Philippine Journal of Crop Science 2003, 28(3): 31-47
Copyright 2005, Crop Science Society of the Philippines
Released February 2005
SOIL FERTILITY STATUS OF PHILRICE CES RICEFIELDS
IN MALIGAYA, NUEVA ECIJA BY SOIL ANALYSIS &
MINUS-ONE-ELEMENT TECHNIQUE (MOET)
T AZHIRI-SIGARI, HC GINES, MC CASIMERO & LS SEBASTIAN
In 2001, soils of 118 blocks of the PhilRice Central Experiment Station (CES) ricefields in Maligaya,
Science City of Muñoz, Nueva Ecija, were sampled and comparatively evaluated for fertility limitations
through the minus-one element technique (MOET) and soil analysis. Soil samples assigned for MOET
were kept moist while samples for laboratory analysis were air-dried and sieved. Each MOET set
included 8 pots filled with 4 kg saturated soil each assigned to one of the eight MOET-based fertilizer
formulas: control, minus N, minus P, minus K, minus Zn, minus S, minus Cu, and complete (with N,
P, K, Zn, S, Cu). The fertilizers were incorporated into the soil before seeding and N was applied 14
days after seeding (DAS). Five pre-germinated seeds of rice cultivar IR64 were initially sown into each
pot, then thinned to three seedlings/pot at 14 DAS. The soil in the pot was maintained submerged and
water depth was increased to 3-5 cm as the seedling grew taller. Weekly observations were made
starting 14 DAS for the occurrence of nutrient deficiency symptoms, and for the measurement of plant
height and tiller count. At 60 DAS, plants were harvested from the base for the measurement of leaf
area (LA), leaf dry weight (LDW), stem dry weight (STDW), total shoot dry weight (TSDW) and relative
shoot dry weight (RSDW). If the RSDW obtained was less than 80% of that in the complete formula, the
soil was considered deficient. Likewise, soil analysis was done to measure pH, %OM, %OC, total N,
available P, K, Zn, S and Cu. Soils with 0.2% total N, 6 ppm Olsen P, 0.2 cmol/kg soil exchangeable K,
1 ppm available Zn, 6 ppm available S and 0.2 ppm available Cu were classified as deficient.
Lack of N in the soil is the only common factor in all soils as determined by both approaches to
analysis for soil nutrient deficiency, suggesting that this is the single most limiting factor in the growth
of the rice plant. However, the MOET results indicate that majority of the soils (72.5%) are multiple
element-deficient, ranging from 2 to 6 nutrient elements, and these cannot simply be ignored. Further
evaluation of the MOET compared with the traditional soil analysis is recommended. In addition, the
MOET can be validated through on-farm observational studies and calibrations.
Keywords minus-one element test, soil analysis, soil fertility limitations
INTRODUCTION
One of the most critical aspects of soil use
and management is the maintenance of soil
productivity, which is affected by soil nutrient
status or soil fertility. Indeed, the ease with
which many nutritional problems can be
corrected and the spectacular results that often
follow, have made soil fertility one of the more
readily accepted aspects of soil management. In
spite of its widespread popularity, however, the
fundamentals of fertility control are not well
understood, a fact that has frequently led to the
improper use of fertilizers.
The paddy soil-rice system has an efficient
nutrient-replenishing mechanism. This is shown
in the fact that in some Asian paddy fields, rice
has been cultivated for hundreds of years
without receiving any fertilizer and yet yields of
1.6 to 2 t/ha have been sustained (Kyuma 1996).
Intensified cropping with increased yield
does remove substantial amounts of nutrients
from the soil that must be replaced to sustain
soil productivity. This having been ignored, the
stagnation of rice yields as recently observed in
the lowlands of Asia has become a major
agronomic concern. Specific reasons for this
include decreasing nutrient productivity and an
increasing imbalance of nutrient supply versus
its removal from the soil (Mutert 1996). Longterm fertility experiments on NPK fertilization
conducted by the International Rice Research
Institute (IRRI) has shown that rice responds
initially only to nitrogen, but after 8-10
consecutive croppings, responses to P and/or K
are observed (De Datta 1988, Cassman et al
1995). As crop yield increases, soil nutrients
other than N, P and K are mined at increased
levels (Descalsota et al 2000). Once nutrient
imbalance takes place, maximum responses to
major fertilizer applications are no longer
obtained.
Descalsota et al (2000) evaluated soil fertility
status of 144 paddy fields in 19 provinces in the
Philippines to identify areas of multiple nutrient
limitations. Based on normally accepted critical
levels of several essential soil nutrient elements
examined, only two sites had sufficient nutrient
supply. Eleven sites had single nutrient
deficiency and the remaining were multiple
nutrient-deficient ranging from two to five
nutrient elements. The study showed a growing
number of rice areas becoming multiple nutrientdeficient.
Soil fertility limitations can be evaluated by
soil analysis, field experiments, plant tissue
analysis, observations on the incidences of
deficiency or toxicity symptoms, and biological
test. Recently a biological method known as
minus-one element technique (MOET) was
developed by PhilRice (Descalsota et al 1999,
2000, 2001). MOET is based on the principle that
plant growth responds to the most limiting
nutrients. The response partly is manifested as
32
reduced plant height and tiller counts, delayed
maturity, smaller panicles and by the presence
of distinct discoloration such as chlorosis,
necrosis and/or streaks. Results of past studies
(Descalsota et al 1999) showed that MOET was
able to identify incipient deficiencies, which
could not be checked by soil analysis.
The present locations of PhilRice experiment
stations represent a diverse spectrum of
landscape and agro-pedological, as well as
climatic conditions. Moreover, the inter- and
intra-spatial variations among sites or stations
could be attributed to the interaction effects of
physical/natural factors and anthropogenic
interactions.
These
factors
often
cause
unexplained anomalies affecting yield results of
experiments within PhilRice stations. To update
the information of their fertility status, and to
compare the efficacy of soil analysis and MOET in
the description of soil fertility, soils of PhilRice
Central Experiment Station (CES) ricefields were
evaluated through both soil analysis and MOET in
2001. In this report, soil fertility limitations of
PhilRice CES ricefields are identified.
METHODOLOGY
For the MOET and soil analysis, the entire
PhilRice CES ricefields were considered. As the
ricefields were composed of blocks separated by
dikes and/or irrigation canals, composite soil
samples (up to 20 cm deep) were collected from
118 blocks. A portion of each sample was airdried and pulverized for the soil analysis and the
other portion kept moist for the MOET.
A net house was installed to contain the
MOET set. Each included eight plastic pots (20 cm
in diameter and 18 cm in height) filled with 4 kg
wet soil, assigned for the following nutrient
fertilizer formulas: complete, control, minus N,
minus P, minus K, minus Zn, minus S and
minus Cu (Descalsota et al 1999). The soil in the
pots was kept submerged for two weeks prior to
seeding. The appropriate nutrients, except N,
were applied and mixed within 3-5 cm of the soil
surface before seeding. Nitrogen was added 14
Fertility Status Of PhilRice CES Soils
days after seeding (DAS). Initially 5 pregerminated seeds of rice cultivar IR64 were sown
into each pot, then thinned to three seedlings/pot
14 DAS. The soil was kept submerged and water
depth was increased to 3-5 cm as the seedlings
grew taller. Tiller count and plant height were
measured weekly starting 14 DAS. Observations
were also made on plant growth patterns and on
the occurrence of deficiency symptoms. At 60
DAS, the rice plants were clipped from the base
and growth factors such as leaf area (LA), ovendried weight of leaf (LDW), stem (STDW), and total
shoot (TSDW) and relative shoot dry weight
(RSDW) were measured. Soils where RSDW (% to
that obtained from respective soil fertilized with
complete fertilizer formula) was less than 80%
were classified as deficient for the corresponding
nutrient element (Descalsota et al 2000).
Likewise, soil samples were analyzed for pH
(1:1 soil: water), organic carbon (OC) and organic
matter content (OM) (by Walkley-Black method),
total N (Kjeldal method), available P (Olsen
method), exchangeable K (ammonium acetate),
available Zn (DTPA), S (turbidimetric method),
and available Cu (DTPA). Following the values
accepted as critically low levels of soil nutrient
content in lowland rice ecosystems (Table 1),
soils with equal to or less than 0.2% N, 6 ppm
Olsen P, 0.2 cmol/kg soil exchangeable K, 1 ppm
available Zn, 6 ppm available S and 0.1 ppm
available Cu, were identified as deficient in those
specific nutrients.
RESULTS
pH
The soil pH not only influences the
occurrence of disease but also the availability of
nutrients for plant growth. Based on soil
analysis, soil pH averaged 5.73 with majority of
the soils (77.5%) having pH equal to or less than
6.1 (Figure 1).
There can be severe Fe toxicity in an acid
sulfate soil (Solivas & Ponnamperuma 1980). For
acid or sulfate soils, there are at least three
approaches. One is breeding and selection for
TA Sigari et al
tolerance to stress; two is soil amendment; and
three is mixed cropping.
Torres et al (1988) found that upland rice
was compatible with cowpeas in upland soils of
pH 4.6-5.0.
Garrote et al (1986) found that in a highly
acidic site (pH 4), application of N alone was
detrimental to crop growth. This was a study to
develop an appropriate fertility management
strategy for upland rice on acid infertile soils.
Thanh-Tuyen & Dionzon (1991) reported on
their study of generating variability in upland
rice cultivars through somaclonal variation for
developing stress-tolerant lines, specifically to
acidic soils (pH 4.8-5.2) in Leyte.
Organic Matter
Organic matter (OM) content of majority of
the soils (82.9%) was more than 2%; the overall
average was 2.46% (Figure 2), which can be
considered a moderate level of OM.
Mandac & Herdt (1978) reported that the
more technically efficient farmers in the
Philippines were located in ‘the better-endowed
environments or in soils with more organic
matter.’
Even so, the soil pH and organic matter
content of the soil could be high but available Zn
could be low (Abilay Jr & De Datta 1978).
A study by Quidez (1978) showed that soils
high in organic matter but were poorly drained
could be deficient in available P, exchangeable K,
and available Zn.
Interestingly, Lantin et al (1990) reported
that in the Philippines, rice production is limited
by problems such as acid sulfate soils and soils
with excess organic matter.
The MOET
The soils in the MOET setup were evaluated
through RSDW. RSDW in minus N averaged 21.5%
and was almost similar to that of control (21.4%);
that of minus P was 78.2%; that of minus K was
92.58; that of minus Zn was 95.4%; that of minus
S was 71.92%; and that of minus Cu was 98.94%
(Table 2).
33
Nitrogen
Figure 3A graphs the data on total N (%) as
determined by soil analysis and Figure 3B as
determined by MOET. The differences in the
Table 1.
to or less than 0.1%, and the N content of the
rest of the soils ranged from 0.1% to 0.19%.
Figure 3B shows that the RSDW equal to or
less than 80% for minus N averaged 21.5% and
Accepted values of critically low levels of soil pH and nutrient
elements in a lowland rice ecosystem
Description
Accepted values of critically low level
Source
pH
3-4 extremely acid
BSWM, personal
communication
4-5 acidic
5-6 Slightly acidic
6-7 slightly neutral
> 7 alkaline
Organic matter
content (%)
Less than 1%
BSWM, personal
communication
C : N ratio
>50 presence of high amounts of biomass
BSWM, personal
communication
15-30 well humified
10 optimum
Total N (%)
< 0.2% low
Descalsota et al
(1999)
Available P (ppm)
Olsen method
< 6 ppm low
Doberman and
fairhurst (2000)
5-10 ppm medium
> 10 ppm high
< 0.2 cmol/kg soil low
Available Zn (ppm)
≤ 1 ppm low
Doberman and
fairhurst (2000)
Available S
≤ 6 ppm low
Doberman and
fairhurst (2000)
Available Cu (ppm)
≤ 0.1 ppm low
Doberman and
fairhurst (2000)
respective data are due to the nature of the
respective analysis. This is in view of the fact
that soil analysis measures what is in the soil
while the MOET measures indirectly the amount
of nutrient that was (or was not) taken by the
plant from the soil. Interestingly, Figure 3A
shows that 26.5% of the soils had total N equal
34
Doberman and
fairhurst (2000)
Exchangeable K
(cmol/kg soil)
was almost equal to that of the control (21.4%).
Available P
The data by soil analysis shows that
available P ranged from 5.2 to 51 ppm, with an
average of 13.7 ppm (Figure 4A).
The data by MOET shows that the RSDW equal
Fertility Status Of PhilRice CES Soils
to or less than 80% for minus P was 78.2%,
indicating that many of the soils are deficient in
phosphorus.
Exchangeable K
As determined by soil analysis, with an
average of 0.23 cmol/kg soil, exchangeable K
ranged within 0.1 to 0.6 cmol/kg soil, with
majority (75.2%) having exchangeable K equal to
or less than 0.2 cmol/kg soil (Figure 5A).
By the MOET, the RSDW equal to or less than
Table 2.
Available S
By soil analysis, available S averaged 13 ppm
with 61.5% of the soils having available S more
than 10 ppm (Figure 7A).
By the MOET, the RSDW equal to or less than
80% for minus S was 69.2%, indicating S
deficiency in majority of the soils (Figure 7B).
Available Cu
By soil analysis, all the soils were identified
with high amounts of available Cu, with an
Relative yield of rice cultivar IR64 obtained by the minus-one-element
technique (MOET)
Treatment
Average Relative Yield
Range
(g.g -1.102)
(g.g -1.102)
Control
21.4
9-44
-N
21.5
9-45
-P
78.2
17.2-163
-K
92.5
20-160
-Zn
95.4
61-187
-S
71.9
15-157
-Cu
98.9
44-156
80% for minus K was 92.58% (Figure 5B). This
indicates that most of the soils are deficient in
the nutrient K.
Available Zn
By soil analysis, most of the soils (85.6%)
were identified with available Zn of more than 1
ppm, with a small percentage (4.25%) having
available Zn more than 5 ppm (Figure 6A). Soil
available Zn averaged 2.68 ppm and ranged from
0.49 ppm to 8.3 ppm.
Measured by the MOET, the RSDW equal to or
less than 80% for minus Zn was 95.4%, which
indicates that a very high number of the soils are
deficient in Zn.
TA Sigari et al
average of 12.40 ppm within the range of 1.4 to
22.4 ppm (Figure 8A).
By the MOET, the RSDW equal to or less than
80% for minus Cu was 32.4%, which indicates
that about one third of these soils are deficient in
this soil nutrient.
Relative Yield Of Control
Similar to minus N, the RSDW of the control
was much lower than 80% (Figure 9). This
means that the control lacks N.
DISCUSSION
Presenting the results of the two approaches
to the determination of soil nutrient deficiency,
35
Figure 10 shows the comparative extent of
deficient soils in particular nutrient element(s)
based on soil analysis and the MOET. Overall, the
data shows that the findings of these two
different approaches are strikingly very
different, except for N, where 100% of the soils
were identified deficient by both evaluation
tests. This suggests that N is the most deficient
of all the nutrients.
With the rest of the individual nutrients, the
data indicates the great differences in the
deficiency values between those determined
through soil analysis and through the MOET. On
one hand, the MOET finds deficiencies in five
nutrients other than N – P, K, Zn, S, and Cu –
ranging from 20% of the soils to 45%. On the
other hand, the soil analysis finds no soils with
deficiency in Cu, and only a few soils with
deficiency in P; it finds a little more of the rest of
the soils deficient in Zn (10%) and in S (5%).
Reyes et al (1985) found that 65% of the soils
they studied were N deficient and over 57% were
Zn deficient, less than 25% deficient in P or K.
Descalsota et al (2003) studied the fertility
status of 144 sites in the Philippines through soil
analysis and found that 90% of the sites were
deficient in 2 or more nutrients. The group of
Descalsota is the one who developed the MOET;
one of their recommendations in the paper cited
above was to use ‘proven technical procedures in
assessing or characterizing’ farms, and/or the
‘development of simplified techniques in nutrient
assessment,’ implying the MOET.
In the current study, by the MOET majority of
the soils (72.5%) were found to be multiple
element-deficient, ranging from 2 to 6 nutrient
elements (Figure 11). In 1990, Lantin et al
reported that cultivated rice suffered from multideficiencies: N, P, Zn, S, and Fe. In the
Descalsota et al paper cited above (2003), 42% of
the sites studied were found multiple-deficient in
nutrients.
Nitrogen deficiency appears to be the one
and only common factor in all soils as
determined by both approaches to analysis for
soil nutrient deficiency. There are two ways to
36
look at this finding, and these are:
One view is to propose that N is the most
important factor enhancing vegetative growth of
the rice plant. According to Brady (1984),
nitrogen is a regulator that governs to a
considerable degree the utilization of K, P and
other nutrient constituents with all plants. The
amount of N in available form is small, while the
quantity withdrawn annually by crop is
comparatively large (Brady 1984). According to
De Datta (1981), a rice crop yielding 7.9t/ha
rough rice and 7t/ha straw removes a total of 123
kg nitrogen from the soil. Much of the nitrogen
in the soil is actively lost from the plant soil
system by plant uptake and removal, leaching,
erosion, and emission of gaseous compounds. In
this study, as the RSDW values of minus N and
the control are compared, the collective impact of
other nutrient elements seems negligible.
Another view is to propose that it is no longer
valid to assert that N is the most limiting
nutrient in lowland rice soils (Descalsota et al
2003). In the current study, the soils were found
to have deficiencies not only in N but also in P,
K, Zn, S, and Cu, ranging from 20% to 45% of the
soils analyzed.
While exchangeable K of 75% of the soils was
around the critical level of 0.2 cmol/kg soil the
frequency of soils identified as K-deficient was
much lower in MOET. According to Tandon &
Sekhon (1988), the non-exchangeable fraction of
K also makes a major contribution of the K
absorbed by crops, thus measurement of
available K can also take this fraction into
account. The non-exchangeable form of K is in
dynamic equilibrium with the available forms
and, therefore, acts as an important reserve of
slowly available K.
Interactive effect of nutrients may either
enhance or depress availability and or uptake of
a particular nutrient element. Luxurious growth
of plants may also accelerate depletion of
nutrient elements especially micronutrients
which otherwise can be in enough amounts to
meet normal growth of plant. Davide (1960)
concluded that the beneficial effect of flooding on
Fertility Status Of PhilRice CES Soils
P depends on the intensity of redox condition of
submerged soil and Fe content. Studies at IRRI
indicate that P fixation in flooded rice is rapid in
acid and neutral soils (De Datta 1981). The
fixation of P is considerably slower in slightly
alkaline soils. Soils containing hydrated Fe and
Al oxides, hollysites, and allophanes fix P in both
upland and lowland soils (De Datta 1981). Zn
uptake is depressed because of an increase in Fe,
Ca, Mn, Cu, and P after flooding. In flooded soils,
formation of Zn-phosphate or ZnS reduces soil
available Zn to the plants. The mobility of Zn is
affected by pH, percentage of clay, organic
matter, Ca and P status. Giordano et al (1974)
showed that Fe and Cu strongly depress both Zn
uptake and translocation. Heavy NPK or nitrogen
fertilizer application intensifies Cu and Zn
deficiencies.
RECOMMENDATIONS
Inasmuch as results of the MOET differ much
from the results of the soil analysis, it is
recommended
that
further
comparative
evaluation of the MOET compared with the
traditional soil analysis be need. The MOET can
be validated through on-farm observational
studies and calibrations.
Acknowledgement
The efforts of M Constancia from BSWM, Mr Richard V Carnage and Mr Numeriano J Corpuz from PhilRice
CES are hereby acknowledged.
LITERATURE CITED
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transplanted and direct-seeded wetland rice. Philippine Journal of Crop Science 3(3): 190-194
Brady N C 1985. The Nature And Properties Of Soils. Macmillan Publishing Company, New York,
USA.
Cassman KG, SK De Datta, DC Olk, JM Alcantara, MI Samson, JP Descalsota & MA Dizon. 1995.
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Chang SC. 1971. Chemistry of Paddy Soils. ASPAC Food Fertilizer. Technology Center Extension
Bulletin 7, 26 pp
Davide PM. 1960, Phosphate Studies In Flooded Soils. Unpublished Ph D dissertation, North
Carolina State College, Raleigh, North Carolina. 167pp
De Datta SK, KA Gomez & JP Descalsota. 1988. Changes in yield responses of major nutrients and
soil fertility under intensive rice cropping. Soil Science 164: 350-358
De Datta SK. 1981, Principles and Practices in Rice Production. John Wiley & Sons, New York,
USA.
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rice soils in the Philippines. Paper presented at the 2nd annual meeting and symposium of the
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Benguet, May 20-21
Descalsota JP, CP Mamaril & GO San Valentin. 2003. Fertility status of rice soils in the Philippines.
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element technique of diagnosing nutrient limitation and balancing fertilizer application in
TA Sigari et al
37
lowland rice soils. Paper presented in 14th National Rice Research and Development Conference,
PhilRice, Maligaya, Muñoz, Nueva Ecija, March 7-9
Descalsota JP, CP Mamaril, GO San Valentin, TM Corton & SR Obien. 2000. Biological method for
diagnosis of nutrient limitations and balancing fertilizer application to lowland rice soils. Paper
presented at the Bureau of Agricultural Research 12th National Research Symposium, Oct 4-5
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Garrote BP, A Mercado Jr & DP Garrity. 1986. Soil fertility management in acid upland
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Kyuma K. 1996. Ecological sustainability of paddy soil-rice system in Asia. In Appropriate Use Of
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Appropriate Use of Fertilizers, held in Taiwan, November 6-14 1995. pp 128-142
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humid tropics: Past development and strategies for the 21st century. Philippine Journal of Crop
Science 15(1): 41-47
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yields in the Philippines. Philippine Journal of Crop Science 3(3): 172-181
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Ponnamperuma FN. 1972. The chemistry of submerged soils. Advances in Agronomy. 2:29-96
Quidez BG. 78. Effects of nitrogen, phosphorus, potassium, copper, molybdenum and zinc on the
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Thanh-Tuyen Nguyen T & Merlina N Dionzon. 1991. Somaclonal variation in upland rice. Philippine
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upland rice-based cropping systems. Philippine Journal of Crop Science 13(2): 91-98
38
Fertility Status Of PhilRice CES Soils
30
25
20
15
10
5
0
4. 9-5. 2
5. 2-5. 5
5. 5-5. 8
5. 8-6. 1
6. 1 -6. 4
6.4-6. 7
6. 7-7
pH
F i g 1 . F r e q u e n c y d i st r i b u t i o n o f P h i l R i c e
C E S c r o p f i e l d so i l s f o r p H
40
35
30
25
20
15
10
5
0
1 - 1 .5
1 .5 - 2
2 - 2 .5
2 .5 - 3
3 - 3 .5
3 .5 - 4
O r g a n i c m a t t e r c o n t e n t ( %)
F i g 2 . F r e q u e n c y d i st r i b u t i o n o f P h i l R i c e C E S
c r o p f i e l d so i l s f o r o r g a n i c m a t t e r c o n t e n t
TA Sigari et al
39
40.00%
35.00%
30.00%
25.00%
20.00%
1 5.00%
1 0.00%
5.00%
0.00%
.0 4 - .0 7
.0 7 - .1 0
.1 - .1 3
.1 3 - .1 6
.1 6 - .1 9
T o t a l N ( %)
Fig 3. A
F r e q u e n c y d i st r i b u t i o n o f
P hilR ic e C ES
c r o p f i e l d so i l s f o r T o t a l N ( %)
50
45
40
35
30
25
20
15
10
5
0
,8 - 1 5
1 5 -2 2
2 2 -2 9
R S D W ( g .g
2 9 -3 6
-1
.1 0
2
3 6 -4 5
)
Fi g 3. B Fr equency di st r i but i on of P hi l R i ce C E S
c r o p f i e l d s o i l s f o r R SD W i n mi n u s N e l e me n t t e s t
40
Fertility Status Of PhilRice CES Soils
40
35
30
25
20
15
10
5
0
,5-1 0
,1 0-1 5
1 5-20
20-25
25-30
30-35
35-40
40-45
45-51
Available P ( ppm )
Fig 4.A
F r e q u e n c y d i st r i b u t i o n o f
P hilR ic e C ES
c r o p f i e l d so i l s f o r a v a i l a b l e P ( p p m )
40
35
30
25
20
15
10
5
0
1 7-38
Fi g 4. B
38-59
59-80
80-1 01
1 22-1 43
1 43-1 64
Fr eque ncy di st r i but i on of P hi l R i c e C E S cr op f i e l d
s o i l s f o r R SD W
TA Sigari et al
1 01 -1 22
RSDW
i n mi n u s P e l e me n t t e s t
41
80
70
60
50
40
30
20
10
0
.1 - .2
.2 - .3
.3 - .4
.4 - .5
.5 - .6
E x c ha ng e a b le K ( c mo l/ k g )
Fig 5.A
F r e q u e n c y d i st r i b u t i o n o f P h i l R i c e C E S
c r o p f i e l d so i l s f o r e x c h a n g e a b l e K
40
35
30
25
20
15
10
5
0
20-40
40-60
60-80
80-1 00
1 00-1 20
1 20-1 40
1 40-1 60
R SD W
Fig 5 .B
F r e q u e n c y d i st r i b u t i o n o f P h i l R i c e C E S
c r o p f i e l d so i l f o r R S D W i n m i n u s K e l e m e n t t e st
42
Fertility Status Of PhilRice CES Soils
40
35
30
25
20
15
10
5
0
0-1
, 1 -2
, 2-3
, 3-4
, 4-5
, 5-6
, 6-7
, 7-8
, 8-9
A vailab le Z n ( p p m)
Fig 6 . A
F r e q u e n c y d i st r i b u t i o n o f C E S c r o p
f i e l d so i l s f o r a v a i l a b l e Z n
50
40
30
20
10
0
60-80
80-1 00
1 00-1 20
1 20-1 40
1 40-1 60
1 60-1 80
1 80-200
R SD W
Fig. 6.B
F r e q u e n c y d i st r i b u t i o n o f P h i l R i c e C E S
c r o p f i e l d so i l s f o r R S D W i n m i n u s Z n e l e m e n t t e st
TA Sigari et al
43
45
40
35
30
25
20
15
10
5
0
3. 5-6. 75
6. 75-1 0
1 0-1 3. 25
1 3. 25-1 6. 5
1 6. 5-1 9. 75
1 9. 75-23
A v a ila b le s ulf ur ( p p m)
Fig 7.A
F r e q u e n c y d i st r i b u t i o n o f P h i l R i c e C E S
c r o p f i e l d so i l s f o r a v a i l a b l e su l f u r
35
30
25
20
15
10
5
0
1 4-36
36-58
58-80
80-1 02
1 02-1 24
1 24-1 46
1 46-1 68
R SD W
F i g 7 . B F r e q u e n c y d i st r i b u t i o n o f P h i l R i c e C E S
c r o p f i e l d so i l s f o r R S D W i n m i n u s S e l e m e n t t e st
44
Fertility Status Of PhilRice CES Soils
35
30
25
20
15
10
5
0
1 . 4-4.4
4. 4-7. 4
7. 4-1 0. 4
1 0. 4-1 3.4
1 3. 4-1 6. 4
1 6. 4-1 9. 4
1 9.4-22.4
A vailab le C u ( p p m)
F i g 8 . A F r e q u e n c y d i st r i b u t i o n o f P h i l R i c e C E S
c r o p f i e l d so i l s f o r a v a i l a b l e C u
35
30
25
20
15
10
5
0
40-60
60-80
80-1 00
1 00-1 20
1 20-1 40
1 40-1 60
1 60-1 81
RSDW
TA Sigari et al
45
60
50
40
30
20
10
0
,6 -1 7
1 7 -2 8
R elat ive yield ( g .g
2 8 -3 9
-1
.1 0
2
3 9 -5 0
)
F ig 9 . F r e q ue nc y d is t r ib ut io n o f P hilR ic e
C E S cro p f ield so il f o r relat ive yield in
c o nt r o l
MO ET %
LA B %
100
90
80
70
60
50
40
30
20
10
0
N
P
K
Zn
S
Cu
N u t r i e n t e l e me n t
F i g 1 0 . F r e q u e n c y o f so i l s i d e n t i f i e d d e f i c i e n t t
t h r u m i n u s- o n e e l e m e n t t e st a n d so i l a n a l y si s
46
Fertility Status Of PhilRice CES Soils
30
one element
two elements
25
three elements
four elements
20
five elements
six elements
15
10
5
0
Number of elements
Fig 11. Frequency of soils identified in one or more elements through MOET
TA Sigari et al
47