Waste watersWater reuseIrrigated farmingRiceYieldsFertilizersFishWomen

Jayakody, Priyantha

Raschid-Sally, Liqa

Tuan, D. D.

English

Research Papers in Economics

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Impact of Wastewater Use on Farm Households in Nam Dinh, Vietnam 
I  Liqa Raschid-Sall/ ' Doan Doan Tuan'  and Priyantha Jayakod/ 
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Introduction 
In many urban and peri-urban areas in Vietnam, irrigation and drainage canals receive wastewater 
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which is then used for agricultural purposes and aquaculture. This is a common occurrence in many 
cities  (Raschid-Sally  et  ai.,  2004).  The  impacts  of such  application  on  farming  households  in 
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Vietnam, have never been investigated. The objective of this study was to  understand wastewater 
farming  practices in rice  cultivation systems and their socio-economic, environmental and health 
impacts, through an in-depth quantitative and qualitative analysis. 
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Methodology 
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The  detailed  study  on the  impact of wastewater use  on farm  households  was  conducted  in  the 
district of My Loc to the north of Nam Dinh city, Vietnam. The My Loc district has a capital town 
and  10  communes  including  the  communes  of My  Tan  (where  farmers  have  plots  in  both 
wastewater irrigated and clean water irrigated locations) and My Trung (located next to  My Tan, 
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however  having  essentially  clean  water  irrigated  plots)  from  which  the  sample  villages  were 
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selected.  My  Tan  commune  receives  water  from  the  Quan  Chot  pumping station which  pumps 
wastewater  from  the  wastewater  drain  serving  the  north-east  catchment  of the  city,  into  the 
irrigation canal. My Tan commune has  79 ha of  agriculture lands which 42 ha, where rice is the 
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main crop.  In addition the aquaculture ponds in the  commune receive wastewater. My Trung has 
478 ha of agricultural lands and gets irrigation water from Huu Bi pumping station that takes water 
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from Red River. 95% of  My Trung land gets clean irrigation water. 
Based on the  total  numbers  of non-agricultural  and agricultural households in the  study  area,  a 
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sample of288 households was selected randomly from 3 villages in the My Tan commune, and 250 
from 3 villages in the My Trung commune which was equivalent to 10% of  the total population for 
each ofthe communes. 
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The  survey was  a one-off survey of the selected households  using  a pre-designed questionnaire. 
Prior to  applying the questionnaire, a situation analysis was  conducted using Participatory Rural 
Appraisal (PRA) tools at the commune and village levels with participation of commune leaders, 
representatives  of local  level  organizations and  local  technical  authorities.The  pre-tested  survey 
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questionnaire was then applied to each of  the households selected and information pertaining to the 
socio-economic characteristics of the users, history and pattern of wastewater usage, land holding, 
land  use,  cropping patterns, farm/plot sizes, farm  inputs (water, fertilizer,  pesticides) and  outputs 
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farmer  perception  of  advantages  and  disadvantages,  was  collected.  Information  relating  to 
aquaculture as impacted by wastewater and  information on non-farm income was also gathered to 
quantify the contribution from different sources. 
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I  Senior Researcher, International Water Management Institute, Ghana. PMB CTl12. Accra, Ghana  I.raschid:'tl1cgiar.org 
2 Deputy Director, Center for Participatory Irrigation Management, Vietnam Institute for Water Resources Research,  171  Tay Son 
Str., Dong Da, Hanoi, Vietnam. Email: doantuan((j)hotmaiLcomcpimrtL;vnn.vn 
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3 Researcher, International Water management Institute, Sri Lanka. PO Box 2075, Colombo, Sri Lanka 
p.jayakody@cgiar.org 
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Results and Discussion 
i) Analysis of farmer households 
The average family size of a household is 4.2 persons. 80-90% were agricultural households ie their 
primary source of income was from agriculture and 21  % of  the households were female-headed. In 
both  communes,  there  is  a  predominance  of women  in certain  tasks  like  fertilizer  application, 
transplanting and weeding. Irrigation and animal husbandry are also activities where women are  in 
the  majority.  The  average  farm  area per household varied between 0.21  and  0.28  ha  in  the  two 
communes. Between 54  and 58  % of nouseholds in the two communes had ponds for  aquaculture 
and the average pond area varied between 0.06 and 0.075 ha. 
H) Analysis of wastewater and Clean water agriculture at plot level 
Comparisons between clean water and wastewater agriculture were conducted through a plot level 
analysis and not at the household level. For the two communes studied the number of clean water 
plots was three to four times the number of  wastewater plots, and plot distribution per household is 
shown in Figure 01. My Trung had few wastewater plots, so comparisons between the two types of 
plots were done mainly with data from the My Tan commune. 
Irrigation water use and Water depth: 
Data shows  that irrespective of the  growth period,  water usage  in  the summer is  higher than in 
spring  in  both clean and  wastewater areas  and  the  difference  is  significant (p=  0).  Furthermore 
irrespective of season and growing period, wastewater plots show consistently higher water depths 
than clean water plots. This is explained by the fact that wastewater plots are in the lowest elevation 
areas in the respective locations. In the wastewater irrigated areas it is  the  lowest elevation plots 
which would be the most impacted by wastewater 
1.0 
No of 
HH  120 
100 
so 
6() 
40 
20  S(d  Oev ~ 301 
h~,..jMean::5 
0 
Number of  Plots 
Fig. 01. Plot distribution among households in both communes 
(MTA an MTU) in spring season 
Rice yield differences 
Wastewater  plots  gave  a  significantly  lower  yield  than  clean  water  (p=O.O 11),  but  this  yield 
reduction was  still only 7%.  In analyzing this difference further within a single commune (Table 
01), the difference was significant only in the spring season yields. 
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Table 01. Rice yield differences by season and water quality 
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Spring yield Kg/sao  P val  Summer yield Kg/sao  P value 
My Tan  Clean water  174.9  0.03  I  Clean water  92.06  0.208 
Wastewater  164.3  Wastewater  97.2 
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In  summer wastewater plots did not appear to  be  worse affected than the  clean water plots in the 
commune.  A  possible .explanation  is  that  in  wastewater areas,  from  the  water depth  analysis, 
summer season has higher water depths, so there is greater immersion in wastewater, but the quality 
is diluted due to the rains and therefore the overall effect is beneficial. The reduction in yield in the 
I  spring season for wastewater may be due to the excess application of nutrients (see Table 02) which 
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shows that similar amounts of fertilizer and manure are being applied to the wastewater and clean 
water plots irrespective of inherent nutrients in the wastewater, or due to  other inhibiting factors. 
There is a significant but small difference only in urea application. 
Interestingly a farmer opinion tally of rice yield reduction in  wastewater showed that 62% of the
I  190  respondents  from  My  Tan  commune  felt  there  was  a  20-30%  reduction  in  yield  in  their 
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wastewater  plots  compared  to  clean  water.  This  is  a  gross  overestimation  of the  actual  yield 
reductions as  described  by  the farmers  themselves. It is possible that this is  because the  farmers 
compare the yield lost in the worst case scenario of  wastewater, with normal clean water condition. 
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Furthermore, a comparison between My Tan wastewater yields and My Trung clean water yields 
for showed that in spite of poor water quality, yields from My Tan wastewater plots (131  kg/sao), 
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were still significantly higher (p=0.007) than My Trung clean-water plots (127 kg/sao). This may be 
attributed to  the  overall  lower application of fertilizer and  manure in My Trung  and to  poor soil 
quality and the overall irrigation and drainage conditions. 
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Use ofManure and Chemical Fertilizer as nutrients: 
Nutrient input  data was  analyzed  for  rice  crop  as  being the  predominant crop  in  both  seasons. 
Nutrients used were manure, Nitrogen fertilizer (urea), Phosphate fertilizer (P04), potassium (K) 
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and in addition aggregate fertilizer (NPK). In general it can be stated that most farming households 
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(66%) apply manure to their plots, both clean-water and wastewater, the reason being its value as a 
soil  conditioner.  45%  of clean  water farmers  used  NPK in  addition  to  using  manure  and  other 
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fertilizers. 
Within the  My  Tan commune  application of manure,  urea  and  phosphate  fertilizer  in  spring  is 
significantly higher than in summer; but when a comparison was  made  between clean-water and 
wastewater plots, this difference is manifested significantly only in urea application (Table 2.0 and 
Fig. 2.0). The difference however is small (0.6kg/sao). Why wastewater farmers used less urea but 
I  apply other fertilizer in equal amounts is  not clear. It is surmised that farmers, realizing that urea 
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contributes  to  excessive  leaf growth,  avoid  its  application.  In  the  case  of chemical  fertilizer 
application, fluctuations in levels of Phosphate (P04) and Potassium (K) in wastewater or simply 
ignorance of their presence in wastewater may be leading farmers to continue to add these types of 
chemical fertilizer. 
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Table 02. Differences in Fertilizer inputs, seasonally and  by type of plot (My Tan commune) 
i  Input (k~/sao)  Spring  Summer  P=  CW  WW  P= 
iP04  19.5  18  0.051  t 
18.5 ±  19 
0.462 
K 
NPK 
N (Urea) 
Manure 
4.7  4.4  0.138 
19.5  18.9  0.451 
9.9  8.3  0 
273  233  0 
20~----··············  ----.......................................................  - .............................  , 
10 
16  ~  9 
o 
ftI 
~ 
~  12 
~  8 
8 
Spring  Summer  CW  WW 
4.3  4.7 
19.3  19.2 
9.5  8.9 
269  253 
Spring  Sumner  ON  VWV 
Fig. 02. Differences in Fertilizer inputs, seasonally and by 
type of plot (My Tan commune) 
iii) Aquaculture (fish and water birds): 
0.109 
0.954 
0.012 
0.114 
Data from  143  clean water ponds and 60 wastewater ponds  was  analyzed.  Results  from  the two 
communes showed that clean water ponds were  being used  mainly for  fish production, whilst in 
wastewater ponds, the predominant activity was breeding of  fingerlings. Nearly 50 % of  wastewater 
ponds  bred  fingerlings  whereas  this  was  only  20  %  for  clean  water.  The  reason  for  this  was 
explained as habits and tradition in the commune. However poor quality of fish produced in these 
wastewater  ponds  and  lower prices,  may  also  have  been  a  deterrent.  Farmers  complained  that 
wastewater bred fish smelt bad and their flesh was black and spoiled early.  It was difficult without 
detailed study to generalize this to wastewater fish culture. Farmers with wastewater ponds avoided 
fish breeding and bred only fingerlings (which sold at the same price whatever the origin),  to avoid 
loss of  income. Overall income figures from aquaculture show no significant differences. 
Data from a single commune (My Tan) was analyzed for differences between wastewater and clean 
water aquaculture production. There is  no  significant difference in production/sao between clean­
water and wastewater ponds whether its fish or fingerlings being cultured (p values between 0.2 and 
0.6).  On  an  average  whether  from  clean  water  or  wastewater  aquaculture  (breeding  or  fish 
production), between 230-250 kg of fish, were sold annually by a household. 
iv)  Household  consumption  of produce:ln general  irrespective  of quality  of water  used  for 
production, 92-96% of households consumed 100% of their agricultural produce. With aquaculture, 
produce  either  in  the  form  of fingerlings  or  fish  was  mostly  sold and  only  6%  of households 
interviewed explicitly spoke of domestic consumption of up  to  30% of their produce. 97 % of the 
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households said they sold nearly all of their produce, indicating that fish was produced mostly for 
commercial purposes and not usually for domestic consumption. 
v) Reasons for using wastewater: 
In  the My Tan commune, where wastewater use  is  predominant, 60% of the  respondents used it 
because no alternatives were available.  In effect the  IDMC pumps  wastewater into the irrigation 
canal in the wastewater areas because the clean irrigation water from the river does not reach these 
areas. 35% of the respondents said it was a dependable source when clean water was lacking. 15% 
appreciated the fertilizer value in it. 
vi) Share of production and loss of income: 
As shown earlier, 5 plots was the average per household and in the My Tan commune, 3 out of the 
5 plots were irrigated with wastewater. Table 3 below shows that farmers from My Tan earned  11 
million Vietnam Dong (VNDf  compared to 9 million VND for My Trung. For households in My 
Tan having both clean water and wastewater plots, the  share of household income contributed by 
the  wastewater plots  is  only  22  %  of total  family  income,  but is  as much as  50%  of the total 
agricultural income. Wastewater contributes significantly to these farming households who have no 
other source ofwater for their plots. 
Table 03. Share of household income from wastewater 
Cultivation, Fishery and 
Commune  1-:__ ---.,w,.:..a:.:.t:...:e..::.r..:..b:...:i.::,.rd=----__---1  Husband  ry 
WW  Total 
My Tan 
MyTrun 
% 
21.7 
8.5 
Conclusions and Perspectives 
% 
39.2 
55.4 
Total 
agriculture 
Other 
income 
% 
54.9 
43.5 
Total 
income 
Almost all the cities in Vietnam, to some extent, use wastewater for agriculture or aquaculture or 
both. This brings significant income for poor farmers in urban and peri-urban areas. 
In the  communes studied wastewater use  is  related to  the  topography of the plots and  its  use  is 
predominantly  in the  spring season when rainfall  is  scarce  and plots require the  most irrigation 
deliveries. Yield variations between wastewater and clean water plots was only significant in the 
spring crop but even such differences did not exceed 7%. 
Farmers seem to recognize that wastewater contains nitrogen (urea) and so apply less urea fertilizer 
to their plots leading to some savings. However for all other types of  fertilizer application there was 
no significant difference. It appears that they add  fertilizer in spite of the presence of nutrients in 
wastewater, because they have no quantification of the levels and cannot control and regulate its 
application depending on plant needs. More optimal use of nutrients in wastewater would require 
well prepared extension services. 
Tasks  undertaken  by  women  in  relation to  the  crops  cultivated  may result  in  higher levels  of 
exposure to wastewater and risks. In the case of rice culture, this requires standing in water when 
transplanting  and  weeding.  They  require  special  attention  and  awareness  raising  to  minimize 
exposure and risk . 
• 1 USD  approx 15000 Vietnam Dong in 2004 
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Whilst wastewater provides opportunities and greater cropping flexibility  in  water scarce regions 
(Van der Hoek et al 2002),  wastewater may impose certain restrictions under specific conditions as 
is  the case with aquaculture in Nam Dinh.  Living in a monsoon region with abundance of water 
sources, farmers are unhappy with waste water and do not always appreciate its nutrient value. They 
use it because they have no choice of alternatives and because the authorities in a sense impose its 
use. 
Household  consumption of their  own  produce  even  of wastewater  origin  indicates  that  these 
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products are not perceived as harmful. Other studies have shown that this is the case in many parts 
of  the world where wastewater agriculture is practiced. 
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Under abundant water conditions, unplanned disposal of wastewater generated by cities is polluting 
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irrigation  water  sources  and  impacting  poor  suburban  farmers.  Improved  waste  water 
disposal/management is necessary and should be  enforced while alternative sources and other risk 
mitigation measures must be put in place in the short term (IWMI policy brief, 2006) 
References 
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I  1.  Raschid-Sally, L. Tuan DD.,Abayawardana S (2004) National Assessments on Wastewater Use 
in  Agriculture  and  an  Emerging  Typology:  The  Vietnam  Case  Study.  Scott  C.  Faruqui Nt 
Raschid-Sally L.  (eds.)  Wastewater Use  in Irrigated Agriculture:  Confronting the  Livelihood 
and  Environmental  Realities,  Commonwealth  Agricultural  Bureau  International,  Orient­
Longman, and International Development Research Centre, Ottawa, Canada.81-90 
I  2.  IWMI Policy Brief 17 (2006). International Water Management Institute, Colombo Sri Lanka. 
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3.  Van der Hoek W. Mehmood ul Hassan. Ensink JHJ. Feenstra S. Raschid-Sally L. Safraz Munir 
S.  Aslam  R.  Hussain R.  and Matsuno Y (2002).  Urban  wastewater:  a valuable  resource  for 
agriculture,  a case study from Haroonabad, Pakistan. Research Report 63, IWMI, Colombo, Sri 
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Lanka. 
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Tuan DD.,Abayawardana S

Urban wastewater: a valuable resource for agriculture, a case study from Haroonabad, Pakistan. Research Report 63, IWMI, Colombo, Sri I Lanka.

Impact of wastewater use on farm households in Nam Dinh, Vietnam

http://publications.iwmi.org/pdf/H038717.pdf

Impact of wastewater use on farm households in Nam Dinh, Vietnam

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