This document summarizes the role of nitrogen for plant growth and development. It discusses how nitrogen is essential for plants and is required for key physiological processes like protein synthesis and chlorophyll formation. It is needed in large quantities by plants. The document reviews how nitrogen increases crop yields and positively impacts growth parameters for important crops in Pakistan like wheat, rice, sugarcane, cotton, and oilseeds. Optimum nitrogen rates are discussed for maximizing yields of these crops. The conclusion is that nitrogen deficiency is widespread in Pakistani soils and judicious nitrogen application is needed to boost agricultural production and improve food quality.

1. Advances in
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Copyright © 2016 by authors and Copyrigh
Role of Nitrogen for
Review
1Shah Jahan Leghari,2Niaz Ahmed
4Ghulam MustafaBhabhan, 5Khalid Hussain
6Ayaz Ahmed Lashari
1
Department of Agronomy, 2
Horticulture, 5
Soil Science
4
Sugarcane section, Agriculture Research, Tandojam, Sindh, Pakistan
3
Government Boys Degree College Sakrand, District
6
Agriculture Extension Department, Government
Address For Correspondence:
Shah Jahan Leghari, Department of agronomy, Sindh Agriculture
E-mail: leghari222@gmail.com; Cell No. 00923013344123
This work is licensed under the Creative Commons Attribution International License (CC BY).
http://creativecommons.org/licenses/by/4.0/
Received 17 July 2016; Accepted 28 September 2016; Available online 30 September 2016
ABSTRACT
All plants utilize nitrogen (N) in the form of NO
which significantly increases and enhances the yield and its quality by playing a vital role in biochemical and physiological
plant. Pivotal N is required in larger quantity about 1000 ug kg
deficient in Pakistani soils due to low organic matter content, additionally, various factors are associated with the insufficiency such as
improper application, methods, timings and harve
An estimate 78-79% N is available in the atmosphere in inert structure (N
available from industrial, atmospheric and biological as well as organic fixation. Therefore, nutrient management practices should be
technical and most advantageous. This review research paper is lighting up with full spectrum on the role of N for plants and
beneficial knowledge to the farmers, students and researchers. Furthermore, in this detailed review, it was concluded that nitro
contributes in agriculture. Only big cause of limited yield with lower most quality of crops throughout the world is du
judicious use of N and its reason is lack of awareness.
KYEWORDS: Nitrogen, Role, Plant, Growth, Development
Nitrogen (N) occupies a conspicuous place in plant metabolism system. All vital processes in plants are
associated with protein, of which nitrogen is an essential constituent. Consequently to get more crop production,
nitrogen application is indispensabl
crop yield [1]. Nitrogen not only enhances the yield but also i
increases photosynthetic processes, leaf area production, leaf area duration as well as net assimilation rate [3].
The maximum leaf area (LA) and total leaf biomass of plant
the previous fifty years, the yield of various crops
management practices [5].All plants including cereals, oilseeds, fiber, and sugar producing
require a balanced amount of nitrogen for vigorous growth and development
ensures greatest harvest with better quality. Nitrogen is showing a fundamental role in enhancing the
productivity of four major crops of Pakistan like, wheat, rice, sugarcane and cotton. Wheat growth and yield
parameters, plant height (cm), number of tillers m
nEnvironmental Biology, 10(9)September2016, Pages: 209-218
AENSI Journals
ces inEnvironmental Biology
ISSN-1995-0756 EISSN-1998-1066
Journal home page: http://www.aensiweb.com/AEB/
Copyright,American-Eurasian Network for Scientific Information (AENSI Publication).
Role of Nitrogen for Plant Growth and Development: A
Niaz Ahmed Wahocho, 1Ghulam Mustafa Laghari,3Abdul
Khalid HussainTalpur,1Tofique Ahmed Bhutto,2Safdar Ali Wahocho
Soil Science, Sindh Agriculture University, Tandojam, 70060-Pakistan
Sugarcane section, Agriculture Research, Tandojam, Sindh, Pakistan
ys Degree College Sakrand, District Shaheed Benazirabad, Sindh, Pakistan
lture Extension Department, Government of Balochistan, Pakistan
Shah Jahan Leghari, Department of agronomy, Sindh Agriculture University, Tandojam, 70060-Pakistan
Cell No. 00923013344123
This work is licensed under the Creative Commons Attribution International License (CC BY).
http://creativecommons.org/licenses/by/4.0/
Accepted 28 September 2016; Available online 30 September 2016
All plants utilize nitrogen (N) in the form of NO3
-
and NH4
+
. It is most imperative element for proper growth and development of plants
which significantly increases and enhances the yield and its quality by playing a vital role in biochemical and physiological
plant. Pivotal N is required in larger quantity about 1000 ug kg-1
dry matter, so, it is compulsory supplied to plants. It is top most 100%
to low organic matter content, additionally, various factors are associated with the insufficiency such as
improper application, methods, timings and harvesting causes losses through volatilization, leaching, denitrification and crop rem
N is available in the atmosphere in inert structure (N2) that is not useful for plants, and thus not up
strial, atmospheric and biological as well as organic fixation. Therefore, nutrient management practices should be
technical and most advantageous. This review research paper is lighting up with full spectrum on the role of N for plants and
eficial knowledge to the farmers, students and researchers. Furthermore, in this detailed review, it was concluded that nitro
of limited yield with lower most quality of crops throughout the world is du
is lack of awareness.
Nitrogen, Role, Plant, Growth, Development
INTRODUCTION
occupies a conspicuous place in plant metabolism system. All vital processes in plants are
associated with protein, of which nitrogen is an essential constituent. Consequently to get more crop production,
nitrogen application is indispensable and unavoidable. Nitrogen plays a key role in agriculture by increasing of
only enhances the yield but also improves the food quality [2]. Optimum, rate of N
increases photosynthetic processes, leaf area production, leaf area duration as well as net assimilation rate [3].
The maximum leaf area (LA) and total leaf biomass of plants are a determinant of higher crop yield [4]. Sinc
he yield of various crops increased globally due to maximum use of N along with good
management practices [5].All plants including cereals, oilseeds, fiber, and sugar producing
require a balanced amount of nitrogen for vigorous growth and developmental process
greatest harvest with better quality. Nitrogen is showing a fundamental role in enhancing the
of Pakistan like, wheat, rice, sugarcane and cotton. Wheat growth and yield
parameters, plant height (cm), number of tillers m-2
, number of spikelet’s spike-1
, grains spike
(AENSI Publication).
rowth and Development: A
Abdul HafeezLaghari,
Safdar Ali Wahocho,
Pakistan
Accepted 28 September 2016; Available online 30 September 2016
for proper growth and development of plants
which significantly increases and enhances the yield and its quality by playing a vital role in biochemical and physiological functions of
atter, so, it is compulsory supplied to plants. It is top most 100%
to low organic matter content, additionally, various factors are associated with the insufficiency such as
losses through volatilization, leaching, denitrification and crop removals etc.
and thus not up-taken directly. N is
strial, atmospheric and biological as well as organic fixation. Therefore, nutrient management practices should be
technical and most advantageous. This review research paper is lighting up with full spectrum on the role of N for plants and providing a
eficial knowledge to the farmers, students and researchers. Furthermore, in this detailed review, it was concluded that nitrogen greatly
of limited yield with lower most quality of crops throughout the world is due to improper and non-
occupies a conspicuous place in plant metabolism system. All vital processes in plants are
associated with protein, of which nitrogen is an essential constituent. Consequently to get more crop production,
plays a key role in agriculture by increasing of
[2]. Optimum, rate of N
increases photosynthetic processes, leaf area production, leaf area duration as well as net assimilation rate [3].
s are a determinant of higher crop yield [4]. Since
increased globally due to maximum use of N along with good
management practices [5].All plants including cereals, oilseeds, fiber, and sugar producing and horticultural
al process. Judicious use of N
greatest harvest with better quality. Nitrogen is showing a fundamental role in enhancing the
of Pakistan like, wheat, rice, sugarcane and cotton. Wheat growth and yield
, grains spike-1
, and length of

2. 210 Shah Jahan Leghari et al, 2016
Advances inEnvironmental Biology, 10(9) September 2016, Pages: 209-218
spike and1000-grain weight increased by nitrogen fertilization [6]. Increasing levels of nitrogensignificantly
influence on grain yield of crop. The maximal grain yield of wheat 3.848 tons ha-1
was obtained through
application of 180kg N [7]. Another important grain crop is rice, which is cultivated worldwide. The chemical
nutrient nitrogen produces the highest yield. Nitrogen at rate 120 kg ha-1
showed promising results, for plant
height of rice, number of tillers , dry weight , length of panicle , number of filled grains / panicle , straw yield ,
biological yield , harvest index, benefit cost ratio and grain yield 4.66 tonsha-1
[8]. Similarly, in the cotton crop,
judicious use of nitrogenous fertilizer is more important. Nitrogen is being essential nutrient effects plant
growth, fruiting and yield of cotton [9]. Nitrogen levels had significant differences in yield components and seed
cotton yield. Nitrogen 100kg ha-1
produced more seed cotton yield due to more number of monopodial branches
(where from vegetative parts develops) and sympodial branches (where from reproductive parts develops), bolls
plant-1
, average boll weight and 100 cotton seed weight. 100kg nitrogen ha-1
is recommended [10]. For
sugarcane crops, nitrogen is also backbone. It improves the vegetative parts and thus increases the cane weight.
China and India obtain doublet yield, because of their recommendation application of nitrogen is about 300kg
ha-1
. In other countries, N is usually applied at the rate of 150 to 200kg ha-1
. Yield and quality constituents of
sugarcane were declared significant through increasing rate of N at 195.5kg ha-1
. In further 299kg nitrogen ha-
1
determined adverse effect on the quality of sugarcane was recorded poor [11]. Among oil seed crops mustard
and sunflower are widely cultivated throughout the country. Nitrogen at the rate of 180kg ha-1
significantly
increases yield of sunflower crop in semiarid conditions [12].Nitrogen is not an element which is useful for a
specific crop or providing limited results for a particular crop. It is great food for every living plant. Nitrogen
requirement of horticultural crops is valuable, but its role some time becomes hidden specially in ornamental
and large fruit tree crops, mainly due to lack of knowledge and awareness in Pakistan. Proper rate of N is
essential for improvement of horticultural crops. In this sector, the major crops are citrus, mango, onion and
potato in the country. However, vegetables including chilies, tomato, turnip, okra, carrot, cauliflower, peas,
tinda gourd, garlic, radish, cucumber, brinjal etc are also cultivated at a wider range. From the floricultural point
of view, the flowers like, marigold, calendula officinale, bougainvillea and rose are important crops. Nitrogen
takes good place for enhancement of yield and quality of mango fruit. Application of N fertilizer to mango tree
markedly increased the number of fruit tree-1
, pulp content as well as fruit quality [13]. The increased fruit yield
due to frequent fertilizer application [14]. Where as in the citrus, the recommended rate of N for younger plants
are commonly depends upon leaf N analysis or N removal in harvested fruit. The recommended rates start at 0.2
- 0.5kg N tree-1
year-1
. In Texas (USA), N levels of six to eight year older plant of citrus ranges from 0.5 to 0.6kg
tree-1
year-1
[15]. Leaves, branches and roots are directly or indirectly contribute yield of many vegetables.
Nitrogen functions in accumulation of biomass as it is utilized from roots and leaves, since its major role in
vegetative growth of vegetables. It increases leaf size of spinach and color. Nitrogen forms are widely used in
vegetable production [16]. It is an essential constituent of protein, nucleic acids, chlorophyll and growth
hormones [17]. It is luminary as input of crop production that is a single element which contributes very much
in agriculture. It enhances the metabolic processes that based on protein, leads to increases in vegetative,
reproductive growth and yield of the crop.
In view of great importance of nitrogen in agriculture, current research review article is written to explore
the role of nitrogen in different angles and show the scope of nitrogen study for boosting of crop yield.
Nitrogen and Plants:
Nitrogen being a major food for plants is an essential constituent of protein (build from amino acids that
involves in catalization of chemical responses and transportation of electrons) and chlorophyll (enable the
process of photosynthesis) present in many major portions of the plant body. Nitrogen plays a most important
role in various physiological processes. It imparts dark-green color in plants, promotes leaves, stem and other
vegetative part’s growth and development. Moreover, it also stimulates root growth. Nitrogen produce rapid
early growth, improve fruit quality, enhances the growth of leafy vegetables, increases protein content of fodder
crops; It encourages the uptake and utilization of other nutrients including potassium, phosphorous and controls
overall growth of plant [18,19].Deficiency of nitrogen causes reduced growth, appearances of chlorosis
(changing of the green color into yellow color of leaves), and appearances of red and purple spots on the leaves,
restrict lateral bud growth (from which leaves, stem and branches develop). Commonly, the deficiency
symptoms first appear on older leaves [20] then leaf senescence starts and excessive application of nitrogen has
adverse effects on plant growth, promotes extra dark-green color on the leaves, makes succulents the entire
growth and favors less fruit quantity with less quality. Overuse of N causes excess vegetative growth
particularly in tropical areas. Plants only uptake nitrogen in useful form, most plants takes nitrogen in nitrate
structure, however, it is not functional in some soils like submerged, whereas NH4
+
is most suitable and stable
for rice [21]. Proper growth and development of plants require optimum supply of nitrogen. Too little
application of nitrogen directly reduces crop yield while excess of N also causes negative effects on plant and
this issue getting focus continuously in crop production [22, 23].

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Fig. 1: Chlorophyll formation rate increase in plant toward increase in utilization of N
The soil and climatic conditions play a significant role in uptake and utilization of N. It is therefore
mandatory that soil and climatic conditions of a particular region must be considered before conducting any
experiments on response of N on growth and productivity of di
which applied to plants from soil and return back to soil from plants residues during decomposition process and
in this way soil fertility remains maintained.
Table 1: All about nitrogen [24, 25].
Name Nitrogen
Discovered In 1772 by
Name purposed Jean
Mother Atmosphere
Availability in air 78
Symbol N
Group 15/Va at periodic table
Atomic number 7
Atomic weight 14.00674
Point of milting -
Point of boiling -
Classified as Non metallic/Macro element
Naturally presence isotopes (2) 14
Artificially radioisotopes (07) 12
Color Colorless
Various forms N
Plant uses NH
Fixed from Industrial fixation, Atmospheric fixation, Biological fixation, Organically fixation
First Industrial produced by Scientist Caro in 1901 from CaC
Harber & Bosh produced Ammonia from N
Concentration of N Sea water, crust rocks & streams (0.00005, 0.002 , 0.000024 % respectively )
Deficiency in Pakistani soils 100%
Get losses due to Leaching, Volatilization, Crop removal, Erosion etc
Deficiency symptom in plant First yellowing of older leaves
Excess symptom Promotes highly dark
Known as Most important macro nutrient
Contribution in agriculture Boosting of yield
N-Use Efficiency Of Plants And Management:
There are numerous factors influencing N use efficiency like plant age, plant characteristics and behavior of
soil and climatic factors. General concept is that, whe
development than nitrogen use efficiency becomes higher but plant age and its genetic characteristic are not
considered in any agriculture disciplines except plant breeding and genetics. Applicatio
phase of growth (germination and seedling development) where plant has no well developed root system and it
has short roots and plus has fewer number of leaves than how plant can uptake maximum N from soil or foliar
applied?. Under these conditions, application of higher dose of nitrogen to the plants is the waste of money
because it will not produce meaningful results. When plant’s roots completely developed and leave also become
wider in size then N utilization increases. The de
contribute rapid and maximum photosynthesis process which stimulates physiological activity of plant that help
in N use efficiency. Foliar application of N at this stage of the plant is useful
plant where leaf area is smaller (Fig. 02). Plant N use efficiency generally decreases at full maturity stage of
plant when plant shifting to completion of life cycle phase and normally stops the vegetative growth. It is
therefore mandatory that at this stage nitrogen should not be applied to plants in a smaller rate.
Shah Jahan Leghari et al, 2016
Environmental Biology, 10(9) September 2016, Pages: 209-218
Chlorophyll formation rate increase in plant toward increase in utilization of N
tic conditions play a significant role in uptake and utilization of N. It is therefore
mandatory that soil and climatic conditions of a particular region must be considered before conducting any
experiments on response of N on growth and productivity of diverse crop species. Nitrog
to plants from soil and return back to soil from plants residues during decomposition process and
in this way soil fertility remains maintained.
Nitrogen
In 1772 by Daniel Rutherford
Jean-Antoine Chaptal during 1790
Atmosphere
78-79%
N
15/Va at periodic table
7
14.00674
-210.00°C
-195.79°C
Non metallic/Macro element
14
N &15
N
12
N 13
N 16
N NN17
N 18
N 19
N
Colorless
N2, NO2, NH3, NH4
+
, NO3
-
, C-NH2
NH4
+
, NO3
-
, C-NH2
Industrial fixation, Atmospheric fixation, Biological fixation, Organically fixation
Scientist Caro in 1901 from CaC2 and N2
Ammonia from N2& H2 in 1912
Sea water, crust rocks & streams (0.00005, 0.002 , 0.000024 % respectively )
100%
Leaching, Volatilization, Crop removal, Erosion etc
First yellowing of older leaves
Promotes highly dark-green color and excess vegetation
Most important macro nutrient
Boosting of yield
And Management:
There are numerous factors influencing N use efficiency like plant age, plant characteristics and behavior of
soil and climatic factors. General concept is that, when soil and climate are most favorable for plant growth and
development than nitrogen use efficiency becomes higher but plant age and its genetic characteristic are not
considered in any agriculture disciplines except plant breeding and genetics. Application of N to pla
seedling development) where plant has no well developed root system and it
has short roots and plus has fewer number of leaves than how plant can uptake maximum N from soil or foliar
er these conditions, application of higher dose of nitrogen to the plants is the waste of money
because it will not produce meaningful results. When plant’s roots completely developed and leave also become
n N utilization increases. The deeper root system enhances the intake of N, while larger leaves
contribute rapid and maximum photosynthesis process which stimulates physiological activity of plant that help
in N use efficiency. Foliar application of N at this stage of the plant is useful compare to at that stage of the
plant where leaf area is smaller (Fig. 02). Plant N use efficiency generally decreases at full maturity stage of
plant when plant shifting to completion of life cycle phase and normally stops the vegetative growth. It is
refore mandatory that at this stage nitrogen should not be applied to plants in a smaller rate.
tic conditions play a significant role in uptake and utilization of N. It is therefore
mandatory that soil and climatic conditions of a particular region must be considered before conducting any
verse crop species. Nitrogen is that element
to plants from soil and return back to soil from plants residues during decomposition process and
20 19
N
Industrial fixation, Atmospheric fixation, Biological fixation, Organically fixation
Sea water, crust rocks & streams (0.00005, 0.002 , 0.000024 % respectively )
There are numerous factors influencing N use efficiency like plant age, plant characteristics and behavior of
n soil and climate are most favorable for plant growth and
development than nitrogen use efficiency becomes higher but plant age and its genetic characteristic are not
n of N to plant at initial
seedling development) where plant has no well developed root system and it
has short roots and plus has fewer number of leaves than how plant can uptake maximum N from soil or foliar
er these conditions, application of higher dose of nitrogen to the plants is the waste of money
because it will not produce meaningful results. When plant’s roots completely developed and leave also become
eper root system enhances the intake of N, while larger leaves
contribute rapid and maximum photosynthesis process which stimulates physiological activity of plant that help
compare to at that stage of the
plant where leaf area is smaller (Fig. 02). Plant N use efficiency generally decreases at full maturity stage of
plant when plant shifting to completion of life cycle phase and normally stops the vegetative growth. It is
refore mandatory that at this stage nitrogen should not be applied to plants in a smaller rate.

4. 212 Shah Jahan Leghari et al, 2016
Advances inEnvironmental Biology, 10(9) September 2016, Pages: 209-218
Plant N use efficiency is greatly affected by soil and climatic factors [26, 27]. They are listed as soil pH
(power of hydrogen), soil texture, structure, crop removal, leaching, soil compaction, organic matter, moisture,
presence of other nutrients, use of high performance varieties, oxidation and reduction, volatilization, burning
and erosion, method of application of nitrogen and timing etc. Soil pH that is hydrogen (H) ions concentration
or Hydroxyl (Ions) interferes with nitrogen utilization. N-use efficiency in crops is excellence at normal soil pH
rang (6.5-7.0), but nitrogen being macro nutrient is maximum available at higher pH, same time availability
does not mean of its increased utilization because raised pH disorders the plant root growth and all other plant
part’s functions. On the other hand, soil texture (percentage of sand, silt and clay) is technically considered in
nitrogen management system, sandy and coarse soils do not hold N. The clay, clay loam and loamy soils have
maximum capacity to hold N for plants. Therefore N use efficiency is higher in those crops grown under clay
and loamy soils. Soil texture can be enhanced by addition of organic manures. They increase nitrogen uses
efficiency from different ways. Generally greatest crop removal is found maximum nutrients removal, when
nitrogen availability starts decreasing than its efficiency also decrease. Optimum availability of N is necessary
for their proper intake by plants.
Fig. 2: Plant N use efficiency at different growth stages
Amongst nitrogen limiting factors, the leaching is one of the major problems. Applied N to crop, dissolve in
irrigation water and leaches down from the top soil surface to the downward portion. This process causes N
deficiency which can easily be defined as ‘’limited nitrogen means limited its use efficiency’’. In a clear sense
lower availability of nitrogen reduces growth and development of plant.
Soil compaction:
Compacted soil has aeration problem and water movement issue. Optimum amount of water and air is
necessarily required for the process of breaking of N (Nutrients) and its dissemination in the root zone which
intensify the N uptake efficiency.
Manuring:
Organic manures such as farm yard manures (FYM), compost, green manure (GM), poultry and other
manures improves soil fertility as well as soil texture, and encourages microbial activity ultimately
conditionalize nitrogen efficacy by supporting of utilization of N.
Moisture:
Moist soils help to intake of N by plants while, drought conditions of the soil adversely effects on its
availability and uptake process which also result in the loss of N from soil due to volatilization. Better N use
efficiency can be achieved by application of optimum water to the plants.
High level presence of other chemical elements:
N availability and utilization efficiency is reduced in those soils where other nutrients are excessively
available.
High N response varieties:
Plant breeding and genetic engineering have developed many high yielding, high response varieties of
various crops like wheat and cotton etc. Such varieties have got potential to uptake and utilize N more
efficiently.

5. 213 Shah Jahan Leghari et al, 2016
Advances inEnvironmental Biology, 10(9) September 2016, Pages: 209-218
Oxidation and reduction:
Here a chemical reaction process takes place where electron (s) loosed and gained which change the shape
of nutrient from useful form to toxic form (non-useful structure).
Volatilization:
Nitrogen starts lacking in soil due to high volatilization process. It caused by deficit moisture in the surface
of the soil, especially in arid areas, where irrigation water is not available in sufficient amount and the
temperature is higher. High temperature rise transpiration rate and increase the water requirement in the root
zone and leads drought condition around the plant’s growing region. Nitrogen losses into the atmosphere in the
form of ammonia gas (NH3). Rapid volatilization decrease N use efficiency in plants. To withstand in such
situations, a little amount of irrigation should be applied for maintenance of continues the response of the plant
to nitrogen.
Burning and Erosion:
Both terms are defined as the loss of nitrogen from soil, but in a different way. Burning is that which kill or
suppress microorganisms of soil and damage the structure and texture of soil and eventually decreases nutrient
availability specially N. Burning of straw of wheat, flax and oat losses about 98-100% N [28]. While, erosion
caused by wind storm and heavy water flow of rain. They erode the upper surface of soil which contains N.
Removal of N from soil surface significantly reduces its content and utilization efficiency in the plants.
Uptake Process of Nitrogen:
There are three different ways from which nutrient up taken by the plants. They are mass-flow, diffusion
and root interception. Nitrogen is typically taken by plants through mass-flow process from the applied
fertilizers. It is the procedure in which nutrient dissolve in water and transported within the plant in the flow of
water. Nitrogen is normally supplied to plant in the process of mass-flow. Before, must be dissolved and then it
has an obligation to cross at least one membrane. Nutrients uptake from the soil takes place by cation exchange
where the roots begin pumping H into the soil through the proton pump. Moreover, root interception process
also takes place when nitrogen shifted from plant’s range due to deep percolation or at distance from the plant’s
root zone due to soil characteristics and wrong placement of nutrient during application because root
interception is the process in which roots rapidly grow and directly come in contact with soil particles and
nutrient where they are available.
Plants consist of three principal organs, roots, stem and leaves. Nitrogen is primarily absorbed from roots
and leaves. Further, process of photosynthesis also occurs in leaves. They also involve in nitrogen (N)
assimilation by reduction of NO3 and NH4 into amino acids which are building block of proteins. Third major
organ of plants is stem that connects roots and leaves and encourages shoot. Plant has two physiological
pathways for transportation of energy, xylem (vessels) and the phloem (tubes). Soil applied N (nutrient) are
move from the roots to leaves in the process of xylem (drink to up) after absorption of roots, while foliar applied
N are transported from leaves to roots by the process of phloem (living cells). The NO3
-
(nitrate) and the amino
acids are two major elements transported through the process of xylem [29]. Plants are composed of different
genetic materials, xylem vessels (tissue) composition is depends upon plant type, and it can be of single or
double in different cells. Some plants like ferns contain ‘’straws’’ xylem. They are prepared of cells in slender
shape known as tracheids. While, other plants including flowering (plants) consist an extra xylem vessels. They
are known as vessel elements and they are larger and wider in size, so, have ability for much transportation of
water with fasting frequency thus applied N to these plants is more beneficial. Phloem section of the plant is
composed of two different cell types. Cells of phloem do not die during maturity but xylem (cells) die. In
phloem sieve tubes plays important role in the flow process during transportation of energy. It is a complex
tissue [30, 31]. The phloem completely performs functions to supply proteins, sugar and organic compounds.
The xylem mainly transports water and nutrients such as applied N to plants and other elements. Plants having a
vascular system have ability to perform vigorous growth. It is suggested that plant’s xylem and phloem process
should be understand for application of nutrients. For that, plants of different crops must be investigated from
functioning toward response of essential nutrients utilization. In future, nitrogen application must be avoided at
time of evening and night because in both times there is less or no transpiration rate (loss of water from leaves)
and plants xylem does not work fast. When transpiration starts then vegetative parts of plant increases pressure
and maximum flow of water and nutrient starts in the xylem to the entire plant.

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Fig. 3: Functional root system of plant
Sources of Nitrogen (N):
Nitrogen is available for plants from many different sources such as industrial N fixation, atmospheric N
fixation, biological N fixation and organic resources. Industrially availability of nitrogen is the
source of nitrogen in the world (Table.1).
Industrial N fixation: Industrial production of N was the first time introduced by scientist Caro during 1901.
He used N2 and Ca CN2 (lime N) from the CaC
prepared ammonia using atmospheric gas (N
to 60000
C and greatest pressure about 200 to 1000 a
Atmospheric nitrogen fixation:
Atmospheric nitrogen fixation takes place when enormous lightening energy breaks N2 into nitric oxide
(NO2) and then combines it with oxygen (O
rainfall. This fixation of nitrogen contributes a small amount of
Biological nitrogen fixation:
It is nitrogen fixation process there microorganisms involves. They fix atmospheric nitrogen (N
converting into ammonium (NH4) by ammonifiying bacteria and then nitrifying bacteria such as nitrosomonas,
nitrosospira and nitrosococcus converts NH
nitrobacter, nitrospira, nitrospina and nitrococcus, oxidize NO
form of N for plant growth and developme
biological nitrogen (BNF) fixer In crop production the N
bacterias [34].
Organically nitrogen fixation:
There are various types of organic
farm yard manures (0.5% N), poultry manure (3.03% N), compost including Farm (0.5% N) and refuse of town
(1.4% N) and green manure (G.M)
castor, cotton, safflower, coconut, groundnut, linseed, rapeseed, safflower, seasumetc contains 4.3, 3.9, 4.9, 3.0,
7.3, 4.9, 5.9, 6.2 percentage of N respectively. They are of plant’s origin. While from animals, they are blood
meal, fish meal, raw bone meal, horn and hoof meal etc, they have 10 to 12, 10.5, 4 to 10, 13, 3 to 4 and 1 to 2
percentage of N respectively. Concentrated organic manures contain relatively maximum amount of N
compares to bulky organic manures [36
Table 2: Some most common and famous industrially available nitrogen fertilizers
NAME
Urea
Ammonium sulphate (AS)
Ammonium nitrate (AN)
Diammonium phosphate (DAP)
Monoammonium phosphate (MAP)
Shah Jahan Leghari et al, 2016
Environmental Biology, 10(9) September 2016, Pages: 209-218
Functional root system of plant showing N transportation
Nitrogen is available for plants from many different sources such as industrial N fixation, atmospheric N
fixation, biological N fixation and organic resources. Industrially availability of nitrogen is the
source of nitrogen in the world (Table.1).
Industrial N fixation: Industrial production of N was the first time introduced by scientist Caro during 1901.
ime N) from the CaC2 (calcium carbide). After Caro, scientist Har
prepared ammonia using atmospheric gas (N2) and hydrogen (H2) at an extreme degree of temperature about 400
C and greatest pressure about 200 to 1000 atm with catalysts of iron [32].
fixation takes place when enormous lightening energy breaks N2 into nitric oxide
) and then combines it with oxygen (O2) farming nitrate (NO3) that is carried into the earth along with
rainfall. This fixation of nitrogen contributes a small amount of N kg per year ha-1
.
It is nitrogen fixation process there microorganisms involves. They fix atmospheric nitrogen (N
) by ammonifiying bacteria and then nitrifying bacteria such as nitrosomonas,
nitrosospira and nitrosococcus converts NH4 into NO2 and then other genera of nitrifying bacteria like
nitrobacter, nitrospira, nitrospina and nitrococcus, oxidize NO2 into NO3 structure, that is most known as best
form of N for plant growth and development [33]. Plants belong to leguminosae family are well known as
n crop production the N-fixation also encouraged through artificial prepared
There are various types of organic manures contains nitrogen. They are bulky organic manures includes
farm yard manures (0.5% N), poultry manure (3.03% N), compost including Farm (0.5% N) and refuse of town
[35], press mud etc. The concentrated organic manur
castor, cotton, safflower, coconut, groundnut, linseed, rapeseed, safflower, seasumetc contains 4.3, 3.9, 4.9, 3.0,
7.3, 4.9, 5.9, 6.2 percentage of N respectively. They are of plant’s origin. While from animals, they are blood
, fish meal, raw bone meal, horn and hoof meal etc, they have 10 to 12, 10.5, 4 to 10, 13, 3 to 4 and 1 to 2
percentage of N respectively. Concentrated organic manures contain relatively maximum amount of N
res [36; 37; 38].
Some most common and famous industrially available nitrogen fertilizers
CHEMICALFORMULAE
CO(NH2)2
(NH4)2SO4
NH4NO3
(NH4)2HPO4
NH4H2PO4
Nitrogen is available for plants from many different sources such as industrial N fixation, atmospheric N
fixation, biological N fixation and organic resources. Industrially availability of nitrogen is the most common
Industrial N fixation: Industrial production of N was the first time introduced by scientist Caro during 1901.
alcium carbide). After Caro, scientist Harber and Bosh
) at an extreme degree of temperature about 400
fixation takes place when enormous lightening energy breaks N2 into nitric oxide
) that is carried into the earth along with
It is nitrogen fixation process there microorganisms involves. They fix atmospheric nitrogen (N2)
) by ammonifiying bacteria and then nitrifying bacteria such as nitrosomonas,
and then other genera of nitrifying bacteria like
structure, that is most known as best
nt [33]. Plants belong to leguminosae family are well known as
fixation also encouraged through artificial prepared
manures contains nitrogen. They are bulky organic manures includes
farm yard manures (0.5% N), poultry manure (3.03% N), compost including Farm (0.5% N) and refuse of town
, press mud etc. The concentrated organic manures such as oil cakes of
castor, cotton, safflower, coconut, groundnut, linseed, rapeseed, safflower, seasumetc contains 4.3, 3.9, 4.9, 3.0,
7.3, 4.9, 5.9, 6.2 percentage of N respectively. They are of plant’s origin. While from animals, they are blood
, fish meal, raw bone meal, horn and hoof meal etc, they have 10 to 12, 10.5, 4 to 10, 13, 3 to 4 and 1 to 2
percentage of N respectively. Concentrated organic manures contain relatively maximum amount of N/nutrients
N%
46
21
26
18
11

7. 215 Shah Jahan Leghari et al, 2016
Advances inEnvironmental Biology, 10(9) September 2016, Pages: 209-218
Fig. 4: Various organic sources of nitrogen for plant[36; 37; 38]
Nitrogen Management Practices:
The application method of nitrogen and its timings is very much important in crop production. In history of
agriculture, the broadcasting application of N was famous in traditional cultivation system of Sindh, Pakistan
and still, it is used due to easy and rapid distribution of N fertilizers, but loss of N is greater and low usage by
plants is a problem. The conventional practice of application of N has been replaced with the help modern
techniques like, Fertigation and flooded application technology of nitrogenous fertilizer in addition to foliar
application and so forth. The latest techniques of N applications significantly minimized the risk of N losses and
enhanced its uptake by the plant. Before applying of nitrogen, some main things must be considered. They are
number 1. Plant/Crop verities and its characteristics of root, 2. Plant N needs toward its growth stage, 3. Soil
properties (physical and chemical), 4. Soil moisture status, 5. Source of irrigation water, its type, 6. Rate of
irrigation and its frequency and formulation type of N fertilizer to be used. Fertilizer application method plays
better role in nutrient management. Some fertilizer application techniques are highlighted below.
1.1 Broadcasting method:
The broadcasting application method of fertilizer is defined as throwing of fertilizer in the soil and crop. It
is uniform distribution of fertilizer in the entire field. Broadcasting required maximum fertilizer. This method is
suitable in dense growing crops. Nitrogen of granular form is mostly used in the country. The broadcasting
method is further sub divided into basal application and top dressing.
Basal application:
In this method the fertilizer is applied at the time of sowing, fertilizer distributed uniformly on the entire
area of the field and where it is mixed with soil.
Top dressing:
This practice is useful for densely grown plants (crops). Therefore it is best useful for paddy and wheat
crops. Besides advantages, the disadvantages include N loss is higher from broadcasting method when directly
applied on the soil surface of standing crop, weeds easily take up N and N cannot well uptake by plants thus
reduce its use efficiency.
1.2. Placement method:
It is a method of nitrogen fertilizer application in which N fertilizer is placed into the soil. The practice is
good when N fertilizer is available in less quantity and plant’s roots functioning slow and poorly developing due
to soil characteristics. Placement application of fertilizer is further divided into closely placement or localizing
addition and deep placement etc. Localizing placement is that where nitrogen fertilizers are applied in soil
closely to growing plant or seed. The objective is to supply adequately N to root zone of plant and increases its
more mobilization as possible. Another hand deep addition or placement of nitrogen is the technique where

8. 216 Shah Jahan Leghari et al, 2016
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ammonium (NH4
+
) is mostly applied in order to maximize uptake process of plant. The main goal is to prevent
losses of N from run-off and leaching along with to avoid N nutrition or contact with weeds.
1.3. Starter application of solution:
It is one of the modern nitrogen fertilization application techniques. Nitrogen solution along with P and K
(Ratio 1:2:1) is supplied to plants during transplanting rice. Main advantage of this method is to support
vigorous growth of the seedling.
1.4. Foliar method:
Nitrogen fertilizer is dissolved in water or liquid N is applied on foliages (Vegetative parts) of plants. Foliar
application of N is discovered significant for maximizing of crop yield by enhancement of plant growth and
development. In this method, sprayers are commonly used.
1.5. Fertigation method:
Solution of nitrogen (N) is applied through irrigation flow. Tanks are usually utilized in fertigation
technique. This method of N application is viewed as most economic and most ideal for nitrogenous fertilizers
since it minimizes risk of N losses and insures the greatest accessibility of N to plants and their increased uptake
efficiency [35].
Fig. 5: Different nitrogen fertilizer application methods
Conclusion:
In the highlights of above scientific description about nitrogen from different technical aspects, we are
giving conclusion that nitrogen has great role for plants and it should be more improved through the awareness
among farmers and they trained for beneficial use of nitrogen. Only big reason of limited yield with lower most
quality of crops throughout the world is improper and non-judicious use of nitrogen. Proper management of N
for crop is essential. N must be applied before soil test and after analysis reports, the suggestions should be
gathered from agricultural experts for right quantity application of nitrogen and its methods. Like foliar
application provides advantages in salinity conditions, where broadcasting could is not best used, since fertilizer
losses. Similarly fertigation shows better results compare to broadcasting and placement is cost saving for
garden plants.
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