Efficacy of Controlled-Release Urea Fertilizers and Nitrogen Uptake by Rice
The efficiency of urea fertilizer as Nitrogen (N) source is uncertain as found in many laboratory studies. It is subjected to rapid hydrolysis and NH3-N volatilization. Ideal urea fertilizer should be soluble in soil and continuously regulated in amount that coincides with the rate of plant uptak...
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| Format: | Thesis |
| Language: | English English |
| Published: |
2008
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/10695/1/FP_2008_19.pdf http://psasir.upm.edu.my/id/eprint/10695/ |
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| Summary: | The efficiency of urea fertilizer as Nitrogen (N) source is uncertain as found in many
laboratory studies. It is subjected to rapid hydrolysis and NH3-N volatilization. Ideal
urea fertilizer should be soluble in soil and continuously regulated in amount that
coincides with the rate of plant uptake. Controlled Release Urea (CRU) is a fertilizer
that has been amended in such a way that the N is released over a period of time that
coincides with plant requirement. This is achieved by coating the urea granule with
material such as polymer that regulates the N releases to the soil solution. The CRU
releases nutrients during the entire growing-season, reduces N loss and increases yield.
Studies of behavior of CRU under tropical condition are limited. With this in view, this
study was carried out with the main objective; to identify efficient CRU on selected
soils. Laboratory and field studies were undertaken to evaluate the physical and chemical properties of CRU, to quantify the N transformation of CRU on selected
Malaysian soils and to detennine yield and N uptake by rice from CRU. Six types of
CRU used were CDU Uber-l0, Meister-20, Meister-27, Humate Coated Urea, Duration
Type-V, Sulfur Coated Urea (Gold N) and Urea fertilizer as control. Laboratory
evaluation was carried out on seven types of soil series; Serdang series (Typic
Paleudult), Munchong series (Typic Hapludox), Segamat series (Typic Hapludox),
Selangor series (Typic Tropaquept), Rengam series (Typic Kandiudult), Holyrood
series (Typic Kandiudult) and Bakau series (Typic Tropaquept).
The measurements of thickness of CRU coating and microphotographic observation of
the coating were performed using Scanning Electron Microscope. The thickness of
fertilizer coatings was in the range from 16.7 um - 73.2 um depending on the coating
type. Humate Coated Urea has the highest value (73.2 um) while the lowest value (16.7
f.UD.) was obtained from Gold-N. No coating was found in Urea granule and COU Uber-
10.
Experiment results showed, there were significant differences among treatments in
percentage of coating. Highest coating percentage was found in Meister-27 (11.23%)
followed by Gold-N (11.20010), Meister-20 (10.53%) and Duration Type-V (6.69010). No
coating was found in COU Uber-IO and Humate Coated Urea, therefore are categorized
as composite fertilizers. Fertilizer N analyses were carried out and compared with the
total N content given by the manufacturers. Total N content of all the CRU analyzed
were similar to the manufacturer's values. |
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