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Comparative Performance of Biofertilizers on Irrigated

Lowland Rice (Oryza sativa L.)

Article · May 2012

DOI: 10.32945/atr3412.2012

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Annals of Tropical Research 34[1]:24-41(2012)
© VSU, Leyte, Philippines

Comparative Performance of Biofertilizers on

Irrigated Lowland Rice (Oryza sativa L.)

Michelle B. Castillo and Cezar P. Mamaril

Philippine Rice Research Institute Los Baños, College 4031 Laguna, Philippines

ABSTRACT

Biofertilizers have been claimed as an alternative source of nutrients

for plants in order to increase yield and reduce the inorganic fertilizer use
by 50%. Sixteen (16) trials were undertaken nationwide covering the
provinces of Ilocos Norte, Isabela, Nueva Ecija, Laguna, Camarines Sur,
Negros Occidental, Leyte, Samar, Bohol, Agusan, and North Cotabato during
wet and dry seasons of 2008-2010 to verify the effectiveness of
biofertilizers (Bio N, Vital N, BioCon) under lowland or anaerobic
ecosystem. The experiment consisted of 9 treatments which include
control, and biofertilizers applied alone or in combination with inorganic
fertilizers either at one-half or full recommended rate. Generally, the
biofertilizers evaluated showed no positive effect on grain and straw yields
of lowland rice as well as on yield components such as plant height, tiller
count, number of productive tillers, spikelet count, number of filled grains
and unfilled grains, and weight of 100 grains. The positive effect of BioCon,
Vital N and Bio N on root length at seedling stage may be attributed to the
microorganisms producing plant growth hormones which might have
enhanced root growth under “dapog” seedbed condition. This is probably
because the condition in the seedbed is not totally anaerobic. However, the
beneficial effect on root growth was not sustained and reflected on the
yield when the seedlings were transplanted in the field. It is quite evident
that biofertilizers evaluated were not effective under anaerobic condition.

Key Words: anaerobic condition, biofertilizers, microorganisms, root

growth

Correspondence: M. B. Castillo. Address: Philippine Rice Research Institute Los Baños, College 4031
Laguna, Philippines. E-mail:miccute_21@yahoo.com.ph / mbcastillo@email.philrice.gov.ph . Tel/Fax:
049-501-1917
26
Castillo and Mamaril

INTRODUCTION

Demand to produce food crops especially rice has increased in recent

years not only to improve the livelihood of farmers but most especially to
avert food shortage due to ever-increasing population. However, cost of
producing rice has been rising due to increasing cost of fertilizers making it
difficult for subsistence farmers to improve their yields and earn more
income. With these constraints, more farmers are motivated to use
alternative products including locally produced nutrient sources to
improve soil productivity and crop yields at lower cost.
Numerous commercial products are now introduced in the market
which claims to improve soil productivity, enhance crop growth, and
increase yields. Besides commercial organic fertilizers and compost, plant
growth promoting hormones, and other products containing varying types
of microorganisms with various functions are in the market. Some of them
are called microbial inoculants, microbial activators, biofertilizers etc. but
they are generally categorized as “microbial fertilizers”. These microbial
fertilizers or biofertilizers such as Bio N, Vital N, BioCon, etc. are said to
contain unique and beneficial strains of soil microorganisms that can fix
atmospheric nitrogen, mobilize and release nutrient elements in the soil,
produce plant growth promoting substances that will enhance the growth
of the crop, promotes faster decomposition of organic materials, serve as
biocontrol agent against pest and diseases, keeps plants healthy and green
even during droughts and pest infestation, and maintains the soil natural
properties. The microorganisms contained in Bio N were two strains of
bacteria namely Azospirillum lipoferum and Azospirillum brasilense. The
effective microorganism in Vital N is also Azospirillum while BioCon
contains the fungi Trichoderma with the following species T.
parceramosum, T. pseudokoningii, and a UV-irradiated strain of T.
harzianum (Javier and Brown, 2009).
Advocates of these biofertilizers claim that these materials could
replace the nitrogen requirement of plants by about 30 to 50 percent, thus
reducing the cost of producing crops (Javier and Brown, 2009).
Unfortunately, the perception that these materials can be considered as
fertilizers is questionable because most of them only provide small amount
of nutrients or none at all, unless fortified as in the case of Vital N which is
supplemented with vitamins and minerals, which is required by high
yielding crops, be it rice or any other crop. In a study conducted by Perrig et
al. (2007), negative results were obtained in terms of siderophore
 27
Comparative performance of biofertilizers

production and phosphate solubilization of Azospirillum brasilense

conducted in a chemically defined medium. Siderophores are small, high-
affinity iron chelating compounds secreted by microorganisms such as
3+
bacteria and fungi which are amongst the strongest soluble Fe binding
agents known. Phosphate solubilization refers to hydrolyzing organic and
inorganic phosphorus from insoluble compounds.
Proponents of these products have claimed that numerous
experiments have been undertaken and have shown positive benefits.
However, many of their claims were anecdotal in nature or the studies were
not properly designed statistically or the results were not statistically
analyzed. Moreover, several of the studies failed to show any additional
benefit (Parr et al., 1984). The organisms present in most, if not all, of these
biofertilizers have been isolated from soils under aerobic conditions.
Therefore, it is likely that these organisms may give beneficial effects only
on crops grown under aerobic condition but not on irrigated lowland rice
which is grown in anaerobic condition. Flores (2008) conducted a field trial
on irrigated rice which showed that the biofertilizers evaluated did not give
positive benefit.
Because of these conflicting claims about these products, it was
imperative that a properly conducted nationwide study was undertaken to
verify the effectiveness of some of the biofertilizers under anaerobic
condition, with irrigated lowland rice as test crop, to verify further the
performance of these materials.
The specific objectives of the study are to (1) determine the
comparative performance of three biofertilizers namely, Bio N, Vital N and
BioCon under anaerobic condition, (2) determine the soil and
environmental conditions that influence if any, the performance of these
biofertilizers and (3) generate a general guideline where these
biofertilizers can be effectively used to increase crop yields and sustain soil
productivity.

MATERIALS AND METHODS

The study was conducted in collaboration with PhilRice (Philippine

Rice Research Institute) branch stations, DA-RFUs (Department of
Agriculture-Regional Field Units) and SUCs (State Universities and
Colleges). Sixteen (16) field trials were conducted at different locations of
the country with 7 dry season and 9 wet season croppings from 2008-
2010. The experimental areas were located at Quiling, Batac, Ilocos Norte;
28
Castillo and Mamaril

San Mateo, Isabela; Maligaya, Muñoz, Nueva Ecija; Los Baños, Laguna;
Masaya, Bay, Laguna; San Jose, Pili, Camarines Sur; Murcia, Negros
Occidental; Abuyog, Leyte; San Jorge, Samar; Ilijan Norte, Tubigon, Bohol;
Gabi, Ubay, Bohol; Basilisa, Agusan; and Bual Norte, Midsayap, North
Cotabato.

Soil Characteristics and Rice Varieties Used in the Study

Different varieties of rice such as traditional, selection, certified, and

hybrid were used depending on the variety widely grown in the area. Table
1 shows the location and cropping season of the biofertilizer trials as well
as the characteristics of the rice varieties used. Soil samples were analyzed
chemically at the Analytical Soils Laboratory, University of the Philippines
at Los Baños, Laguna (ASL-UPLB). The soil chemical properties were quite
variable with pH ranging from acidic to basic, 5.1 to 8, respectively; organic
matter (OM) ranged from very low to high, 0.53% to 5.68%; total nitrogen
(N) content ranged from highly deficient to sufficient, 0.04% to 0.28%;
available phosphorus (P), 0.8-100 ppm; exchangeable potassium (K), 0.05-
1.85 cmol(+) kg-1 soil; sulfate-sulfur (SO4-S), 2-342 ppm; zinc (Zn), 0.03-24
ppm; copper (Cu), 0.2-36 ppm (Table 2). More nutrients were found to be
deficient using Minus-one Element Technique (PhilRice, 2008) analysis
compared to chemical analysis for irrigated soils. The rates of inorganic
fertilizer applied varied among sites and were decided by the collaborators
as shown in Table 3.
Table 1. Location, cropping season, and characteristics of rice varieties used in the
biofertilizer trials
DISEASE AND INSECT PEST REACTIONS AGRONOMIC CHARACTERISTICS
Max.
No. Experimental Site Season Variety used Blast BLB Tungro BPH GLH Stemborer Ave. yield yield Maturity Height
(ton ha-
(ton ha-1) 1) (days) (cm)
Batac, Ilocos Norte and WS 2009 PSB Rc82
1 Muñoz, Nueva Ecija DS & WS 2009 (Peñaranda) R I S I MS I 5.4 12 110 100
NSIC Rc136H
2 San Mateo, Isabela DS 2008 (Mestiso 7) I I S MS MS MR (MS) 6.7 10.6 107 108

4 Bay, Laguna DS 2008 MS 6 - - - - - - - - 105-110 -

NSIC Rc146 (PJ7)
5 Los Baños, Laguna DS 2009 TPR S I S S MS MR (MS) - 6.9 110 101

6 Pili, Camarines Sur WS 2009 SR 10 - - - - - - - - 90-100 -

NSIC Rc120
7 Murcia, Negros Occidental WS 2009 (Matatag 6) I I R MR MR MR 4.8 5.1 109 91
NSIC Rc150
8 Abuyog, Leyte WS 2009 (Tubigan 9) I I S (S) MS MS - 0 8.5 109 96
NSIC Rc154
9 Abuyog, Leyte DS 2009 (Tubigan 11) S I S (S) I I - 0 8.1 110 95

San Jorge, Samar, WS & DS 2009

PSB Rc18 (Ala) I I I I I MS 5.1 8.1 123 102
10 Midsayap, North Cotabato DS 2010
WS 2009 & WS NSIC Rc158
I I S (I) MS I - 6 8.1 113 94
11 Ubay and Tubigon, Bohol 2009 (Tubigan 13)
NSIC Rc160
12 Basilisa, Agusan VWS 2009 (Tubigan 14) TPR I I S (S) MS I - 5.6 8.2 - 96

I: Intermediate, R: Resistant, S: Susceptible, S(S): Susceptible both for controlled and field condition MS: Moderately
susceptible, MR: Moderately resistant ,MR(MS): Moderately resistant under controlled but moderately susceptible
under field condition, -: no information provided
Source: PhilRice: Philippine Seedboard (PSB)/NSIC Varieties
 29
Comparative performance of biofertilizers

Table 2. Soil nutrient status of lowland sites based on chemical laboratory analysis
Cropping OM N P K SO4 Zn Cu Textural
No. Experimental Site Season pH % % (Olsen) cmol(+) ppm ppm ppm Grade
ppm kg-1 soil
1 Batac, Ilocos Norte WS 2009 8.0 1.71 0.09 27.0 1.09 224 0.50 0.2 Silty Clay
2 San Mateo, Isabela DS 2008 6.0 2.48 0.13 *4.3 0.28 86 11.00 33.0 Clay loam
3 Maligaya, Nueva Ecija DS 2009 5.3 2.93 0.12 *1.8 0.13 122 12.00 36.0 Clay
4 Maligaya, Nueva Ecija WS 2009 5.8 2.67 0.13 *9.0 0.19 66 9.00 19.0 Silty Clay Loam
5 Bay, Laguna DS 2008 6.8 5.68 0.24 21.0 0.71 88 15.00 20.0 Clay loam
6 Los Baños, Laguna DS 2009 6.3 - 0.14 *45.0 0.98 46 9.00 24.0 Silty Clay
7 Pili, Camarines Sur WS 2009 5.1 4.61 0.25 *0.8 0.17 114 3.00 18.0 Clay
8 Murcia, Negros Occidental WS 2009 5.1 1.01 0.05 *21.0 0.05 51 2.00 4.0 Sandy Clay Loam
9 Abuyog, Leyte WS 2009 6.4 3.61 0.16 32.0 0.35 342 17.00 11.0 Sandy Loam
10 Ubay, Bohol WS 2009 5.4 0.61 0.04 *4.8 0.17 75 6.00 3.0 Sandy Loam
11 Tubigon Bohol WS 2009 6.9 2.64 0.15 41.5 0.53 235 11.00 27.0 Silty Clay
12 Basilisa, Agusan WS 2009 6.0 2.48 0.13 *4.3 0.28 70 0.03 33.0 Loam
13 Midsayap, North Cotabato DS 2010 6.2 4.12 0.28 *71.0 0.44 70 24.00 31.0 Silty Clay

pH: Acidity or alkalinity, OM: Organic matter, N: Total Nitrogen, P: Available Phosphorus, K:
Exchangeable Potassium, SO4: Sulfate, Zn: Zinc, Cu: Copper, *: P determination using Bray P2 Method
Accepted Critical Level of Nutrients Under Irrigated Condition: Less than 2% organic matter or 0.20%
N = N deficient, Less than 10 ppm Olsen P = P deficient, Less than 0.20 cmol/kg Exch. K = K deficient,
Less than 1.0 ppm Zn = Zn deficient, Less than 10 ppm Avail. S (SO4-S) = S deficient, Less than 0.20
ppm Avail. Cu = Cu deficient

Table 3. Comparison of diagnostic tools (chemical analysis and MOET) in identification

of nutrient deficiencies and fertilizer rates applied at different sites
No. Experimental Site Cropping Deficiencies based Deficiencies Fertilizer
Season on soil chemical based on Rates Applied (kg)
analysis MOET results (N-P2O5-K2O-SO4-Zn)
1 Batac, Ilocos Norte WS 2009 N,Zn N,P,Zn 48-60-0-0-9
2 San Mateo, Isabela DS 2008 N N,P,K 120-60-60
3 Maligaya, Nueva Ecija DS 2009 N,P,K N, P, K, S 88-42-72-12
4 Maligaya, Nueva Ecija WS 2009 N,P,K N,P,K,S 90-30-30-25
5 Bay, Laguna DS 2008 None N,S 120-20-20-20
6 Los Baños, Laguna DS 2009 N N,S 120-0-0-24
7 Pili, Camarines Sur WS 2009 P,K N,P,K 25.5-0-25.5
8 Murcia, Negros Occidental WS 2009 N,K N,K,S 46-0-30
9 Abuyog, Leyte WS & DS 2009 N N,K,S 100-0-30-34
10 San Jorge, Samar WS & DS 2009 - N 50-0-0
11 Ubay, Bohol WS 2009 N,P,K N,P 47-30-0
12 Tubigon Bohol WS 2009 N N,P,K 51-28-58
13 Basilisa, Agusan VWS 2009 N,P,K,Zn N,P,K,S,Zn 78-21-51-12
14 Midsayap, North Cotabato DS 2010 None N 120-0-0

-: No data provided

Each of the sites was characterized by climatic type, soil type consisting
of a series name and textural grade. A series is a group of soils that have the
same genetic horizons, similar major morphological characteristics, and
similar parent material. It comprises of soils having essentially the same
general color, structure, consistency, range of relief, natural drainage
condition, and other important internal and external characteristics.
Lowland rice was planted to different relief or topography from level,
undulating, rolling to hilly. In terms of drainage and permeability, not all
sites planted to rice are poorly drained especially those located in sloping
areas, which are prone to drought and erosion. Soil color, an indicator of soil
30
Castillo and Mamaril

fertility varied among sites. Darker soil color (dark brown to black) suggest
more fertile while lighter soil color such as light reddish brown is less
fertile (Table 4).

Experimental Design and Crop Establishment

There were nine (9) treatments in all sites arranged in Randomized

Complete Block Design (RCBD) and replicated 3 times. The minimum plot
size used was 4 x 5 m (20 m2). The treatments are as follows: (T1) Control,
(T2) ½ recommended rate of inorganic fertilizer (RR), (T3) Full rate of
inorganic fertilizer (FRR), (T4) Bio N only, (T5) Bio N + ½ RR, (T6) Vital N
only, (T7) Vital N + ½ RR, (T8) BioCon only, and (T9) BioCon + ½ RR.
Table 4. Climate and soil characterization of the experimental sites
No Source of Permeabilit
. Experimental Site Type of Soil Type Relief Drainage Parent Soil Color y
Climat
e Internal External Material
1 Quiling, Batac, Ilocos I San Manuel clay Level Good Good Alluvial Grayish brown to -
Norte deposits brown
2 San Mateo, Isabela - San Manuel - - - - - -
silty clay
3 Maligaya, Nueva - Maligaya clay - - - - - -
Ecija
4 Masaya, Bay, Laguna I Calumpang silty Level to - - Volcanic tuff Brownish gray to dark -
clay undulating gray
5 Los Baños, Laguna I Lipa Clay Undulating to - - Volcanic tuff Brown to dark brown -
rolling
6 San Jose, Pili, II and Pili Clay Level to nearly Poor Poor Older alluvial - Slow
Camarines Sur IV level deposits
7 Murcia, Negros I and III Guimbalaon - - - Older - -
Occidental loam alluvium
8 Abuyog, Leyte I and IV San Manuel Level Fair Fair Alluvial Dark gray or grayish -
loam deposits brown
9 San Jorge, Samar II and San Manuel clay Nearly level Good to Good to fair - Brown to grayish -
IV fair brown
10 Gabi, Ubay, Bohol IV Ubay loam Rolling Good to Good to Shale, Grayish brown to light Fast
excessive excessive sandstone or reddish brown
conglomerate
11 Ilijan Norte, Tubigon IV Annam clay Rolling and hilly - - Conglomerat Brown, reddish brown Fast
Bohol e and Basalt to brick red
12 Bual Norte, Brown, dark brown,
Midsayap, North Level to nearly Alluvium of dark gray to almost
Cotabato B Kabacan clay level Poor Poor mixed origin black -

Types of Climate: I - Two pronounced seasons: dry from November to April, wet during the rest of
the year, II - No dry season with a very pronounced maximum rainfall from November to January
III - Season not very pronounced; relatively dry from November to April and wet during the rest of
the year, IV - Rainfall more or less evenly distributed throughout the year, B - No very pronounced
maximum rain period and no dry season
Sources: Alicante et al. 1948, Alicante et al. 1951, Barrera et al. 1969, Barrera et al. 1954, Lucas et al.
1965, Manloňgat et al. 1968, Mojica et al. 1963, Mojica et al. 1952, Simon et al. 1975

The rate and method of application of the biofertilizers were based on

the manufacturers' recommendations. The rates of biofertilizers applied
-1 -1
for Bio N were 400 g ha for 40 kg inbred rice and 200 g ha for 20 kg hybrid
rice. During the wet season cropping of lowland rice at Nueva Ecija, 800 g of
-1 TM
Bio N per hectare was applied. For Vital N, 100 g ha Vital N Green was
 31
Comparative performance of biofertilizers

-1
used. For Biocon, 250 g ha was applied for 20 kg hybrid or 40 kg inbred
rice. All the biofertilizers used in the study were purchased directly from
the respective manufacturers to insure that the microorganisms in the
products were still viable. All the three biofertilizers used were applied
through seed coating before incubation period except for experiments
conducted in Bohol wherein the biofertilizers were applied through
soaking of rice roots to dilute solution of biofertilizers for at least 1 h before
transplanting.

Parameters Measured

Root development of the rice seedlings before transplanting were

measured in terms of root length. In “dapog” preparation of seedbed, 10
plants were picked at random from each treatment before transplanting
and the average length of roots were recorded.
Grain and straw yields, yield components such as plant height, tiller
count, productive tiller count were measured and recorded. Other yield
components such as spikelet count, number of filled and unfilled grains,
and weight of 100 grains were also measured in some sites. Grain and straw
2
yields were obtained from a harvested area of 3 x 4 m per plot. Grain yield
-1
was expressed in tons ha at 14% moisture content while straw yield was
expressed in oven-dried weight. Samples consisting of 12 hills randomly
selected at the inner borders of each plot were collected at harvest to
determine the growth response of various treatments on plant height,
number of tillers, and number of productive tillers. Also from the 12 hills, 2
panicles per hill were randomly selected having a total of 24 panicle
samples per plot. These samples were measured for number of spikelets,
filled, and unfilled grains. The relative weight of grains per plot was
determined by weighing 100 filled grains collected from the 24 panicles.

Data Analysis

Statistical analysis using SAS 9 program was done to determine the

differences between treatment means at 5% level of significance by Least
Significant Difference (LSD).
32
Castillo and Mamaril

RESULTS AND DISCUSSION

Effects of the Biofertilizers on Root Development

The microorganisms present in biofertilizers are said to encourage

longer, stronger and well developed-root system to explore larger volume
of soil thus increase the nutrient absorption capacity of the plant (Javier
and Brown, 2009). Moreover, certain soil microorganisms are said to
produce growth hormones which induce root growth. Cornejo et al. (2009)
reported that wild-type arabidopsis seedlings inoculated with either
Trichoderma virens or Trichoderma atroviride showed characteristic auxin-
related phenotypes, including increased biomass production and
stimulated lateral root development. When grown under axenic
conditions, T. virens produced the auxin-related compounds indole-3-
acetic acid, indole-3-acetaldehyde, and indole-3-ethanol. Perrig et al.
(2007), showed an intrinsic capacity of Azospirillum strains Az39 and Cd to
produce and release various growth-promoting compounds in chemically
defined media through direct physiological mechanisms such as
phytohormones (IAA, Z, GA, ABA, ethylene, and growth regulators
putrescine, spermine, spermidine) and cadaverine (CAD) production in
addition to biological nitrogen fixation.
Table 5. Comparison of root length before transplanting of irrigated rice after plant as
affected by different fertilizer treatments
Root length (cm)
Pili, Midsayap,
Masaya, Maligaya, Basilisa, San Jorge, Batac, Ilocos
Abuyog, Leyte Camarines North
Laguna Nueva Ecija Agusan Samar Norte
Sur Cotabato

DS 2008 WS 2009 DS 2009 DS 2009 VWS 2009 WS 2009 DS 2010

NSIC NSIC
Treatments MS 6 Rc150 Rc154 PSB Rc82 NSIC Rc160 PSB Rc18 PSB Rc82 SR 10 PSB Rc18
1. Control 5.7 b 5.6 b 4.5 c 11.6 a 7.7 c 47.3 b 54.9 b 10.2 a 8.2 a
2. Bio N only 6.4 ab 9.0 a 6.0 bc 10.2 a 10.5 b 77.8 a 56.9 b 10.9 a 7.4 ab
3. Vital N only 7.0 ab 4.3 b 7.4 b 10.9 a 7.2 c 56.6 b 96.6 a 10.6 a 8.0 a
4. BioCon only 7.8 a 5.6 b 9.8 a 11.5 a 11.3 a 60.5 b 55.3 b 10.7 a 5.9 b

DS: Dry season, WS: Wet season

Results in Table 5 showed that in some cases Bio N, Vital N and BioCon-
treated seedlings had significantly longer roots than the untreated plants.
BioCon increased significantly the rice root length of MS 6 (Laguna), NSIC
Rc154 (Leyte) and NSIC Rc160 (Agusan) over control. Likewise, Bio N
showed a positive effect on root length of NSIC Rc150 (Leyte) and PSB Rc18
(Samar) while Vital N had a significant effect on the root length of PSB Rc82
(Ilocos Norte). However, this effect was only observed at the seedling
 33
Comparative performance of biofertilizers

(“dapog”) stage and such phenomenon did not persist through the entire
growth stage of the crop as it should have been reflected in the yield
obtained. This could be due to the change in soil condition from aerobic at
seedbed stage to anaerobic when transplanted in the field. A “dapog”
seedbed is not totally anaerobic because it makes use of double-layered
plastic mosquito nets as linings on top of the soil where the seeds are sown
or simply a thin layer of soil embedded in plastic or banana stalks. Being
aerobic microorganism, they cannot survive under anaerobic condition.

Grain Yield

Grain yields at each of the irrigated rice experimental sites are

presented in Table 6. In general, the highest yield was obtained from plots
receiving the full dose of recommended inorganic fertilizer (FRR). It was
followed by the treatments with one-half rate of inorganic fertilizer (1/2
RR) which is not significantly different from the yields obtained by ½ RR
plus biofertilizers. Statistically, control plots had the lowest yield. However,
the yield attained by the plots treated with biofertilizer alone did not vary
significantly with the control plots. This trend is clearly illustrated in
Figure 1 where average yields of all treatments across all sites for wet and
dry season croppings are shown. During the dry season, the highest yield
was obtained by FRR with 5.6 t ha-1. Yield of biofertilizers only and the
-1
control ranged from 3.7-3.8 t ha while treatments with ½ RR with or
without biofertilizers yielded 5.0 t ha-1. In the wet season, the control and
biofertilizers applied alone attained yields from 3.1 to 3.2 t ha-1 which were
the lowest, while ½ RR applied alone or in combination with biofertilizers
had 3.8 to 4.0 t/ha. This suggests that the organisms in the biofertilizers
tested could not persist under anaerobic or saturated soil conditions, thus
unavailable to fix atmospheric N as claims.
While there were sites (Laguna, Camarines Sur, Samar, and Agusan)
where the differences were not quite appreciable between treatments
receiving inorganic fertilizers alone as against biofertilizers applied alone
or in combination with inorganic fertilizers, it was evident that
biofertilizers did not show any positive effect on the grain yield of irrigated
rice. There were no significant differences observed between the fertilizer
treatments. Some other factors might have affected the yields obtained,
thus, it was difficult to draw conclusion from the results. In Laguna, NSIC
Rc146 established during 2006 dry season yielded low, 3.1-3.9 t ha-1, due to
heavy rainfall and unfavorable weather conditions that occurred during
34
Castillo and Mamaril

Table 6. Comparison of grain yields at 14% MC of irrigated rice as affected by different

fertilizer treatments
Grain Yield (t ha-1)
Murcia, Pili,
San Los Batac, Midsayap
Masaya, Maligaya, Basilisa, San Jorge, Ubay, Tubigon Negros Cama
Mateo, Abuyog, Leyte Baños, Ilocos , North
Laguna Nueva Ecija Agusan Samar Bohol , Bohol Occiden rines
Isabela Laguna Norte Cotabato
tal Sur
DS
WS DS WS VWS DS WS DS
DS 2008 200 WS 2009 DS 2010
2009 2009 2009 2009 2009 2009 2009
9
Mestis NSIC NSIC NSIC NSIC PSB NSIC
MS 6 PSB Rc82 PSB Rc18 NSIC Rc158 SR 10 PSB Rc18
Treatments o7 Rc150 Rc154 Rc160 Rc146 Rc82 Rc120
3.4
1. Control 4.6 c 2.7 b 1.9 d 3.3 c 5.2 b 3.9 b 3.2 b abc 3.5 b 3.8 b 3.7 d 3.9 bcd 3.3 d 1.8 d 2.3 b 3.2 b
5.2
2. 1/2 RR 6.0 b 5.6 a 2.9 abc ab 6.7 a 5.5 a 4.0 ab 3.9 ab 4.1 ab 4.2 ab 5.2 ab 3.7 cd 4.8 a 2.4 bc 2.8 a 3.6 ab
3. FRR 7.8 a 6.5 a 3.5 a 5.9 a 6.9 a 5.2 a 3.8 ab 3.9 ab 3.7 ab 4.2 ab 5.7 a 4.9 a 4.7 a 3.3 a 2.7 a 4.0 a
4. Bio N only 4.4 c 3.7 b 2.2 cd 3.5 c 5.3 b 4.3 b 3.5 ab 3.1 c 4.4 a 4.2 ab 3.4 d 3.5 d 2.6 ef 1.7 d 2.9 a 3.2 b
5. Bio N + 1/2
RR 6.2 b 6.0 a 2.6 bcd 4.6 b 6.8 a 5.3 a 3.8 ab 3.9 a 3.9 ab 4.0 ab 4.6 c 3.8 cd 4.2 bc 2.3 bcd 2.7 a 3.6 ab
3.3
6. Vital N only 4.6 c 3.1 b 2.3 bcd 3.2 c 5.1 b 3.9 b 3.5 b abc 4.1 ab 4.1 ab 3.6 d 4.3 abc 2.4 f 1.7 d 2.8 a 3.1 b
7. Vital N + 3.6
1/2 RR 6.3 b 5.7 a 3.1 ab 4.5 b 6.8 a 5.4 a 4.4 a abc 4.2 ab 4.4 a 4.8 bc 4.5 ab 4.0 c 2.6 b 2.8 a 3.5 ab
8. BioCon only 4.8 c 3.6 b 1.9 d 3.0 c 5.0 b 3.9 b 4.1 ab 3.2 bc 4.0 ab 4.0 ab 3.6 d 3.5 d 3.0 de 1.9 cd 2.7 a 3.1 b
9. BioCon + 3.7
1/2 RR 6.4 b 6.0 a 2.4 bcd 4.4 b 6.9 a 5.1 a 4.1 ab abc 3.8 ab 4.1 ab 5.1 bc 4.0 bcd 4.5 ab 2.5 b 2.7 a 3.3 ab
c.v. (%) 12 14 17 13 6 9 14 10 11 7 7 10 7 13 7 14

DS: Dry season, WS: Wet season

the vegetative and reproductive stages of the rice plant. Figure 2 shows the
amount of rainfall (mm) received by the crop during its growth period. In
Agusan, low yields of NSIC Rc160 were also obtained which ranged from
-1
3.2-4.4 t ha due to high amount of rainfall (Figure 3) during the first two
months of crop growth which coincide with the vegetative stage of the rice
crop. During the reproductive stage however, there was a significant
decrease in rainfall and possibly experience some drought stress. Although
there was a trend that biofertilizers have an effect, it was not significant.
The crop could have been under fertilized also since only 78 kg of N was
applied (Table 3). It was not enough to sustain the need of the crop to
achieve maximum yield. The soil was also found to be deficient in zinc but
was not amended accordingly resulting to poor growth of the crop. In
-1
Camarines Sur, very low yields of SR 10 (2.3-2.9 t ha ) were obtained.
Although, the control treatment had significantly lower yield compared to
the fertilizer treatments, it cannot be concluded that biofertilizers
expressed a positive effect since there were no significant differences
observed among all the fertilizer treatments. The low yield may be
attributed to low rate of N, P, and K added which is only 25.5 kg N – 0 kg P –
25.5 kg K (Table 3). Further, the collaborator failed to add P fertilizer
inasmuch as it was detected to be limiting based on MOET and chemical
analysis. In Samar, no clear trend can be drawn from the two cropping
seasons of PSB Rc18 as there were no significant differences observed
among the fertilizer treatments. The fertilizer recommendation given at
50-0-0 is quite low, thus, even the yield of fertilizer treatments were
comparable to the control.
 35
Comparative performance of biofertilizers

DS: Dry season, WS: Wet season

Figure 1. Average grain yield (t ha-1) at 14% MC of 16 irrigated rice trials, 7 for DS and 9
for WS, as affected by different biofertilizer treatments

Figure 2. Amount of rainfall (mm) from March to July 2009 at

Los Baños, Laguna
36
Castillo and Mamaril

Figure 3. Amount of rainfall (mm) from January to April 2009 at Butuan, Agusan

Table 7. Comparison of straw yields (oven-dried) of irrigated rice as affected by different

fertilizer treatments
Straw Yield (t ha-1)

Los San Batac, Murcia, Pili, Midsayap,

Bay, Maligaya, Nueva Basilisa, Ubay, Tubigon,
Abuyog, Leyte Baños, Jorge, Ilocos Negros Camarines North
Laguna Ecija Agusan Bohol Bohol
Laguna Samar Norte Occidental Sur Cotabato

DS
DS 2008 WS 2009 DS 2009 2009 WS 2009 VWS 2009 DS 2009 WS 2009 DS 2010
NSIC NSIC NSIC NSIC PSB PSB
MS 6 PSB Rc82 NSIC Rc158 NSIC Rc120 SR 10 PSB Rc18
Treatments Rc150 Rc154 Rc160 Rc146 Rc18 Rc82
1. Control 3.3 c 5.5 d 7.8 de 2.0 bc 4.7 e 3.3 b 6.8 ab 14.6 c 3.4 c 3.1 abcd 3.3 cde 5.0 c 2.2 b 4.5 cde
2. 1/2 RR 5.1 ab 8.3 ab 11.2 ab 2.4 ab 7.3 ab 3.9 ab 7.1 ab 15.7 bc 5.0 ab 3.0 cd 3.9 bcd 8.4 b 3.6 ab 5.8 abc
3. FRR 5.8 a 9.0 a 12.7 a 2.4 ab 8.7 a 5.0 a 6.6 ab 19.4 a 5.5 a 3.4 abc 4.8 ab 11.0 a 3.6 ab 7.1 a
4. Bio N only 3.7 bc 5.9 cd 8.2 cde 1.9 c 5.6 bcde 4.3 ab 4.7 b 15.6 bc 3.0 c 2.8 d 2.1 f 5.1 c 3.0 ab 3.9 e
5. Bio N + 1/2
RR 5.1 ab 7.0 bcd 10 bc 2.4 ab 7.2 ab 4.1 ab 5.2 b 15.7 bc 4.7 b 3.0 bcd 4.3 abc 8.6 b 3.0 ab 5.6 bcd
6. Vital N only 3.5 bc 6.5 bcd 7.4 e 1.9 c 5.2 de 4.4 a 5.2 b 16.5 abc 3.1 c 3.3 abc 2.8 def 5.6 c 3.2 ab 4.9 cde
7. Vital N + 1/2
RR 4.5 abc 9.2 a 9.7 bcd 2.3 ab 7.0 abc 4.4 a 6.2 ab 18.8 ab 4.5 b 3.5 a 5.0 a 7.5 b 4.3 a 6.6 ab
8. BioCon only 3.6 bc 5.9 cd 6.8 e 1.8 c 5.5 cde 4.4 a 7.1 ab 16.4 abc 4.0 c 2.8 d 2.7 ef 4.9 c 3.4 ab 4.2 de
9. BioCon + 1/2
RR 4.5 abc 7.6 abc 9.5 bcd 2.5 a 6.7 bcd 4.9 a 7.2 ab 17.8 abc 4.9 ab 3.5 ab 5.3 a 8.4 b 4.1 a 6.5 ab

Straw Yields

In general, the trend of straw yields obtained was similar to those of the
grain yields, showing no positive response of biofertilizers (Table 7). The
average yield during dry and wet seasons were 4.5-4.9 t ha-1 and 3.8-4.3 t
-1 -1
ha for control and biofertilizer only treatments, 4.5-6.3 and 5.2-5.7 t ha
for ½ RR applied alone or in combination with biofertilizers. FRR
-1
treatment produced the highest yield of 6.9 and 6.4 t ha , respectively, for
dry and wet seasons (Figure 4).
 37
Comparative performance of biofertilizers

DS: Dry season, WS: Wet season, No data for San Mateo, Isabela (DS 2008) and San Jorge,
Samar (DS and WS 2009)
Figure 4. Average straw yields (t ha-1) of 13 irrigated rice trials, 5 for DS and 8 for WS, as
affected by different biofertilizer treatments

In other experimental sites such as Laguna, Camarines Sur, Samar,

Bohol, and Agusan, no significant differences were observed among the
treatments.

Yield Components

Yield components of irrigated rice including plant height, tiller

count, number of productive tillers, spikelet count, number of filled
grains, number of unfilled grains and weight of 100 grains were also
measured. The same trend of results as in grain and straw yields was
also observed in terms of plant height, tiller count and number of
productive tillers (Figures 5-7). Generally, no significant differences were
observed among the treatments in terms of spikelet count, number of
filled and unfilled grains and weight of 100 grains.
38
Castillo and Mamaril

DS: Dry season, WS: Wet season

Figure 5. Average plant height (cm) of 16 irrigated rice trials, 7 for DS and 9 for WS, as
affected by different biofertilizer treatments

DS: Dry season, WS: Wet season, No data for San Mateo, Isabela (DS 2008), Maligaya,
Nueva Ecija (WS 2009), Ubay, Bohol (WS 2009), Tubigon, Bohol (WS 2009), Batac, Ilocos
Norte (WS 2009) and Pili, Camarines Sur (WS 2009)
Figure 6. Average tiller count (n) of 10 irrigated rice trials, 6 for DS and 4 for WS, as
affected by different biofertilizer treatments
 39
Comparative performance of biofertilizers

DS: Dry season, WS: Wet season, No data for Abuyog, Leyte (DS and WS 2009) and Basilisa,
Agusan (WS 2009)
Figure 7. Average productive tiller count (n) of 13 irrigated rice trials, 6 for DS and 7 for
WS, as affected by different biofertilizer treatments

IMPLICATION OF THE RESULTS

In determining the efficacy of the three biofertilizers (Bio N, Vital N and

BioCon), the treatments of biofertilizers applied alone were compared
with the control. If the biofertilizers do fix atmospheric nitrogen or
stimulate root growth as claimed by the developers of these materials,
differences should have been observed in yield compared to the control.
Furthermore, if treatments receiving biofertilizers plus ½ RR produced
yields significantly higher than ½ RR alone, then it can be concluded that
biofertilizers had positive effect. However, such effect has not been
observed. The ½ RR alone yielded statistically the same as ½ RR plus the
biofertilizers suggesting that the biofertilizers have no positive effect.
Generally, grain and straw yields of irrigated rice including yield
components, such as plant height, tiller count, number of productive tillers,
spikelet count, number of filled grains, number of unfilled grains, and
weight of 100 grains showed no positive effects of biofertilizers. The
positive effect of BioCon, Vital N and Bio N on root length at seedling stage
40
Castillo and Mamaril

may be attributed to the microorganisms producing plant growth

hormones which might have enhanced root growth under “dapog” seedbed
condition. This is probably because the condition in the seedbed is not
totally anaerobic. However, upon subjecting to a completely flooded or
anaerobic condition after transplanting, most of these microorganisms
may not have survived. Thus, the beneficial effect at seedling stage is not
sustained throughout the entire growth stage of the lowland rice crop.
Otherwise, the beneficial effect of root growth at seedling stage should
have been reflected on the yield at harvest. It is therefore quite evident that
biofertilizers are not effective under anaerobic condition.
The term biofertilizer is a misnomer since biofertilizers do not
contribute nutrients but merely make nutrients available from other
sources such as inorganic fertilizers and indigenous or applied organic
matter. Boiero et al. (2007), showed negative results of siderophore
production and phosphate solubilization of Azospirillum brasilense in a
chemically defined medium.
Biofertilizers are said to contain microorganisms that fix atmospheric
nitrogen in the atmosphere. Biological nitrogen fixation requires a lot of
energy to fix nitrogen from the atmosphere. Therefore, nitrogen fixation is
restricted whenever energy is abundant in the environment. Thus, when
the soil is added with readily available nutrient source such as inorganic
fertilizer, microorganisms tend to consume the available nitrogen present
in the soil instead of fixing it from the atmosphere. Deacon (1996) stated
that Azospirillum species have been shown to fix nitrogen when growing in
the root zone (rhizosphere) of tropical grasses in field conditions but these
bacteria can make only a small contribution to the nitrogen nutrition of the
plant, because nitrogen-fixation is an energy-expensive process, and large
amounts of organic nutrients are not continuously available to microbes in
the rhizosphere.

CONCLUSION

In general, based from the results of this study, it can be concluded that
biofertilizers were not effective in promoting growth and increasing the
yield of irrigated rice which is grown in lowland or anaerobic condition. It
was also not affected by differences in soil type including topography,
drainage, parent material, permeability or climate type nor the chemical
nutrient status (pH, OM, N, P, K, S, Cu, Zn).
Proponents of biofertilizers should be more stringent in terms of
 41
Comparative performance of biofertilizers

quality control including the shelf-life and proper handling of the product
after coming out of the production site up to the time it reaches the farm. It
is likely that the viability of the microorganisms could be drastically
reduced when the product is subjected to harsh conditions during the
intervening period from the manufacturing site to the farm gate. This could
be a contributing factor why the biofertilizers evaluated in this study failed
to show positive benefits. Nevertheless, the biofertilizers used in this study
were obtained directly from the manufacturing site, thus the question of
viability could not be a major cause for the failure of obtaining positive
effects of the biofertilizers evaluated.
The microorganisms contained in the biofertilizer are claimed to be
isolated under aerobic conditions and therefore, works best under
conditions where oxygen is not limited. Further research on the use of
biofertilizers under upland condition using upland rice, corn or other
upland crops using the same experimental design can be done for
validation of biofertilizer's efficacy under aerobic condition.

ACKNOWLEDGEMENT

The authors wish to thank the Philippine Rice Research Institute

(PhilRice) for funding this research project. We also would like to express
our sincere gratitude for the researchers, field personnel and farmer
cooperators from collaborating agencies for their tireless efforts in the
implementation of the study. The collaborators are Joel Cantoneros,
Thelma Rapis, Adelina Aparado and Elvira Torres from Department of
Agriculture-Eastern Visayas Integrated Agricultural Research Centers
Leyte and Samar; Evelyn F. Javier and Corazon A. Santin from PhilRice
Nueva Ecija; Genevieve A. Nemeño and Mr. Fidel M. Siclay from PhilRice
Agusan; Ning S. Sosa, Ryan Baldovino and Ferdinand D. Garcia from
PhilRice Isabela; Alvin Palanog from PhilRice Negros; Mel Joy Gapi, Alma
Aguinaldo, Elias Bagintok and Cecilio Cases from PhilRice Batac;
Concepcion Payapaya and Eugene Cahiles from Agricultural Promotion
Center, Bohol; Fe Perlas, Marissa Joy Villano, Jayson Valera, Jobelly Pacis
and Presie Nangorog from Central Bicol State University of Agriculture,
Camarines Norte; and Kathy Loren Tafere, Joana Rose Vergara, Diosdado
Valencia, Hermogenes Bautista and Celedonio Gibas from PhilRice Los
Baños.
42
Castillo and Mamaril

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