EFFECT OF NITROGEN SOURCE, SOIL TYPE AND
DEPTH OF APPLICATION ON AMMONIA
VOLATILIZATION
By
Ibrahim Ali Osman
B.Sc. (Agric - Honors) 2004
University of Khartoum
Supervisor
Dr. Abd Elkarim Hassan Awad Elkarim
A thesis submitted to the University of Khartoum in partial fulfillment of the
requirement for the Degree of M.Sc (Agric)
Department of Soil and Environment Sciences
Faculty of Agriculture
University of Khartoum
December 2008
DEDICATION
To my
Parents
Family
Friends
Ibrahim
ACKNOWLEDGMENT
I acknowledge with gratitude to my supervisor, Dr Abd Elkarim
Hassan Awad Elkarim for supporting, advising and encouraging me
throughout the project of my study.
Also I would like to thank my friends Sami, Badri, Abdala and Nour
Eldeen for supporting this study.
My sincere thanks to my colleagues and members of the department
of soil and environment science for their helpful, gesture and friendly
attitude during this study.
Special thanks to my brother Osman Ali for supporting me.
ABSTRACT
A field experiment was conducted to study the effect of soil type and
methods of fertilizer application the ammonia volatilization when three
orders of Sudan soils (Aridisols, Vertisols and Entisols) were fertilized by
three types of nitrogenous fertilizers; namely, (Aqueous ammonia, Urea and
Ammonium
sulphate)
in
Berber,
Gezira
and
Shambat
Gerf,
respectively.These fertilizers were applied by three methods: superficial
application with irrigation water and injection in depth of 5 cm and 15 cm at
a rate of 200 kg N/ha. A closed system was prepared around the points of
application to collect volatile ammonia gas on diluted sulfuric acid 0.25 N
and ventilation was ensured by using a semi- permissible membrane called
parafilm. Sulfuric acid was analyzed using steam distillation apparatus
containing sodium hydroxide, and then titrated with hydrochloric acid.The
effect of nitrogen fertilizers and soil type on the movement of nitrogen in the
soil was studied after one month in soil samples taken from the place of
application and the external edge of the design. The results indicated that the
rate of ammonia loss by volatilization in Aridisols was lower than Vertisols
and Entisols and this is attributed to the different climatic conditions. In
Berber the experiment was carried out during winter when temperature is
low, causing a decrease in volatilization decreased, while in Gezira and
Shambat the experiment was carried out in summer, and high rate of
ammonia loss by volatilization was observed in Entisols and this is may be
ascribed to high silt content in this soil. The results demonstrated that
surface application of nitrogen fertilizers increased loss of ammonia by
volatilization more than in method of application since the fertilizers on
surface is exposed more to heat that increase volatilization. In Vertisols and
Entisols, the rate of ammonia volatilization decreased gradually from the
first week to the fourth week. But in Aridisols, increased rate of
volatilization occurred in the fourth week due to negative impact of cold
season on the microbial growth which limits the hydrolysis of ammonium
carbonate resulting in delaying of volatilization process. In Vertisols and
Entisols, high rates of ammonia volatilization were noticed in aqueous
ammonia more than in urea and ammonium sulphate due to the fast
hydrolysis of aqueous ammonia compared with other types of fertilizers,
while in Aridisols, the ammonia volatilization recorded inconsistent values
which attributed to cold weather. The results showed that, in all treatments,
ammonium content was lower in samples taken from the edge compared to
those taken from the place of application. This is attributed to the difficulty
in movement of positively charged ammonium which adsorbed on negative
charges of clay, while the amount of nitrate in the edge sample was greater
than in the sample taken from the place of fertilizers application. This is
possibly due to the presence of the negative charge in the nitrate which may
increase the ion exchange with calcium and other cations in soil.
‫ﺍﻟﻤﺴﺘﺨﻠﺹ‬
‫ﺃﺠﺭﻴﺕ ﺘﺠﺭﺒﺔ ﺤﻘﻠﻴﺔ ﻟﺩﺭﺍﺴﺔ ﺘﺄﺜﻴﺭ ﻨﻭﻉ ﺍﻟﺘﺭﺒﺔ ﻭﻁﺭﻕ ﺍﻀﺎﻓﻪ ﺍﻟﺴﻤﺎﺩ ﻋﻠﻲ ﺘﻁﺎﻴﺭ ﻏﺎﺯ‬
‫ﺍﻻﻤﻭﻨﻴﺎ ﻭ ﺫﻟﻙ ﻋﻨﺩ ﺘﺴﻤﻴﺩ ﺜﻼﺙ ﺭﺘﺏ ﻤﻥ ﺍﻟﺘﺭﺒﺔ ﻫﻰ ﺍﻻﺭﻴﺩﺴﻭل‪ ,‬ﺍﻟﻔﻴﺭﺘﺴﻭل ﻭ ﺍﻻﻨﺘﺴﻭل ﺒﺜﻼﺜﻪ‬
‫ﺍﻨﻭﺍﻉ ﻤﻥ ﺍﻷﺴﻤﺩﺓ ﺍﻟﻨﻴﺘﺭﻭﺠﻴﻨﻴﺔ )ﺍﻻﻤﻭﻨﻴﺎ ﺍﻟﺴﺎﺌﻠﻪ‪ ,‬ﺍﻟﻴﻭﺭﻴﺎ ﻭ ﻜﺒﺭﻴﺘﺎﺕ ﺍﻻﻤﻭﻨﻴﻭﻡ( ﻓﻲ ﺒﺭﺒﺭ ﻭ‬
‫ﺍﻟﺠﺯﻴﺭﺓ ﻭ ﺸﻤﺒﺎﺕ ﺍﻟﺠﺭﻑ ﻋﻠﻰ ﺍﻟﺘﻭﺍﻟﻲ‪ .‬ﺃﻀﻴﻔﺕ ﻫﺫﻩ ﺍﻻﺴﻤﺩﻩ ﻟﻠﺘﺭﺒﺔ ﺒﺜﻼﺙ ﻁﺭﻕ‪ :‬ﺍﻀﺎﻓﻪ ﺴﻁﺤﻴﻪ‬
‫ﻤﻊ ﻤﺎﺀ ﺍﻟﺭﻱ ﻭ ﺤﻘﻥ ﻓﻲ ‪5‬ﺴﻡ ﻭ ﻓﻲ ‪15‬ﺴﻡ ﺒﻤﺎ ﻴﻌﺎﺩل ‪ 200‬ﻜﺠﻡ ﻨﻴﺘﺭﻭﺠﻴﻥ‪/‬ﻫﻜﺘﺎﺭ‪ .‬ﺘﻡ ﺘﺠﻬﻴﺯ‬
‫ﻨﻅﺎﻡ ﻤﻐﻠﻕ ﺤﻭل ﻤﻜﺎﻥ ﺍﻻﻀﺎﻓﺔ ﻭ ﺫﻟﻙ ﻟﺠﻤﻊ ﻏﺎﺯ ﺍﻻﻤﻭﻨﻴﺎ ﺍﻟﻤﺘﻁﺎﻴﺭ ﻋﻠﻲ ﺤﻤﺽ ﺍﻟﻜﺒﺭﻴﺘﻴﻙ ﺍﻟﻤﺨﻔﻑ‬
‫)‪ (0.25‬ﻋﻴﺎﺭﻱ ﻤﻊ ﻭﺠﻭﺩ‬
‫ﻗﻠﻴل ﻤﻥ ﺍﻟﺘﻬﻭﻴﺔ ﻋﺒﺭ ﻏﺸﺎﺀ ﻤﺴﺎﻤﻲ ﺸﺒﻪ ﻤﻨﻔﺫ ﻴﺴﻤﻲ ﺒﺎﺭﺍﻓﻴﻠﻡ ‪ .‬ﺘﻡ‬
‫ﺘﺤﻠﻴل ﻫﺫﺍ ﺍﻟﺤﻤﺽ ﻤﻌﻤﻠﻴﺎ ﺒﺠﻬﺎﺯ ﺍﻟﺘﻘﻁﻴﺭ ﺒﺎﺴﺘﺨﺩﺍﻡ ﻫﻴﺩﺭﻭﻜﺴﻴﺩ ﺍﻟﺼﻭﺩﻴﻭﻡ ﻭ ﻤﻌﺎﻴﺭﺘﻪ ﺒﺠﻤﺽ‬
‫ﺍﻟﻬﻴﺩﺭﻭﻜﻠﻭﺭﻴﻙ‪ .‬ﻜﺫﻟﻙ ﺘﻤﺕ ﺩﺭﺍﺴﺔ ﺘﺎﺜﻴﺭ ﻨﻭﻉ ﺍﻟﺴﻤﺎﺩ ﻭ ﻨﻭﻉ ﺍﻟﺘﺭﺒﺔ ﻓﻲ ﺍﻟﺜﻼﺙ ﺭﺘﺏ ﺍﻟﺴﺎﺒﻕ ﺫ ﻜﺭﻫﺎ‬
‫ﻋﻠﻲ ﺤﺭﻜﺔ ﺍﻟﻨﻴﺘﺭﻭﺠﻴﻥ ﺒﺼﻭﺭﺓ ﻋﺭﻀﻴﺔ ﻓﻲ ﺍﻟﺘﺭﺒﺔ ﺨﻼل ﺸﻬﺭ ﻤﺴﺘﺨﺩﻤﻴﻥ ﻓﻲ ﺫﻟﻙ ﻋﻴﻨﺎﺕ ﺘﺭﺒﺔ‬
‫ﺍﺨﺫﺕ ﻤﻥ ﻤﻜﺎﻥ ﺍﻻﻀﺎﻓﺔ ﻭ ﻤﻥ ﺍﻟﺤﺎﻓﺔ ﺍﻟﺨﺎﺭﺠﻴﺔ ﻟﻠﺘﺼﻤﻴﻡ‪ .‬ﺍﻭﻀﺤﺕ ﺍﻟﻨﺘﺎﺌﺞ ﺍﻥ ﻤﻌﺩل ﺘﻁﺎﻴﺭ ﻏﺎﺯ‬
‫ﺍﻻﻤﻭﻨﻴﺎ ﻓﻲ ﺍﻻﺭﻴﺩﺴﻭل ﺍﻗل ﻤﻥ ﺍﻟﻔﻴﺭﺘﺴﻭل ﻭ ﺍﻻﻨﺘﺴﻭل ﻭﻴﺭﺠﻊ ﺫﻟﻙ ﻟﻼﺨﺘﻼﻓﺎﺕ ﺍﻟﻤﻨﺎﺨﻴﺔ ﺒﻴﻥ‬
‫ﻤﻨﺎﻁﻕ ﻫﺫﻩ ﺍﻟﺘﺭﺏ ﺤﻴﺙ ﺃﺠﺭﻴﺕ ﺍﻟﺘﺠﺭﺒﺔ ﻓﻲ ﺒﺭﺒﺭ ﻓﻲ ﻓﺼل ﺍﻟﺸﺘﺎﺀ ﺤﻴﺙ ﺘﻨﺨﻔﺽ ﺩﺭﺠﺎﺕ ﺍﻟﺤﺭﺍﺭﻩ‬
‫ﻤﻤﺎ ﻴﻘﻠل ﻤﻥ ﺍﻟﻔﻘﺩ ﺒﺎﻟﺘﻁﺎﻴﺭ‪ ,‬ﺒﻴﻨﻤﺎ ﺃﺠﺭﻴﺕ ﺍﻟﺘﺠﺭﺒﺔ ﻓﻲ ﺍﻟﺠﺯﻴﺭﺓ ﻭ ﺸﻤﺒﺎﺕ ﻓﻲ ﻓﺼل ﺍﻟﺼﻴﻑ ﺤﻴﺙ‬
‫ﻨﻼﺤﻅ ﺍﺭﺘﻔﺎﻉ ﻤﻌﺩل ﺘﻁﺎﻴﺭ ﻏﺎﺯ ﺍﻻﻤﻭﻨﻴﺎ ﻓﻲ ﺍﻻﻨﺘﺴﻭل ﻭ ﺍﻟﺫﻱ ﻴﻌﺯﻱ ﺍﻟﻲ ﺍﺭﺘﻔﺎﻉ ﻨﺴﺒﺔ ﺍﻟﻁﻤﻰ ﻓﻲ‬
‫ﻫﺫﻩ ﺍﻟﺘﺭﺒﺔ‪ .‬ﺍﻤﺎ ﺒﺎﻟﻨﺴﺒﺔ ﻟﺘﺎﺜﻴﺭ ﻁﺭﻕ ﺍﻀﺎﻓﺔ ﺍﻟﺴﻤﺎﺩ ﻓﻘﺩ ﻟﻭﺤﻅ ﺍﻥ ﺍﻻﻀﺎﻓﻪ ﺍﻟﺴﻁﺤﻴﺔ ﺘﻌﻁﻲ ﺍﻜﺒﺭ‬
‫ﻜﻤﻴﻪ ﻤﻥ ﻏﺎﺯ ﺍﻷﻤﻭﻨﻴﺎ ﺍﻟﻤﻔﻘﻭﺩ ﺒﺎﻟﺘﻁﺎﻴﺭ ﻭﻴﺭﺠﻊ ﺫﻟﻙ ﻟﺴﻬﻭﻟﺔ ﺍﻟﻔﻘﺩ ﻤﻥ ﺍﻟﺴﻁﺢ ﺃﻜﺜﺭ ﻤﻥ ﺍﻷﻋﻤﺎﻕ‬
‫ﺍﻷﺨﺭﻱ ﺤﻴﺙ ﻴﻜﻭﻥ ﺍﻟﺴﻤﺎﺩ ﻓﻲ ﺍﻟﺴﻁﺢ ﺃﻜﺜﺭ ﻋﺭﻀﺔ ﻟﻠﺤﺭﺍﺭﻩ ﺍﻟﺘﻲ ﺘﺯﻴﺩ ﻤﻥ ﺍﻟﺘﻁﺎﻴﺭ‪ .‬ﻓﻲ ﺍﻟﻔﻴﺭﺘﺴﻭل‬
‫ﻭ ﺍﻷﻨﺘﺴﻭل ﻴﻘل ﻤﻌﺩل ﺘﻁﺎﻴﺭ ﻏﺎﺯ ﺍﻷﻤﻭﻨﻴﺎ ﺘﺩﺭﻴﺠﻴﺎ ﻤﻥ ﺍﻷﺴﺒﻭﻉ ﺍﻷﻭل ﻭ ﺤﺘﻲ ﺍﻷﺴﺒﻭﻉ ﺍﻟﺭﺍﺒﻊ‪ ,‬ﺃﻤﺎ‬
‫ﻓﻲ ﺍﻷﺭﻴﺩﺴﻭل ﻓﻴﺤﺩﺙ ﺃﺭﺘﻔﺎﻉ ﻓﻲ ﻤﻌﺩل ﺘﻁﺎﻴﺭ ﻏﺎﺯ ﺍﻷﻤﻭﻨﻴﺎ ﻓﻰ ﺍﻷﺴﺒﻭﻉ ﺍﻷﺨﻴﺭ ﻭ ﻴﻌﺯﻱ ﺫﻟﻙ ﺍﻟﻲ‬
‫ﺍﻟﺘﺄﺜﻴﺭ ﺍﻟﺴﻠﺒﻲ ﻟﻔﺼل ﺍﻟﺸﺘﺎﺀ ﻋﻠﻲ ﺍﻟﻨﻤﻭ ﺍﻟﻤﻴﻜﺭﻭﺒﻲ ﻤﻤﺎ ﻴﻘﻠل ﻤﻥ ﺘﺤﻠل ﻜﺭﺒﻭﻨﺎﺕ ﺍﻷﻤﻭﻨﻴﻭﻡ ﻭ ﺒﺎﻟﺘﺎﻟﻲ‬
‫ﺘﺄﺨﻴﺭ ﻋﻤﻠﻴﺎﺕ ﺍﻟﺘﻁﺎﻴﺭ‪ .‬ﻴﻼﺤﻅ ﺃﺭﺘﻔﺎﻉ ﻤﻌﺩل ﺘﻁﺎﻴﺭ ﻏﺎﺯ ﺍﻷﻤﻭﻨﻴﺎ ﻤﻥ ﺍﻷﻤﻭﻨﻴﺎ ﺍﻟﺴﺎﺌﻠﻪ ﺃﻜﺜﺭ ﻤﻥ‬
‫ﺍﻟﻴﻭﺭﻴﺎ ﻭ ﻜﺒﺭﻴﺘﺎﺕ ﺍﻷﻤﻭﻨﻴﻭﻡ ﻭ ﺫﻟﻙ ﻓﻲ ﺍﻟﻔﻴﺭﺘﺴﻭل ﻭ ﺍﻷﻨﺘﺴﻭل ﻭ ﻴﺭﺠﻊ ﺫﻟﻙ ﻟﺴﻬﻭﻟﺔ ﺘﺤﻠل‬
‫ﺍﻷﻤﻭﻨﻴﺎ ﺍﻟﺴﺎﺌﻠﻪ ﺃﻜﺜﺭ ﻤﻥ ﺃﻨﻭﺍﻉ ﺍﻷﺴﻤﺩﺓ ﺍﻷﺨﺭﻱ ﻭ ﺒﺎﻟﺘﺎﻟﻲ ﺘﻔﻘﺩ ﺒﺼﻭﺭﺓ ﺃﻜﺒﺭ‪ .‬ﺃﻤﺎ ﻓﻲ ﺒﺭﺒﺭ ﻓﺎﻥ‬
‫ﺘﻁﺎﻴﺭ ﺍﻷﻤﻭﻨﻴﺎ ﻴﻌﻁﻲ ﻗﻴﻡ ﺸﺎﺫﺓ ﻨﻭﻋﺎ ﻤﺎ ﻭ ﻴﻌﺯﻱ ﺫﻟﻙ ﻷﺠﺭﺍﺀ ﺍﻟﺘﺠﺭﺒﺔ ﻓﻲ ﻓﺼل ﺍﻟﺸﺘﺎﺀ ﺤﻴﺙ‬
‫ﺍﻨﺨﻔﺎﺽ ﺩﺭﺠﺎﺕ ﺍﻟﺤﺭﺍﺭﺓ ﺍﻟﺘﻲ ﺒﺎﺭﺘﻔﺎﻋﻬﺎ ﻋﺎﺩﺓ ﻤﺎ ﺘﺴﺎﻋﺩ ﻓﻲ ﺍﻟﻔﻘﺩ ﺒﺎﻟﺘﻁﺎﻴﺭ‪.‬ﻜﺫﻟﻙ ﺃﻭﻀﺤﺕ ﺍﻟﻨﺘﺎﺌﺞ‬
‫ﺃﻥ ﻤﺤﺘﻭﻱ ﺍﻟﺘﺭﺒﺔ ﻤﻥ ﺍﻷﻤﻭﻨﻴﻭﻡ ﻓﻲ ﺍﻟﺤﺎﻓﻪ ﺃﻗل ﻤﻥ ﺍﻟﻌﻴﻨﺔ ﺍﻟﻤﺄﺨﻭﺫﺓ ﻤﻥ ﻤﻜﺎﻥ ﺍﻷﻀﺎﻓﺔ ﻭ ﺫﻟﻙ ﻓﻲ‬
‫ﻜل ﺍﻟﻤﻌﺎﻤﻼﺕ ﻭ ﻴﺭﺠﻊ ﺫﻟﻙ ﺍﻟﻲ ﺼﻌﻭﺒﺔ ﺍﻟﺤﺭﻜﺔ ﺍﻟﻌﺭﻀﻴﺔ ﻓﻲ ﺘﺭﺏ ﺍﻟﺴﻭﺩﺍﻥ ﺨﺼﻭﺼﺎ ﺍﻷﻤﻭﻨﻴﻭﻡ‬
‫ﻤﻭﺠﺏ ﺍﻟﺸﺤﻨﺔ ﺍﻟﺫﻱ ﻴﺩﻤﺹ ﻋﻠﻲ ﺍﻟﺸﺤﻨﺎﺕ ﺍﻟﺴﺎﻟﺒﻪ ﻓﻲ ﺍﻟﻁﻴﻥ‪ .‬ﻜﻤﺎ ﺘﻭﻀﺢ ﺍﻟﻨﺘﺎﺌﺞ ﺯﻴﺎﺩﺓ ﻜﻤﻴﺔ‬
‫ﺍﻟﻨﺘﺭﺍﺕ ﻓﻲ ﺍﻟﻌﻴﻨﺔ ﺍﻟﻁﺭﻓﻴﻪ ﺒﺼﻭﺭﺓ ﺃﻜﺒﺭ ﻤﻥ ﺍﻟﻌﻴﻨﺔ ﺍﻟﻤﺄﺨﻭﺫﺓ ﻤﻥ ﻤﻜﺎﻥ ﺍﻀﺎﻓﺔ ﺍﻟﺴﻤﺎﺩ ﻭﻴﻌﺯﻯ ﺫﻟﻙ‬
‫ﻟﻭﺠﻭﺩ ﺍﻟﺸﺤﻨﺎﺕ ﺍﻟﺴﺎﻟﺒﻪ ﻓﻲ ﺍﻟﻨﺘﺭﺍﺕ ﻭ ﺍﻟﺘﻲ ﺘﺯﻴﺩ ﻤﻥ ﺍﻟﺘﺒﺎﺩل ﺍﻻﻴﻭﻨﻲ ﻤﻊ ﺍﻟﻜﺎﻟﺴﻴﻭﻡ ﻭ ﺍﻟﻜﺎﺘﻴﻭﻨﺎﺕ‬
‫ﺍﻻﺨﺭﻱ ﻓﻲ ﺍﻟﺘﺭﺒﺔ‪.‬‬
CONTENTS
DEDICATION
i
ACKNOWLEDGMENT
ii
CONTENTS
iii
ABSTRACT
vi
ARABIC ABSTRACT
viii
CHAPTER ONE: INTRODUCTION
1
CHAPTER TWO: LITERATURE REVIEW
5
2.1
Nitrogen sources
5
2.1.1
Natural sources of nitrogen
5
2.1.2
Inorganic nitrogen sources
7
2.2.
Ammonia
7
2.2.1.
Structure and basic chemical properties
8
2.2.2.
Natural occurrence
9
2.2.3.
History
9
2.2.4.
Synthesis and production
10
2.2.5.
Properties
13
2.2.6.
Uses
14
2.2.6.1. Nitric acid production
14
2.2.6.2. Fertilizer
15
2.2.7.
Liquid ammonia as a solvent
15
2.2.8.
Safety
16
2.3.
Urea fertilizer
16
2.3.1.
Environmental fate
17
2.4.
Ammonium sulphate
18
2.4.1.
Uses
18
2.5.
Ammonia volatilization
19
2.5.1.
Factors regulating ammonia loss
20
2.5.1.1.
Soil moisture
22
2.5.1.2. Temperature and soil pH
22
2.5.1.3. Soil CEC
23
2.5.1.4.
Method and depth of application
24
2.6.
Transformation and movement of nitrogen fertilizers
25
2.7.
Aridisols
26
2.8.
Vertisols
27
2.9.
Entisols
27
CHAPTER THREE: MATERIALS AND METHODS
29
3.1
Introduction
29
3.2
The pertinent properties of the soils
3.3
Sources of fertilizers
3.4
Land preparation
29
3.5
Analytical method
30
3.6
Statistical analysis
31
CHAPTER FOUR: RESLUTS
29
29
35
4.1.
Ammonia volatilization in the sites
35
4.2.
Effect of method of application on the volatilization
35
4.3.
Effect of time on ammonia loss by volatilization
39
4.4.
Effect of nitrogen source on ammonia loss by volatilization
45
4.5.
Ammonia volatilization as affected by method of application
during 4 weeks in three sites
4.6.
51
Interaction effect of, soil type and method of application on the
ammonia volatilization
67
4.7.
Interaction effect of, soil type and time on the ammonia
volatilization
4.8.
Interaction effect of, soil type and source of nitrogen on the
ammonia volatilization
4.9.
67
67
Movement of mineral nitrogen from three sources of nitrogen
fertilizer in three soil types
74
4.9.1.
Ammonium
74
4.9.2.
Nitrate
74
CHAPTER FIVE: DISCUTION
89
5.1
Effect of treatments on the ammonia loss by volatilization
89
5.1.1
Effect of soil type
89
5.1.2
Effect of method of application
89
5.1.3
Effect of time
90
5.1.4
Effect of nitrogen source
90
5.2
Effect of treatments on the lateral movement of mineral nitrogen 91
5.2.1
Ammonium
91
5.2.1.1 Effect of soil type
91
5.2.1.2 Effect of nitrogen source
91
5.2.1.3 Effect of distance
91
5.2.2
Nitrate
91
5.2.2.1
Effect of soil type
91
5.2.2.2
Effect of nitrogen source
92
5.2.2.3
Effect of distance
92
CONCLUTIONS
94
REFERANCES
96
CHAPTER ONE
CHAPTER ONE
INTRODUCTION
This study is focusing on the possibility of utilizing aqueous ammonia
that obtained as a by-product from Khartoum Petroleum Refinery in
agriculture as a nitrogenous fertilizer. Ammonia is used in Khartoum
Petroleum Refinery so as to neutralize acid waters produced during oil
fractionation into its different economic components. Acid waters will
otherwise cause corrosion of pipes and metal works. About 5184 tons of
ammonia was produced during 2006, and this is expected to rise to 10368
tons at the end of 2010. These large amounts of ammonia possess a health
and environmental hazard to life in and around the Petroleum Refinery. It is
currently discarded into the surrounding semi desert land, often causing local
animals and wild bird's fatalities
Ammonia volatilization is one of several possible sources of nitrogen
loss from soil, particularly, in arid and semi arid regions, just the case in
Sudan soils. A greater understanding of effect of the different soils
conditions and sources of nitrogen fertilizers on the rate of ammonia
volatilization under such conditions is very important to obtain optimal yield
for agricultural crops.
Gaseous loss of nitrogen from soil following application of
nitrogenous material is not a new concept, but only within the last few years
has it been recognized to be sufficiently large to justify intensive study.
Liquid ammonia is used as source of nitrogen to crops in many of the
developed countries world wide. However, it is not currently used in Sudan,
since its use under arid and semi arid conditions of the Sudan may require
some research investigation.
If the use of liquid ammonia proved to be technically and
economically feasible, its utilization in agriculture will enable Khartoum
Petroleum Refinery to safely dispose of this hazardous product, while
providing a very cheap source of nitrogen to crops in Khartoum area and
else were in Sudan. Nitrogen fertilizers are among the major fertilizers used
for growing vegetables, fruit and forage crops. The use of cheap liquid
ammonia can raise production, and at the same time reduce production cost,
which will contribute positively towards better living conditions for the
inhabitants of Khartoum state and possibly other states. Present expectations
promise and expansion of petroleum industry and widespread increase of oil
refining activities throughout the country .Thus, the establishment of a local
technology of fertilizing by liquid ammonia will avail the transfer of this
technology to different parts of the Sudan, which will be reflected positively
on the socioeconomic status of the Sudanese society. The 10368 tons of
ammonia at concentration 21% N, expected to be produced by the end of
2010, will provide about 1793053 Kg of nitrogen. If one cultivated Fadden
needs 35.56 Kg of nitrogen (35.36 kg = 2N = 80 Ib N/Fadden) the annual
production of ammonia is enough to fertilize 50423 Fadden's of forages,
vegetables or fruits. It is fortunate that Sudan petroleum is sweet crude
devoid of heavy metals that are detrimental to human and animal health
(according to analysis carried out in Canada by Talisman Petroleum
Company in 2001-2002). This will, of course, be further verified during the
course of this study. Ammonia-a waste product from petroleum industry
causes many environmental hazards. To eliminate these hazards, this
ammonia must be handled rationally; there is possibility of using it in
agriculture as a nitrogen fertilizer.
The main objectives of this research are to investigate the amount of
ammonia volatilization from applied aqueous ammonia as compared with
other sources of nitrogen fertilizers in the three sites under investigation.
Also possibility of using the aqueous ammonia as a by-product material
from Khartoum Petroleum Refinery as a rich source of nitrogen fertilizer,
and to safe the environmental hazards from disposing the aqueous ammonia
into the lands neighboring the Khartoum Petroleum Refinery, north
Khartoum, also to chose the best method of application in the three sources
of nitrogen fertilizers, finally to determined the chemical behavior and
movement of mineral nitrogen in the three sites.
Outputs expectation of this study are possibility of utilizing the
ammonia waste from Khartoum Petroleum Refinery as a cheap source of
nitrogen fertilizer with reducing the rate of ammonia loss to the minimum,
also to reduce impact of environment.
CHAPTER TWO
CHAPTER TWO
LITERATURE REVIEW
2.1. Nitrogen Sources
Nitrogen is an essential plant nutrient. It is a key component in plant
proteins and chlorophyll. This fact will discuss natural and man-made
nitrogen sources and will describe the fate of nitrogen in the soil (Dorn T,
2001)
2.1.1. Natural Sources of Nitrogen
Some plants "make their own nitrogen". If a legume (i.e., soybeans,
alfalfa, clovers) is colonized by certain strains of Rhizobium bacteria,
nodules will form on the plant roots where the bacteria live and reproduce.
Within these nodules, a symbiotic relationship develops between the bacteria
and the host plant. The bacteria utilize plant sugars as a source of energy and
in turn "fix" nitrogen, converting nitrogen gas into forms that can be used by
the plant. Once nodules form, the plant usually receives all of the nitrogen
necessary for growth from that "fixed" by the bacteria. Other crops,
including all grass crops (e.g., corn, sorghum, wheat, forage grasses, etc.)
and non-leguminous broadleaf crops (e.g., sunflowers, potatoes, sugar beets,
cotton, etc.) are not colonized by nitrogen fixing bacteria and therefore must
obtain the nitrogen they need from the soil (Dorn T, 2001)
In addition to nitrogen fixed by Rhizobium bacteria, other natural
sources that contribute to the soil nitrogen include: mineralization of organic
matter and nitrogen released as plant residues are broken down in the soil.
Animal waste is a good source of natural nitrogen as well. Barnyard or
poultry manure and other animal waste products (e.g., bat guano) were used
as a source of supplemental nitrogen long before inorganic nitrogen fertilizer
came into popular use (Dorn T, 2001). Barbarick (2006) mentioned that crop
residues decompose in the soil to form soil organic matter. This organic
matter contains about 5 percent nitrogen. An acre-foot of soil having 2
percent organic matter would contain about 3,500 pounds of nitrogen.
Generally, about 1 to 3 percent of this organic nitrogen is converted per year
by microorganisms to a form of nitrogen that plants can use.
A small amount of nitrogen is also contributed by rainfall in the form
of nitric acid (HNO3), which when dissolved in the soil water disassociates
into hydrogen and nitrate ions. The nitric acid is formed when nitrogen and
oxygen gases are combined with water by the intense heat of a lightening
bolt during a thunderstorm (Dorn T, 2001). Barbaric 2006 also indicated
that rainfall adds about 10 pounds of nitrogen to the soil per acre per year.
The nitrogen oxides and ammonium that are washed to earth are formed
during electrical storms, by internal combustion engines and through
oxidation by sunlight. Some scientists also believe that some of the gaseous
products that result from the transformation of nitrogen fertilizers may cause
a depletion of the ozone (O3) layer around the earth. The extent of this
possible damage has not been substantiated.
While all these natural sources can make significant contributions to
soil nitrogen levels, they usually do not supply enough nitrogen to meet all
of the needs of high yielding non-leguminous crops in what are now
considered "conventional" agricultural systems. Additional nitrogen in the
form of added fertilizer is usually required for optimum yield (Dorn T,
2001).
2.1.2. Inorganic nitrogen sources
The air we breathe is about 78% nitrogen in the form of N2 gas and
about 21% oxygen in the form of O2 gas. The remaining one percent of the
atmosphere is a combination of all the other gases, including carbon dioxide
that is the source of carbon used by green plants. Even though there are
33,000 tons of nitrogen in the air over every acre, the nitrogen gas is so
chemically stable, plants cannot directly use it as a nutrient. Plants readily
take up and use two forms of soil nitrogen, ammonium (NH4+) and nitrate
(NO3-). Other forms of nitrogen must be converted to one of these
compounds by natural or artificial means before plants can utilize them
directly as a source of nitrogen for plant growth. The ammonium molecule
(NH4+) carries a positive electrical charge and is attracted to the clay and
organic matter in the soil, which carry negative charges. Once attached to
the soil matrix, ammonium becomes part of the cation (pronounced "kat-in") exchange process whereby plants exchange a hydrogen ion (H+) for one
of the positively charged molecules in the soil. Besides ammonium, other
essential nutrients obtained by cation exchange include: potassium, calcium,
magnesium, iron, manganese, and zinc (Dorn T, 2001).
2.2. Ammonia
Ammonia is a compound with the formula NH3. It is normally
encountered as a gas with a characteristic pungent odor. Ammonia
contributes significantly to the nutritional needs of terrestrial organisms by
serving as a precursor to foodstuffs and fertilizers. Ammonia, either directly
or indirectly, also is a building block for the synthesis of many
pharmaceuticals. Although in wide use, ammonia is both caustic and
hazardous. Ammonia, as used commercially, is often called anhydrous
ammonia. This term emphasizes the absence of water in the material.
Because NH3 boils at -33 °C, the liquid must be stored under high pressure
or at low temperature. Its heat of vaporization is, however, sufficiently great
that NH3 can be readily handled in ordinary beakers in a fume hood.
"Household ammonia" or "ammonium hydroxide" is a solution of NH3 in
water. The strength of such solutions is measured in units of baume
(density), with 26 degrees baume (about 30 weight percent ammonia at 15.5
°C) being the typical high concentration commercial product (IPCS 2004).
All other forms of inorganic commercial nitrogen fertilizer are derived
from anhydrous ammonia. They are more expensive per pound of nitrogen
because of the additional processing steps involved in their manufacture and
greater transportation costs because they have lower nutrient density than
anhydrous ammonia. These other forms of nitrogen fertilizer have
advantages in terms of personal safety and ease of storing, handling, and
application which make them attractive to many farmers in spite of the
higher cost per pound of nitrogen (Dorn T, 2001).
2.2.1. Structure and basic chemical properties
The ammonia molecule has a trigonal pyramidal shape, as predicted
by VSEPR theory. The nitrogen atom in the molecule has a lone electron
pair, and ammonia acts as a base, a proton acceptor. This shape gives the
molecule a dipole moment and makes it polar so that ammonia readily
dissolves in water. The degree to which ammonia forms the ammonium ion
increases upon lowering the pH of the solution— at "physiological" pH (7),
about 99% of the ammonia molecules are protonated. Temperature and
salinity also affect the proportion of NH4+. NH4+ has the shape of a regular
tetrahedron. The main use of ammonia is for fertilizer (83% in 2003).
Another major application is its conversion to explosives, because nitric acid
is made via oxidation of ammonia. The entire nitrogen content of all
manufactured organic compounds is derived from ammonia (Wiley and
Weinheim., 2002).
2.2.2. Natural occurrence
Ammonia is found in small quantities in the atmosphere, being
produced from the putrefaction of nitrogenous animal and vegetable matter.
Ammonia and ammonium salts are also found in small quantities in
rainwater, whereas ammonium chloride (sal-ammoniac), and ammonium
sulfate are found in volcanic districts; crystals of ammonium bicarbonate
have been found in Patagonian guano. The kidneys secrete NH3 to neutralize
excess acid. Ammonium salts also are found distributed through all fertile
soil and in seawater. Substances containing ammonia, or those that are
similar to it, are called ammoniacal (Kirschbaum et al, .1999).
2.2.3. History
The Romans called the ammonium chloride deposits they collected
from near the Temple of Jupiter Amun (Greek
µµων Ammon) in ancient
Libya 'sal ammoniacus' (salt of Amun) because of proximity to the nearby
temple (Eponyms2003) Salts of ammonia have been known from very early
times; thus the term Hammoniacus sal appears in the writings of Pliny,
although it is not known whether the term is identical with the more modern
sal-ammoniac (URL 2006).
In the form of sal-ammoniac, ammonia was known to the alchemists as early
as the 13th century, being mentioned by Albertus Magnus. It was also used
by dyers in the middle Ages in the form of fermented urine to alter the
colour of vegetable dyes. In the 15th century, Basilius Valentinus showed
that ammonia could be obtained by the action of alkalis on sal-ammoniac. At
a later period, when sal-ammoniac was obtained by distilling the hoofs and
horns of oxen and neutralizing the resulting carbonate with hydrochloric
acid, the name "spirit of hartshorn" was applied to ammonia (URL 2006).
Gaseous ammonia was first isolated by Joseph Priestley in 1774 and
was termed by him alkaline air; however it was acquired by the alchemist
Basil Valentine (Abraham et al, 1990) Eleven years later in 1785, Claude
Louis Berthollet ascertained its composition.
The Haber process to produce ammonia from the nitrogen in the air
was developed by Fritz Haber and Carl Bosch in 1909 and patented in 1910.
It was first used on an industrial scale by the Germans during World War I
(Wiley and Weinheim., 2002).
2.2.4. Synthesis and production
Because of its many uses, ammonia is one of the most highly
produced inorganic chemicals. Dozens of chemical plants worldwide
produce ammonia. The worldwide ammonia production in 2004 was
109 million metric tonnes. The People's Republic of China produced 28.4%
of the worldwide production followed by India with 8.6%, Russia with
8.4%, and the United States with 8.2%. About 80% or more of the ammonia
produced is used for fertilizing agricultural crops (Karmer, 2005).
Before the start of World War I, most ammonia was obtained by the
dry distillation (Haber process.1918) of nitrogenous vegetable and animal
waste products, including camel dung, where it was distilled by the
reduction of nitrous acid and nitrites with hydrogen; in addition, it was
produced by the distillation of coal, and also by the decomposition of
ammonium salts by alkaline hydroxides (URL2006) such as quicklime, the
salt most generally used being the chloride (sal-ammoniac) thus:
2 NH4Cl + 2 CaO → CaCl2 + Ca (OH)2 + 2 NH3
Today, the typical modern ammonia-producing plant first converts
natural gas (i.e., methane) or liquified petroleum gas (such gases are propane
and butane) or petroleum naphtha into gaseous hydrogen. Starting with a
natural gas feedstock, the processes used in producing the hydrogen are:
The first step in the process entails removal of sulfur compounds from
the feedstock, because sulfur deactivates the catalysts used in subsequent
steps. Catalytic hydrogenation converts organosulfur compounds into
gaseous hydrogen sulfide:
H2 + RSH → RH + H2S(g)
The hydrogen sulfide is then removed by passing the gas through beds
of zinc oxide where it is absorbed and converted to solid zinc sulfide:
H2S + ZnO → ZnS + H2O
Catalytic steam reforming of the sulfur-free feedstock is then used to form
hydrogen plus carbon monoxide:
CH4 + H2O → CO + 3 H2
In the next step, the water gas shift reaction is used to convert the carbon
monoxide into carbon dioxide and more hydrogen:
CO + H2O → CO2 + H2
The carbon dioxide is then removed either by absorption in aqueous
ethanolamine solutions or by adsorption in pressure swing adsorbers (PSA)
using proprietary solid adsorption media.
The final step in producing the hydrogen is to use catalytic methanation to
remove any small residual amounts of carbon monoxide or carbon dioxide
from the hydrogen:
CO + 3 H2 → CH4 + H2O
CO2 + 4 H2 → CH4 + 2 H2O
To produce the desired end-product ammonia, the hydrogen is then
catalytically reacted with nitrogen (derived from process air) to form
anhydrous liquid ammonia. This step is known as the ammonia synthesis
loop (also referred to as the Haber-Bosch process):
3 H2 + N2 → 2 NH3
The steam reforming, shift conversion, carbon dioxide removal and
methanation steps each operate at absolute pressures of about 25 to 35 bar,
and the ammonia synthesis loop operates at absolute pressures ranging from
60 to 180 bar, depending upon which proprietary design is used. There are
many engineering and construction companies that offer proprietary designs
for ammonia synthesis plants. Haldor Topsoe of Denmark, Lurgi AG of
Germany, Uhde of Germany, and Kellogg, Brown and Root of the United
States are among the most experienced companies in that field (URL 2006).
As the availability and usage of fossil fuel become problematic (see
peak oil and climate change), the hydrogen required for ammonia synthesis
could in principle be obtained from electrolysis (currently 4% of hydrogen
production is from electrolysis) or thermal chemical cracking of water, but
these alternatives are presently impractical. The heat needed for thermal
cracking can be obtained from nuclear reaction, while the electricity needed
for electrolysis can be obtained from various renewable energy sources such
as wind, solar, hydroelectricity, and various forms of ocean energy
especially that of OTEC. A possible use for the excess electricity would be
to use electrolysis on water to acquire the needed hydrogen. Alternatives to
the production of ammonia from natural gas and air are uneconomic and the
environmental benefits have not been established (OTEC 2008).
2.2.5. Properties
Ammonia is a colorless gas with a characteristic pungent smell similar
to human urine, as urine decomposes to release ammonia. It is lighter than
air, its density being 0.589 times that of air. It is easily liquefied due to the
strong hydrogen bonding between molecules; the liquid boils at -33.3 °C,
and solidifies at -77.7 °C to a mass of white crystals. Liquid ammonia
possesses strong ionizing powers (ε = 22), and solutions of salts in liquid
ammonia have been much studied. Liquid ammonia has a very high standard
enthalpy change of vaporization (23.35 kJ/mol, cf. water 40.65 kJ/mol,
methane 8.19 kJ/mol, phosphine 14.6 kJ/mol) and can therefore be used in
laboratories in non-insulated vessels at room temperature, even though it is
well above its boiling point. It is miscible with water. Ammonia in an
aqueous solution can be expelled by boiling. The aqueous solution of
ammonia is basic. The maximum concentration of ammonia in water (a
saturated solution) has a density of 0.880 g /cm³ and is often known as '.880
Ammonia'. Ammonia does not burn readily or sustain combustion, except
under narrow fuel to air mixtures from 15-25% air. When mixed with
oxygen, it burns with a pale yellowish-green flame. At high temperature and
in the presence of a suitable catalyst, ammonia is decomposed into its
constituent elements. Chlorine catches fire when passed into ammonia,
forming nitrogen and hydrochloric acid; unless the ammonia is present in
excess, the highly explosive nitrogen trichloride (NCl3) is also formed. The
ammonia molecule readily undergoes nitrogen inversion at room
temperature - that is, the nitrogen atom passes through the plane of
symmetry of the three hydrogen atoms; a useful analogy is an umbrella
turning itself inside out in a strong wind. The energy barrier to this inversion
is 24.7 kJ/mol in ammonia, and the resonance frequency is 23.79 GHz,
corresponding to microwave radiation of a wavelength of 1.260 cm. The
absorption at this frequency was the first microwave spectrum to be
observed (Cleeton et al 1934).
2.2.6. Uses
2.2.6.1. Nitric Acid production
The most important single use of ammonia is in the production of
nitric acid. A mixture of one part ammonia to nine parts air is passed over a
platinum gauze catalyst at 700 °C - 850 °C, ~9 atm (Tong., 1995),
whereupon the ammonia is oxidized to nitric oxide.
4 NH3 + 5 O2 → 4 NO + 6 H2O
2 NO + O2 → 2 NO2
2 NO2 + 2 H2O → 2 HNO3 + H 2
The catalyst is essential, as the normal oxidation (or combustion) of
ammonia gives dinitrogen and water: the production of nitric oxide is an
example of kinetic control. As the gas mixture cools to 200–250 °C, the
nitric oxide is in turn oxidized by the excess of oxygen present in the
mixture, to give nitrogen dioxide. This is reacted with water to give nitric
acid for use in the production of fertilizers and explosives.
2.2.6.2. Fertilizer
In addition to serving as a fertilizer ingredient, ammonia can also be used
directly as a fertilizer by forming a solution with irrigation water, without
additional chemical processing. This later use allows the continuous growing
of nitrogen dependent crops such as maize (corn) without crop rotation but
this type of use leads to poor soil health. Also ammonia commonly used in
refrigeration units prior to the discovery of dichlorodifluoromethane in 1928,
also known as Freon. Other use of ammonia to neutralizes the nitrogen
oxides (NOx) pollutants emitted by diesel engine tailpipes (Aaron., 2008).
2.2.7. Liquid ammonia as a solvent
Liquid ammonia is the best-known and most widely studied nonaqueous ionizing solvent. Its most conspicuous property is its ability to
dissolve alkali metals to form highly coloured, electrically conducting
solutions containing solvated electrons. Apart from these remarkable
solutions, much of the chemistry in liquid ammonia can be classified by
analogy with related reactions in aqueous solutions. Comparison of the
physical properties of NH3 with those of water shows that NH3 has the lower
melting point, boiling point, density, viscosity, dielectric constant and
electrical conductivity; this is due at least in part to the weaker H bonding in
NH3 and the fact that such bonding cannot form cross-linked networks since
each NH3 molecule has only 1 lone-pair of electrons compared with 2 for
each H2O molecule. The ionic self-dissociation constant of liquid NH3 at
−50 °C is approx. 10-33 mol²·l-2 (Mercier et al, 2005).
2.2.8. Safety
The U. S. Occupational Safety and Health Administration (OSHA)
has set a 15-minute exposure limit for gaseous ammonia of 35 ppm by
volume in the environmental air and an 8-hour exposure limit of 25 ppm by
volume (FAO 2004). Exposure to very high concentrations of gaseous
ammonia can result in lung damage and death (FAO 2004). Although
ammonia is regulated in the United States as a non-flammable gas, it still
meets the definition of a material that is toxic by inhalation and requires a
hazardous safety permit when transported in quantities greater than 13,248 L
(3,500 gallons) (HM 2005).
2.3. Urea Fertilizer
Urea, white crystalline solid containing 46% nitrogen, is widely used
in the agricultural industry as an animal feed additive and fertilizer here we
discuss it only as a nitrogen fertilizer. Commercially, fertilizer urea can be
purchased as prills or as a granulated material. In the past, it was usually
produced by dropping liquid urea from a "prilling tower" while drying the
product. The prills formed a smaller and softer substance than other
materials commonly used in fertilizer blends. Today, though, considerable
urea is manufactured as granules. Granules are larger, harder, and more
resistant to moisture. As a result, granulated urea has become a more
suitable material for fertilizer blends. The advantages of fertilizer urea
consists to possibility of applied to soil as a solid or solution or to certain
crops as a foliar spray also urea usage involves little or no fire or explosion
hazard, finally urea manufacture releases few pollutants to the environment.
Nitrogen from urea can be lost to the atmosphere if fertilizer urea remains on
the soil surface for extended periods of time during warm weather. The key
to the most efficient use of urea is to incorporate it into the soil during a
tillage operation. It may also be blended into the soil with irrigation water. A
rainfall of as little as 0.25 inches is sufficient to blend urea into the soil to a
depth at which ammonia losses will not occur (Overdahl et al,. 1991).
2.3.1. Environmental Fate
When released to soil, this material will hydrolyze into ammonium in
a matter of days to several weeks. When released into the soil, this material
may leach into groundwater. When released into water, this material may
biodegrade to a moderate extent. When released into water, this material is
not expected to evaporate significantly. This material has an experimentallydetermined bioconcentration factor (BCF) of less than 100. This material is
not expected to significantly bioaccumulate. When released into the air, this
material is expected to be readily degraded by reaction with photochemically
produced hydroxyl radicals. When released into the air, this material is
expected to have a half-life of less than 1 day (MSDS 2007).
2.4. Ammonium Sulphate
Ammonium sulfate, ((NH4)2SO4), is an inorganic chemical compound
commonly used as a fertilizer. It contains 21% nitrogen as ammonium ions
and 24% sulfur as sulfate ions. Ammonium sulfate is not soluble in alcohol
or liquid ammonia. The compound is slightly hygroscopic and absorbs water
from the air at relative humidity > 81% (at ca. 20°C). Ammonium sulfate is
prepared commercially by reacting ammonia with sulfuric acid (H2SO4).
Ammonium sulfate is prepared commercially from the ammoniacal liquor of
gas-works and is purified by recrystallisation. It forms large rhombic prisms,
has a somewhat saline taste and is easily soluble in water. The aqueous
solution on boiling loses some ammonia and forms an acid sulfate.
2.4.1. Uses
It is used largely as an artificial fertilizer for alkaline soils. In the soil
the sulfate ion is released and forms sulfuric acid, lowering the pH balance
of the soil (as do other sulfate compounds such as aluminium sulfate), while
contributing essential nitrogen for plant growth.
It is also used as an agricultural spray adjuvant for water soluble
insecticides, herbicides, and fungicides. There it functions to bind iron and
calcium cations that are present in both well water and plant cells. It is
particularly effective as an adjuvant for 2,4-D (amine), glyphosate, and
glufosinate herbicides. It is also used in the preparation of other ammonium
salts. In biochemistry ammonium sulfate precipitation is a common method
for purifying proteins. Ammonium sulfate is also listed as an ingredient for
many United States vaccines per the Center for Disease Control (JAMA,
2000).
2.5. Ammonia Volatilization
Nitrogen may be lost from the soil by plant removal, denitrification,
leaching, erosion and volatilization (Barbarick, 2006). Volatilization is the
loss of a gas to the atmosphere. In the case of urea, hydrolysis converts the
urea to ammonia, and if the urea is not incorporated, the ammonia is lost to
the air. Volatilization losses of urea are highly dependent on the rate of
hydrolysis which in turn is influenced by soil temperature, soil pH,
moisture/humidity, and residue of coverage of the soil surface (Franzen
2008). Farmers want to minimize losses of nitrogen nitrogen by
volatilization of ammonia when adding fertilizers and improve fertilizer
recovery of nitrogen by plants (Sigunga et al, 2002).
Transport of gaseous ammonia is recognized as important in the
terrestrial nitrogen cycle and the formation of gaseous NH3 in soil, plants
and water can lead to considerable losses of N from agricultural land. Some
reports (e.g. Fenn & Kissel, 1974; Freney et al., 1983; Whitehead and
Raistrick, 1990; Jayaweera and Mikkelsen, 1991) show that as much as 70%
of nitrogen fertilizers applied to the soil surface may be lost in this way. In
addition, the gaseous ammonia can be toxic to plants (Bremner, 1995).
Soil, weather, type of fertilizer and management are influenced the
magnitude of ammonia volatilization. The most important soil characteristics
include pH, buffering capacity, cation exchange capacity (CEC),
temperature, moisture content and urease activity (Kowalenko and Cameron,
1976; Fenn and Hossner, 1985; Koelliker and Kissel, 1988). The pH of the
soil solution determines the equilibrium between NH4+ and NH3 in the
system (Freney et al., 1983; Fenn and Hossner, 1985). At a given
temperature, the relative concentration of NH3 increases with increasing pH
above 7, while NH4+
concentration decreases (Koelliker and Kissel,
1988). Since the equilibrium between NH4+ and NH3 depends on pH, the
soil's buffering capacity affects NH3 volatilization. Reports by Vlek and
Stumpe (1978) and Ferguson et al. (1984) showed that the amount of NH3-N
lost from fertilizer in soil varied with the soils' buffering capacities.
Ammonia is sorbed by, or desorbed from, soil colloids (Rolston et al.,
1972), and the amount of NH4+ that a soil can sorb is influenced by the soil's
CEC (Kowalenko and Cameron, 1976).
2.5.1. Factors regulating ammonia loss
Ammonia is formed constantly in soils because of the biological
degradation of organic compounds and NH4+ yielding mineral and organic
fertilizers. As it is a gas, any NH3 present in soils, water or fertilizers can
volatilize to the atmosphere. However, NH3 reacts with protons, metals and
acidic compounds to form ions, compounds or complexes of varying
stability. Ammonia has a strong affinity for water, and its reactions in water
are fundamental to regulating the rate of loss. After its application to the soil,
the NH4+ can remain on the exchange sites, nitrify to NO3_, or decompose to
NH3, depending on soil and environmental conditions:
NH4 (absorbed) → NH4 (solution) → NH3 (solution) → NH3 (soil) → NH3 (atmosphere)
NH4↔ NH3+ H+
NH4+ + 1.5O2→2H+ + H2O +NO2
NO2 + 0.5 O2→ NO3
In fertilized fields the input of NH4+ depends on: fertilizer type; the rate and
mode of fertilizer application; soil moisture content, infiltration rate, and
CEC; and urease activity (in the case of urea). The difference in NH3 partial
pressure between the ambient atmosphere and that in equilibrium with moist
soil, floodwater, or the intercellular air space of plant leaves drives ammonia
volatilization. The partial pressure of NH3 in the soil is controlled by the rate
of removal of ammonium or NH3 in solution, or by displacing any of the
equilibria in some other way. Wind speed (regulating the exchange between
soil and air), temperature, and the pH of the soil solution or irrigation water
are important regulating factors, as all three variables affect the partial
pressure of NH3 (Bouwman and Batjes,2001).
Increasing temperature increases the relative proportion of NH3 to
NH4+ present at a given pH, decreases the solubility of NH3 in water, and
increases the diffusion of NH3 away from the air-water or air-soil interface
(Cardenas et al, 1993).
Other variables influencing NH3 volatilization include the pH buffer
capacity and the CEC of the soil. The CEC is important as the negatively
charged CEC absorbs the positively charged NH4+. A major part of the soil's
NH3 holding capacity is attributable to soil organic matter. Other factors
include: the level of urease activity (in the case of urea application, or urine);
the availability of moisture; soil texture; the nitrification rate; and the
presence of plants or plant residues (Bowmer and Muirhead, 1987).
2.5.1.1. Soil Moisture
The effect of soil moisture on ammonia volatilization depends on
whether the water is added to the soil before or after the fertilizer. Fenn and
Escarzaga (1976) reported that evaporation enhanced ammonia loss from
originally wet soil. In another report Fenn & Escarzaga (1977) found that
initially wet soil, brought to 60±80% of water saturation, resulted in greater
ammonia losses in most soils with both ammonium nitrate and ammonium
sulphate than those from initially dry soils. In the same report they showed
that adding increasing quantities of water after fertilizer application reduced
ammonia loss. Soil moisture content is determined primarily by the pattern
of rainfall, especially where irrigation is not practised. Wind helps to
volatilize ammonia from soil, solution and plant surfaces by sweeping away
the ammonia-laden layer, thereby diminishing the ammonia partial pressure
there (Denmead et al., 1982; Freney et al., 1983).
The volatilization of ammonia from both ammonium nitrate and
ammonium sulphate was greater at 80% of the water holding capacity than
at only 60%, possibly because the water soil solubilized the fertilizer more
(Sigunga et al, 2002).
2.5.1.2. Temperature and soil pH
In particular, the pH affects the equilibrium between NH4+ and NH3 so that
the relative concentration of NH3 increases from 0.1 percent to 1, 10 and 50
percent as the pH increases from 6 to ~7, ~8 and ~9, respectively. The
volatilization process itself produces acidity. The nitrification process can
reduce NH3 volatilization in two ways: by decreasing NH4+ availability; and
by producing acidity (FAO 2004). These results agree with the finding of ElKarim et al., (2004), however the high salinity may negatively affected the
microbial growth and decrease urea hydrolysis to ammonium carbonates
which may decrease the overall process of volatilization.
Improved understanding of nitrogen sources, environmental factors, and
nitrification effects on NH3 volatilization is needed for optimal management
of nitrogen in crop production systems. The kinetics of NH3 volatilization
from four N sources surface applied to an Alfisol (a Riviera fine sand, pH
7.9) followed an initial rapid reaction, and then a slow reaction, which was
adequately described by a Langmuir kinetic model. The potential maximum
NH3 volatilization (qm) under the experimental conditions, as predicted by
the Langmuir equation, decreased in the order: NH4HCO3 (23.2% of applied
NH4-N) > (NH4)2SO4 (21.7%) > CO(NH2)2 (21.4%) > NH4NO3 (17.6%).
With an increase in NH4-N application rate, NH3 volatilization increased
significantly for (NH4)2SO4, CO(NH2)2, and NH4HCO3 but decreased for
NH4NO3. Ammonia volatilization was minimal at the initial soil pH of 3.5
and increased rapidly with increasing pH up to 8.5. The potential maximum
NH3 volatilization increased by 2- and 3-fold, respectively, with an increase
in the incubation temperature from 5 to 25 (degrees)C, and from 25 to 45
(degrees)C, respectively. The greatly enhanced NH3 volatilization at 45
(degrees) C, compared with that at 25 (degrees)C, was related to the
inhibition of nitrification at the high temperature, which increased the
availability of NH4 for NH3 volatilization over a prolonged period of time.
(Williams et al, .1999).
2.5.1.3. Soil CEC
The CEC was most highly correlated with ammonia volatilization, while
among the three positive correlation factors (Duan 2000). Toole et al.,
(2006) also indicated that ammonia volatilization was apparently controlled
by buffered CEC and initial pH and was related to variations in soil organic
matter and texture.
2.5.1.4. Method and Depth of Application
Recovery of spring applied NH3 in the corn plants was between 58
and 69%, and about 7% remained in the soil, primarily as organic nitrogen
and fixed NH4. Recovery decreased with an increase in the amount of
nitrogen applied. About half of the all applied fertilizer nitrogen
incorporated into the organic-N fraction was released the following spring,
but fertilizer-derived organic-N from Spring-applied NH3 was largely
unavailable to soil microorganisms. From 60 to 80% of the Spring applied
fertilizer nitrogen fixed by day was released during cropping. The major
pathway for loss of fertilizer nitrogen was presumed to be either leaching or
denitrification. Some below the point of placement by the following
fertilizer-derived (NO2 + NO3)-N was leached as much as 60 to 75 cm
Spring. At this depth it would be unavailable to the following crop until the
roots had penetrated deeply. The results suggest that fall application of NH3
is not desirable, from an agronomic or an environmental point of view,
because of potential nitrogen fertilizer losses, particularly by leaching. At
least in the soil studied, Fall application has an advantage in that less
fertilizer nitrogen is retained in an unavailable form (Chalk and Keeney
1975).
Incorporating fertilizer within the 0-5cm soil layer or, somewhat
deeper, should be encouraged whenever there is risk of loosing nitrogen by
volatilization (Sigunga et al, 2002).
2.6. Transformation and Movement of Nitrogen Fertilizers
Nitrogen exists in a number of chemical forms and undergoes
chemical and biological reactions. The following transformation processes
are including the following (Barbarick, 2006):-
1. Organic nitrogen to ammonium nitrogen (mineralization). Organic
nitrogen comprises over 95 percent of the nitrogen found in soil. This form
of nitrogen cannot be used by plants but is gradually transformed by soil
microorganisms to ammonium (NH4+). Ammonium is not leached to a great
extent. Since NH4+ is a positively charged ion (cation), it is attracted to and
held by the negatively charged soil clay. Ammonium is available to plants.
2. Ammonium nitrogen to nitrate nitrogen (nitrification). In warm, welldrained soil, ammonium transforms rapidly to nitrate (NO3-). Nitrate is the
principle form of nitrogen used by plants. It leaches easily, since it is a
negatively charged ion (anion) and is not attracted to soil clay. The nitrate
form of nitrogen is a major concern in pollution.
3. Nitrate or ammonium nitrogen to organic nitrogen (immobilization). Soil
microorganisms use nitrate and ammonium nitrogen when decomposing
plant residues. These forms are temporarily "tied-up" (incorporated into
microbial tissue) in this process. This can be a major concern if crop
residues are high in carbon relative to nitrogen. Examples are wheat straw,
corn stalks and sawdust. The addition of 20 to 70 pounds of nitrogen per ton
of these residues is needed to prevent this transformation. After the residues
are decomposed, the microbial population begins to die back and processes 1
and 2 take place.
4. Nitrate nitrogen to gaseous nitrogen (denitrification). When soil does not
have sufficient air, microorganisms use the oxygen from NO3- in place of
that in the air and rapidly convert NO3- to nitrogen oxide and nitrogen gases
(N2). These gases escape to the atmosphere and are not available to plants.
This transformation can occur within two or three days in poorly aerated soil
and can result in large loses of nitrate-type fertilizers.
5. Ammonium nitrogen to ammonia gas (ammonia volatilization). Soils that
have a high pH (pH greater than 7.5) can lose large amounts of NH4+ by
conversion to NH3 gas. To minimize these losses, incorporate solid
ammonium-type fertilizers, urea and anhydrous ammonia below the surface
of a moist soil.
2.7. Aridisols
Aridisols (or desert soils) are a soil order in USA soil taxonomy.
Aridisols (from the Latin aridus, for “dry”) form in an arid or semi-arid
climate. Aridisols dominate the deserts and xeric shrublands which occupy
about one third of the Earth's land surface. Aridisols have a very low
concentration of organic matter. Water deficiency is the major defining
characteristic of Aridisols. Also required is sufficient age to exhibit sub-soil
weathering and development. Imperfect leaching in Aridisols often results in
one or more subsurface soil horizons in which suspended or dissolved
minerals have been deposited: silicate clays, sodium, calcium carbonate,
gypsum or soluble salts. These subsoil horizons can also be cemented by
carbonates, gypsum or silica. Accumulation of salts on the surface can result
in salinization (NRCS 2006).
2.8. Vertisols
Vertisols are clay-rich soils that shrink and swell with changes in
moisture content. During dry periods, the soil volume shrinks, and deep
wide cracks form. The soil volume then expands as it wets up. This
shrink/swell action creates serious engineering problems and generally
prevents formation of distinct, well-developed horizons in these soils.
Globally, Vertisols occupy ~2.4% of the ice-free land area. In the US, they
ccupy ~2.0% of the land area and occur primarily in Texas.Vertisols are
divided into 6 suborders: Aquerts, Cryerts, Xererts, Torrerts, Usterts, and
Uderts (University of Idaho 2006).
2.9. Entisols
Entisols are soils of recent origin. The central concept is soils
developed in unconsolidated parent material with usually no genetic
horizons except an A horizon. All soils that do not fit into one of the other
11 orders are Entisols. Thus, they are characterized by great diversity, both
in environmental setting and land use. Many Entisols are found in steep,
rocky settings. However, Entisols of large river valleys and associated shore
deposits provide cropland and habitat for millions of people worldwide.
Globally Entisols are extensive, occupying ~16% of the Earth's ice-free land
area. Only Inceptisols are more extensive. In the US, Entisols occupy
~12.3% of the land area.Enttisols are divided into 5 suborders: Aquents,
Arents, Psamments, Fluvents, and Orthents (University of Idaho 2006).
CHAPTER THREE
CHAPTER THREE
MATERIALS AND METHODS
3.1 Introduction
In these experiments, three soil types of Sudan soils were used. The sites
were selected in order to cover wide variation in soil properties and texture.
The first soil type in Berber was Aridisol. The second soil type in Shambat
Gerf was Entisols in the gerf of River Nile. The third soil type in El Gezira
was Vertisols.
3.2 The Pertinent Properties of the Soils
Table 1 focusing on the pertinent properties of the three types of soils
that were used in the study. These characteristics were determined according
to the method reported by Richards (1954). Representative soil samples (030cm) were air dried and ground to pass a 2mm sieve before analysis.
3.3 Source of Fertilizers
The fertilizers used in the experiment were aqueous ammonia,
conc.9.5% (nitrogen content 7.8 %,) which was collected from Khartoum
Petroleum Refinery. Urea (nitrogen content 46%) and ammonium sulphate
(nitrogen content 21%) purchased from the market in Khartoum North.
3.4 Land Preparation
The experimental areas (Micro plot) were prepared and leveled by hand;
finally they were divided into plot 2×4m. The micro plot (Unit of
experiment) was putted into this plot.
3.5 Analytical Method
Experimental areas were treated with three sources of nitrogen fertilizers
comprising aqueous ammonia; urea and ammonium sulphat at a rate
equivalent to 200kg N/ha dissolved in certain amount of distilled water
(5ml).
The solutions of nitrogen fertilizers were added at three depths by
adding with irrigation water and injection in depth of 5cm and 15cm. The
treatments were replicated three times for every source of nitrogen. The
experimental areas were irrigated weekly by water.
To collect volatilized ammonia, a design containing bottle with
suspended vial was used (Fig 1). The bottle was put on the place intended
for every treatment, and covered an area of 105cm2. This bottle is covered
on the upper side by a semi permissible membrane (Para film) which permits
ventilation. The lower side of the bottle is open and fixed to soil. In Berber,
the suspended vial contained 10 ml sulphuric acid 0.25N and 20 ml in
Shambat and Gezira. Using larger amount of acid in the latter was due to hot
season that causes more evaporation. The role of the acid was to collect the
volatilized ammonia from the treated soil. The sulphuric acid in the vial was
changed and collected at weekly interval for 4 weeks. After that the acid was
analyzed by using steam distillation apparatus, then titration was carried out
(Kjeldahl Method).
Two samples of soils were collected from the depth of application
(5cm) for all treatments in the three sites. The first sample was taken from
the middle of the treated area (105cm2) and from the edge, second sample
was taken. The mineral nitrogen (ammonium-nitrate) for these samples was
determined according to ICARDA (2001) method, in order to assess the
movement of nitrogen in the soil, depending on nitrogen source and soil
type.
Similar experiment was conducted as control in the three soil types to
the exclusion of the treatments.
3.6 Statistical Analysis
The experiments consist of 4 treatments arranged in nestted design
with three replications and the means were separated using Duncan’s
Multiple Range Test (P ≤ 0.05).
Table 1: Pertinent Properties of Soil Samples
pH
ECe Ca
Mg
Na
K
N
P
Soil Types Paste dSm mq\L mq\L mq\L mq\L mg\L %
SAR Sand Clay Silt
%
%
%
1
Aridisols
7.64
2.3
20
9
2.17
0.51
28
0.01
0.57
69.2
21.3
9.5
Vertisols
7.58
1.7
20
9
16.74
0.19
84
0.01
4.39
10.03 73.07
16.9
Entisols
7.47
1.3
18
10.5
0.09
0.026
42
0.007 0.023 31.63
26.3
42.07
Figure 1: Design of Experiment
Cover (Par film)
Stand
Bottle
Vial
Sulphuric acid
0.25N
Soil
CHAPTER FOUR
CHAPTER FOUR
RESULTS
4.1. Ammonia Volatilization in the Three Sites
Data presented in table 2 showed the effect of soil type on the
volatilization of ammonia after 4 weeks from addition of three different
types of nitrogen fertilizers. The analysis of samples indicated significant
differences (P ≤ 0.05) in volatilization due to the soil types and
environmental conditions at site. Regarding to the different seasons in sites,
the effect was significant. However, volatilization on Aridisols (Berber) was
about 5.78 mg\10g which revealed lower values when compared with that
volatilization on Vertisols (Gezira) and Entisols (Shambat) soils which
recorded 28.62mg\10g and 34.35mg\10g respectively.
Figure 2 indicated the effect of site on the volatilization after 4 weeks
from added fertilizers. The general trend of the results indicated that the
released amount of the ammonia increased gradually according to their soils.
4.2. Effect of method of application on the volatilization
Nitrogen loss by volatilization was significantly (P ≤ 0.05) affected by
the method of application: M0 (at soil surface) ,M1(5cm depth) and M2
(15cm depth) in the three soil types under investigation as presented in Table
3, Table 4 and Table 5 respectively.
The ammonia volatilization differed according to the method of
application, whereas the highest values in all sites were recorded in the M0
treatment. On the other hand, it was significantly (P ≤ 0.05) reduced between
M0 and M1 in Berber, M1 and M2 in Gezira and Shambat.
Table 2: Effect of soil types on nitrogen loss by volatilization
Berber
Gezira
Shambat
5.78b ±0.5
28.62a ±3.6
34.35a ±9.5
Minimum
0.67
0.67
0.67
Maximum
32.67
252
868.67
M ± SE
For each row means having the same letter(s) do not significantly different
(P ≤ 0.05), using Duncan's multiple range test.
M: Method M0: Method1 M2: Method2 M3: Method3 N: Nitrogen Source
N1: Aqueous ammonia N2: Urea N3: Ammonium Sulphate W: Week W1:
Week1 W2: Week2 W3: Week3 W4: Week4
Table 3: Effect of method of application on the nitrogen loss by
volatilization in Berber
M0
M± SE
M1
7.222b±0.495 6.556b ±0.495
M2
3.574a ±0.495
Minimum
2
1.33
0.67
Maximum
22
32.67
10.67
For each row means having the same letter(s) do not significantly different
(P ≤ 0.05), using Duncan multiple range test.
Symbols were defined in table 2.
Table 4: Effect of method of application on the nitrogen loss by
volatilization in Gezira
M0
M1
M2
66.574b ±2.9
12.389a ±2.9
6.926a ±2.9
Minimum
16.67
2.0
0.67
Maximum
252
27.33
21.33
M± SE
For each row means having the same letter(s) do not significantly different
(P ≤ 0.05), using Duncan multiple range test.
Symbols were defined in table 2.
Table 5: Effect of method of application on the nitrogen loss by
volatilization in Shambat
M0
M± SE
M1
M2
94.148b±8.818 5.444a ±8.818 3.463a ±8.818
Minimum
4.67
1.33
0.67
Maximum
868.67
11.33
6.67
For each row means having the same letter(s) do not significantly different
(P ≤ 0.05), using Duncan multiple range test.
Symbols were defined in table 2.
Figure 2 : Ammonia Volatilization as
Affected by Different SoilTypes
40
35
30
N mg\10g
25
20
15
10
5
0
Berber
Gezira
Shambat
4.3. Effect of Time on Ammonia Loss by Volatilization
The ammonia loss due to volatilization in Berber soil was slightly
higher at weeks 1 and 4 when compared with weeks 2 and 3 (Tables 6). But
in Gezira and Shambat soils the volatilization was slightly higher at week 2
than weeks 3 and 4 (Tables 7 and 8). Time exerted no significant effect in
Berber soil, however, a slight decrease in volatilization was observed at
week 2 and week 3.
The results of ammonia loss by volatilization in Berber are presented
in figure 3. No significant variations were demonstrated between W1and W4
or between W2 and W3 on the ammonia volatilization. But demonstrated
significant variations were observed between W1, W2, W3 and W4 in
Gezira and Shambat soils (Figures 4and 5).
Table 6: Ammonia Volatilization as Affected by Different Periods
of Time in Berber
W1
M± SE
W2
6.691b ±0.81 5.037a ±0.81
W3
W4
4.667a ±0.81 6.741b ±0.81
Minimum
1.33
1.33
0.67
0.67
Maximum
22
17.33
17.33
32.67
For each row means having the same letter(s) do not significantly different
(P ≤ 0.05), using Duncan multiple range test.
Symbols were defined in table 2.
Table 7: Ammonia Volatilization as Affected by Different Periods
of Time in Gezira
W1
W2
W3
W4
43.802c
32.370b
20.716a
17.629a
±4.74
±4.74
±4.74
±4.74
Minimum
6
3.33
2
0.67
Maximum
252
119.33
100
78
M± SE
For each row means having the same letter(s) do not significantly different
(P ≤ 0.05), using Duncan multiple range test.
Symbols were defined in table 2.
Table 8: Ammonia Volatilization as Affected by Different Periods
of Time in Shambat
W1
W2
W3
W4
82.272b
23.704a
17.185a
14.247a
±14.4
±14.4
±14.4
±14.4
Minimum
2.67
0.67
1.33
1.33
Maximum
868.67
146.67
78
74.67
M± SE
For each row means having the same letter(s) do not significantly different
(P ≤ 0.05), using Duncan multiple range test.
Symbols were defined in table 2.
Figure 3 : Ammonia Volatilization as
Affected by Different Periods of Time in
Berber Soil
8
7
N loss mg\10g
6
5
4
3
2
1
0
W1
W2
W3
Times
W4
Figure 4 : Ammonia Volatilization as
Affected by Different Periods of Time in
Gezira Soil
50
45
40
N loss mg\10g
35
30
25
20
15
10
5
0
W1
W2
W3
Times
W4
Figure 5 : Ammonia Volitilization as
affected by Different Periods of Time in
Shambat Soil
90
80
70
N loss mg\10g
60
50
40
30
20
10
0
W1
W2
Times W3
W4
4.4. Effect of Nitrogen Source on Ammonia Loss by
Volatilization
Data of table 9, 10 and 11 exhibited the effect of treatments on the
nitrogen loss by volatilization in three soil types. Volatilization in Berber
contained significant (P≤ 0.05) variation between N1and N3 when compared
with N2. Statistical analysis showed significant (P≤ 0.05) differences
between N1 and N3 in Gezira, but in Shambat; the results indicated
significant differences (P≤ 0.05) when compared N2 and N3 with N1.
Figure 6, 7 and 8 show the means of volatilization values as affected
by adding nitrogen sources. Analysis samples were detected to be
significantly affected by treatments in both soil types. Volatilization values
of Shambat were found to be significantly higher than those of the Gezira
and Berber soils.
Table 9: Ammonia Volatilization as Affected by Different Sources
of Nitrogen Fertilizers in Berber
N1
N2
N3
3.815a ±0.7
8.722b ±0.7
4.815a ±0.7
Minimum
0.67
2
1.33
Maximum
17.33
32.67
10.67
M±SE
For each row means having the same letter(s) do not significantly different
(P ≤ 0.05), using Duncan multiple range test.
Symbols were defined in table 2.
Table 10: Ammonia Volatilization as Affected by Different
Sources of Nitrogen Fertilizers in Gezira
N1
N2
N3
34.907b ±4.1
27.741ab ±4.1
23.241a ±4.1
Minimum
0.67
1.33
2
Maximum
252
104.67
114.67
M±SE
For each row means having the same letter(s) do not significantly different
(P ≤ 0.05), using Duncan multiple range test.
Symbols were defined in table 2.
Table 11: Ammonia Volatilization as Affected by Different
Sources of Nitrogen Fertilizers in Shambat
N1
N2
N3
68.481b ±12.5
11.815a ±12.5
22.759a ±12.5
Minimum
0.67
1.33
0.67
Maximum
868.67
72
137.33
M±SE
For each row means having the same letter(s) do not significantly different
(P ≤ 0.05), using Duncan multiple range test.
Symbols were defined in table 2.
Figure 6 : Ammonia Volatilization as
Affected by Different sources of Nitrogen
in Berber Soil
10
9
8
N loss mg\10g
7
6
5
4
3
2
1
0
N1
N2
sources of nitrogen
N3
Figure 7 : Ammonia Volatilization as
Affected by Different sources of Nitogen in
Gezira Soil
40
35
N loss mg\10g
30
25
20
15
10
5
0
N1
N2
sources of nitogen
N3
Figure 8 : Ammonia Volatilization as
Affected by Different Sources of Nitrogen
in Shambat Soil
80
70
N loss mg\10g
60
50
40
30
20
10
0
N1
N2
sources of nitogen
N3
4.5. Ammonia Volatilization as Affected by Method of
Application during 4 Weeks in Three Sites
Figures 9, 10 and 11 show the effect of the method of application
within experimental time of 4 weeks on the rate of ammonia loss by
volatilization as applied from three different sources of nitrogen fertilizers in
Berber.
Analysis of variance showed that the ammonia volatilization from
urea (N2) was significantly affected by method of applications when
compared with aqueous ammonia (N1) and ammonium sulphate (N3).
However, a slight decrease was recorded in rate of ammonia loss in N1 and
N3 in Berber (Tables 12, 13, 14).
The effect of the method of application on the ammonia volatilization
during 4 weeks in Gezira is presented in figures 12, 13 and 14. The general
trend of these curves is decrease gradually with time except M1 which
observed to increase after the third week.
Tables 15, 16 and 17 indicated insignificant differences (P ≤ 0.05) in
ammonia volatilization among the three nitrogen sources applied in the
Gezira due to M0 and M2. Regarding M1 treatment, ammonia volatilization
in the second source of nitrogen was very high compared to the first and
third sources of nitrogen.
The ammonia volatilization increased in M0 significantly (P ≤ 0.05)
according to the first source of nitrogen fertilizer (N1) compared with N2
and N3 (Table 18). Whereas, tow methods of application M1 and M2
applied in Shambat gave almost the same values (Table 19, 20).
The observations of ammonia loss by volatilization in Shambat
depending on the methods of application were recorded in figures 15, 16 and
17. Method of applications by injection in both depths (5 cm and 15 cm) was
detected to exert not significant on the ammonia loss from Shambat.
Whereas, in the case of the surface addition (M0), the rate of volatilization
significantly affected by fertilizer type when compared with M1 and M2.
.
Figure 9: Ammonia Volatilization as
Affected by M0 during 4 Weeks in Berber
Soil
45
40
35
N loss mg\10g
30
25
Aqueous Ammonia
Urea
Ammonium Sulphate
20
15
10
5
0
0
2
4
Weeks
6
Figure10: Ammonia Volatilization as
Affected by M1 during 4 Weeks in Berber
Soil
50
45
40
N loss mg\10g
35
30
Aqueous Ammonia
Urea
Ammonium Sulphate
25
20
15
10
5
0
0
2
4
Weeks
6
Figure 11: Ammonia Volatilization as
Affected by M2 during 4 Weeks in Berber
Soil
25
N loss mg\10g
20
15
Aqueous Ammonia
Urea
Ammonium Sulphate
10
5
0
0
2
4
Weeks
6
Table 12: Ammonia Volatilization as Affected by the First Method
of Application during 4 Weeks in Berber
N1
N2
N3
7.111ab ±1.29
9.833b ±2.04
4.7222±a 0.43
Minimum
2
2
2
Maximum
17.33
22
6.67
M±SE
For each row means having the same letter(s) do not significantly different
(P ≤ 0.05), using Duncan multiple range test.
Symbols were defined in table 2.
Table 13: Ammonia Volatilization as Affected by the Second
Method of Application during 4 Weeks in Berber
N1
N2
N3
2.611a ±0.38
11.56b ±2.72
5.5a ±1.16
Minimum
1.33
3.33
1.33
Maximum
5.33
32.67
14
M±SE
For each row means having the same letter(s) do not significantly different
(P ≤ 0.05), using Duncan multiple range test.
Symbols were defined in table 2.
Table 14: Ammonia Volatilization as Affected by the Third
Method of Application during 4 Weeks in Berber
N1
N2
N3
1.7222a ±0.22
4.222b ±0.74
4.778b ±0.72
Minimum
0.67
2
1.33
Maximum
3.33
10.67
10
M±SE
For each row means having the same letter(s) do not significantly different
(P ≤ 0.05), using Duncan multiple range test.
Symbols were defined in table 2.
Table 15: Ammonia Volatilization as Affected by the First Method
of Application during 4 weeks in Gezira
N1
N2
N3
57.722a ±8.76
54.722a ±9.61
Minimum
87.278a
±19.53
25.33
23.33
16.67
Maximum
252
104.67
114.67
M±SE
For each row means having the same letter(s) do not significantly different
(P ≤ 0.05), using Duncan multiple range test.
Symbols were defined in table 2.
Table 16: Ammonia Volatilization as Affected by the Second
Method of Application during 4 Weeks Gezira
N1
N2
N3
11.389a ±1.33
17.556b ±1.75
8.222a ±1.73
Minimum
5.33
6
2
Maximum
21.33
27.33
19.33
M±SE
For each row means having the same letter(s) do not significantly different
(P ≤ 0.05), using Duncan multiple range test.
Symbols were defined in table 2.
Table 17: Ammonia Volatilization as Affected by the Third
Method of Application during 4Weeks in Gezira
N1
N2
N3
6.056a ±0.94
7.944a ±1.93
6.778a ±1.66
Minimum
0.67
1.33
2
Maximum
10
21.33
21.33
M±SE
For each row means having the same letter(s) do not significantly different
(P ≤ 0.05), using Duncan multiple range test.
Symbols were defined in table 2.
Figure 12: Ammonia Volatilization as
Affected by M0 during 4 Weeks in Gezira
Soil
400
350
300
N loss mg\10g
250
200
Aqueous Ammonia
Urea
Ammonium Sulphate
150
100
50
0
0
2
4
Weeks
6
Figure 13: Ammnia Volatilization as
Affected by M1 during 4 Weeks in Gezira
Soil
80
70
N loss mg\10g
60
50
Aqueous Ammonia
Urea
Ammonium Sulphate
40
30
20
10
0
0
2
4
Weeks
6
Figure 14: Ammonia Volatilization as
Affected by M2 during 4 Weeks in Gezira
Soil
35
30
N loss mg\10g
25
20
Aqueous Ammonia
Urea
Ammonium Sulphate
15
10
5
0
0
2
4
Weeks
6
Table 18: Ammonia Volatilization as Affected by the First Method
of Application during 4 Weeks in Shambat
N1
N2
N3
195.5b ±69.13
27.222a ±6.58
Minimum
65.33
4.67
59.722a
±12.25
20
Maximum
868.67
63.33
137.33
M±SE
For each row means having the same letter(s) do not significantly different
(P ≤ 0.05), using Duncan multiple range test.
Symbols were defined in table 2.
Table 19: Ammonia Volatilization as Affected by the Second
Method of Application during 4 Weeks in Shambat
N1
N2
N3
6±a 0.88
4.722a ±0.76
5.611a ±0.66
Minimum
2.67
1.33
2.67
Maximum
11.33
10.6667
9.33
M±SE
For each row means having the same letter(s) do not significantly different
(P ≤ 0.05), using Duncan multiple range test.
Symbols were defined in table 2.
Table 20: Ammonia Volatilization as Affected by the Third
Method of Application during 4 Weeks in Shambat
N1
N2
N3
3.945a ±0.59
3.5a ±0.44
2.945a ±0.41
Minimum
0.67
1.33
0.67
Maximum
6
6.67
4
M±SE
For each row means having the same letter(s) do not significantly different
(P ≤ 0.05), using Duncan multiple range test.
Symbols were defined in table 2.
Figure 15: Ammonia Volatilization as
Affected by M0 during 4 Weeks in
Shambat Soil
900
800
700
N loss mg\10g
600
500
400
300
200
Aqueous Ammonia
Urea
Ammonium Sulphate
100
0
0
2
4
Weeks
6
Figure 16: Ammonia Volatilization as
Affected by M1 during 4 Weeks in
Shambat Soil
30
25
N loss mg\10g
20
15
Aqueous Ammonia
Urea
Ammonium Sulphate
10
5
0
0
2
Weeks
4
6
Figure 17: Ammonia Volatilization as
Affected by M2 during 4 Weeks in
Shambat Soil
18
16
14
N loss mg\10g
12
10
Aqueous Ammonia
Urea
Ammonium Sulphate
8
6
4
2
0
0
2
4
Weeks
6
Figure 18 presented histogram shows ammonia loss by volatilization
as affected by method of applications in Berber. The effect of methods was
erratic, whereas the method of injection at 5cm and the surface application
tested gave approximately the same values.
Figures 19and 20 presented the effect of methods of application on the
ammonia volatilization after 4 weeks from the three sources of nitrogen
fertilizer in Gezira and Shambat, respectively. The analysis of results
indicated significant differences between M1 and M2 compared with M0 in
both soil types.
4.6. Interaction Effect of, Soil Type and Method of
Application on the Ammonia Volatilization
The different amounts of ammonia volatilization from the three soil
types depending on the three methods are presented in figure 21.The
ammonia volatilization was significantly affected by M0 compared with
M1and M2.
4.7. Interaction Effect of, Soil Type and Time on the Ammonia
Volatilization
Figure 22 shows the effect of soil type and time in ammonia
volatilization. Interactions of time with all soil types were noted to exert
significant effects on ammonia loss, specifically W1 in Shambat and Gezira
soils where the higher rates of volatilization was observed.
4.8. Interaction Effect of, Soil Types, Source of Nitrogen on
the Ammonia Volatilization
The different types of nitrogen fertilizers were detected to exert
significant effects on the ammonia volatilization on all soil types. With
regarded to source of nitrogen fertilizer (N1) in Berber the loss of ammonia
was registered the lower values than those of other soil types (Figure 23).
Figure 18: Ammonia Volatilization from the
Three Sources of Nitrogen Fertilizers as
Affected by Method of Application during 4
Weeks in Berber
8
7
N loss mg\10g
6
5
4
3
2
1
0
M0
M1
Methods
M2
Figure 19: Ammonia Volatilization from the
Three Sources of Nitrogen Fertilizers as
Affected by Method of Application during 4
Weeks in Gezira
70
60
N loss mg\10g
50
40
30
20
10
0
M0
M1
Methods
M2
Figure 20: Ammonia Volatilization from the
Three Sources of Nitrogen Fertilizers as
Affected by Method of Application during 4
Weeks in Shambat
100
90
80
N loos mg\10g
70
60
50
40
30
20
10
0
Mo
M1
Methods
M2
Figure 21: Interaction Effect of Soil Type
and Method of Application on the
Ammonia Volatilization
100
90
80
N mg\10g
70
60
Berber
Gezira
Shambat
50
40
30
20
10
0
M0
M1
Methods
M2
Figure 22 :Interaction Effect of Soil Type
and Time on the Ammonia Volatilization
90
80
70
Berber
Gezira
Shambat
N loss mg\10g
60
50
40
30
20
10
0
W1
W2
W3
Times
W4
Figure 23 :Interaction Effect of Soil Type
and Nitrogen Source on the Ammonia
Volatilization
80
Berber
Gezira
Shambat
70
N loss mg\10g
60
50
40
30
20
10
0
N1
N2
N3
sources of Nitrogen Fertilizers
4.9. Movement of Mineral Nitrogen from Three Sources of
Nitrogen Fertilizer in Three Soil Types
4.9.1. Ammonium
Data are presented in table 21. Statistical analysis revealed significant
(p≤0.05) differences in ammonium-N measured to estimate lateral
movement in different sites. The effect of soil type was significant.
However, amount of ammonium-N in Berber soil was about 6.3mg\10g
more in height compared with those amounts on Gezira and Shambat soils.
The analysis of samples indicated significant differences due to soil type
(Figure 24).
Amounts of ammonium-N in the three soil types at this experiment
were significantly (p≤0.05) affected by treatments (Table 22).The amounts
of ammonium-N were increased with changing sources of nitrogen from
N1,N2 and N3, where the highest values were recorded in N3 treatment.
Movement of ammonium-N in three soil types according to nitrogen
sources are shown in figures 25, 26 and 27. Applying the three sources of
nitrogen fertilizers showed clear differences in lateral movement of
ammonium-N from point of application to a distance of 12cm. except N1
and N3 in Berber soil.
The differences in the amount of ammonium-N between distances in three
soil types are demonstrated in figure 28.
4.9.2. Nitrate
Analysis of variance showed that the nitrate-N contents of three
sources of nitrogen fertilizer were significantly affected by three soil types.
Calculated results were detected to be significantly (P≤0.05) affected by
treatments in all sites. Nitrate-N values of Berber soil were found to be
significantly (P≤0.05) higher than those of the Gezira and Shambat soils
(Table 23).
Figure 28 shows the effect of soil type on the amount of nitrate-N after four
weeks.
The observations in soil contents of nitrate-N in three soil types were
recorded in table 24. The differences in the amount of nitrate-N were erratic,
whereas the three nitrogen sources tested gave similar values.
Figures 29, 30 and 31 show the effect of nitrogen sources on the
nitrate-N content in Berber, Gezira and Shambat respectively. Statistical
analysis indicated no significant differences between treatments.
The differences in the amount of nitrate-N between distances in three soil
types are demonstrated in figure 32.
Table 21: Amounts of Ammonium after 4 Weeks Depending on
Soil Types
Berber
Gezira
Shambat
6.3 b±0.34
1.77a ±0.34
1.13a ±0.34
Minimum
3.5
0.49
0.35
Maximum
9.1
5.39
2.66
M± SE
For each row means having the same letter(s) do not significantly different
(P ≤ 0.05), using Duncan multiple range test.
Symbols were defined in table 2.
Table 22: Amounts of Ammonium in the Three Types of soil after
4 Weeks Depending on the Nitrogen Sources
N1
N2
N3
2.62a ±o.34
3.15ab ±o.34
3.43b ±o.34
Minimum
0.35
0.42
0.49
Maximum
7.7
8.4
9.1
M± SE
For each row means having the same letter(s) do not significantly different
(P ≤ 0.05), using Duncan multiple range test.
Symbols were defined in table 2.
Figure 24 : Amounts of Ammonium after 4
Weeks i the Three Soil Types
7
6
N mg\10g
5
4
3
2
1
0
Berber
Gezira
Soil Type
Shambat
Figure 25 : Movement of Ammonium
according to Nitrogen Sources in Berber
Distance 1
Distance 2
8
7
6
N mg\10g
5
4
3
2
1
0
N1
N2
Nitrogen Sources
N3
Figure 26 : Movement of Ammonium
accordig to Nitrogen Sources in Gezira
3.5
3
N mg\10g
2.5
2
Distance 1
Distance 2
1.5
1
0.5
0
N1
N2
Nitrogen sources
N3
Figure 27 : Movement of Ammonium
according to Nitrogen Sources in
Shambat
2.5
Distance 1
Distance 2
N mg\10g
2
1.5
1
0.5
0
N1
N2
Nitrogen Sources
N3
Figure 28 : Movement of Ammonium in
the Three Soil Types
4
3.5
3
N mg\10g
2.5
2
1.5
1
0.5
0
1
2
Distances
Table 23: Amounts of Nitrate after 4 Weeks Depending on Soil
Types
Berber
Gezira
Shambat
4.122b ±o.46
0.771a ± o.46
0.673a ± o.46
Minimum
0.7
0.14
0.21
Maximum
8.4
2.8
1.89
M± SE
For each row means having the same letter(s) do not significantly different
(P ≤ 0.05), using Duncan multiple range test.
Symbols were defined in table 2.
Table 24: Amounts of Nitrate in the Three Types of soil after 4
Weeks Depending on the Nitrogen Sources
N1
N2
N3
1.875a ±046
1.497a ±046
2.198a ±046
Minimum
0.21
0.14
0.28
Maximum
8.4
6.3
7.7
M± SE
For each row means having the same letter(s) do not significantly different
(P ≤ 0.05), using Duncan multiple range test.
Symbols were defined in table 2.
Figure 29 : Amounts of Nitrate after 4
Weeks in the Three Soil Type
4.5
4
3.5
N mg\10g
3
2.5
2
1.5
1
0.5
0
Berber
Gezira
Soil Type
Shambat
Figure 30 : Movement of Nitrate according
to Nitrogen Sources in Berber
6
5
N mg\10g
4
Distance 1
Distance 2
3
2
1
0
N1
N2
Sources of Nitrogen
N3
Figure 31 : Movement of Nitrate according
to Nitrogen Sources in Gezira
1.8
1.6
1.4
N mg\10g
1.2
1
Distance 1
Distance 2
0.8
0.6
0.4
0.2
0
N1
N2
Sources of Nitrogen
N3
Figure 32 : Movement of Nitrate according
to Nitrogen Sources in Shambat
1.2
1
N mg\10g
0.8
Distance 1
Distance 2
0.6
0.4
0.2
0
N1
N2
Sources of Nitrogen
N3
Figure 33 : Movement of Nitrate in the
Three Soil Types
2
1.95
1.9
N mg\10g
1.85
1.8
1.75
1.7
1.65
1.6
1
Distances
2
CHAPTER FIVE
CHAPTER FIVE
DISCUSSION
5.1 Effect of Treatments on the Ammonia Loss by
Volatilization
5.1.1 Effect of Soil Type
The results obtained from Berber (Aridisols) were recorded lower
values of ammonia volatilization than Gezira (Vertisols) and Shambat
(Entisols) soils. This can be attributed to the high content of sand in Berber
which increase permeability and consequently rise ammonia loss by
infiltration, also may be due to the different climatic conditions between
Berber (Aridisols) and those sites (Gezira and Shambat), because the
experiment in the first site was conducted in November, but at March the
experimental work was carried out in Gezira and Shambat. The higher
amount of ammonia loss by volatilization in Entisols may be attributed to
the high rate of silt compared with other soils under investigation.
5.1.2 Effect of Method of Application
The higher loss was recorded from the first method of application on
all soil types can be attributed to the surface addition that probably indicate
more available nitrogen for the volatilization compared with second and
third methods of application. Also the ammonia was increased gradually
from M2, M1 and M0 in Aridisols, Vertisols and Entisols.
The general trend of ammonia volatilization from the aqueous
ammonia was decrease in the third method of application (Tables 14 and
16).
The reduction in ammonia loss by volatilization was markedly
observed by increasing depth as shown in the third method of application
(15 cm).
5.1.3 Effect of Time
The effect of time on the ammonia volatilization was observed in both
soil types (Gezira and Shambat), but it was pronounced in the first soil type
(Berber). This can be attributed to the beneficial effect of cold season on the
ammonia volatilization. All soils were decreased in amount of ammonia
volatilization during W1, W2, W3 and W4 gradually except Aridisols, this
was attributed to relatively low temperature in the first site which may
negatively affect the microbial growth and decrease urea hydrolysis to
ammonium carbonates which may decrease the overall process of
volatilization (El-Karim et al., 2004)
5.1.4 Effect of Nitrogen Source
Seasonal variability was noted and this was obviously due to the
different climatic conditions prevailed in the ammonia volatilization. The
merit of Entisols was regular in the rate of ammonia volatilization from
different sources of nitrogen fertilizer. The higher values of ammonia loss in
Vertisols and Entisols were obtained from aqueous ammonia; this may
possibly due to the easiness to analysis. The values of ammonia
volatilization in Aridisols were erratic, this discrepancy in values can be
attributed to the soil type, with regard to amount of salts in this soil which
affect to the nitrogen hydrolysis, and also the experiment was occurred in the
cold season.
5.2 Effect of Treatments on the Lateral Movement of
Mineral Nitrogen
5.2.1 Ammonium
5.2.1.1 Effect of Soil Type
The cold season in the first site (Aridisols) was decreased the amount
of ammonia loss by volatilization significantly compared with experiments
in second and third sites (Vertisols and Entisols) which were occurred in hot
season. So high amount of ammonium-N could be extracted form soil when
lateral movement of ammonium-N was determined. Higher movement was
observed in Berber soil and this is because of light texture as compared with
high clay content soil as the case in Gezira soil. Nevertheless high negative
charge associated with high clay content may reduce the movement of
ammonium-N which holds positive charge.
5.2.1.2 Effect of Nitrogen source
Aqueous ammonia was more released compared with urea and
ammonium sulphate. The residual amount of ammonium-N in ammonium
sulphate was higher in the first distance could possibly be explained the
difficult loss by volatilization than those types of nitrogen fertilizer.
5.2.1.3 Effect of Distance
The amount of ammonium-N in the second distance was slightly
lower than first distance; this may be attributed to the difficult horizontal
movement of ammonium ions charged with positive charge in clay soil.
5.2.2Nitrate
5.2.2.1 Effect of Soil Type
The discrepancy in amount of nitrate in three soil types may be
attributed to the different texture of soils under investigation. The higher
amount of nitrate-N was obtained in the first site (Aridisols), which the
experiment was carried out in sandy soil that means the lower amount of
ammonia loss by volatilization increase the residual amount of nitrate-N to
be extracted from the soil.
5.2.2.2 Effect of Nitrogen sources
The reduction in amount of nitrate from the second and third of
nitrogen fertilizers compared with aqueous ammonia may be attributed to
the status of fertilizers and nitrogen content. The first source of nitrogen was
liquid; this will be easy in movement through the soil.
5.2.2.3 Effect of Distance
[
The higher amount of nitrate in distance two compared with lower
amount in the first distance may be attributed to the negative charge in
nitrate which the same as in clay which may ease the lateral movement of
nitrate-N.
CONCLUSIONS
Conclusions
• Differences in locations (Berber-Gezira-Shambat) results significant
decrease in ammonia loss by volatilization in Berber soil compared
with those locations.
• Treatment (Addition of fertilizers in depth 5cm, 15cm and surface
soil) recorded higher loss significantly in the third method of
application in all locations.
• Effect of time on ammonia loss by volatilization was result regular
reduction in Gezira and Shambat soils, except Berber soil gave erratic
values.
• Nitrogen sources results significant loss from aqueous ammonia
compared with urea and ammonium sulphate in Shambat soil, but in
Gezira soil there was no any significant loss from urea compared with
both nitrogen sources. However, volatilization was significant
between urea and both fertilizers (Aqueous ammonia and Ammonium
sulphate) in Berber soil.
• Movement of mineral nitrogen (Ammonium and Nitrate) in Berber
was significant compared with Gezira and Shambat soils, but there
were no any significant differences between fertilizers in ammonium
and nitrate, except urea and ammonium sulphate in ammonium.
• Nitrate-N gave high movement from point of application to a distance
of 12cm, especially Shambat soil. But in ammonium-N there were no
significant differences between distances.
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