Effects of peat derived humic acid on ammonia volatilization from urea fertilizer
There are about 2.7 million hectares of peat swamps in Malaysia, which account for 8% of the country’s total area. 1.7 million hectares are in Sarawak (63%). Peats are well-known for their high organic matter. For instance, humic matter can be further categorized into humin, fulvic and humic aci...
Saved in:
| Main Author: | |
|---|---|
| Format: | Thesis |
| Language: | English |
| Published: |
2011
|
| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/78032/1/FSPM%202011%205%20ir.pdf |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | There are about 2.7 million hectares of peat swamps in Malaysia, which
account for 8% of the country’s total area. 1.7 million hectares are in
Sarawak (63%). Peats are well-known for their high organic matter. For
instance, humic matter can be further categorized into humin, fulvic and
humic acids. Being organic in nature, humic acid is an ideal material to be
mixed with ammonium and potassium to produce organically amended
fertilizer. However, there are several factors that limit the production of the
fertilizer mentioned above. For instance, extraction of humic acids is a time
consuming process. Furthermore, type and concentration of extractant also
influence the yield of humic acids. These information are critical in the study
of humic acids but they are lacking for humic acids isolated from Sarawak
peat. Hence, first part of this study was to investigate the effect of different levels of extractant concentration on the yield of humic acid extracted from
Sarawak peat soil (saprists). Modified standard procedure was adopted by
using six different concentrations of NaOH and KOH to extract humic acid.
Results showed that there was a linear relationship between levels of
concentrations and yield of humic acid and the concentration that gave
optimum yield was 0.5 M. In terms of economics, this finding might be useful
especially in large scale isolation of humic acids from tropical peats. As
humic acids contain quinone that could function as urease inhibitor, humic
acids are useful in reducing ammonia loss from urea. However, limited
information is known regarding effect of humic acids isolated from Sarawak
peat on ammonia volatilization. Hence, the objective of second part of the
study was to evaluate the effect of peat derived humic acid on ammonia
volatilization from urea. Effectiveness of the organically amended urea was
evaluated under laboratory condition. Ten treatments namely, urea (liquid),
0.5 M KOH, urea + 0.5 M KOH, urea + humic acid without purification (0.75,
1.00 and 4.00 g), urea + humic acid purified once (0.75, 1.00 and 4.00 g) and
control (soil alone) were used in this study with the aim of reducing nitrogen
loss from urea. A closed dynamic air flow system was used to estimate
nitrogen loss from soil. A 250 g of mineral soil at field capacity (60% moisture
content) was used. The amounts of ammonia loss from the applied
treatments were evaluated daily where the ammonia collected in boric acid
was titrated with 0.01 M HCl every 24 hours until the loss decreased to less
than 0.1%. Similar experiment was also set up in order to determine the
actual time of ammonium and nitrate retention in soil. At the end of the fertilizer evaluation, soil samples were analyzed for pH (water and KCl),
ammonium and nitrate contents. Results showed that the use of 4.00 g of
humic acids significantly reduced ammonia volatilization. Treatments with
humic acid also showed significantly higher amount of exchangeable
ammonium and available nitrate compared to treatments without humic acid.
However, there was no significant difference between humic acid without
purification and humic acid purified once. This suggests that purification
could be ignored if large scale extraction of humic acids is to be done. Apart
from reducing the time needed to obtain humic acid, the outcome of this
study will also help to reduce their production cost. |
|---|