Alternative Uses of Rice Straw for Mitigating Methane Emission in Vietnam and the
Philippines: II. Cost – benefit assessment of shifting to rapid composting and straw
mushroom production
Ngo Thi Thanh Truc1, Zenaida M. Sumalde2 and Reiner Wassmann 3
Abstract
Based on the two surveys of rice straw management in the Mekong Delta, Vietnam and
Central Luzon, Philippines, a cost – benefit analysis was conducted to assess whether
rapid composting and straw mushroom production are options for Vietnam and
Philippines to mitigate methane emission. The analysis showed that both the alternatives
have potential to mitigate methane emission in Vietnam and Philippines. In the Mekong
Delta, Vietnam shifting to straw mushroom production brings positive and higher NPV
than shifting to rapid composting. The later only brings environmental gain in CH4
reduction but not economic gain as indicated by their negative NPVs. In Central Luzon,
Philippines, shifting from leaving the straw in the field to rapid composting and straw
mushroom production gave high NPV and CH4 reduction as the former would result in
higher CH4 emission. Shifting from burning to rapid composting result in negative NPV
whereas shifting from burning to straw mushroom growing would yield positive NPV.
Growing straw mushroom is a potential in augmenting farmers’ income in both Mekong
Delta and Central Luzon; however, requires them to invest more than other uses of rice
straw.
Key words: rapid composting, Trichoderma, straw mushroom, Volvariella volvacea, rice
straw burning
1. Introduction
Rice straw management is significant strategy to mitigate greenhouse gas
emission, especially methane (IPCC 2006; and Wassmann et al. 2000). Whereas,
alternative of rice straw uses is very limited and the most common rice straw practice is
burning rice straw (open burning), which causes air pollution, health impacts and nutrient
1
School of Economics and Business, Can Tho University, 3/2 Street. Ninh Kieu District, Can Tho City,
Vietnam. Email: ntttruc@ctu.edu.vn
2
College of Economics and Management, University of the Philippines Los Baños, College,
Laguna, Philippines
3
International Rice Research Institute, DAPO Box 7777, Metro Manila, Philippines; working at IRRI as
Integrated Expert funded by GTZ/ CIM
loss (Truc 2005; Mendoza Samson 1999; Oanh and Sally 2000; Yevich and Logan
2003; and Slolomon et al. 2001, 2002, 2003).
Rapid composting (with activator, e.i. Trichoderma) and straw mushroom
(Vovariella volvacea) production are two alternatives introduced in both Vietnam and
Philippines to improve soil quality and gain household’s income (Truc 2005 and Truc
2011). The question is whether these two alternatives are options to mitigate greenhouse
gas emission in these two countries. To specific, these alternatives need to have both
methane mitigation potential and economic viability. To answer these questions, this
paper will present the methane emission factors of the rice straw uses, which deriving
from the survey in Mekong Delta, Vietnam and Central Luzon, cost-benefit analysis of
shifting from current practice of rice straw to rapid composting and straw mushroom
production.
2. Data and methods
2.1.
Data collection
To identify current uses of rice straw and costs and benefits of these uses, 417 farmerinterviewed respondents were using a pre-tested structured questionnaires in four
villages, namely, Truong Lac Commune, O Mon District, Can Tho City and My Thanh
Nam Commune, Cai Lay District, Tien Giang Province in Mekong Delta, Vietnam in
June 2008 and Barangay Matingkis, Science City of Muñoz and Barangay Santo Rosario,
Santo Domingo Municipality, Nueva Ecija Province, Central Luzon, Philippines in June
2009 (Figure 1). Besides, farmers practicing Trichoderma and other activators and
mushroom growers were also interviewed to calculate cost and return of their activities In
the Mekong Delta, 27 mushroom growers in Truong Lac Commune, O Mon District, Can
Tho City, 28 mushroom growers in Thom Rom, Thot Not District, Can Tho City and 5
mushroom growers in Tan Hoa commune, Lai Vung District, Dong Thap Province; 25
farmers practicing rapid composting. In Central Luzon, 12 farmers practicing rapid
composting, and key informants and 8 farmers growing straw and oyster mushroom and
spore supplier in Guimba, Talavera, San Jose, and Munoz in Nueva Ecija Province were
interviewed.
The data of methane emissions of rapid composting and straw mushroom
production was based on the results of rapid composting and straw mushroom production
experiments (Truc, 2011). Then these results were reviewed by the literature together
with other uses of rice straw find out the methane emission factor for each use of rice
straw.
Figure 1. Map of study sites in Mekong Delta, Vietnam and Central Luzon, Philippines
2.2.
Data analysis
2.2.1. Estimation of Quantity and Value of CO2 Equivalent
of Methane Emissions of Rice Straw Uses
Based on CH4 emission factors of rice straw uses, the quantity of CO2 equivalent
(CO2 eq) (equation (1) and (2)) and cost of CO2 eq of CH4 emission of rice straw uses
(equation (3) and 4) is calculated by the following equations:
QCO2eq (ton CO2 eq ton-1 straw dw) = QCH4 x fCH4 (1)
Where QCO2eq is the quantity of CO2 per ton of straw dry weight (dw); QCH4 is
methane emission factor of each rice straw uses (g CH4 ton-1 straw dw) and fCH4 is global
warming potential for CH4 factor (fCH4 = 25, Wikipedia 2011 and 2006 IPPC Guidelines);
QCO2eq (ton CO2 eq hectare-1 year-1) = QCH4 x fCH4 x fSRR x YR(2)
Where fSRR is straw : grain ratio, fSRR = 1 : 1, IRRI 2003 and Truc 2005) and YR is
paddy yield per hectare per year (ton ha-1year-1). rice straw dry weight is rice straw tdried
at 1050C in 6 hours and its of rice grain is 140C (IRRI 2003).
Indirect cost of CH4 emissions of uses of rice straw is cost of CO2eq:
ICCH4 (USD ton-1 straw) = QCO2eq (1) x PCO2eq (3)
ICCH4 (USD ha-1 year-1) = QCO2eq (2) x PCO2eq (4)
Where PCO2eq is average price of one ton of CO2 eq, PCO2eq = USD 10 ton-1
(Ecobusiness link 2011).
2.2.2. Benefit-Cost Analysis
The benefit-cost analysis was applied to analyze each strategy of rice straw use.
Specifically, the analysis used “with” and “without” scenarios. The “without” scenario is
the status quo, the current uses of rice straw, especially burning rice straw and
leaving/incorporating fresh rice straw in Mekong Delta, Vietnam, and Central Luzon,
Philippines, while the “with” scenarios were the scenarios of other uses of rice straw such
as rapid composting and/or growing mushroom. In “with” scenarios, rapid compost,
straw mushroom, and rapid compost and mushroom combined in a year were developed
as options or strategies.
Benefit cost analysis was done to determine the financial and economic viability
of the different options/strategies. The total benefits of rice straw uses included direct and
indirect benefits. The direct benefits of rice straw uses were actual benefits of rice straw
uses e.i the value of compost and straw mushroom produced. The indirect benefits were
the benefits from the reduction in fertilizers used, increase in rice yield, saving cost from
land preparation, fire spread prevention, rodent and insect prevention. The data to
estimate the benefits relied mostly on the actual case study in the two study areas.
The total costs of rice straw uses consisted of direct and indirect costs. The direct
costs of rice straw uses were the actual cost of rice straw uses e.i. cost of land
preparation, cost of gap filling due to poison of organic decomposition, production cost
of producing compost or mushroom. The indirect costs of rice straw uses were costs of
methane emission of each rice straw use, which was estimated by the amount of CO2 eq
multiplied by the current price of CO2 eq in the market. The price of CO2 eq used to
calculate in this study was USD 10 per ton of CO2 eq. This was the average price most
used in the renewable project (Ecobusiness link, 2011). The data to derive costs were
based on the actual case study in the two study areas. The descriptions of different
components of costs and benefits of current rice straw uses and the alternatives (rapid
composting and straw mushroom production) are based on Truc, 2011.
The benefits and costs of the “with” and ‘without” scenarios were estimated
through the incremental benefits and incremental costs. Then, the incremental net
benefits were derived to calculate the net present value of incremental net benefits.
Incremental Net Benefit
Net Present Value (NPV) =
(1+r)t
Where L is the projected period, which was set to 15 years and r is the selected
discounted rate, which was set to 5% (development projects). The use or option that gives
the highest NPV was recommended.
The assumptions in projection were based on the predicted situation in the next 15
years about the prices of outputs and inputs. The assumption about the percentage of
adoption was based on the results of the surveys (percentage of acceptance), experiences
in agricultural extension in introducing new agricultural technologies to farmers in
Mekong Delta and Central Luzon, and target goals from the local authorities.
3. Results and Discussions
3.1.
Methane Emissions from Different Uses of Rice Straw in the Study
Areas
3.1.1. Methane Emission Factors from Different Uses of Rice Straw
The survey reported that there are eight different practices in rice straw, namely 1)
rice straw burning, 2) feeding cattle, 3) mulching for vegetables and fruit garden (nonflooded crops), 4) rapid composting with activators or compost, 5) straw mushroom
growing, 6) leaving or incorporating fresh rice straw, 7) incorporating composted rice
straw or compost, and 8) mulching rice straw to the rice field. Table 1 summarizes the
methane emission factors for the practices cited above. Truc, 2011 presented in detail
how these emission factors of rice straw uses were derived (Appendix 3 and Appendix
Tables 7 – 10) while Appendix Table 11 in this reference also reported the methane
emission factors used in this study with detailed explanations on their original methane
emission factors, sources and remarks.
Table 1 Greenhouse gas emission factors, CO2 eq, and cost of CO2 equivalent from the different uses
of rice straw
USES OF RICE STRAW
1. Burning
2. Feeding cattle
3. Mulching fresh rice straw to vegetables,
fruit gardens (non-flooded)
4. Rapid Compost + rice field
5 Rapid Compost + other crops (non-flooded)
6. Compost + rice field
7. Compost + other crops (non-flooded)
8. Straw mushroom
9. Leave straw in the paddy field/Incorporate
fresh rice straw
10. Mulching fresh rice straw to the paddy
field
GREENHOUSE GAS
EMISSIONS
g CH4
ton CO2 eq
ton-1 straw
ton-1 straw
dw
dw
2,200.0
0.0550
15,000.0
0.3750
CO2 COST
(USD ton-1
straw dw)
0.550
3.750
0
1,804.3
4.3
1,830.0
30.0
72.7
0
0.0451
0.0001
0.0458
0.0008
0.0018
0
0.451
0.001
0.458
0.008
0.018
46,000.0
1.1500
11.500
6,200.0
0.1550
1.550
Note: 1g CH4 = 25 g CO2 equivalent, 1 ton CO2 eq = USD 10
The quantity and value of CO2 eq ton-1 straw dry weight applied equations (1) and (2)
Details on the methane emission factors and their assumption are presented in Appendix 3,
Appendix Tables 7 - 10 and summary in Appendix Table 11 of Truc, 2011.
Burning rice straw.
In 2003, Yevich and Logan estimated the CH4 emission
from rice straw burning to 2.2 CH4 kg-1 rice straw or 2,200g CH4 ton-1 rice straw. This
emission factor was derived from an extensive literature review, thus, deemed the most
appropriate methane factor from burning rice straw and biomass. The same was used for
calculation in this study.
Removing rice straw from the field.
In line with the 2006 IPCC Guidelines,
methane emission factor from removing rice straw from the field was estimated at zero
within the balance of rice fields. Potential off-field emissions after removing rice straw
from the field was attributed to other sources (e.g. emission from rice straw fed to cattle
was seen as part of livestock emissions of rice production). Nevertheless, these factors
are compiled in Appendix Table 11 of Truc, 2011 to present a comprehensive assessment
for rice straw.
Feeding cattle. Methane emission factor from using rice straw for cattle feed was
15,000 (10,000 – 20,000) g CH4 ton-1 rice straw (Singhal et al., 2005 and other
assumptions). The information used was indigenous cattle with average age and multipurpose use (dairy or nondairy), 300 kg body weight, 2 kg dry mater intake (DMI) 100
kg-1 body weight.
Mulching. The rice straw used to mulch vegetables, onion, fruit garden was
considered as rice straw for mulching non-flooded crops. The estimated methane
emission for mulching was zero (aerobic decomposition without inundated water)
(guessing).
Rapid composting and composting. The methane emission of rapid composting
or composting was estimated in two stages. The first stage was done during the
production of rapid compost or compost and second stage was during its application into
the rice field or to other crops, i.e. vegetables, fruit trees and flowers (non-flooded).
The methane emission of rapid composting during producing rapid compost was
4.3 (3.4 – 5.2) g CH4 ton-1 rice straw. This result was estimated from the rapid compost
experiment (Appendix 2 of Truc, 2011) and multiplied three times for the factor of big
size in practice (Beck-Friis et al, 2000 and guessing) (Truc, 2011, Appendix 3 and
Appendix Table 11). The condition of producing rapid compost is assumed aerobic
decomposition from scattering rice straw to the field and adding activators or producing
rapid compost in a well-mixed heap.
When rice straw was used to produce compost in big heap, the methane emission
factor was 30 g (20 – 40) CH4 ton-1 rice straw. This factor was based on the 2006 IPCC
Guidelines and other assumptions (30% C in rice straw, 0.005–0.02% C converted to CH4
during composting). The condition of producing compost in this case is more anaerobic
decomposition.
When rapid compost or compost was applied into the padding field (incorporate
rapid compost or compost), methane emission factor was 3,600 g CH4 ton-1 compost or
1,800 g CH4 ton-1 rice straw. This result was based on the 2006 IPCC Guidelines and
Wassmann et al., 2000. Meanwhile, when it was applied to other crops (i.e. vegetables,
fruit trees and flowers), the methane emission factor was zero (guessing). The conditions
in applying rapid compost or compost to other crops assumed aerobic decomposition
without inundated water.
Thus, the methane emission factor of rapid composting applied to the paddy field
was 1,804.3 g CH4 ton-1 rice straw and the emission factor of rapid composting applied to
other crops (non-flooded) was 4.3 g CH4 ton-1 rice straw. The emission factor of compost
applied to the paddy field was 1,830 g CH4 ton-1 rice straw and the emission factor of
compost applied to other crops (non-flooded) was 30 g CH4 ton-1 rice straw (Table 1).
Straw mushroom growing.
The emission factor from using rice straw for
mushroom production was 72.7 g (35.0 – 110.4) CH4 ton-1 rice straw, as derived from the
results in the mushroom experiment (Truc, 2011, Appendix 2), multiplied three times for
the factor of big size in practice (Truc, 2011, Appendix 3 and Appendix Table 11).
Incorporate/return rice straw to the field.
There are three ways to
incorporate/return rice straw into the field, namely 1) incorporate fresh rice straw, 2)
incorporate compost (discussed in CH4 emission factors of compost and rapid compost),
and 3) mulching rice straw. The emission factors of these uses were based on the 2006
IPCC Guidelines and Wassmann et al., 2000. Methane emission factor in incorporating
fresh rice straw into the paddy field was 46,000 g CH4 ton-1 rice straw. To incorporate
rice straw compost into the paddy field, on the other hand, the emission factor was 3,600
g CH4 ton-1 compost or 1,800 g CH4 ton-1 rice straw plus methane emission factor during
producing compost (rapid compost 4.3 g or compost 30 g CH4 ton-1 rice straw) (as
discussed above). Lastly, emission factor to mulch rice straw into the field was 6,200 g
CH4 ton-1 rice straw (Table 1).
3.2.
Methane Emissions and Value of Methane Emission
in Mekong Delta and Central Luzon
Table 2 Quantity and value of CO2 equivalent in the Mekong Delta, Vietnam and Central Luzon,
Philippines
USES OF RICE STRAW
1. Burning
2. Feeding cattle
3. Mulching fresh rice straw to
vegetables, fruit gardens (other
crops (non-flooded))
4. Rapid Compost + rice field
5. Rapid Compost + other crops
(non-flooded)
6. Compost + rice field
7. Compost + other crops (nonflooded)
8. Straw mushroom
9. Leave straw in the paddy
field/Incorporate fresh rice straw
10. Mulching fresh rice straw to
the paddy field
Note:
MEKONG DELTA
Tons ha-1
USD ha-1
0.9515
9.515
6.4875
64.875
CENTRAL LUZON
Tons ha-1
USD ha-1
0.6105
6.105
4.1625
41.625
0
0.7804
0
7.804
0
0.5007
0
5.007
0.0019
0.7915
0.019
7.915
0.0012
0.5078
0.012
5.078
0.0130
0.0314
0.130
0.314
0.0083
0.0202
0.083
0.202
19.8950
198.950
12.7650
127.650
2.6815
26.815
1.7205
17.205
Paddy : Straw = 1:1, 1 ton CO2 eq = USD 10
The yield in Mekong Delta per year is 17.1 tons/ha (three crop per year).
The yield in Central Luzon per year is 11.1 tons/ha.
The quantity and value of CO2 eq ha-1 applied equations (3) and (4)
Among the rice straw uses, leaving or incorporating fresh rice straw into the field
released the highest amount and value of CO2 eq ha-1, followed by the amount and value
from feeding cattle and mulching fresh rice straw into the paddy field. Less methane were
emitted from rapid composting than from ordinary composting (more anaerobic
condition). Similarly, less methane was emitted from applying rapid compost into the
paddy field than from incorporating fresh rice straw. However, emissions were still very
high as compared to applying rapid compost to other crops, i.e. vegetables, fruit trees and
flowers (non-flooded) (Table 2).
Mushroom production also emitted very low methane as compared to other
current uses of rice straw. Thus, rapid composting and straw mushroom culture are
potential options to mitigate CH4 emissions.
3.3.
Strategies of Shifting from Current Rice Straw Uses to
Rapid Composting and Straw Mushroom Production
3.3.1. Rationale
Farmers can adopt rapid composting and straw mushroom production to change
their current practices in rice straw. Depending on their conditions, they can choose only
one option for the whole year or different options for each season.
Rapid composting requires the following: 1) good quality of Trichoderma or
activators; 2) minimum of two weeks for straw decomposition; 3) availability of water; 4)
extra labor for scattering straw, moving straw out of the field or applying compost; and 5)
presence of vegetables, fruit gardens or flower gardens besides paddy. The last condition
is optional, thus, farmers can decide to apply compost to paddy field, other cash crop or
fruit or flower garden. Based on these conditions, each study site can decide the best
season/s for applying Trichoderma in rapid composting.
Meanwhile, mushroom growing requires the following: 1) good quality of
mushroom spore; 2) space to grow mushroom; 3) substantial amount of rice straw to
supply a whole-year production (from using their own rice and buying rice straw from
other places); 4) techniques in mushroom growing; 5) available labor for transferring
rice straw, composting, preparing and maintaining mushroom beds, and harvesting; and
for pre-processing mushroom (boiling and salting, and drying); and 7) a ready market or
an outlet to sell their mushroom produce.
No combination of rapid composting and straw mushroom production is possible
for one cropping season in a particular site that can assure that the production site will not
be contaminated with Trichoderma.
3.3.2. Description of the Different Strategies
The rationale presents three main strategies for the two alternative uses of rice
straw, as presented in Table 3. The first strategy was rapid composting using
Trichoderma or other activators the whole year in both countries.
The second strategy was to use rice straw to grow mushroom the whole year,
which can promote large-scale mushroom production in the study sites. At present, only
small-scale mushroom farming exists in these sites. Farmers and local authorities can
only grow straw mushrooms after harvest period and only engages in the practice by
buying more rice straw and other materials (i.e. banana leaves).
Another strategy was to apply the two strategies at different seasons of the year.
Based on the interests of farmers, local authorities and agricultural extensions in Mekong
Delta, two options are possible. One is to grow straw mushrooms during the first or third
cropping whereas the second is to do rapid composting during the other cropping seasons.
The first option can avoid the constraints of limited water supply during the dry season
whereas the second option can improve the current condition of growing mushroom
while taking advantage of the available labor during the flood season. In Central Luzon,
farmers can use rice straw to grow mushrooms or rapid composting during either the dry
or wet season.
Table 3 Proposed strategies and combinations of rapid composting and straw
mushroom production in Mekong Delta, Vietnam and Central Luzon, Philippines
VIETNAM
STRATEGIES
PHILIPPINES
Santo
Central
Muñoz
Domingo Luzon
O Mon
Cai Lay
Mekong
Delta
1. Only rapid compost
(RC)
- 1st season
- 2nd season
- 3rd season
RC
RC
RC
RC
RC
RC
RC
RC
RC
RC
RC
RC
RC
RC
RC
2. Only straw mushroom
growing (SM)
- 1st season
- 2nd season
- 3rd season
SM
SM
SM
SM
SM
SM
SM
SM
SM
SM
SM
SM
SM
SM
SM
3. Combinations of rapid
composting and straw
mushroom growing
3.1.
- 1st season
- 2nd season
- 3rd season
SM
RC
RC
SM
RC
RC
SM
RC
RC
SM
SM
SM
RC
RC
RC
VIETNAM
STRATEGIES
O Mon
Cai Lay
Mekong
Delta
RC
RC
SM
RC
RC
SM
RC
RC
SM
PHILIPPINES
Santo
Central
Muñoz
Domingo Luzon
3.2.
- 1st season
- 2nd season
- 3rd season
RC
RC
RC
SM
SM
SM
Note: RC: Rapid Composting and SM: Straw mushroom
3.4.
Benefit-Cost Analysis of the Different Strategies
To calculate the economic viability of the proposed strategies, the costs and
benefits of each rice straw use per hectare, assuming100 % adoption, for each cropping
season and for the whole year in Mekong Delta and Central Luzon were estimated. The
incremental benefits and incremental costs were computed using the “with” and
“without” framework. The different strategies presented the “with” scenarios whereas the
burning and current uses were the “without” scenario. Then, the incremental net benefit
for each strategy was estimated by getting the difference between incremental benefit and
incremental cost. The Net Present Value (NPV) of each strategy was estimated by
discounting the stream of incremental net benefit.
3.4.1. Estimation of Costs and Benefits of
Rice Straw Uses
Table 4 and 5 present the summary of total costs, total benefits, net benefits and
quantity and cost of CO2 eq of the indirect cost of CH4 emissions from different rice
straw uses per hectare per year in Mekong Delta and Central Luzon. The detailed
explanations of the costs and benefits components of each rice straw uses by cropping
season and their totals for the whole year per hectare in the Mekong Delta, Vietnam and
Central Luzon, Philippines can be found in Table 13 – 19 in this appendix.
The summary of total costs, total benefits, net benefits, quantity and cost of CO2
eq of CH4 emission of each use of rice straw per hectare per year in Mekong Delta are
presented in Table 4. Using rice straw for growing mushroom brought the highest net
benefit of USD 368 ha-1year-1, followed by scatter burning with USD 161 ha-1year-1.
Using rice straw for feeding, rapid composting (scattering), dump burning and rapid
composting (heap) came next with net benefits of USD 148, USD 141, USD 100 and
USD 82 for every hectare, respectively. Leaving rice straw in the field had negative net
benefit as it brought the highest CH4 emission, thus, highest cost of CH4 emission.
Table 4 Costs, benefits, net benefits and quantity and cost of CO 2 eq of CH4 emission of uses of rice
straw per hectare per year in Mekong Delta, Vietnam (USD ha-1)
USES OF RICE
STRAW
1. Growing
mushroom
2. Scatter burning
3. Feeding cattle
4. Rapid Compost
(scatter)
5. Dump burning
6. Rapid Compost
(heap)
7. Leaving straw in
the field
NET
BENEFIT
(2) – (1)
COST
(1)
BENEFIT
(2)
TONS OF
CO2 EQ
COST OF
CO2 EQ
211.81
44.13
146.61
579.57
204.71
294.23
367.76
160.58
147.63
0.0314
0.9515
6.4875
0.31
9.52
64.88
196.80
32.59
337.55
132.40
140.74
99.81
0.7804
0.9515
7.80
9.52
255.15
337.55
82.40
0.7804
7.80
250.87
57.69
(193.18)
19.8950
198.95
Note: Details on the costs and benefits components of each use of rice straw by cropping season and whole
year in Mekong Delta are presented in Table 13 – 19 in this Appendix.
Details on the quantity of CO2 eq and cost of CO2 eq of CH4 emission of rice straw uses in Mekong
Delta are presented in Tables 2.
USD 1 = VND 20,800 (March, 2011)
In Mekong Delta, Vietnam leaving/incorporating fresh rice straw into the paddy
field gave the highest quantity of CO2 eq of CH4 emission amounting to 19.9 tons CO2
eq/ha/year and valued at USD 199 ha/year due to the highest CH4 emitted from the field.
Using rice straw to feed cattle came in next in CO2 eq and cost of CO2 eq of CH4
emission (6.5 tons CO2 eq and USD 65 ha-1year-1). On the other hand, growing
mushroom had 0.031 tons of CO2 eq and USD 0.31 ha-1year-1. Rapid composting both in
heap and in scattered and returning rice straw compost back to the paddy field appeared
to have the highest potential to mitigate GHG mitigation with CO2 eq amounting to 0.78
tons and valued at USD 7.8 ha-1year-1 (Table 4).
The total costs, total benefits, net benefits, the quantity and cost of CO2 eq of the
costs of CH4 emission of each use of rice straw per hectare per year in Central Luzon are
summarized in Table 40. Rice straw mushroom for growing mushroom yielded the
highest net benefit of USD 1,158 /ha/year, followed by scatter burning at USD 91
/ha/year, dump burning (USD 70 ha-1year-1), mulching onions (USD 64 ha-1year-1) and
rapid composting (USD 51 ha-1year-1). Similar with the results in Mekong Delta, leaving
rice straw in the field gave negative net benefits in Central Luzon as indicated by the
highest emissions leading to highest indirect cost of CH4 emission.
Based on the quantity of CO2 per ha per year, using rice straw for growing
mushrooms and for rapid composting had the highest potential in mitigating greenhouse
emissions due to their low CO2 equivalent of CH4 emissions. Similar to the results in
Mekong Delta, using rice straw to feed cattle and leaving it on the field would be
detrimental to the environment because these practices cause high CH4 emissions and
eventually, high CO2 equivalent.
Table 5 Cost, benefits, net benefits, and quantity and cost of CO 2 eq of CH4 emission for each uses of
rice straw per hectare per year in Central Luzon, Philippines (USD/ha)
USES OF RICE
STRAW
1. Growing mushroom
2. Scatter burning
COST
(1)
902.13
10.69
BENEFIT
(2)
2,060.98
101.79
NET
BENEFIT
(2) – (1)
1,158.85
91.10
TONS OF
CO2 EQ
0.0202
0.6105
COST OF
CO2 EQ
0.20
6.11
3. Dump burning
4. Mulching
5. Rapid Compost
6. Feeding cattle
7. Leaving straw in the
field
6.11
13.76
41.69
179.17
76.34
77.95
92.62
226.96
70.24
64.19
50.93
47.79
0.6105
0.5078
4.1625
6.11
5.01
41.62
134.53
46.31
(88.22)
12.765
127.65
Note: Details on the costs and benefits components of each use of rice straw by cropping season and whole
year in Central Luzon are presented in are presented in Table 13 – 19 in this Appendix.
Details on the quantity of CO2 eq and cost of CO2 eq of CH4 emission of rice straw uses by cropping
season and whole year in Central Luzon are presented in Tables 2.
USD 1 = PhP 43.62 (March, 2011)
3.4.2. “With” and “Without” Scenarios in
Mekong Delta and Central Luzon
The computed costs and benefits for Mekong Delta and Central Luzon were
projected for a 15-year period starting 2011, as well as the incremental net benefits for
each year using the “with” and “without” scenarios for the different options. Table 6
presents the different options for Mekong Delta.
Scatter burning and dump burning in the status quo scenario were compared with
using rice straw for rapid composting and for straw mushroom production. Rapid
composting can be done either by scattering the rice straw on the field for decomposition
or by rapid composting in heap. In total, there are six options for Mekong Delta, three
each for the two major strategies.
Table 6 Alternative strategies/options for the “with” and “without” scenarios
in Mekong Delta, Vietnam
STRATEGY/
OPTION
A
B
LABEL
SCENARIO
A1
A2
A3
Without
1. Scatter burning
2. Scatter burning
3. Scatter burning
With
Rapid composting (scatter)
Rapid composting (heap)
Growing mushroom
B1
B2
B3
1. Dump burning
2. Dump burning
3. Dump burning
Rapid composting (scatter)
Rapid composting (heap)
Growing mushroom
Note: Rapid composting (scatter): Scattering rice straw with activators for decomposition in the field
Rapid composting (heap): Transferring rice straw out of the field and producing rice straw compost
in heap with activators
Growing mushroom: Using rice straw to grow straw mushroom
Over the 15-year projected period, only three of the six options resulted in
positive incremental net benefits whereas the rest were negative. Those with favorable
incremental net benefits were: scatter and dump burning combined with using rice straw
to grow rice straw mushrooms; and dump burning with rapid composting while scattering
the rice straw onto the field. Under these options, the economic and environmental
benefits outweigh the cost. On the other hand, the remaining three options with negative
incremental benefits entailed higher cost than benefits.
Similar to Mekong Delta, six alternative options were possible for Central Luzon,
These six, however, were grouped into three major options with two alternatives in each
(Table 7). The “without” scenario for the three major options were scatter burning, dump
burning and leaving rice straw in the field whereas the “with” alternatives were scatter
rapid composting and using rice straw for straw mushroom production.
Table 7 Alternative strategies/options for the “with” and “without” scenarios
in Central Luzon, Philippines
STRATEGY/
OPTION
A
Note:
LABEL
SCENARIO
A1
A2
Without
1. Scatter burning
2. Scatter burning
With
Rapid composting
Growing mushroom
B
B1
B2
1. Dump burning
2. Dump burning
Rapid composting
Growing mushroom
C
C1
C2
1. Leaving rice straw in the field
2. Leaving rice straw in the field
Rapid composting
Growing mushroom
Rapid composting: Scattering rice straw with activators for decomposition in the field
Growing mushroom: Using rice straw to grow straw mushroom
Four alternatives resulted in positive incremental net benefits. These included
shifting from scatter and dump burning to using rice straw for straw mushroom
production and from leaving rice straw in the field to rapid composting or straw
mushroom growing. Shifting from the current uses of rice straw to using straw to produce
mushroom would give the highest incremental net benefit. On the other hand, shifting
from scatter or dump burning to using rice straw for composting resulted in negative
incremental net benefit, implying that these alternatives are not economically viable
despite the higher environmental gain from reduced CH4 emission and CO2 equivalent.
3.4.3. Net Present Value of “With” and “Without” Strategies
in Mekong Delta and Central Luzon
The Net Present Value (NPV) of a program or project tells the present worth of
the future sum of the stream of incremental net benefit that came from the program or
activity. In this study, it would be the incremental net benefit of shifting from the current
uses rice straw to other alternative uses. The NPVs of the stream of incremental net
benefit of each strategy for Mekong Delta and Central Luzon were estimated using a 5%
discount rate, the rate normally used for development projects.
For Mekong Delta, three option yielded positive incremental net benefit. These
included shifting from scatter burning to growing straw mushroom, and from dump
burning to scatter rapid composting or growing mushroom. The other options resulted in
negative incremental net benefit all throughout the 15-year period.
Table 8 NPV and reduction in CO2 eq of each alternative in Mekong Delta, Vietnam
MEKONG DELTA
STRATEGIES
1. Scatter burning
 Rapid Composting (scatter)
2. Scatter burning
 Rapid Composting (heap)
3. Scatter burning
 Growing mushroom
4. Dump burning
 Rapid Composting (scatter)
5. Dump burning
 Rapid Composting (heap)
6. Dump burning
 Growing mushroom
LABEL
NPV
(USD ha-1)
tons CO2 eq
(tons ha-1)
A1
-400
-2.57
A2
-1,578
-2.57
A3
4,182
-13.80
B2
826
-2.57
B1
-352
-2.57
B2
5,409
-6.65
Note: Costs and benefits projected for a 15-year period from 2011 onwards are assumed to increase by 10%
annually based on the 10% average annual increase in Vietnam’s Consumer Price Index (CPI)
Negative value in tons CO2 eq means reduction in CO2 equivalent when shifting from “without” to
“with” strategy
Among the options that resulted in positive incremental net benefits, shifting from
scatter and dump straw burning to using rice straw for mushroom growing resulted in the
highest positive NPV and higher reduction in CH4 and thus, CO2 equivalent. Shifting
from dump burning to using straw for mushroom growing produced the highest NPV
(USD 5,409 ha-1) and CO2 reduction (13.8 tons-1 ha-1) (Table 8). The practices that
yielded incremental net benefit definitely had negative NPVs that range from –USD 52
(dump burning vs scatter rapid composting) to –USD 1,578 (scatter burning vs rapid
composting in heap), and produced the lowest reduction in CO2 equivalent at 2.57
tons/ha. Hence, these are not economically viable while having limited potential to
mitigate greenhouse gases.
As discussed earlier, there are four alternatives that resulted in positive
incremental net benefits for central Luzon. Therefore, they also yielded positive NPV.
Shifting from leaving the straw in the rice field to using straw for growing mushroom
gave the highest NPV of USD 20,398 ha-1 and highest the highest reduction in CO2
emission amounting to 191 tons/ha over a 15-year period (Table 44). This is followed by
dump burning to growing mushroom with USD 17,807 ha-1 and scatter burning to
growing mushroom with USD 17,465 ha-1 and reduction in CO2 equivalent of 8.85 tons
ha-1. Shifting from leaving rice straw in the field to using rice straw for rapid composting
gave the least NPV at USD 2,276 ha-1.
Table 9 NPV and reduction in CO2 eq of each alternative in Central Luzon, Philippines
STRATEGIES
1. Scatter burning
 Rapid Compost
2. Scatter burning
 Growing mushroom
3. Dump burning
 Rapid Compost
4. Dump burning
 Growing mushroom
5. Leaving straw in the field
 Rapid Compost
6. Leaving straw in the field
 Growing mushroom
LABEL
CENTRAL LUZON
NPV
tons CO2 eq
-1
(USD ha )
(tons ha-1)
A1
-657
-1.65
A2
17,465
-8.85
B1
-316
-1.65
B2
17,807
-8.85
C1
2,276
-183.96
C2
20,398
-191.17
Note: Costs and benefits projected for a 15-year period from 2011 onwards are assumed to increase by 10%
annually based on the 7% average annual increase in Philippines’s Consumer Price Index (CPI)
Negative value in tons CO2 eq means reduction in CO2 equivalent when shifting from “without” to
“with” strategy
On the other hand, shifting from scatter and dump burning to using rice straw for
rapid composting resulted in negative economic gains. Although they would bring
environmental gains, the gains would be relatively small (reduction of CO2 equivalent of
1.65 tons/ha over 15 years) compared to the others.
3.4.4. Sensitivity Analysis and Concerns
In reality, certain uncertainties would affect the result of the analysis. In this
study, these uncertainties included the decreases in benefit and in farmers’ level of
adoption. Thus, a sensitivity analysis was conducted to examine the change in NPV when
cost and benefit components of rice straw uses changes. The two scenarios in this
analysis were: 1) the decrease in the level of adoption from 100 % to 50 % and 30 %; and
2) the decrease in benefits of straw mushroom growing under the assumption that
mushroom prices would decrease as more farmers grow mushrooms. In the second
scenario, it was assumed that the benefits of mushroom would be the same in the first
five years, but would decrease gradually by 5% due to falling mushroom prices.
When the level of adoption decreases in the first scenario, signs of NPV does not
change (from positive to negative or opposite) although the NPVs and of CO 2 eq
reduction decrease with level of adoption (Tables 10 and 11).
Table 10 Changes in NPV and quantity of CO2 eq over a 15-year period by strategy per hectare, by
cropping seasons, and by different percentages of adoption in Mekong Delta, Vietnam
STRATEGIES
Scatter burning
 Rapid Compost (scatter)
Scatter burning
 Rapid Compost (in heap)
Scatter burning
 Growing mushroom
Dump burning
 Rapid Compost (scatter)
Dump burning
 Rapid Compost (in heap)
LABEL
A1
A2
A3
B2
B1
MEKONG DELTA
NPV
Tons CO2 eq
with different
with different
percentage of
percentage of
adoption
adoption
-1
(USD ha )
(tons ha-1)
50%
30%
50%
30%
-200
-120
-1.28
-0.77
-789
-473
-1.28
-0.77
2,091
1,255
-6.90
-4.14
413
248
-1.28
-0.77
-176
-105
-1.28
-0.77
Dump burning
 Growing mushroom
B2
2,705
1,623
-6.90
-4.14
Note: Negative value in tons CO2 eq means reduction in CO2 equivalent when shifting from “without” to
“with” strategy
On the other hand, in the second scenario, NPVs in shifting from the status quo
(scatter or dump burning in the Mekong Delta and scatter or dump burning and leaving
straw in the field in Central Luzon) to straw mushroom are very sensitive to the changes
in mushroom price. In Mekong Delta, NPVs in both two strategies become negative
whereas in Central Luzon, they remain positive although the values significantly
decreased. These changes in NPVs may affect the farmers’ decision in choosing those
strategies (Table 12).
Table 11 Changes in NPV and quantity of CO2 eq over a 15-year period by strategies per hectare, by
cropping seasons, and by different percentages of adoption in Central Luzon, Philippines
STRATEGIES
1. Scatter burning
 Rapid Compost
2. Scatter burning
 Growing mushroom
3. Dump burning
 Rapid Compost
4. Dump burning
 Growing mushroom
5. Leaving straw in the field
 Rapid Compost
6. Leaving straw in the field
 Growing mushroom
LABEL
A1
A2
B1
B2
C1
C2
CENTRAL LUZON
NPV
Tons CO2 eq
with different
with different
percentage of
percentage of
adoption
adoption
(USD ha-1)
(tons ha-1)
50%
30%
50%
30%
-329
-197
-0.82
-0.49
8,733
5,240
-4.43
-2.66
-158
-95
-0.82
-0.49
8,903
5,342
-4.43
-2.66
1,138
683
-91.98
-55.19
10,199
6,120
-95.59
-57.35
Note: Negative value in tons CO2 eq means reduction in CO2 equivalent when shifting from “without” to
“with” strategy
Table 12 Changes in NPV of the different strategies due to 5% decrease in prices of straw starting on
the 6th year, Mekong Delta and Central Luzon, Philippines (USD/ha)
MEKONG DELTA, VIETNAM
Strategies
1. Scatter burning to
mushroom growing
2. Dump burning to
mushroom growing
CENTRAL LUZON, PHILIPPINES
NPV
NPV
Strategies
-1
(USD ha )
(USD ha-1)
-2,280 1. Scatter burning to
2,379
mushroom growing
-3,108 2. Dump burning to
2,720
mushroom growing
3. Leaving straw in the
4,900
field to mushroom
growing
Note: Benefits of the first five years are the same and decrease gradually 5% after five years, over
the 15-year period in both study sites
4. Conclusions and recommendations
The study showed that the alternatives (rapid composting and straw mushroom
production) have the potential to mitigate methane emission in Vietnam and Philippines,
which are chiefly agricultural rice producing countries. In both Mekong Delta and
Central Luzon, shifting from dump burning to growing mushroom yielded the highest
NPV. Meanwhile, shifting from rice straw burning to rapid composting only reduced
methane emissions.
Between the two shifting strategies in Mekong Delta (from the current rice straw
practices to the alternative uses), shifting to straw mushroom production brings positive
and higher NPV than shifting to rapid compost. The latter only brings environmental gain
in CH4 reduction but not economic gain as indicated by their negative NPVs. However,
shifting to mushroom growing require farmers to invest more, as compared to other uses
of rice straw.
In Central Luzon, shifting from leaving the straw in the field to rapid composting
and to straw mushroom production return high NPV and CH4 reduction as the former
result in higher CH4.emission. Shifting from burning to rapid composting returns negative
NPV whereas shifting from burning to straw mushroom growing returns positive NPV.
The strategy to shift to mushroom growing requires farmers to invest more, as compared
to other uses of rice straw.
Shifting from the present and common practices in rice straw to the several
alternatives tested in this study showed good potential in augmenting farmers’ income
and in mitigating greenhouse gas emission.
The calculation of cost and benefit of each rice straw uses has included full costs
and benefits of rice straw uses. Of which, indirect cost of CH4 emission, which is external
cost of these rice straw practices has never mentioned. In other words, when farmers
shifting from current practice to rapid composting and straw mushroom production, they
create external benefit of reducing methane emission. Thus, there is a mechanism to
compensate for farmers to encourage them to practice alternative of rice straw that can
mitigate greenhouse gases.
In order to speed up the shifting process (from current practice – burning/leaving
rice straw in the rice field to rapid composting and straw mushroom production), farmers
should get more knowledge about rapid composting and straw mushroom production,
effects of current rice straw uses, enablers for these alternatives (supply system of
Trichoderma and Volvariella spore and other activators, market activities for rapid
compost and straw mushroom) and research to improve the economic viability of rapid
composting and straw mushroom production. More research on straw mushroom demand
to secure the price of mushroom and pre-processing and processing technologies and
market research on rice straw compost, especially for upland crop to improve the
economic viability of this technology.
Acknowledgement This article is part of the doctoral dissertation of Dr. Ngo Thi Thanh
Truc titled “Comparative Assessment of Using Rice Straw for Rapid Composting and
Straw Mushroom Production in Mitigating Greenhouse Gas Emissions in Mekong Delta,
Vietnam and Central Luzon, Philippines”. The study was funded by the Southeast Asian
Regional Centrer for Agriculture and Graduate Studies (SEARCA) and the Rice and
Climate Change Consortium (RCCC) of the International Rice Research Institute (IRRI).
Appendix
Table 13 – 19 summarized in detail the cost and benefit analysis of rice straw uses
in the Mekong Delta, Vietnam. These figures were derived from the survey (describe in
part 2 of data collection).
Table 13 Cost and Benefit Analysis of Scatter Burning in Mekong Delta, Vietnam and Central
Luzon, Philippines (USD ha-1)
Mekong Delta, Vietnam
ITEMS
1st SS
2nd SS
3rd SS
1. Benefit
67.40
78.85
58.46
Whole
year
204.71
1.1. Direct Benefit
1.2. Indirect Benefit
- Benefit from saving
scattering rice straw for natural
decompose
- Save labor cost from moving
rice straw outside the
field/ploughing
- Benefit from saving cost of
land preparation
- Benefit of burning rice straw
to clean the field, kill insects,
pests, weeds, rats
- Benefit from the ash
67.40
78.85
58.46
204.71
Central Luzon,
Philippines
DS
WS
Whole
year
50.89
50.89
101.79
50.89
50.89
101.79
3.44
3.44
6.88
19.23
19.23
19.23
57.69
-
-
-
-
19.23
-
19.23
1.15
1.15
2.29
25.96
22.21
25.96
14.42
25.96
13.27
77.88
49.90
23.15
23.15
23.15
23.15
46.31
46.31
2. Cost
19.62
12.37
12.15
44.13
5.70
4.99
10.69
2.1. Direct Cost
15.38
9.62
9.62
34.62
2.29
2.29
4.59
- Scatter rice straw
- Fire spread prevention
9.62
5.77
9.62
-
9.62
-
28.85
5.77
2.29
-
2.29
-
4.59
-
2.2. Indirect Cost
4.24
2.75
2.53
9.52
3.41
2.70
6.11
- Cost of CH4 emission
4.24
2.75
2.53
9.52
3.41
2.70
6.11
47.78
66.48
46.32
160.58
44.19
45.91
91.10
3. Net benefit
Note: 1st SS = SW = Spring Winter Season, 2nd SS = SA = Summer Autumn Season and 3rd SS = Autumn
Winter Season
DS = Dry Season and WS = Wet Season
In Vietnam, 1 kg Paddy = VND 6,000, USD 1 = VND 20,800 (2011)
In the Philippines, 1 kg Paddy = PhP 15, 1 bag of fertilizer = PhP 1,010; USD 1 = PhP 43.62 (2011)
Table 14 Cost and Benefit Analysis of Dump Burning in Mekong Delta, Vietnam and Central Luzon,
Philippines (USD ha-1)
ITEMS
1. Benefit
1.1. Direct Benefit
1.2. Indirect Benefit
- Benefit from saving
scattering rice straw for
natural decompose
- Benefit from saving land
preparation
- Save labor cost from
moving rice straw outside
the field/ploughing
- Benefit from saving cost
fire spread prevention in SA
- Benefit of burning rice
straw to clean the field, kill
insects, pests, weeds, rats
- Benefit from the ash
2. Cost
2.1. Direct Cost
- Cost of land preparation
of SA
- Cost of gap filling due to
poison of organic
decomposition
2.2. Indirect Cost
- Cost of CH4 emission
3. Net benefit
Mekong Delta, Vietnam
2nd SS
3rd SS
Whole
year
53.56
40.00
38.85
132.40
1st SS
Central Luzon, Philippines
DS
WS
Whole
year
38.17
38.17
76.34
-
-
-
-
-
-
-
53.56
40.00
38.85
132.40
38.17
38.17
76.34
-
-
-
-
2.29
2.29
4.59
-
-
-
-
1.15
1.15
2.29
19.23
19.23
19.23
57.69
-
-
-
5.77
-
-
5.77
-
-
-
6.35
22.21
4.24
-
6.35
14.42
23.90
21.15
6.35
13.27
4.45
1.92
19.04
49.90
32.59
23.08
11.58
23.15
3.41
-
11.58
23.15
2.70
-
23.15
46.31
6.11
-
-
19.23
-
19.23
-
-
-
4.24
4.24
49.32
1.92
2.75
2.75
16.10
1.92
2.53
2.53
34.39
3.85
9.52
9.52
99.81
3.41
3.41
34.76
2.70
2.70
35.48
6.11
6.11
70.24
Note: 1st SS = SW = Spring Winter Season, 2nd SS = SA = Summer Autumn Season and 3rd SS = Autumn
Winter Season
DS = Dry Season and WS = Wet Season
In Vietnam, 1 kg Paddy = VND 6,000, USD 1 = VND 20,800 (2011)
In the Philippines, 1 kg Paddy = PhP 15, 1 bag of fertilizer = PhP 1,010; USD 1 = PhP 43.62 (2011)
Table 15 Cost and Benefit Analysis of Leaving Rice Straw in the Field in Mekong Delta, Vietnam
(USD ha-1)
ITEMS
1. Benefit
1.1. Direct Benefit
1.2. Indirect Benefit
- Save labor cost from
moving rice straw outside
the field/ploughing
- Benefit from nutrient
2. Cost
2.1. Direct Cost
- Loss land to store the rice
straw
- Cost to pay chemicals to
kill insects, weeds and rats
- Cost of scattering rice
straw for natural
decompose
- Higher cost of land
preparation
2.2. Indirect Cost
- Cost of CH4 emission
3. Net benefit
Mekong Delta, Vietnam
2nd SS
3rd SS
Whole
year
19.23
19.23
19.23
57.69
19.23
19.23
19.23
57.69
1st SS
Central Luzon, Philippines
DS
WS
Whole
year
23.15
23.15
46.31
23.15
23.15
46.31
19.23
105.86
17.31
19.23
74.81
17.31
19.23
70.21
17.31
57.69
250.87
51.92
23.15
74.74
3.44
23.15
59.79
3.44
46.31
134.53
6.88
14.42
14.42
14.42
43.27
-
-
-
2.88
2.88
2.88
8.65
-
-
-
-
-
-
-
2.29
2.29
4.59
88.55
88.55
- 86.63
57.50
57.50
- 55.58
52.90
52.90
- 50.98
198.95
198.95
- 193.18
1.15
71.30
71.30
- 51.58
1.15
56.35
56.35
-36.63
2.29
127.65
127.65
-88.22
Note: 1st SS = SW = Spring Winter Season, 2nd SS = SA = Summer Autumn Season and 3rd SS = Autumn
Winter Season
DS = Dry Season and WS = Wet Season
In Vietnam, 1 kg Paddy = VND 6,000, USD 1 = VND 20,800 (2011)
In the Philippines, 1 kg Paddy = PhP 15, 1 bag of fertilizer = PhP 1,010; USD 1 = PhP 43.62 (2011)
Table 16 Cost and Benefit Analysis of Using Rice Straw to Feed Cattle in Mekong Delta, Vietnam
and Central Luzon, Philippines (USD ha-1)
ITEMS
1. Benefit
1.1. Direct Benefit
1.2. Indirect Benefit
- Benefits from no loss land
to store rice straw
- Benefits from avoiding
insects, weeds and rats
- Benefit of saving time to
collect grass to feed cattle
- Benefits from saving cost
of scattering rice straw to
the field
- Benefits from saving from
easy land preparation
- Benefit from opportunity
cost to find job in the time
of collecting grass to feed
cattle
2. Cost
2.1. Direct Cost
- Cost of moving rice straw
from the field to store rice
straw to feed cattle
- Cost of gap filling due to
poison of organic
decomposition
2.2. Indirect Cost
- Cost of CH4 emission
3. Net benefit
Mekong Delta, Vietnam
2nd SS
3rd SS
Whole
year
98.08
98.08
98.08
294.23
98.08
98.08
98.08
294.23
1st SS
Central Luzon, Philippines
DS
WS
Whole
year
113.48
113.48 226.96
113.48
113.48
226.96
14.42
14.42
14.42
43.27
-
-
-
2.88
2.88
2.88
8.65
-
-
-
40.38
40.38
40.38
121.15
-
-
-
-
-
-
-
2.29
2.29
4.59
-
-
1.15
1.15
2.29
-
40.38
54.84
25.96
40.38
46.63
27.88
40.38
45.13
27.88
121.15
146.61
81.73
110.04
92.03
68.78
110.04
87.15
68.78
220.08
179.17
137.55
25.96
25.96
25.96
77.88
68.78
68.78
137.55
-
1.92
1.92
3.85
28.88
28.88
43.24
18.75
18.75
51.44
17.25
17.25
52.94
64.88
64.88
147.63
23.25
23.25
21.45
18.38
18.38
26.33
41.62
41.62
47.79
Note: 1st SS = SW = Spring Winter Season, 2nd SS = SA = Summer Autumn Season and 3rd SS = Autumn
Winter Season
DS = Dry Season and WS = Wet Season
In Vietnam, 1 kg Paddy = VND 6,000, USD 1 = VND 20,800 (2011)
In the Philippines, 1 kg Paddy = PhP 15, 1 bag of fertilizer = PhP 1,010; USD 1 = PhP 43.62 (2011)
Table 17 Cost and Benefit Analysis of Using Rice Straw to Produce Rapid Compost and Apply to the
Rice Field in Mekong Delta, Vietnam and Central Luzon, Philippines (USD ha-1)
ITEMS
1. Benefit
1.1. Direct Benefit
1.2. Indirect Benefit
- Benefits from lo loss
land to store rice straw
- Benefits from saving
fertilizers
- Benefits from saving
pesticides
2. Cost (1)
2. Cost (2)
2.1. Direct Cost (1)
- Producing rapid compost
in heap
2.2. Direct Cost (2)
- Scattering rice straw and
add Trichoderma/EM
2.3. Indirect Cost
- Cost of CH4 emission
3. Net benefit (1)
3. Net benefit (2)
Mekong Delta, Vietnam
2nd SS
3rd SS
Whole
year
139.18
99.18
99.18
337.55
139.18
99.18
99.18
337.55
1st SS
Central Luzon, Philippines
DS
WS
Whole
year
46.31
46.31
92.62
46.31
46.31
92.62
14.42
14.42
14.42
43.27
-
-
-
76.68
51.11
51.11
178.89
46.31
46.31
92.62
48.08
109.47
84.47
106.00
33.65
72.93
56.26
70.67
33.65
72.75
56.08
70.67
115.38
255.15
196.80
247.35
-
-
-
106.00
81.00
70.67
54.00
70.67
54.00
247.35
189.00
18.34
18.34
36.68
81.00
3.47
3.47
29.71
54.71
54.00
2.26
2.26
26.25
42.93
54.00
2.08
2.08
26.43
43.11
189.00
7.80
7.80
82.40
140.74
18.34
2.80
2.80
25.17
18.34
2.21
2.21
25.76
36.68
5.01
5.01
50.93
Note: 1st SS = SW = Spring Winter Season, 2nd SS = SA = Summer Autumn Season and 3rd SS = Autumn
Winter Season
DS = Dry Season and WS = Wet Season
In Vietnam, 1 kg Paddy = VND 6,000, USD 1 = VND 20,800 (2011)
In the Philippines, 1 kg Paddy = PhP 15, 1 bag of fertilizer = PhP 1,010; USD 1 = PhP 43.62 (2011)
Table 18 Cost and Benefit Analysis of Using Rice Straw to Grow Straw Mushroom in Mekong Delta,
Vietnam and Central Luzon, Philippines (USD ha-1)
ITEMS
1. Benefit
1.1. Direct Benefit
- Revenue from mushroom
production
1.2. Indirect Benefit
- Benefits from no loss land
to store rice straw
- Benefits from avoiding
insects, weeds and rats
- Benefits from saving cost
of scattering rice straw to
the field
- Benefits from saving of
easy land preparation
2. Cost
2.1. Direct Cost
- Cost of mushroom
production
- Cost of gap filling due to
poison of organic
decomposition
2.2. Indirect Cost
- Cost of CH4 emission
3. Net benefit
Mekong Delta, Vietnam
2nd SS
3rd SS
Whole
year
252.16
169.81
157.61
579.57
234.85
152.50
140.30
527.65
Central Luzon, Philippines
DS
WS
Whole
year
1,030.49 1,030.49
2,060.98
1,027.05 1,027.05
2,054.10
234.85
17.31
152.50
17.31
140.30
17.31
527.65
51.92
1,027.05 1,027.05
3.44
3.44
2,054.10
6.88
14.42
14.42
14.42
43.27
-
-
-
2.88
2.88
2.88
8.65
-
-
-
-
-
-
-
2.29
2.29
4.59
92.56
92.42
62.03
61.94
57.22
57.14
211.81
211.50
1.15
451.08
450.96
1.15
451.05
450.96
2.29
902.13
902.13
92.42
60.01
55.21
207.65
450.96
450.96
902.13
0.14
0.14
159.60
1.92
0.09
0.09
107.78
1.92
0.08
0.08
100.39
3.85
0.31
0.31
367.76
0.11
0.11
579.41
0.09
0.09
579.44
0.20
0.20
1,158.85
1st SS
Note: 1st SS = SW = Spring Winter Season, 2nd SS = SA = Summer Autumn Season and 3rd SS = Autumn
Winter Season
DS = Dry Season and WS = Wet Season
In Vietnam, 1 kg Paddy = VND 6,000, USD 1 = VND 20,800 (2011)
In the Philippines, 1 kg Paddy = PhP 15, 1 bag of fertilizer = PhP 1,010; USD 1 = PhP 43.62 (2011)
Table 19 Cost and Benefit Analysis of Using Rice Straw to Mulch Vegetables (Onions) in Central
Luzon, Philippines (USD ha-1)
ITEMS
1. Benefit
1.1. Direct Benefit
1.2. Indirect Benefit
- Benefits from saving cost
of watering and weeding
- Benefits from nutrient
2. Cost
2.1. Direct Cost
- Cost of collecting rice
straw and mulching
2.2. Indirect Cost
- Cost of CH4 emission
3. Net benefit
Mekong Delta, Vietnam
2nd SS
3rd SS
Whole
year
-
1st SS
Central Luzon, Philippines
DS
WS
Whole
year
38.97 38.97
77.95
38.97 38.97
77.95
-
-
-
-
16.05 16.05
22.93 22.93
6.88 6.88
6.88 6.88
32.10
45.85
13.76
13.76
-
-
-
-
6.88 6.88
32.10 32.10
13.76
64.19
Note: 1st SS = SW = Spring Winter Season, 2nd SS = SA = Summer Autumn Season and 3rd SS = Autumn
Winter Season
DS = Dry Season and WS = Wet Season
In Vietnam, 1 kg Paddy = VND 6,000, USD 1 = VND 20,800 (2011)
In the Philippines, 1 kg Paddy = PhP 15, 1 bag of fertilizer = PhP 1,010; USD 1 = PhP 43.62 (2011)
Mulching is not popular at the study sites in the Mekong Delta, Vietnam
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