers
Types
Examples
Single nutrient or
straight fertilizer
Supplies only one primary plant nutrient, namely nitrogen or
phosphorus or potassium. E.g. Urea, ammonium sulfate,
potassium chloride and potassium sulfate.
Multinutrient or
complex fertilizer
1. Binary
2. NPK
Supplies 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. DAP, nitro-
phosphates and ammonium phosphate.
Mixed fertilizers
physical mixtures of straight fertilizers, contain two or three
primary plant nutrients
IV. On the Basis of the Type of Nutrient Present
Types
Examples
Macronutrient fertilizer
Contains either one or two essential macronutrient.
Micronutrient fertilizer
Contains either one or two micronutrient.
V. On the Basis of Application of Fertilizer
Types
Examples
Foliar fertilizer
Water soluble straight nitrogen fertilizer is applied directly to the
leaves or fruits of high value crops.
Controlled &
Slow released
fertilizer
Slow and controlled-release fertilizers are fertilizers containing a
plant nutrient in a form which either
a) Delays its availability for plant uptake and use after application,
or b) which is available to the plant significantly longer than a
reference ‘rapidly available nutrient fertilizer’ such as
ammonium nitrate or urea, ammonium phosphate or potassium
chloride (AAPFCO, 1995), the microbially decomposed N
products, such as UFs (Urea-Formaldehydes), are commonly
referred to in the trade as slow-release fertilizers and coated or
encapsulated products as controlled-release fertilizers.
Nitrogen based
fertilizer with
certain chemicals
that enhance
their efficiency
Nitrification inhibitor suppresses the conversion of ammonia to
nitrate that is more prone to leaching. Eg, 1-carbamoyl-3-
methylpyrazole (CMP), nitrapyrin (2-chloro-6-
trichloromethylpyridine) and 3, 4-Dimethylpyrazole phosphate
(DMPP).
Urease inhibitor slows the hydrolytic convertion of urea into
ammonia, which is prone to evaporation as well as nitrification.
Eg, urea ammoniums nitrate (UAN).
4. Impact of Chemical Fertilizers on Natural Resources
The World agricultural systems is using a large number of chemicals
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such a fertilizers, pesticides, herbicides to achieve more production per unit
area but using more doses than optimum or recommended of these chemicals
and fertilizers leads to several problems like environment pollution (soil,
water, air pollution), reduced input efficiency, decreased food quality,
resistance development in different weeds, diseases, insects, soil
degradation, micronutrient deficiency in soil, toxicity to different beneficial
living organism present above and below the soil surface, less income from
the production, etc. Despite these many problems, there is also a challenge to
meet the food demands of the world’s growing population. Therefore, there
is a need to produce nutrition rich and chemicals free agricultural produce
for the human and animal consumption without deteriorating are natural
resources that is why emphasis should be laid on the production of food rich
in quality as well as quantity.
Fertilizer use is no doubt beneficial to plant in providing deficient
nutrients; also they have several other conveniences such as the cheaper
source of nutrient, higher nutrient content and its solubility hence immediate
availability, then it’s required in less amount, which makes it more
acceptable than organic fertilizer. There is abundance of evidence that
inorganic fertilizers can improve the yield of crop significantly [18]. Fertilizers
raise soil fertility so that the yield of crops is independent and no longer be
limited by the deficient amounts of plant nutrients [19]. Despite these benefits,
fertilizer has several negative effects on the environment because of its
growing consumption and lowering nutrient use efficiency. Therefore, the
major challenge in intensive agricultural production systems is to combine
intensive cultivation with high nutrient use efficiency.
4.1 Deleterious Effects of Chemical Fertilizers
Soil nutrient level gets decreased over time when crop plants get
harvested, and these nutrients get replenished either through natural
decomposition process or by adding fertilizers. Hence fertilizer is an
essential component of modern agriculture.
But though chemical fertilizers are the major cause of sufficient crop
production for the world population, their overuse is bringing serious
challenges to the present and future generations like polluted air, water, and
soil, the degraded lands, depleted soils and increased emissions of
greenhouse gases. These synthetic fertilizers are not only becoming
hazardous for our environment but also to humans, animals and to the
microbial life forms too. It’s high time that everyone understands the ill
effects of using excess chemical fertilizers and take initiatives for reducing
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the use of chemical fertilizer and pesticides substituting it with other organic
amendments like organic manures which not only provides essential
nutrients to the plants but also maintains the soil health for the subsequent
crops. There are so many other technologies developing like slow or
controlled released fertilizers, prilled or granulated fertilizer, nitrification
inhibitors, Nano-fertilizer etc., all these are the promising options we can use
to overcome these serious challenges and can save our environment as well
as the ecosystem. Let us now learn about the different hazards occurring due
to excessive use of chemical fertilizers used for enhancing the crop
production.
4.1.1 Effects of Chemical Fertilizers on Water Pollution
As the nutrient use efficiency of the chemical fertilizer is very less hence
these are applied in quantities much more actually required and when these
are applied in unfavorable environmental condition then these get lost in the
environment by different ways. These can be leaching, drainage or surface
flow, for example, in most cultivated upland soils, mineral N is likely to be
oxidized to nitrate due to microbial activity. As a result, relatively high
fractions of the applied N may potentially be leached or removed from the
root zone into the surface and groundwater [20]. Even when these chemicals
are applied in ideal conditions, plants use only up to 50% of the N fertilizer
applied, 2-20% gets volatilized, 15-25% reacts with organic compounds in
the clay soil and the remaining 2-10% interfere surface and groundwater [21].
One of the most important parameters of the pollution of water is nitrate
which is the basic component of fertilizer. Nitrate is the most common form
of dissolved nitrogen present in groundwater or other water bodies. When
nitrate concentration exceeds 50 mg NO3-/L in drinking water or high nitrate
accumulation can lead to (i) 'blue baby syndrome' (acquired
methemoglobinemia in infants) and in ruminants; (ii) gastric cancer, for
which a possible link with nitrite or nitrosoamines has been suggested; (iii)
other diseases such as goiter, birth defects, and heart disease; and (iv)
eutrophication of surface water [21].
Major deleterious effect of the intensive use of fertilizers (mainly
nitrogen and phosphorus) is water eutrophication. The primary factor
responsible for eutrophication is phosphate. Surface waters should contain ≤
50 μg/liter phosphorus. Nitrogen can also become a factor for eutrophication
when increased biomass growth takes place [17]. Eutrophication result in
increased growth of aquatic plants and algae in the water body covering the
whole water body leading to the loss of other aquatic living species like
fishes due to the reduced oxygen supply. Hence eutrophication can lead to
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the killing of aquatic life, the proliferation of unwanted species, and loss of
recreation due to bad odour, polluted water etc.
4.1.2 Effects of Chemical Fertilizers on Air Pollution
High application rates of chemical fertilizer for enhancing crop
production is generating numerous harmful greenhouse gases, depleting the
protective ozone layer hence exposing the humans to harmful ultraviolet rays
[22]. Agriculture accounts for 60% of anthropogenic N2O emissions, and
agricultural soils are the dominant source [23]. The greenhouse gases like
CO2, CH4 and N2O are produced during the manufacture of nitrogenous
fertilizer. The effects can be combined into an equivalent amount of CO2.
Nitrogen fertilizer can be converted by soil bacteria into nitrous oxide, a
greenhouse gas. Nitrogen fertilizer whose excess use results in an emission
of nitrogen oxides (NO, N2O, NO2) is responsible for severe air pollution [24].
Other gases also responsible for the ozone depletion are water vapour,
carbon dioxide, methane, hydrogen sulfide and chloro-fluoro hydrocarbons
[14]. Nitrous oxide (N2O) has become the third most important greenhouse
gas after carbon dioxide and methane. Its global warming potential is 310
times more than that of carbon dioxide. The main concern regarding the
emission of nitrous oxides has to do with the effect of global warming and
the role of nitrous oxides in ozone destruction that consequently leads to
atmospheric “holes,” thus exposing humans and animals to excessive
ultraviolet radiation [25]. Ammonia volatilized or emitted from fertilized
lands, gets deposited in atmosphere and oxidized to become nitric acid,
sulfuric acids, creating acid rain after the chemical transformations. Acid
rain can damage vegetation, buildings; also can damage organisms that live
in both lakes and reservoirs [14]. Methane emissions from transplanted paddy
fields are also a serious concern, as methane is a potent greenhouse gas and
its concentration is increased by the application of ammonium-based
fertilizers. All these emissions contribute to global climate change [16].
4.1.3 Effect of Chemical Fertilizer on Soil Pollution
The Soil is the natural body and a medium for plant growth. The Soil is
a habitat of soil organisms, is a nutrient recycling system, and provides many
other ecosystem services. The over-use of chemical fertilizers can lead to
soil acidification and soil crust thereby reducing organic matter content,
humus content, beneficial organisms, stunting plant growth, can change the
soil pH, increase pests, and even contribute to the release of greenhouse
gases. The soil acidity diminishes phosphate intake by crops, increases the
toxic ion concentration in the soil, and inhibits crop growth [20]. The
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depletion of humus in the soil reduces its ability to store nutrients.
Greenhouse gases derived from excess nitrogen fertilizer harm the climate.
Nitrogen applied to fields in large amounts destroys the balance between the
three macronutrients, N, P and K over time which would result in lack of
micronutrients; it also damages topsoil, resulting in reduced crop yields.
Sandy soils are much more prone to soil acidification than are clay soils.
Clay soils have an ability to buffer the effects of excess chemical
fertilization. Repeated applications of chemical fertilizer may result in a
toxic buildup of heavy metals such as arsenic, cadmium, and uranium in the
soil. These toxic heavy metals not only pollute the soil but also get
accumulated in food grains, fruits and vegetables. For example, Fertilizers
like Triple superphosphate has trace elements like cadmium and arsenic that
accumulate in plant and through food chains reach to human that may cause
health problems. The effects of chemical fertilizers on soil are great and
irreversible [26].
Fertilizer application without the using soil testing recommendation can
lead to implications such as soil degradation, nutrient imbalance, destruction
of soil structure, increasing bulk density [27]. Fertilizers, more than the
recommended amounts causes formation, accumulation and concentration of
mineral salts of fertilizers which leads to compaction layer and soil
degradation in the long-term.
4.1.4 Other Deleterious Effects of Chemical Fertilizers
1. Excessive use of chemical fertilizer, especially N, can contribute to
crop tip browning, lower leaf yellowing, wilting and crop lodging.
When fertilizer scorches roots, the root may blacken and go limp.
All these symptoms occur due to salt accumulation in the soil which
would cause difficulty in water absorption by plants.
2. Using higher doses of N fertilizers in malt barley may cause
undesirable effect on quality of the beer.
3. Over-application of chemical fertilizer to plants may cause the
leaves to turn yellow or brown, damaging the plant and reducing the
crop yield.
4. The excessive accumulation of nitrate or nitrite in plant parts
consumed by humans or animals is likely to cause the same
detrimental effects associated with nitrate contamination of water
sources [28].
5. Over-fertilization effects reduce the biodiversity resulting from
ammonia deposition in forests and waters [29].
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6. They reduce the mycorrhizal root colonization and inhibit symbiotic
N fixation by rhizobia due to high N fertilization.
7. Nutrients are easily lost from soils through fixation, leaching or gas
emission and can lead to reduced fertilizer efficiency [32].
5. Other Alternatives Besides Using the Chemical Fertilizers
Excessive use of the chemical fertilizer for a long time on the same soil
may lead to soil degradation, loss of beneficial soil microorganisms, and
many other losses as discussed above [30]. Therefore, to ensure both the
enhanced and sustainable agricultural production and to safeguard the
environment integrated use of different types of nutrient suppliant such as
chemical fertilizer, organic manures, biofertilizers and other slow released or
controlled released fertilizers should opt [31]. The use of organic fertilizers
together with chemical fertilizers, compared to the addition of organic
fertilizers alone, had a higher positive effect on microbial biomass and hence
soil health [15].
a) Biofertilizer: It is defined as a substance which contains living
micro-organisms and is known to help with the expansion of the
root system and better seed germination. A healthy plant usually has
a healthy rhizosphere which should be dominated by beneficial
microbes.
Biofertilizers differ from chemical and organic fertilizers in the sense
that they do not directly supply any nutrients to crops and are cultures of
special bacteria and fungi. The production technology for biofertilizers is
relatively simple and installation cost is very low compared to chemical
fertilizer plants [32].
b) Slow-Release Fertilizers: It involves the release of the nutrient in a
slower manner than common fertilizers. However, the rate, pattern,
and duration of release are not well controlled. But the rate, pattern,
and duration of release are well known in controlled release
fertilizers [35]. Different types of slow or controlled release
fertilizers are:
1. Organic-N Low-Solubility Compounds for e.g. Urea-formaldehyde
(UF) and Isobutyledene-diurea (IBDU).
2. Fertilizers in Which a Physical Barrier Controls the Release for e.g.,
the coated fertilizers coated with organic polymer coatings that are
either thermoplastic or resins and fertilizers coated with inorganic
materials such as sulfur- or mineral-based coatings etc.
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3. Inorganic Low-Solubility Compounds: Fertilizers such as metal
ammonium phosphates and partially acidulated phosphates rock
(PAPR).
c) Nanofertilizers: “Nanofertilizers are synthesized or modified form
of traditional fertilizers, fertilizers bulk materials or extracted from
different vegetative or reproductive parts of the plant by different
chemical, physical, mechanical or biological methods with the help
of nanotechnology used to improve soil fertility, productivity and
quality of agricultural produce. Nanoparticles can be made from
fully bulk materials. For example, nano-TiO2 treated seed produced
plant recorded more dry weight, higher photosynthetic rate,
chlorophyll-a formation compared to the control [34].
d) Application Efficiency: Application of any fertilizer should be
done at an economic rate other than optimum rate. Also application
from right source, rate, placement & time will reduce the adverse
effect on both the crop and the environment.
Various techniques that maintain and enrich the soil fertility & the soil
humus content should be used like using compost, manure, agro-forestry,
green manure, mulch manure etc.
Conclusion
Fertilizers application is very vital for today’s agricultural crop
production system as it restores the soil nutrient and promotes crop growth &
yield [14]. But, to reduce the different kinds of hazards taking place due to
excessive use of fertilizers, judicious and sustainable use of fertilizers should
be made for that firstly soil testing and analysis should be done properly and
then, fertilizer should be given to soil. Therefore, to ensure both the
enhanced and sustainable agricultural production and to safeguard the
environment, integrated use of different types of nutrient suppliant such as
chemical fertilizer, organic manures, biofertilizers and other slow released or
controlled released fertilizers should be adopted. To eliminate the pollution
hazards due to chemical fertilizers, improved nutrient use efficient fertilizers
particularly nitrogen should be adopted by using organic manures,
controlled-release or slow-release fertilizers. Using different Nano-fertilizers
which have the greater role in enhancing crop production this will reduce the
cost of fertilizer for crop production and also minimize the pollution hazard.
Current resources should be overhauled in favour of the sustainable use of
resources, also boosting the production simultaneously.
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