Iraq Has a Great Capacity to Diversify
and Boost its Agricultural Products and Exports of N, P, and S Fertilizers
M.S. Berigari*
Abstract
Iraq has
a high capacity to diversify and boost its agricultural products as well as its
exports of NPS fertilizers with its abundant phosphate, sulfur, and fossil fuel
reserves to obtain surplus capital.
Thus, it can invest enough capital in developing the extensive arable
land, water and human resources, and suitable climate and soils for multiple cropping
systems annually. That should enhance its GDP (gross domestic product) and
reduce drastically the currently high rate of unemployment. By using up-to-date technology in intensive
farming management it can increase its agricultural products of the essential grains,
oils, legumes, vegetables, fruits, and forage crops as well as diverse animal
products. Providing the essential nutrients in optimum amounts to
various crops and optimizing other crop production parameters will ensure high
crop yields and giving equal momentum to animal products will represent a giant
step forward in achieving food security in Iraq as a strategic necessity. Moreover, with proper soil drainage the number
one soil problem (soil salinity) can be controlled in the soils of middle and southern Iraq. It can, also, overcome water limitations for
agriculture through efficient drip irrigation systems wherever applicable.
Furthermore, to give a complete picture a list of inorganic fertilizers syntheses
is included in this review.
Recent geological studies by the US Geological
Survey and the Iraqi Geological Survey confirmed that after Morocco, Iraq has world’s largest phosphate rock
reserves of 5.75 billion tons, in Akashat in the Anbar governorate (20). And Iraq has large sulfur deposits in Mishraq
in the Naynewa governorate. That is in addition to its abundant fossil fuel
reserves in many parts of the country. Therefore, Iraq should plan for a large
scale production of ammonia (N), phosphate (P), and sulfate(S) fertilizers to
meet the increasing global and domestic demands for agriculture during the 21st
century. In fact it can become a major
exporter of these fertilizers and their derivatives especially when the world
demand for phosphate fertilizer has been and will be very high.
Because phosphate is a major plant nutrient
with distinct growth-limiting capacity in many soils where it is strongly bound
to the soil solid phase and often becomes unavailable for plant root absorption
but remains in soils. Therefore, global food production relies heavily on
phosphate fertilization. However, world
phosphate reserves are limited and expected to be depleted before the end of
the 21 st century (11). Consequently, world is facing great challenges to find
solutions for this critical problem through intensive research on phosphate
solubilization in soils to enhance its uptake by plant roots for higher crop
yields and to cope with the increasing demand worldwide for food during 21 st
century.
When the economic
impacts of these fertilizers on agriculture of Iraq and their exports are added
to that of petroleum exports, its gross domestic product (GDP) will increase
significantly. That should reduce the
currently high unemployment rate remarkably, enhance the standard of living for
its people, and consequently promote political stability as the absolute goal
and necessity for the Iraqi society to have a brighter future.
The
agriculture capacity of Iraq is very large considering:
1)
Extensive areas of arable land suitable for growth of all types of arid and
semi- arid- zone crops with mechanization along proper soil drainage under
irrigation,
2)
Adequate water resources for efficient drip irrigation systems wherever
applicable to overcome the limited water supply from the two rivers (Tigris and
Euphrates),
3) A long
growing season with excellent sunshine duration for growth of multiple crops annually,
4) Long
term availability of the macronutrients N, P, and K from fertilizers and
possibly K, Ca, Mg, and S presence in the soil minerals, and
5) Enough
human resources.
Therefore,
a great potential exists for agriculture development in Iraq when taking
all these factors together and adopting vigorous plant breeding, certified
seeds , plant protection, soil
fertilization, comprehensive extension program for up- to- date crop production
managements, and adapting new plants. For example, soybean is an excellent
source of protein and cooking oil, canola an excellent source of high quality
cooking oil, and jojoba with its unique liquid wax for many industrial
uses. Jojoba wax resembles in many ways
the sperm whale oil (liquid wax).
However, sperm whale (Physeter
catodon) is an endangered species, its hunting is forbidden and jojoba oil
(wax) is an excellent substitute for its oil (wax). Further, cherry plants should be grown in the
Kurdistan Region where the climate and soils are suitable for their growth
instead of importing this fruit from neighboring countries. Add to the list pecan plant that is expected
to do well in the Kurdistan Region since it is very much like walnut, a good
source of omega-3 fatty acid, and its nut is favorable in terms of its good
taste and thinner shell.
It is
equally important to focus on animal production by a vigorous program for
animal breeding, nutrition, and protection from diseases and pests. Moreover, there
is a definite need for diversification including cattle, sheep, goat, poultry,
fish, and honey bees. The country should introduce and adapt high quality
animals in terms of high milk, meat, and other animal products. For example, Holstein cow with its high milk
production can grow in Kurdistan Region
where the climate is more suitable. In
fact Kurdistan Region has the advantage of specializing in animal production
because of the suitable climate, availability of good quality water resources,
natural pastures, and other cultivated forage crops.
It is clear that Iraq can create an intensive and
diverse agriculture to reach self- sufficiency within a ten year period in most
essential grains, oil crops, legumes, vegetable crops, and fruit trees. That is in addition to various forage crops
for feeding a diverse group of livestock and poultry for their meat (white, and
red), milk and other products, and including fish especially those with high
omega-3 fatty acid content.
The soils of Iraq
in general are slightly to moderately weathered and are high in potassium
supplying power as is the case with other soils of arid and semiarid regions
(11), thus, the need for potassium fertilizer import is not great despite the
fact that K+ is subject to fixation under wet and dry soil
conditions by 2:1 type clays which are abundant in soils of Iraq (3). NH4+ ion has the same
ionic size as K+ ion and is subject to fixation similarly under wet
and dry soil conditions by 2:1 type clays (2).
Fixation of both NH4+ and K+ results in equivalent reduction in soil cation-
exchange capacity(CEC), a very important soil fertility property in retaining
cations from leaching(2,3). ln general
soils of Iraq are, also, calcareous, hence, are very high in Ca and Mg contents
as calcite (CaCO3) and dolomite ( CaCO3.MgCO3)
minerals.
However,
there are numerous gypsic soils (4) containing significant amounts of
sparingly- water soluble gypsum (CaSO4.2H2O) which can
release more available Ca2+ than either calcite or dolomite (1) but
require special management due to sinkhole problems. Therefore, there will be
sufficient quantities of macronutrients preferably in the order
N≥K>Ca>Mg≥ P>S to meet the plant requirement (15) during the coming
decades for agriculture in Iraq. However, soils are less likely to be deficient
in Ca, Mg and S than the other three N, K, and P that are added as fertilizer
elements to soils (15). It is very
important to apply these fertilizers to soils in balanced forms in terms of the
ratio of N: P: K and to other essential plant nutrients for optimum crop yields
keeping in mind the nutritional requirement of each crop or each family of
crops(14 ) .
Soil tests
and diagnostic plant symptoms should help in revealing any deficiencies in the
macronutrients and micronutrients. The micronutrient deficiencies can be corrected
by their small scale incorporation with NPK fertilizer and direct addition to
soils or more effectively through fertigation or as foliar spray applications
when soil pH limits their availability (18).
Because soils in Iraq are dominantly calcareous i.e. are slightly
alkaline, soil pH ˃ 7 which may limits
available micronutrients boron, H3BO3, iron, Fe2+,
copper Cu2+, manganese Mn2+, and zinc Zn2+ but
increases that of molybdenum,MoO42- ( 14 ). Plants are not likely to show deficiencies
in chloride, Cl-, from soils or irrigation water. In fact there is no shortage of Cl-
but a problem of salinity which exists in most cultivated soils mainly as water
soluble NaCl in the middle and southern Iraq
where soils need adequate drainage
If soils contain enough solid phase reserves of
the essential nutrients, plant roots normally exudates enough organic acids to
modify the pH of the rhizosphere where microorganisms, plant roots, and soil
components are actively involved in enhancing the availability of these
micronutrients and other nutrients to crops with few exceptions (5). Moreover,
there is a good possibility that root exudates could chelate various divalent
cations, thus, make them more available.
Plant roots must exudate equivalent quantity of H+ ions to that of nutrient cations taken up by
plant roots and of course equivalent amounts of anions for uptake of nutrient
anions such as NO3-, HPO42-, and SO42-
to balance the overall electrical charge of soil solution. However,
substituting H+ ions for basic cations causes a certain drop in the
pH of the rhizosphere which enhances availability of the nutrient cations K+,
Ca2+, Mg2+, Fe2+, Cu2+, Mn2+,
and Zn2+ whereas soil pH may have variable effects on availability
of H3BO3, Cl- , MoO42-,
PO42-,3- , and SO42- depending on
the concentrations of the divalent cations and soil composition especially Fe
and Al oxides (14). It is important to note that plants vary in relation to the
level of each micronutrient required and, also, to the levels of their toxicity
to various plants (14).
There is
ample evidence that the processes of plant development are controlled by
internal signals that depend on adequate supply of mineral nutrients by soil to
plant roots (5). An earlier study (12)
revealed that equilibration of some calcareous soil samples of Iraq with citric
acid and orthophosphate (P) enhanced available (P) whereas both oxalic and
tartaric acids rendered P relatively unavailable in the soil samples. A more recent study (11) confirmed that
phosphate availability and uptake by the young root system of oilseed- rape was
enhanced by exudation of organic acid anion citrate, and also, facilitated
rapid transport of the two anions citrate and phosphate in soil.
It is clear that Iraq and Kurdistan Region in
particular can adopt a modern system for agricultural products to fully meet
the nutritional requirement of its population.
That is by providing the essential nutrients in optimum amounts to
various crops and optimizing other parameters for high crops yields as well as
the optimum parameters for animal products.
That will represent a giant step forward in achieving food security as
an essential strategy for the country.
1. Methane
Gas, CH4: It is released abundantly from oil wells and
upon its immediate contact with air it is burned wastefully. However, it can be
harnessed and used as a clean source of energy and, also, to generate H2 gas
for the Haber-Bosch process. That
process yields ammonia which is a very important source of nitrogen fertilizers
and played a major role in the green revolution of agriculture during 20 th
century.
Therefore, chemical engineers can widen the scope
of manufacturing plants for N, P, and S fertilizers to increase their export
capacities for a diverse economy to take place in addition to heavy reliance on
fuel oil exports. Alternatively, the Kurdistan Regional and the Federal Iraqi
Governments could obtain economically sound contracts from industrial countries
to built large scale factories at various economically suitable sites. The
route to infrastructure is clear and should be used in addition to its merits
in reducing the unemployment rate of Iraqi population which is a high priority
and is currently too high for any form of political stability.
The following outline is presented as a short-cut
guide and the details are left for the chemical engineers to implement.
2. Hydrogen
Production: The primary
technology currently used for direct production of H2 gas is steam
reforming from hydrocarbons. Many other
alternative methods are available including electrolysis and thermolysis of
water, H2O(9).
2.1 Steam
Reforming: Fossil fuels are the main source of
industrial H2 which is generated from natural gas at approximately
80% efficiency or from other hydrocarbons to a varying degree of
efficiency. Most hydrogen production,
however, is obtained by steam reforming of methane or natural gas (9):
a) At high temperatures (700- 1100 ᴼC = 973-1373 ᴼK)
H2O steam reacts with CH4 to yield CO, H2 and
large quantity of heat in an exothermic reaction:
CH4(g) + H2O(g)
----------> CO + 3H2
+ energy (∆H =
-191.7 kJ/mol)
b) At a second stage, additional H2 is
produced by the lower temperature steam shift reaction at (130 ᴼC = 403 ᴼK)
which is also, an exothermic reaction:
CO(g) + H2O(g) ---------> CO2(g)
+ H2(g) + energy (∆H= -40.4
kJ/mol)
3. Ammonia
Synthesis by the Haber-Bosch Reaction: Fritz Haber, a German chemist, pioneered synthesis of ammonia from
nitrogen and hydrogen gases in 1904, then obtained a patent for his work in
1908, and was awarded a Noble prize in 1918.
The H2 gas produced from the above reactions can be
chemically combined with nitrogen gas from the air through the Haber-Bosch
process to produce ammonia which is the basic source of commercial N fertilizer
(21) and the reaction is not as simple as it looks but the overall reaction
occurs by a series of steps, with hydrazine,N2H4(g),
produced at an intermediate stage (13):
3H2(g) + N2(g) --------˃ N2H4(g) + H2(g)
------> 2NH3(g) + energy (∆H = -92.22k J/mol)
KC = [NH3]2/ [N2]
[H2]3
At (300 ᴼC = 573 ᴼK), KC has a
value of 9.6, indicating that at this temperature, a considerable quantity of
NH3 forms from H2 and N2 reaction. Since the
reaction is exothermic increasing temperature will shift the reaction to the
left according to the Le Châtelier principle (13, 17). Thus, increasing temperature will decrease KC
(14, 20). However, at
low temperatures the speed of the reaction is slow. Therefore, for commercial production of NH3
a catalyst consisting of a mixture of Fe2O3 and Fe3O4
promoted with K2O,, and Al2O3
is used to speed up the Haber-Bosch reaction at temperature between 400-600 ᴼC
= 673-873 ᴼK while maintaining a pressure of 200 atmosphere or 2.03 x 104 k
Pascal (Pa) during the course of the reaction(8, 13).
Moreover,
for an efficient reaction to proceed the NH3 and heat generated must
be constantly removed from reaction system and stored. And, also, increasing the pressure is the
best choice to favor the forward reaction because there are 4 moles of
reactants for every 2 moles of the product and at a constant temperature the
volume is reduced to 2/4 or 1/2 according to Boyle’s Law. Thus, the forward
reaction is favored based on the Le Châtelier principle (17) yet the entropy,
extent of randomness as a universal law, decreases by converting 4moles of the
reactant gases to two moles of the gas product.
Once anhydrous ammonia is produced it can be used to make other forms of
nitrogen fertilizer such as urea, ammonium phosphate, ammonium nitrate, and
ammonium sulfate (8). For example:
4. Urea
Synthesis: Ammonia is a gas at room temperature under one
atmosphere = 101.3 kPascal of pressure and is easily compressed into a liquid
that can be stored and transported. In
the anhydrous form it is applied directly to soils as fertilizer. When ammonia
is reacted with CO2 yielding urea, an organic compound, which is
solid at room temperature and easier to transport and handle by unskilled
workers and when applied to soils it slowly releases nitrogen to crops (14).
2NH3(g) + CO2(g) ----------> NH2 + CO + NH2(s) + H2O(l)
5. Ammonium
Nitrate: This is highly
soluble in water and disassociates into ammonium and nitrate ions (equation b)
both of which are taken up from soil solution by plant roots.
a) NH3(g,
l) + HNO3(l)
-----------˃ NH4 NO3(s) (6)
b) NH4NO3(s) + H2O(l)
-----------> NH4+(aq) + NO3-(aq)
6. Ammonium
Sulfate: Ammonia reaction with sulfuric acid yields this
fertilizer which supplies both nitrogen and sulfur elements when it dissolves in
water or soil solution:
a) 2NH3(g) + H2SO4(l)
----------> (NH4 )2SO4(s) (6)
b) (NH4)2SO4(s)
+ H2O(l) -----------> 2NH4+(aq)
+ SO42-(aq)
7. Ammonium
Phosphate: Reaction of ammonia with phosphoric acid will
produce this compound as a source of nitrogen and phosphorus nutrients for
plant growth:
a) 3 NH3(g) + H3PO4(l)
-----------˃ (NH4)3PO4(s)
b) ( NH4)3PO4(s)
+ H2O(l------------->3NH4+(aq)
+ PO43-(aq)
8. Sulfur
Dioxide Production: Sulfur element from its ores or as a byproduct
from oil refineries is melted, filtered off impurities, and then oxidized with
oxygen in the exothermic reaction:
S(s) +
O2(g) -----------˃ SO2(g)
+ energy (∆H
= -300 kJ/mol)
9. SO2
Conversion to Sulfur Trioxide: The SO2
is reacted with
O2 in the presence of a catalyst, V2O5, to
yield SO3 in the exothermic reaction:
2SO2(g) + O2(g)
----------> 2SO3(g) +
energy (∆H
= -100 kJ/mol)
10.
Sulfuric Acid Formation: The SO3
is then absorbed into counter-current flow of H2SO4 to give more H2SO4 by
the exothermic reaction:
SO3(g) + H2O(l)
-----------˃ H2SO4(l) + energy (∆H
= -200 kJ/mol)
11.
Superphosphate Production:
a) The phosphate rock must be ground until at least
75% is ≤ 75 µ (micron) in diameter, and then perform its composition analysis.
The proportions of various minerals present are amended to give the desired
composition.
b) Phosphate ground rock, sulfuric acid and water
are mixed and allowed to dry and react to yield superphosphate-a mixture of
CaSO4 and Ca(H2PO4)2.H2O
(6):
Ca3(PO4)2(s) +
2H2SO4(l) + 2 H2O ----------˃ Ca(H2PO4).
2H2O(s) + 2CaSO4(s)
The underlined compounds represent more soluble
superphosphate in soil solution (6) that supplies crops with P, S, and Ca
nutrients.
c) Granulation is achieved by grinding the
superphosphate cake to give particles less than 6 mm in diameter.
12. Triple
Superphosphate Reaction: The
compound is a fertilizer produced
from reaction of concentrated phosphoric acid with ground rock phosphate (10):
4H3PO4(aq) + Ca3(PO4)2(s)
----------> 3Ca (H2PO4)2(aq)------------˃ 3Ca2+(aq) + 6H2PO41-(aq)
The active ingredient of the product, monocalcium
phosphate is identical to that of superphosphate except for the absence of
calcium sulfate as the case when sulfuric acid is reacted with ground rock
phosphate instead of phosphoric acid as reactant (8).
13.
Monoammonium Phosphate (MAP): This fertilizer is produced by
the reaction of ammonia as a weak base with concentrated phosphoric acid. The product is soluble in water yielding NH4+
as a source of nitrogen nutrient and H2PO42- as
a source of phosphorus nutrient (7).
NH3(g) + H3PO4(aq)
---------˃ NH4H2PO4(aq) ----------> NH4+(aq)
+ H2PO4-(aq)
14. Diammonium Phosphate (DAP): Using two moles of ammonia to react with
one mole of concentrated phosphoric acid will produce this form of N and P
fertilizer. When it dissolves in water,
it produces two NH4+ ions for every one HPO42-
ion (7).
2NH3(g) + H3PO4(aq)
------------> (NH4)2HPO4(s)
(NH4)2HPO4(s) + H2O(l) ----------˃ 2NH4+(aq)
+ HPO42-(aq)
References
1.
Berigari,
M.S. and F.M. Al-Ani. 1994. Gypsum determination in soils by
conversion to water soluble sodium sulfate. Soil Sci.Soc.Amer.J.58: 1624-1627.
2.
Berigari,
M.S.; F.M. Al-Ani; M.A.Umran and L.H.Ibrahim. 1987. Ammonium
fixation in relation to characteristics of some Entisols and Aridisols
of Iraq. J.Agric.Water Resour.Res., Baghdad, 6(3):65-81 .
3.
Berigari,
M.S.; F.M. Al-Ani and M.A.Umran.
1985. Potassium fixation by some calcareous
soils of Iraq. J.Agric.Water
Resour.Res., Baghdad, 4(4): 89-107.
4.
Buringh, P.
1960. Soils and Soil Conditions
in Iraq (with Soil Maps). Publ. Ministry of Agriculture, Baghdad.
5.
Dakora,
F.D. and D.A.Phillips. 2002. Root exudates as mediators of mineral
acquisition in low nutrient environments. Plant and Soil 245: 35-47.
6.
Hill,
J.W. 1992. Chemistry for Changing Times. 6th
ed. Macmillan Publishing
Company, New York. Maxwell
Macmillan Canada, Toronto: 512-519.
12. Karim, M.I.; M.S.Berigari: F.M.Al-Ani; and
L.H.Ibrahim. 1989. Effect of citric,
oxalic, and tartaric acids on phosphate sorption by some calcareous
soils of
Iraq. J. Agric.Water Resour. Res., Baghdad, 8(1): 51-67.
13.
McMurry, J. and R.C.Fay.
2004. Chemistry. 4 th ed.
Prentice Hall: 841-2.
14.
Olson, R.A.; T.J.Army; J.J.Haway; and V.J.Kilmer (eds.). 1973.
Fertilizer Technology & Use.
15.
Plaster, F.J. 1992. Soil Science and Management. 2nd ed. Delmar Publ., Inc. Soil
Sci. Soc. Amer., Madison, Wisconsin
16. Reese, M. and Marquart, C. 2010.
Modeling the cost of production of
nitrogen fertilizers produced from wind energy: Presented to the Minnesota
Corn Research and Promotion Council, Morris, MN.
phosphate.aspx
21.
www.scifun.org
___________________________________________________________________
*Dr. Mohammed Sa’id Berigari, Senior Soil
and Environmental Chemistry Scientist
5733 Nordeen Oak Court, Burke, Virginia
22015-2209 USA.
للعراق قدرة عاليه على تنويع وزيادة الانتاج الزراعي وصادراته لاسمدة
النتروجين والفسفور والكبريت
محمد سعيد بريكاري
مستخلص
لدى
العراق قدرة فائقة على زيادة الانتاج الزراعي كما ونوعا وكذلك
صادراته من الاسمدة النتروجينية والفوسفورية والكبريتية باستغلال موارده الضخمة من
النفط (البترول) والغاز الطبيعي والفوسفات والكبريت وتحويلها الى راسمال
فائض. وبذلك يمكن استثمار مبالغ كافيه في
تنمية الاراضي الزراعية الواسعة والمصادر
المائية والبشرية وزراعة عدة محاصيل سنويا على نفس القطعة من الارض لملائمة
المناخ والتربة في اكثرمناطق العراق.
وهذا ما سيمكنه من مضاعفة الانتاج او الدخل الوطني الشامل والحد من معدل
البطالة العالية حاليا الى ادنى مستوى.
وبتطبيق التكنولوجيا الحديثة في الزراعة الكثيفة يستطيع العراق زيادة
الانتاج الزراعي لمحاصيل الحبوب , الزيوت, البقوليات , الخضروات , الفواكه ,
والعلف للحيوانات بانواعها المختلفة.
وبتوفير مقادير مثالية من عناصر تغذية النبات الضرورية والعوامل الاساسية
الاخرى لنمو المحاصيل لاجل تحقيق اعلى انتاج,
وباتباع نفس المعايير في الانتاج الحيواني سيخطو العراق خطوة عملاقة باتجاه
تحقيق الامن الغذائي كاستراجية ضرورية له.
وتعتبر ملوحة التربة في وسط وجنوب العراق اهم مشكلة تواجه الزراعة
فيه. ويمكن حل هذه المشكلة بتطبيق نظام
صرف ملائم وكفوء. اما بالنسبة للموارد
المائية المحدودة الى حد ما فيمكن تفاديها باتباع انظمة الري الكفوءة وخاصة الري بالتنقيط
. ولاعطاء صورة كاملة البحث فقداضيفت اليه
قائمة لصناعة مختلف الاسمدة غير العضوية.
