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Archives (2003)
A new lease of life
for the lahar-laden fields
by Ma. Lizbeth J. Baroņa |
October-December
2003
|
 Fertilizers
in capsules? It sounds incredible, but for the farmers in
Central Luzon who have been dealing with marginally productive
lands since that fateful day on June 15,1991, this is music
to their ears.
Researchers from the Central Luzon State University(CLSU)
and Industrial Development Technology Institute of the Department
of Science and Technology (ITDI-DOST) have come up with an
applied fertilizer technology that increases nitrogen efficiency
in lahar-laden soils and coarse agricultural lands, the types
of soil the farmers have to till after the Mount Pinatubo
eruption.
Barren lands
When the second largest volcanic eruption of this century
happened more than a decade ago, the world felt its magnitude.
Global temperature was temporarily affected, and nearly 20
million tons of sulfur dioxide was injected to the earth's
stratosphere, sending warning signals to environmentalists
around the globe.
In the surrounding provinces of the devastating
volcano, however, are dwellers whose concern are far graver
than that of the world's. Materials from the eruption blanketed
the countryside, converting formerly productive rice and sugarcane
fields into a barren land.
Even after more than 10 years, lahar from the volcano is still
heavily embedded in the lands. The soil has very low nutrient
content with poor water holding capacity. Heavy leaching of
nutrients is intensive in this type of land, making the application
of fertilizer useless.
Controlled-release
fertilizer (CRF)
Fertilizers are classified in into three broad groups: soluble,
highly soluble, and slow release. Easily soluble fertilizers
are those that release almost 100% of their nutrients into
the environment immediately after they are applied. Controlled
release fertilizers are classified under the slow-release
fertilizer. CR fertilizers are coated with semi-permeable
material through which nutrients are slowly diffused. This
allows CR fertilizers, usually capsulated, to release nutrients
in a determined fashion. In addition, nutrients are released
at a rate and concentration that counters the specific needs
of the plants.
 Researchers
from CLSU and ITDI-DOST studied the nutrient release characteristics
of CR fertilizers in lahar-laden and coarse textured soils
both under submerged and upland conditions on onion, tomato,
and rice.
First, a test was conducted to determine the
release pattern of nutrients from four CRF formulations manufactured
at the ITDI-DOST, These formulations were diammonium phosphate
(13-35-0), potassium chloride (0-0-42), complete fetilizer
(10.5-7.5-8), and urea (37-0-0). Set-up was terminated as
soon as the CR fertilizers released 90-100% of their nutrients.
A pot test was also done to study the efficiency
of CR fertilizer. Pots filled with 8 kg of lahar were planted
with rice, onion, and tomato. Nine treatments were assigned
in each pot, with each treatment replicated 3 times. These
treatments are: control (T1), recommended rate for onion at
190-70-70, rice at 150-35-35, and tomato at 90-60-60 kg NPK/ha
(T2), 1/2 RR (T3), 1/2 CRF (T4), 1/2 RR+CRF (T5), full CRF
(T6), RR+1/2 CRF (T7), RR+1 ton/ha organic (T8), and CRF+1ton/ha
organic (T9). Coated urea and complete fertilizer were weighed
and placed in nylon screen bags. The bags were buried in the
center of the pots at the depth of 5 cm. Nitrogen was applied
thrice in onion and twice in tomato. In rice, N was applied
twice in the first cropping and five times in the second.
Field test of CR fertilizer was done by placing
nylon screen bags containing the formulations, buried 5 cm
below the surface in rain-fed rice field and eggplant fields.
The performance of onion treated with full
CR fertilizer was best among those treated with conventional
inorganic fertilizer, even those applied with combined with
organic fertilizer and inorganic fertilizer. The onion applied
with full CR fertilizer had the largest bulb diameter reaching
27.86 mm, while its marketable yield increased to 91 grams.
It also grew highest among the other tests. The same was observed
in tomato. After being treated with CR fertilizer instead
of the conventional inorganic fertilizer, it yielded the highest
with the difference of 1.65 tons per hectare. Fertilizer efficiency
was also increased from 35 percent in conventional inorganic
fertilizer to 52 percent in CRF.
Rice yield increased with the application of
recommended amount of nutrients from either pure CR fertilizer,
CR fertilizer combined with either organic fertilizer or full
conventional inorganic fertilizer. Those treated with conventional
inorganic fertilizer (150-35-35 kilogram per hectare N-P2O5-K2O
per hectare) grain yield was at 3.73 tons per hectare. Yield
increased by 1.87 tons per hectare or 50 percent. Reasonably,
fertilizer efficiency increased from 57 to 90 percent.
Decades after the tons of lahar and sulfur
material cascaded down the slopes of Mt. Pinatubo, finally
there's a glimmer of hope for the lahar-blanketed rice and
sugar cane fields.
The place does not seem too barren anymore.
Source: Controlled-release Fertilizer for
Increased Nitrogen Efficiency in Lahar-laden an Coarse-Textured
Agricultural Soils by Clarita Aganon, Ariel Mactal, Maribel
Mananguit, Ron Ryan Mark Ucol, Glenda Gagelonia, Nora Dominquez,
Jose Pontevida, A Central Luzon State University(CLSU)PCARRD-DOST-ITDI.
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2003 Articles]
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