Asian and African Area Studies, 15 (2): 234-256, 2016

Alternate Wetting and Drying (AWD) Irrigation Technology Uptake
in Rice Paddies of the Mekong Delta, Vietnam:
Relationship between Local Conditions and the Practiced Technology
Yamaguchi Takayoshi,* Luu Minh Tuan,** Minamikawa Kazunori***and Yokoyama Shigeki****

Abstract
Worldwide increasing water demands have made alternate wetting and drying (AWD)
irrigation an attractive water-saving technology for paddy rice farming. With AWD,
rice paddies are intermittently irrigated, except during the rooting and flowering
stages, reducing water use by 15%-40%. We assessed AWD uptake by comparing thestandardized AWD used by official institutions and the practiced AWD used by farmers
in An Giang Province, Mekong Delta, Vietnam. We observed that 1) farmers did notuse plastic pipes to measure the water level, although these allow assessment of thecorrect timing for watering and 2) farmers also practiced AWD during the rainy season,
despite it originally being developed as a water-saving technology. These modifications
indicate that farmers have adapted AWD for use in their local farming conditions.
Agrarian certification systems should be used to increase AWD uptake; however, theserequire standardized procedures. Therefore, this disparity between the standardized
and practiced technology should be addressed to improve AWD uptake.

1. Introduction
The 21st century is “the century of water,” and various water issues have been emphasized worldwide[Sunada 2008]. With regard to the issue of water availability, the United Nations [UN 2012]
reported that “11% of the global population, i.e., approximately 783 million people, remains without
access to an improved source of drinking water.” Moreover, there is increasing competition for water
resources between domestic, industrial, and agricultural sectors.
Water availability is a particularly serious issue in Asia as the primary Asian foodstuff is paddy
rice. Irrigated paddy fields are traditionally flooded from transplanting (or sowing) to harvest, which
results in water loss through evapotranspiration and percolation. The International Rice Research   * 山口哲由, National Institute for Agro-Environmental Science   ** Sub-department of Plant Protection in An Giang Province, Vietnam*** 南川和則, National Institute for Agro-Environmental Science**** 横山繁樹, Japan International Research Center for Agricultural Sciences
Accepted January 22, 2016234

Yamaguchi et al.: Alternate Wetting and Drying (AWD) Irrigation Technology Uptake in Rice Paddies of the Mekong Delta

Institute (IRRI) has found that paddy rice only needs to be flooded during the rooting and flowering
stages [Van der Hoek et al. 2001]. Consequently, IRRI developed the alternate wetting and drying(AWD) procedure, whereby paddy fields are only intermittently irrigated except during these criticalstages. AWD procedure (“safe-AWD”) follows strict standards, whereby paddy fields are watered up
to 5 cm and then re-watered when the water level naturally declines to 15 cm below the soil surface,
reducing total water usage by 15%-40% compared with continuous flooding, with no major negative
impact on yield [Humphreys et al. 2010].
IRRI assumed that AWD would be well-received by Asian countries because of its reduction
capacity of irrigation cost; however, it is still not very popular. In Bangladesh, AWD demonstrations
by IRRI did not lead to its subsequent spread because of insufficient extension workers to transfer thetechnology to farmers and disparity between the AWD logic and local farmers’ perception regarding
paddy rice farming [Kurschner et al. 2010]. In the Philippines, AWD was adopted in paddy areas
where farmers were using power pumps; however, it was not adopted in areas where gravity irrigation was utilized as this system included a fixed irrigation fee for each season and did not benefit the
AWD adopting farmers [Lampayan et al. 2009]. In China, it was decided that AWD would not tobe adopted in paddy areas that had no stable water sources [Moya et al. 2004]. However, AWD has
spread more extensively in An Giang Province in the Mekong Delta, Vietnam (Figure 1).
Vietnam is one of the major rice producers of the world, and the Mekong Delta accounts formore than half of Vietnam’s production [MAFFJ 2011]. The total rice production in the Mekong
Delta has been steadily increasing for several decades through the introduction of new rice varieties,
chemical fertilizers, and power pump irrigation. However, farmers’ incomes have not matched thisincrease for two major reasons: relatively poor quality rice grain which has a lower selling price forexport and high production costs as chemical fertilizers or irrigation are used [UNEP 2005]. AWD
is expected to reduce irrigation costs and thus increase farmers’ incomes [Truong Thi Ngoc Chi etal. 2013], and this has been supported by cost-benefit analyses of households that have and have not
adopted AWD in An Giang Province [Diangkinay-Quicho 2013; Lampayan et al. 2015]. However,to date, no detailed studies have investigated AWD uptake by farmers.
According to previous studies [Kurschner et al. 2010; Lampayan et al. 2009; Moya et al. 2004],
widespread AWD uptake has been constrained by a combination of local agricultural conditions
including infrastructure, prevalent political institutions, and farmers’ perceptions. Therefore, weinvestigated AWD adoption and practice in the An Giang Province and subsequently examined how
AWD had integrated into the local agrarian system.

235

Asian and African Area Studies, 15 (2)Fig. 1. Location of the Study Site and Climate in the Mekong Delta
Sources: An Giang Province data were taken from Thieu Vinh An [2014]. The precipitation data for Kien
Giang and Can Tho were taken from Quy Toan Do and Christiansen [2010], and the temperature
data were taken from Raspisaniye Pogodi Ltd. [2015].

2. Methodology
We undertook two separate field investigations in May and September 2014.
In the first investigation, general agrarian information on AWD, including uptake level andcurrent plans, were obtained from the Department of Agriculture and Rural Development in An
Giang Province and Sub-department of Plant Protection in An Giang Province (SDPPA). The generallandscape around An Giang Province was surveyed. Based on this information, we decided to focus
236

Yamaguchi et al.: Alternate Wetting and Drying (AWD) Irrigation Technology Uptake in Rice Paddies of the Mekong Delta

Fig. 2. Paddy Water Management during the Dry Season (taken from household A)
Water depth below the soil surface was unclear because farmers did not use a pani-pipe.
Source: Field investigation in 2014.

the second investigation on the rural commune of Binh Hoa in Chau Tanh District.
In the second investigation, we conducted structured interviews with 21 households, which wereselected by the People’s Committee of the rural commune.1) The prepared questionnaire included
the sections of agricultural outline, adoption and AWD practice, paddy field water management, andirrigation pump use. We also confirmed daily water level changes and the timing of watering during
the dry cropping season (from winter 2013 to spring 2014) (Figure 2).2) Although the interviewees
did not record this information, they carefully observed their paddy fields almost every day and remembered when they watered them and how many days after irrigation the floodwaters disappeared.
During the first investigation, we noticed that the AWD procedures practiced by farmers weredifferent from IRRI’s standardized procedure. Therefore, we focused on these differences andadopted the concept of “reinvention,” which is defined as “the degree to which an innovation ischanged or modified by a user in the process of its adoption and implementation” [Rogers 2007:103]. For an innovation to be adopted and continuously implemented, it must match the user’s
requirements. Agrarian technologies are particularly dependent on the surrounding conditions,
including the natural environment, infrastructure, or farmers’ skills [Suzuki 1998] and, therefore,
any agrarian innovation also needs to fit these. We considered reinvention as transformation of theoriginal innovation into a desired form by the locals, allowing the innovation to take root in the localarea.
We analyzed the differences between the standardized AWD, as outlined in the guide bookpublished by SDPPA [2011] (Figure 3), and the practiced AWD at the site. The guide book explains
the agrarian policy of “one must and five reduction (1M5R),” whereby “one must” requires farmers

1) We could not obtain details around the process of household selection for political reasons. Thus, we attempted tovalidate the data from these households by comparing them with existing studies. We also present median values
and ranges to reduce the likelihood of sampling bias.
2) Where households possessed multiple paddy plots, we requested that they focused their responses on the largest plot.

237

Asian and African Area Studies, 15 (2)Fig. 3. The Guide Book of the “One Must and Five Reduction” Policy, published by SDPPA [2011]

to use certificated seeds rather than autogenous seeds and “five reduction” is recommended to reduce
the sowed seed number and the amounts of agrichemicals, fertilizers, irrigation water, and postharvest loss. This policy aims to increase rice farmers’ incomes by eliminating inefficiencies in rice
farming [Truong Thi Ngoc Chi et al. 2013]. The guide also explains how to implement AWD, which
has been officially adopted as a water-saving technology since 2009.
In the following sections, we first explain the landscape and paddy rice farming practices atthe study site, and then provide an overview of the AWD uptake situation in An Giang Province.
We then provide some real-life examples of AWD adoption and water management based on the
Binh Hoa commune case study. Finally, in the discussion, we examine the differences between thestandardized and practiced AWD.

3. Landscape and Agricultural Practices at the Study Site
In 2008, the total rice production of the Mekong Delta exceeded 20 million tons (husked rice). An
Giang and Kien Giang Province are particularly important for rice production [MAFFJ 2011],
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Yamaguchi et al.: Alternate Wetting and Drying (AWD) Irrigation Technology Uptake in Rice Paddies of the Mekong Delta

Table 1. Basic Information on the Study Site
An Giang Province
Chau Tanh District
Binh Hoa commune

Population
2,142,709a
169,723a
19,568b

Number of households
524,759a—
4,080b

Total area (ha)353,676b
35,507b2,228b

Paddy area (ha)192,594c
27,686c
1,926dSources: a: conditions in 2009 [CPHCSC 2010], b: conditions in 1999 [MICV 2010], c: conditions in 2007
[Nguyen Lam Dao et al. 2009], d: conditions in 2007 (estimate based on a 1/50,000 map).

with An Giang Province contributing 17% of the total rice production. Compared with other riceproducing areas in Vietnam, rice farming in the Mekong Delta occurs in relatively larger fields and isprimarily linked to export [Young et al. 2002].
The Mekong Delta is approximately 40,000 km2 in area and is located between 8°34' and10°55' N. The monthly average air temperature rarely drops below 25°C (Figure 1); paddy rice canbe cultivated year round if water conditions are appropriate. The western part of the Mekong Delta
has an annual precipitation of >2,000 mm due to the monsoon effect from the southwest. However,annual precipitation decreases inland and is approximately 1,300 mm in An Giang Province. Mostof the precipitation tends to occur during the rainy season of June-November (monthly precipitation,
200-300 mm), with much lower levels during the dry season of December-March.
The Mekong River splits into the Hau Giang and Tien Giang Rivers at the Vietnam-Cambodia
border. Kaida [1975] categorized An Giang Province as the floodplain of the Hau Giang River, withpaddy fields accounting for approximately 60% of all provincial land. There are small differences in
the landscape between the 11 districts within the Province, with eastern districts, such as Phu Tanh
and Chu Phu, being prone to flooding and western districts, such as Tinh Bien and Tri Ton, having
several small hills. The Chau Tanh District is also located in the middle of the floodplain, withpaddy fields occupying approximately 80% of the area (Table 1).
Rice production in An Giang Province used to be based on the single-cropping of floating rice
varieties. However, with the introduction of improved fast-growing and high-yielding rice varieties
at the end of the 1960s, farmers could double their crop production, except during the peak flooding
periods from September to November. At the beginning of the 1990s, these improved varieties
prevailed across most of the Province [Otsuka 2014]. At the end of the 1990s, the local government
began to construct the full-dike systems that enclose some settlements and fields [Tran Van Hieu
2010]. These systems use huge pumps to drain excess water during the rainy season, enabling farmers to triple crop. Our case study site, the Binh Hoa commune, has been enclosed by a full-dike since
2010.
239

Asian and African Area Studies, 15 (2)Fig. 4. Agricultural Calendars for Paddy Rice and Their Associated Yield
Yield amounts are median wet weights of husked rice before drying across the surveyed households (n=21).
Numbers shown in parentheses denote the selling price to middlemen; VND=Vietnamese dong.
Source: Field investigation in 2014.

The rice cropping seasons in An Giang Province are separated into hè thu (HT; summerautumn), thu dông (TD; autumn-winter), and dông xuân (DX; winter-spring) (Figure 4). During
HT, farmers seed at the end of the dry season and harvest before the middle of the rainy season; during TD, farming is conducted during the heaviest rainy season of the year; and during DX, farmingis almost the same as dry cropping. Based on the interview results, HT, TD, and DX harvest yields
approximately 7.0, 7.2, and 9.4 ton/ha, respectively (Figure 4).3) It is difficult to directly compare
these harvest amounts because farmers sometimes use different varieties depending on the cropping
season. However, farmers generally consider that DX season yields the best harvest of the year, withproduction tending to decline during HT and TD rainy seasons.

4. AWD Uptake in An Giang Province
IRRI initiated the AWD introduction project in Vietnam in 2003 [Rejesus et al. 2013] and An Giang
Province at around this time [CTIEI 2011]. Since 2005, AWD has been incorporated into agrarianpolicies in An Giang Province [Rejesus et al. 2013], with SDPPA providing training workshops andfield exhibitions; since 2009, the local government has promoted the 1M5R policy, in which AWD
was adopted as the primary water-saving technology [Truong Thi Ngoc Chi et al. 2013].
As shown in Figure 5, Long Xuyen, which is the central township in the Province, had the highest level of AWD uptake in 2009 and 2013, largely due to government efforts having been focusedon this area since 2005. Uptake level is also currently increasing elsewhere, although there are stilllarge differences between districts, with levels of use ranging from 28% in Tinh Bien to 79% in Phu
Tan. Chau Tanh fell between these levels, and the uptake level in the Binh Hoa commune was 58%
in 2013.
3) Most farmers in An Giang Province sold their rice immediately after harvest. Therefore, the weights shown here
denote wet weight of husked rice before drying, which would include 20%-30% water.

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Yamaguchi et al.: Alternate Wetting and Drying (AWD) Irrigation Technology Uptake in Rice Paddies of the Mekong Delta

Fig. 5. Rates of AWD Technology Uptake by Districts in An Giang Province in 2009 and 2013
Numbers denote the changes in AWD uptake rates by the area in each district during dry season farming.
Source: Interview survey on the Sub-Department of Plant Protection in An Giang (SDPPA) in 2014.

As mentioned in section 2, the guide book of the 1M5R policy [SDPPA 2011] explains thestandardized procedure of AWD-namely, that farmers should water their paddy fields at a shallow
height of approximately 5 cm and wait for water to decrease to 15 cm below the soil surface before
re-watering. This strict schedule of water management for paddy rice farming is described as follows.

It needs to moisten the inner paddy soil just after sowing but to avoid flooded irrigation forfirst 7 days. Fertilization should be conducted at 7-10 days after sowing (DAS), the paddy
should be flooded to a depth of 1-3 cm at this period. Water height should be maintained
3-5 cm during 10-20 DAS because flooded irrigation is necessary for rice growth during thisperiod and it also controls weeds. The second fertilization should be conducted 18-22 DAS.
Rice is in vegetative growth during 25-40 DAS, about 60% soil moisture is sufficient forprosperous growth, thus, AWD should be conducted during 25-40 DAS. Additionally, riceis prone to sheath blight disease during this period, shortening of the flooded conditions by
AWD restricts spread of the pathogenic fungus (Rhizoctonia solani). Third fertilization should
be conducted during 40-45 DAS, water depth should be maintained at 1-3 cm for this period.
Nothing significant is noted during 45-60 DAS. The period of 60-75 DAS corresponds to theflowering stage; rice requires large volumes of water, thus, water depth should be continuously
241Asian and African Area Studies, 15 (2)Fig. 6. Sketch of an Installed “Pani-pipe”
Source: Illustrated by the authors based on the explanation in SDPPA [2011].

kept at 5 cm. Farmers should drain the water from the paddy fields 10-15 days before harvest.
Draining the water before harvesting promotes rice ripening and facilitates the machine
harvesting operation. [SDPPA 2011]

The guide also recommends the installation of a plastic “pani-pipe” in the paddy fields to confirm thewater depth below the soil surface using the many holes and scale marks (Figure 6).
The standard AWD procedure outlined by SDPPA is almost identical to IRRI’s safe-AWD procedure, although SDPPA provides a stricter schedule that also includes fertilizer application. In thediscussion, we compare this standardized and practiced AWD on site to investigate the reinvention ofthis procedure.

5. Results
5.1 Paddy Rice Farming
Table 2 provides basic information about the surveyed households and their heads. None of thehousehold heads were engaged in off-farm work, as agrarian activity was their primary income
source. Across the 21 households surveyed, the median area planted with rice was 1.2 ha, with
12 households cultivating 1-2 ha. Similarly, the World Bank [2013] reported that Mekong Delta
households owned a mean 1.5 ha paddy rice area and Truong Thi Ngoc Chi et al. [2013] reported amean 1.64 ha per household paddy field area, based on an extensive survey of 471 households in An
Giang Province. Each household generally possessed one paddy field plot but some possessed several.
242

Yamaguchi et al.: Alternate Wetting and Drying (AWD) Irrigation Technology Uptake in Rice Paddies of the Mekong Delta

Table 2. Basic Information about the Survey Respondents and Their Households

n=21Medianvalue[range]PropertyAge of Standard ofof paddy
informants education*
fields (ha)48
[31-75]

Second. S.
[Prim. S.High S.]

Distance
Number Paddy area
Frequency
fromNumber ofof paddyby plotof field
homestead motorbikes
plots
(ha)
visiting**
to fields (km)1.2
[0.2-6.7]

1
[1-5]

1.0
[0.2-4.5]

1.7[0-11.8]

2
[1-5]

1
[1-3]

* In the Vietnamese education system, people progress from 5 years of primary school (“Prim. S.”) to 4
years of secondary school (“Second. S.”) and 3 years of high school (“High S.”)** Frequency indicates the interval between paddy field visits by farmers.
Source: Field investigation in 2014.

The paddy fields were not always adjacent to their homesteads, with some households needing tomove some distance for management. Because all households surveyed possessed motorbikes, thedistance between their homesteads and paddy fields was not a major issue; most households checked
the conditions of their paddy fields every day.
All paddy plots of the households surveyed were connected with primary or secondary water
channels for irrigation and drainage. Although some households undertook plot-to-plot irrigation in
the past, few fields now depend on this as the local government set up branching water channels at
the farmers request.
Most of the farmers surveyed plow and flood their fields during the inter-cropping periods andthen sow the next season’s crops once the land has drained. All households surveyed used certified
rice seed supplied by private companies or public institutions. One major variety planted in 2013
was jasmine rice, which has a special flavor and is mainly exported to the Middle East; the improved
varieties OM4281, OM5451, and OM6976 were also cultivated.4) Until recently, farmers used tosow by hand-broadcasting and conducted complementary planting; however, following 1M5R riceseed saving policy implementation, most farmers have now switched to using a drum seeder, with
only three of the surveyed households continuing to hand-broadcast seed.
5.2 AWD Adoption and PracticeTable 3 shows AWD adoption and practice among the surveyed households. AWD was first adopted
by some households in 2004, with maximum uptake in 2007. By 2010, all households were practicing AWD. Households chose to use AWD based on information from two sources: the workshops
provided by IRRI and SDPPA, and observations and daily conversations with neighbors. Only one4) The respondents identified the flavored rice as jasmin but did not have detailed information about the variety. The
OM series, e.g., OM4281 and OM5451, are domestic varieties that were developed from the IR rice varieties tosuit local Vietnamese conditions.

243

Asian and African Area Studies, 15 (2)Table 3. Year in Which AWD Was First Implemented and Information Sources Used by Surveyed Households
Information sourcesin adoption

Adoption year
2007
2008
1
0
2
1
7
2
10
3

2004
0
3
3
6

Only from workshops
Only from neighbors
Both workshops & neighbors
Total

2010
0
0
2
2

Total
1
6
14
21

Source: Field investigation in 2014.

Table 4. Reasons Why Surveyed Households Practiced AWD
Reasons for adoption
Improved yield
4

Government
instruction
3

Large scale
paddy field
2

Viet GAP
0

Request bymiddlemen1

As neighbordoing
4

We asked informants to respond using five answers: 0. don’t know; 1. not important; 2. less important;
3. important; and 4. very important. Each number is the median value for 21 households.
Source: Field investigation in 2014.

household adopted AWD based solely on the workshops, with 14 households using a combinationof information from the workshops and neighbors, and six households using only information fromneighbors.
We asked the household heads to evaluate the importance of several interrelated factors in their
AWD practice (Table 4). Most household heads emphasized “increasing productivity” as a primaryreason for uptake, with nearly all stating that AWD increased their rice yield during both the dry
and rainy seasons. The level of increase differed between households, reaching a maximum level of
30% for one household. The household heads also mentioned that it was important to synchronize
harvest timing with neighboring households. Harvesting was generally conducted using a combine
harvester to reduce post-harvest losses, and drying was then performed by middlemen, who generally
moved from one area to another during the harvest periods. Therefore, if one particular household
harvested at a different time from neighboring households, they had to hold onto their harvested
grain until the next visit, during which time the rice would dry out, resulting in a lower rice weight
and thus lower profits (because the selling price is the same regardless of drying condition).
Good Agricultural Practice (GAP) is a certification system that adds value to agrarian products[Nakajima 2010]. Vietnam introduced a domestic version of GAP (“Viet GAP”), which has morerelaxed rules than the international version. In the Mekong Delta, rice farming households with
Viet GAP certification appeared from approximately 2010 [Tran Quoc Nhan et al. 2013]; however,244Yamaguchi et al.: Alternate Wetting and Drying (AWD) Irrigation Technology Uptake in Rice Paddies of the Mekong Delta

Table 5. Advantages of AWD According to the Surveyed Households
MeritsSaving pump cost
Saving fertilizer
Sharing experience
Synchronized calendar
Good relation among farmers
Saving agrochemicals
Saving seed
Advantage of selling price
Facilitation of harvesting
Good relation between farmers and the government

Number of responses
15
8
7
5
5
4
4
4
1
1

Source: Field investigation in 2014.

the surveyed households had a relatively low awareness of Viet GAP, and none of the households
practiced AWD to obtain this. The “large-scale paddy field”5) policy, in which rice farmers form anassociation that contracts with companies to boost their influence, has also been implemented in the
Mekong Delta [Tran Quoc Nhan et al. 2013], but household heads seldom mentioned a relationshipbetween AWD and this policy.
We also asked an open question about AWD advantages (Table 5). In response, 15, 8, and 4
household heads mentioned water-saving benefits, reduced fertilizer use, and reduced seed requirement, respectively. We did not obtain any detailed data on fertilizer and seed used, but no previous
studies have reported a direct link between AWD and reduced levels of these factors. Therefore, it
is possible that those household heads were considering their overall impression of the 1M5R policy
when answering because farmers took a class on this under the government’s guidelines. Fourhousehold heads also mentioned a reduced requirement for agrochemicals as AWD merit, whichis also noted in SDPPA’s guide book. Seven household heads considered the shared experience as
an AWD merit, which may have been generated through the exchange of AWD information—theanswer “Good relations among farmers” would also have a similar meaning.
We also asked about the disadvantages of AWD. However, only two household heads specified
any disadvantages, with reference to the water arrangement issue.
5.3 W ater Management Practices during the Dry Season (DX)
There were clear differences in water management practices between the dry and rainy seasons in5) “Large scale paddy field” is an agrarian policy of the Vietnamese Government that aims to strengthen farmers’
bargaining power through collaboration between small farmers. Farmers need to use the same rice varieties andfarming technologies so that their crops are of equal quality.

245

Asian and African Area Studies, 15 (2)the Binh Hoa commune. During the dry season, water levels in both the paddy fields and irrigation
channels naturally decline; therefore, farmers add water to their fields using power pumps. Conversely, during the rainy season, when there is a large amount of precipitation, farmers need to drainwater from their paddy fields using the huge pumps of the full-dike system.
We prepared pattern diagrams showing the actual water management practices performed
during the dry season by 15 of the households surveyed (e.g., Figure 2); six of the original households
surveyed were excluded due to ambiguous answers.
Contrary to the SDPPA’s guidelines, none of the households continued to use pani-pipes tomeasure water levels after the initial implementation of AWD. Some households used these during
the first few cropping season, but then stopped because of the additional labor requirement. The
households instead used their own criteria to determine the timing of watering. Consequently, nodata on water depth below the soil surface is shown in these diagrams, but the number of days taken
for water to disappear from the soil surface after watering was determined.
The general water management practices are presented in Table 6. All household heads gave
a maximum water height of 5 cm. Almost all households also performed the first flooding at 7-10
days after sowing (DAS). Harvesting was generally conducted at approximately 100 DAS, but mosthouseholds stopped irrigation 10-15 days before harvest to dry up their fields.
At 26-40 DAS, SDPPA recommends practicing AWD, and the fields at the study site were notflooded for approximately 10 days (66%) during this period. At 46-60 DAS, SDPPA does not provide any particular instructions, and the fields were not flooded for approximately 9 days (60%). By
contrast, at 11-20 DAS, SDPPA recommends continuous flooding, but the fields were not flooded for
5 days (50%). At 61-75 DAS (the flowering stage), SDPPA also recommends continuous flooding, but
the fields were not flooded for approximately 5 days (33%). After 75 DAS, most farmers transitioned
to very shallow water management, where the water height was maintained at 1-2 cm.
The AWD instructions provided by IRRI and SDPPA note that farmers should continuously
flood their paddy fields during the flowering stage. At the study site, the ratio of non-flooded days
was significantly lower during the flowering stage (61-75 DAS) than during the recommended period
for AWD (26-40 DAS) (Mann-Whitney U test, p<0.05), which suggests that the surveyed households
did try to keep their fields permanently flooded at this time.
If the water supply is stopped, water height naturally decreases because of evapotranspirationand percolation, the degree of which is referred to as the water requirement rate. Several household
heads stated that floodwaters would disappear 3-4 days after irrigation at the beginning of the cropping season, and 5-7 days after irrigation in the middle of the cropping season. Thus, based on the
246

7
[5-8]

Medianvalue[range]90[80-110]Stopping
irrigationday*
100[100-120]

Day ofharvesting*8[6-10]

Numberof times ofwatering
16[10-20]

12
[7-8]

30
[14-49]

5
[0-8]

10
[5-13]

9[0-15]

247

1 [1-3]

Median value [range]

Fuel fee of pump owner
HHs (n=10, VND/ha/season)200,000[150,000-300,000]

Pump hiring costs
Number of times of watering*
including fuel fee (n=8,Pump owner HHs (n=10) Pump hiring HHs (n=5)
VND/hour)
40,0008.5
7[24,000-40,000][7-10][6-8]

HH=“household”
We interviewed the heads of 21 households, but some were unable to provide detailed answers. Thus, we provide the number of households that responded
for each item.
* Mann-Whitney U test, p<0.05.
Source: Field investigation in 2014.

Number of pumps by
HH (n=13)

Pump owner HHs: 13
Pump hiring HHs: 8

Table 7. Irrigation Costs of Pump-owner and Pump-hiring Households during the Dry Season (DX)5[0-10]

Non flooded days
Maximum
Water
Non flooded
interval days requirement days during during during during duringof watering rate (mm/day) the season** 11-20* 26-40* 46-60* 61-75** Days after sowing.
** Non-flooded days were calculated from the day of first flooding after the rooting stage to the cessation of irrigation before harvest.
Source: Field investigation in 2014.

First
floodedday*

n=15

Table 6. Water Management in Paddy Fields during the Dry Season (DX)

Yamaguchi et al.: Alternate Wetting and Drying (AWD) Irrigation Technology Uptake in Rice Paddies of the Mekong Delta

Asian and African Area Studies, 15 (2)patterns of use, we estimated a median water requirement rate of 12 mm/day for each household’s
paddy field. This value does not include precipitation, but since monthly precipitation is <30 mm
during the dry season, water supplied by rainfall would not be very significant.
The maximum interval between two watering events across the households was 20 days
(median, 16 days). Households watered their paddy fields to reach a level of 5 cm a median of eighttimes during the dry season, except during the very shallow water management period.
5.4 Power Pump Use
During the dry season, farmers at the study site used personal power pumps to irrigate their fields
because the water level in the irrigation channels was lower than that in the soil surface of the paddy
fields. Table 7 shows the use of power pumps among the surveyed households.
Power pumps were owned by 13 surveyed households and were hired by the other eight households during DX and start of HT seasons. Pump owners seldom remembered the actual price of
their pumps, but we received purchase prices of 4.5 million VND6) in 2009 and 5.0 million VND in
2004. Although the capacity of the pumps varied, they were generally able to irrigate a 1-ha paddy
field to up to 5 cm in 3 h, at a fuel cost of 10,000-12,000 VND/ha. The pump-owner households
generally watered their fields 8.5 times during the dry season, at a median cost of 200,000 VND/ha.
Only two pump-hiring household heads knew the total hire costs during the dry season: one
household watered a 0.5-ha field six times during the season and paid 500,000 VND and the otherwatered a 0.45-ha field six times and paid 400,000 VND. However, all pump-hiring households
were able to provide hourly rates, which were a median of 40,000 VND/h including fuel costs.
Therefore, based on this pump hire cost, the number of times the fields were watered (median, seventimes), and the average pump ability (3 h to irrigate a 1-ha field), we estimated that the total irrigation
cost for pump-hiring households was 840,000 VND/ha during the dry season.
Pump-owner households irrigated their fields significantly more often than pump-hiring households. We estimated that pump-hiring households spent approximately four times as much as pumpowner households, not including the cost of transporting a pump from the owner’s household to thefield they needed to irrigate, which likely decreased the number of times these households watered
their fields.
Although personal pump use peaked during DX season, farmers also used pumps during HT
season because it starts at the end of the dry season. However, the rainy season starts in the middleof HT season, and some household heads stated that irrigation costs decreased by approximately
6) VND is the Vietnamese currency unit. 1 JPY was approximately 200 VND at the time of our survey (September,2014).

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Yamaguchi et al.: Alternate Wetting and Drying (AWD) Irrigation Technology Uptake in Rice Paddies of the Mekong Delta

30% due to precipitation.
Farmers did not utilize personal pumps during TD season, which was in the middle of the rainyseason. Instead, water drainage was conducted using the huge pumps of the full-dike system once
per week to reduce the water height in the channels within the dike (Figure 7), following which awater gate at the paddy ridge was opened to naturally drain water from the paddy fields into thechannels. These huge pumps were managed by the farmers’ group at the site, which was comprised
several farmers who invested in the huge pump and its operation. The farmers’ group and all farmers
that used the full-dike met once per year to negotiate the pump operational fee, but the cost usuallyremained unchanged regardless of the number of times it was used for draining. Each farmer paid
1,800,000 VND/ha during the 2014 TD season.
All household heads stated that they also implemented AWD during TD season, although at thistime it was conducted using drainage. Farmers made several trenches within each paddy field plot
(Figure 8). A straight inner trench (30 cm wide, 20 cm deep) extended from the water gate to the opposite paddy ridge, and small winding trenches (20 cm wide, 10 cm deep) crossed the straight trench.
When farmers opened the water gate during the huge pump operation, extra water was drained into
these trenches, reducing the water depth to approximately 15 cm below the soil surface. The amountof water in their fields then gradually increased due to precipitation, following which the huge pump
was operated again. Farmers referred to this repeated up-and-down water management as the AWD
of TD season.

Fig. 7. Drain Pump Fixed at the Full-dike
Huge drain pumps were operated during the rainy season to drain excess water from the dike into the primary
canal.
249

Asian and African Area Studies, 15 (2)Fig. 8. Inner Trenches of a Paddy Field during the Rainy Season
This paddy field was connected to a secondary canal via the water gate. A straight trench extended to the
opposite ridge of the field and a winding trench snaked through the entire field.

6. Discussion
6.1 Differences between the Standardized and Practiced AWD
In the previous sections, we described AWD adoption and practice at the Binh Hoa commune asa case study site and found that there are two major differences between the standardized andpracticed AWD: the non-use of pani-pipes and practicing AWD during the rainy season.
6.1.1 Non-use of Pani-pipes
None of the surveyed households continued to use pani-pipes after the first year of adoption, withall household heads stating that they now decide on the timing of watering using their own observations. Most household members visited their fields every day to check on the plants, soil, and waterconditions and were able to provide detailed information about their fields, as shown in Figure 2.
However, different households used different cues for watering, including “small cracks on the soil
surface” or “no footprint when entering the paddies.”
Figure 9 shows the relationship between the size of the paddy field and maximum interval
between watering events for the surveyed households. Larger paddy fields were watered at significantly shorter intervals, suggesting that farmers were more concerned about dryness in these fields.
Although we did not receive any explanation for this, it is probably related to the fact that it is moredifficult to make the surface of larger paddy fields flat and there are often unequal water manage250

Yamaguchi et al.: Alternate Wetting and Drying (AWD) Irrigation Technology Uptake in Rice Paddies of the Mekong Delta

Fig. 9. Relationship between Paddy Field Area and Maximum Watering Interval
Source: Field investigation in 2014.

ment conditions, such as partial drying or wetting, leading to uneven rice growth and grain quality[Yamaji 1992]. Therefore, the surveyed households may water these larger fields more often to avoid
partial drying during the dry season. Although IRRI recommends that a water depth of 15 cm
below the soil surface is used as a signal for watering under safe-AWD [Humphreys et al. 2010], its
instructions do not refer to the effects of surface flatness or field size, and it is unclear where farmers
should set pani-pipes in large fields with relatively rough surfaces. Thus, in real-life situations, thiscriterion for watering should be varied according to the paddy field conditions (Figure 9), which may
make direct observation of the conditions more reliable than the use of pani-pipes.
6.1.2 P racticing AWD during the Rainy Season
At the study site, paddy fields were irrigated during the dry season using personal pumps; therefore, a
reduction in their use would reduce costs, leading to direct benefits for farmers, particularly in pumphiring households. Conversely, it is necessary to drain excess water from the paddy fields during therainy season; therefore, AWD, which was developed as a water-saving technology, should in theory
be useless. However, household heads mentioned that they practiced AWD during the rainy season
to improve rice production and grain quality. Although we could not obtain detailed data regarding
the effect of AWD on rice production, those surveyed claimed that AWD increased rice production
by 10%-30% during both the dry and rainy seasons. A report from An Giang Province indicated251Asian and African Area Studies, 15 (2)that AWD reduces rice lodging, which increases the rice harvest by approximately 10% [Lampayan
et al. 2015], suggesting that the farmers’ impressions of production improvement are relatively
accurate.
Lampayan et al. [2015] did not explain why AWD reduced rice lodging in An Giang Province,
but we can deduce possible reasons based on “Nakaboshi.” Nakaboshi is a traditional Japanese
irrigation technique where farmers drain their paddy fields once during the rice farming season andhas been used to alleviate the high oxidation potential and to eliminate root rot damage [Kubota
1990]. It has been reported that Nakaboshi can also improve rice lodging and increase rice production [Kubota 1990].
A large part of An Giang Province is covered by acid sulfate soils, including Chau Tanh
District, where the study site was located [SDPPA 2011]. The Mekong Delta paddy fields are usuallycontinuously flooded during the rainy season in the absence of pump drainage, which leads to more
reductive conditions in the soil. Sulfates are naturally reduced to hydrogen sulfide under severe
reductive conditions, which causes root rot [Kyuma 1997]. Pinnschmidt et al. [1995] reported thatrice production in the Mekong Delta has been heavily impacted by root rot; therefore, the implementation of AWD may help to prevent these regional issues.
6.2 R einvention of AWD and Local Agriculture
As shown in Table 3, only one household decided to adopt AWD solely based on the information
provided in the workshops of IRRI and SDPPA. Most household heads emphasized the importanceof information from both the workshops and neighbors and also mentioned that the adoption of
AWD promoted an exchange of agrarian information between farmers (Table 5). This suggests that
farmers are seeking appropriate operational forms of agrarian technologies that apply to the local
conditions. Rogers [2007: 113] mentioned that “people who use an innovation shape it by giving
it meaning as they learn by using the new idea,” which leads to reinvention. AWD would also be
reshaped through daily practicing and the exchange of information between farmers.
In regions where AWD uptake technology has been limited, IRRI has focused on disseminating
the advantages of AWD, e.g., a decrease in methane emissions from paddy fields, and has attemptedto spread the technology using the Clean Development Mechanism [Siopongco et al. 2013],7) andAWD has also been included in the standard Viet GAP technology [Rejesus et al. 2013]. Although
7) The Clean Development Mechanism (CDM) is a flexible process for reducing greenhouse gas (GHG) emissions,as defined in the Kyoto Protocol. Through the CDM, countries that are obliged to reduce GHG emissions under
the Kyoto Protocol provide funds and technologies to emission reduction projects in countries without Kyoto
obligations. The obliged countries obtain emission credits and the countries without obligations attain sustainable
development.

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Yamaguchi et al.: Alternate Wetting and Drying (AWD) Irrigation Technology Uptake in Rice Paddies of the Mekong Delta

these certification systems are valuable for spreading such pro-environmental technologies, they also
require following a standardized procedure. However, agrarian technologies are usually dependent
on local conditions [Suzuki 1998] and are prone to modification according to the natural and social
surroundings. Our case study highlights this disparity between the standardized AWD procedureand the practiced agrarian technologies.

7. Conclusion
Although the number of households interviewed here was insufficient to fully understand AWD
adoption and implement across An Giang Province, we gained a good understanding of farmers’
recognition of AWD. We identified two differences between the standardized and practiced AWD:
the non-use of pani-pipes and the application of AWD during the rainy season. The first difference
reflected the farmers’ adjustment of the AWD technology to suit their own conditions, such as paddy
plot size, whereas the second reflected the soil characteristics and water conditions in the floodplainof the Mekong Delta. Thus, these reinventions allowed AWD to become a useful technology for
local farmers.
The implementation of AWD in An Giang Province has been closely linked to dike conditions
and the dike pumping system. However, these varied within the Province, for example, the huge
pumps of the dike system were operated year round in a commune of Chau Phu District, controllingboth irrigation and drainage; therefore, most farmers did not have personal pumps. Therefore, it islikely that the practiced form of AWD in this district would differ from that in Binh Hoa commune
because of their different water management requirements.
The use of certification systems is a good approach for improving pro-environmental agrarian
technology uptake, such as AWD [e.g. Siopongco et al. 2013]. However, their strict requirements
make it difficult to adapt the technologies to on-site conditions. Therefore, if An Giang Province
case was assumed to be a successful model of AWD uptake, further studies are required to assess thedifferent forms of practiced AWD.
Acknowledgments
We thank Dr. Yanagisawa Masayuki for comments and useful discussions on this manuscript. We are also
deeply indebted to the Binh Hoa commune farmers who answered time-consuming questions. This study
was in part supported by Ministry of Agriculture, Forestry, and Fisheries of Japan through “Technology
development for circulatory food production systems responsive to climate change (development of
mitigation option for greenhouse gas emissions from agricultural lands in Asia).” This study was also fundedby the JIRCAS project “Development of agricultural technologies based on sustainable management ofenvironment and natural resources in developing regions (FY 2011-2015).”253

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