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Session 2
“Socio-economic imperatives”

Challenges for farmer-researcher partnerships for sandy soils
in Northeast Thailand

Caldwell, John S.1, Somsak Sukchan2, and C. Ogura3

  Keywords: Economic options, erosion, farm ponds, mini-watersheds, modeling


Sandy soils cover 80% of Northeast Thailand. Three related challenges for farmer-researcher partnership in sandy soil mini-watersheds are presented. The first is how to reduce erosion in the uplands and its effects in paddies in mini-watersheds. Research with farmers is needed to develop practical solutions to retain more water in the uplands that are compatible with farmer crop and land use choices. The second challenge is how to model watersheds with multiple users for decision-making. Qualitative participatory modeling can lead to identification of needs that go beyond technical research. Institutional coordination and mechanisms are needed to support wider stakeholder involvement. Models combining hydrology, soil movement, pond water use, and crop outcomes, that farmers can use to explore aggregate effects of management options at the watershed scale are needed to complement qualitative participatory approaches. The third challenge is to give farmers more economic options in sandy soil mini-watersheds. Over 65,000 farm ponds have been built since the 1990s, but ponds are not being used intensively to generate income. One reason is inadequate pond water to support other needs, especially rice. Methods for channeling water from uplands into ponds need to be developed with farmers. Augmenting pond water with groundwater may be more compatible with current upland use. Techniques are needed to increase water use efficiency for fruits and vegetables and thereby increase the area that farm ponds can irrigate. Methods to enable farmers to see likely aggregate economic effects of individual decisions could help stimulate more coordination among farmers in marketing.


Sandy soils are a key characteristic of Northeast Thailand, covering 80% of its area (Yuvaniyama, 2001). In contrast, sandy soils cover only 2%, 11%, and 9% of the North, Central/East, and Southern regions of Thailand (Office of Soil Survey & Land Use Planning, 2002). The alluvial plateau of the Korat basin makes up a large proportion of Northeast Thailand, with upland soils comprising 37% of the region’s area (Wongwiwatchai and Paisancharoen, 2002). The topography of the alluvial plateau is undulating, forming a series of mini-watersheds. Farmers in the northeast have converted the bottoms of mini-watersheds into paddies for rice, and plant sugarcane and cassava in the uplands. The climate of Northeast

Thailand is characterized by distinct dry and wet seasons. From November to April, almost no rain falls in the region.

The above characteristics have created a complex of management problems for farmers. First, sandy soils have poor water-holding capacity. This means that in the rainy season, they reach saturation quickly. Excess water runs across the surface, and their loose texture makes them easily subjected to erosion. Water runs across fields of different owners in the mini-watershed. Much rainwater is lost to agriculture.

The low water-holding capacity of sandy soils, combined with their low fertility, in turn reduces the options that farmers can choose from for crop production. Sugarcane and cassava are able to produce well under these conditions of sandy soils and a long dry season. However, both require industrial processing for sale. This means that farmers have to sell to the processing plants in the area. In addition, sugarcane requires a large amount of labour and fertilization. These inputs are costly, and as a result, many farmers carry a high debt load. In one study in a village in Khon Kaen Province, 49% of farmers had debt greater than B50,000, or more than $1,250 (Ando, 2003).

How to address this complex of problems raises several challenges for research. In this paper, I will focus on three related challenges:

  1. How to reduce erosion and its effects at the mini-watershed scale?
  2. How to model watersheds with multiple users to support user decision-making?
  3. How to give farmers more economic options in sandy soil mini-watersheds?

Each of these challenges cannot be addressed only through bio-physical improvements on a specific field, or even a specific farm. These problems result from interactions across farms mediated by water movement. They can only be solved through cooperation among watershed users. This in turn makes participation of watershed users essential for research and development aimed at improvement of sandy soil watersheds to result in change.

Reducing erosion and its effects at the mini-watershed scale

In the mini-watersheds of the Korat Plateau, erosion is more evident in fields planted in cassava and in fallow land, than in fields planted in sugarcane. However, over a large enough catchment area, water flowing through sugarcane fields can attain sufficient volume and carry enough sand to result in major problems in the paddy areas.

In the Rainfed Agriculture Project1), we have worked in one mini-watershed since 2001. In the first year, in a watershed users’ meeting, farmers placed two transects in this watershed to orient researchers to their most important problems, and then we conducted a field survey with farmers having paddy and upland fields on each transect. Figure 1 shows this mini-watershed and the two transects. At the upstream end (to the right of Figure 1), farmers indicated that erosion in paddy fields was the greatest constraint. In the upstream paddy area marked in Figure 1, rice failed or was not planted in 18 of 20 plot-years. Only in one paddy plot, where soil erosion affected only 20% of the plot area, was any rice yield obtained, but even there, normal yields were obtained in only one of five years. The principal reason for failure in these plots was sand deposition due to erosion from sugarcane fields surrounding the paddy plots, as shown in Figure 2a-c (Caldwell et al., 2002).

Management of Tropical
Sandy Soils for Sustainable

Figure 1. Soil erosion, effects, and management in a mini-watershed, Nong Saeng Village, Khon Kaen Province, 2001-2004 (erosion flow lines after T. Shiono, 2002, unpublished data)

Management of Tropical
Sandy Soils for Sustainable

Figure 2a. Soil erosion in uplands leads to: Figure 2b. dike breakage, which results in: Figure 2c. sedimentation in central paddies and rice yield loss

Management of Tropical
Sandy Soils for Sustainable

Figure 3. Flow of water downsteam through side paddies and dike breakage into central paddy area

In 2002, farmers converted all of the upstream paddy area indicated in Figure 1 to sugarcane. However, this simply shifted the head of the paddy area downstream (to the area marked site E), and transferred the problem of erosion from the upland sugarcane fields and sand deposition into that paddy area.

In February 2002, we conducted another farmers’ meeting to present the results of the transect survey together with five technologies from on-station research that had potential to address the two principal problems revealed by the transect survey: 1) erosion and consequent sand deposition in paddies; 2) inadequate water in farm ponds. Farmers choose a technology developed to reduce leakage from ponds and dikes, but proposed using this technology to reinforce dikes at strategic locations where breakages created an entry point for water into a large paddy area. Sites A and B were selected and reinforced in 2002, and sites C, D, and E reinforced in 2004 (Caldwell et al., 2004).

Plots in the paddy area can be classified in two ways. If paddies are viewed on a transect placed perpendicular (vertically in Figure 1) to the downstream flow of water through the watershed (to the left in Figure 1), we can classify paddies into upper, middle, and lower paddies (Ogura et al., 2005). This classi­fication is especially useful for considering paddy water level for rice production, and farmer decision-making on paddy plot use between rice and rainy season fallow for livestock. However, if paddies are viewed in terms of water flow downstream through the watershed, it is useful to distinguish between central and side paddies (Figure 3). Central paddies are groups of lower paddies separated by farm ponds that stop the downstream flow of water. In contrast, side paddies are middle and lower paddies through which water can flow uninterrupted from upstream to downstream.

In Figure 3, a breakage in the dike between a side paddy and the central paddy area at the upstream end, near the farm pond, can provide the entry point for sand to come into the central paddy area and cause sedimentation. In Figure 1, reinforcement of dikes in side paddies at sites B and C protected central paddy areas successfully. The side paddies became water flow pathways for diversion of excess water, as shown in Figure 1. However, reinforcement at site E, at the head of the paddy area, could not handle the volume of water from the upstream sugarcane area. The problem of how to retain more water in the uplands remains. Agroforestry and grass strips are technically feasible, but may conflict with current farmer land use. Splitting upland fields into smaller segments divided by trees or grass strips conflicts with land preparation and other operations done by tractor. Work with farmers to develop practical solutions compatible with farmer crop and land use choices is one challenge for management of sandy soil mini-watersheds.

Modeling watersheds with multiple users for user decision-making

In the mini-watershed shown in Figure 1, most farmers have land in long rectangles perpendicular to the flow of water downstream. Each farmer thus has upland fields on either side of a narrow section of the paddy area. Each farmer’s paddies are affected by water flow coming from both upstream (to the right in Figure 1) and from higher land on either side of the farmer’s section of the paddy area. In two farmers’ meetings (November 2002 and February 2003), we used 3-dimensional watershed models as aids for farmer discussion and decision-making (Figure 4a-b).

In another farmers’ meeting (May 2004), farmers in this watershed indicated that through this approach, they had for the first time realized that they shared problems together. However, to move beyond identification of problems to development of group solutions requires involvement of other stakeholders. Farmers were interested in obtaining support to make a canal along one side of the central paddy area, to be able to safely divert excess water. One approach might have been to invite the local Tambon Administrative Organization (TAO, or “Ow-Baw-Taw” in Thai) to participate in a similar exercise. However, this would go beyond research, and require coordination among multiple institutions. Institutional coordination and mechanisms are needed to move beyond farmer participation in developing technical solutions to wider stakeholder involvement for watershed management.

The use of 3-dimensional models is a qualitative approach. Qualitative approaches are very powerful in accessing farmer knowledge acquired through experience. However, they cannot simulate likely scenarios in the future based on scientific measurements of variables such as rainfall variability, rates of erosion depending on slope, water flow across surfaces, or water arriving at a specific point in the topography of a mini-watershed, such as site E in Figure 1. To complement qualitative participatory approaches with quantitative modeling, several issues need to be addressed:

  1. What are the key parameters for which data are necessary for construction of a quantitative simulation model?
  2. Which parameters must be measured in real-world watersheds?
  3. How can we measure those parameters in real-world watersheds?
  4. For which parameters can we extrapolate or apply results obtained under controlled conditions to estimate their values under conditions in real-world watersheds?
  5. How can we construct a quantitative simulation model using farmers’ terms and concepts, and make it accessible to farmers?

Management of Tropical
Sandy Soils for Sustainable

Management of Tropical
Sandy Soils for Sustainable

Figure 4a. Farmers discussing water flow and sites for water management and dike reinforcement

Figure 4b. Sites considered by farmers

The first four issues involve the components of a quantitative model. These are technical questions for soil scientists, hydrologists, and crop scientists. In contrast, the last issue involves development and use of participatory quantitative modeling. In terms of Figure 3, we are asking, how we can represent, based on quantitative measurements, the likely outcomes of different possible farmer decisions, and let farmers see these outcomes as they consider choices in a participatory setting?

One possible approach involves combining multi-agent systems (MAS) modeling with hydrological and soil movement models. Lacombe (2003) has linked a hydrological model to farmer decisions on farm pond water use. Suzuki and colleagues (2003, 2005) have developed a model linking watershed hydrology and rice yield. But neither of these models includes a soil erosion sub-model linked to surface water movement. And neither of these models has yet been used with farmers in simulation of potential aggregate effects of decisions. Construction of a hydrology and soil movement model coupled with pond use and crop outcomes models, that farmers could use together with researchers and other stakeholders to explore management options at the watershed scale, is another challenge for management of sandy soil mini-watersheds.

Increasing economic options in sandy soil mini-watersheds

To give farmers new economic options in sandy soil mini-watersheds requires a combination of technical research, farmer organization, and marketing research. The construction of over 65,000 farm ponds in the 1990s (Ruaysoongnern and Suphanchaimat, 2002) has created the possibility of small-scale, on-farm irrigation in the dry season. However, Ando (2003) has shown that in one village where 72% of 207 farmers have farm ponds, only 4% of a sample of 55 farms with ponds obtained 5,000 bahts or more income from vegetable production, and only 13% from fruit production. Ponds are not being used intensively.

One reason for lack of intensive use of ponds is inadequate water to support different needs. The same study by Ando (2003) found that 98% of the farmers with ponds used the ponds for rice production. Interaction with farmers in integrated farming trials in 2004 (Sukchan et al., 2005) indicates that farmer concern that pond water will not be sufficient for rice seedbeds and transplanting is a major reason for reluctance to increase fruit and vegetable production using pond water. This concern is supported by the finding of Ando (2003) that 68% of the ponds had less than 1.5 m water depth in April, near the end of the dry season. If the rainy season is late, recharge may not come in time for rice seedling production and transplanting. Better methods for slowing uncontrolled surface water flow across surrounding sandy soil uplands and channeling it into ponds could be one technical solution. However, bands to slow down water movement and water channeling routes need to be designed to be compatible with sugarcane and cassava production. Techniques to reduce water seepage from ponds could also help insure adequate pond water, but economic analysis is needed.

Augmenting pond water from rainfall with groundwater may be more compatible with current upland use. Hamada et al. (2005) have found that groundwater moves from recharge areas above 207 m elevation to discharge areas below 170 m elevation in a typical watershed area in Khon Kaen Province. In effect, this is an underground water transfer route. In low elevation areas, 300-400 m3 day-1 km-2 could be taken out without adversely affecting water level (decrease <10 m within 15 years) (Srisuk et al., 2005). This groundwater could be exploited to augment pond water.

When pond water is a fixed quantity, increasing water efficiency is a way to effectively increase the area that ponds can irrigate. Oda et al. (2005) have developed techniques with farmers that enabled 84% of 44 plots to grow tomato in the dry season with less than 30 mm of applied water and less than 10 water applications. Similar techniques need to be developed with farmers for other vegetable crops and for fruit crops.

What may be a rational decision from the standpoint of farm management for one farmer may not necessarily produce the same expected benefits if many farmers make the same decision at the same time. Lacombe (2003) found that farm ponds would be less effective for early rice seeding if many farmers simultaneously decided to use pond water to seed early. Similarly, if many farmers decide to produce vegetables and fruits, the result may be flooding of the market and less income for all farmers. Marketing research is needed to provide information for simulation of likely aggregate economic effects for farmers to use in making decisions. The market is the economic equivalent of common water resources, and market channels are the economic equivalent of water flow hydrology. In the study by Ando (2003), mango farmers organized into a cooperative were the most successful. Methods to enable farmers to see likely aggregate economic effects of individual decisions could help stimulate more coordination among farmers for marketing.

Conclusions and Future Directions

During this symposium, we will have the opportunity to learn about many research and development approaches that can address the above challenges. Some presentations may add additional challenges. In particular, one area that we have not addressed is fertility management of sandy soils in mini-watersheds. In all of these challenges, we anticipate that we will see that solutions will require a combination of better technical information at multiple scales, and greater farmer participation in the development of solutions using new information.


We thank the Rainfed Agriculture Project of the Japan International Research Center for Agricultural Sciences (JIRCAS) for financial support, and many farmer and researcher collaborators who contributed to this work.


Ando, M. 2003. Potential and constraints for intensive land use with pond irrigation in Northeast Thailand. Paper presented in International Symposium, “Alternate Approaches to Enhancing Small-scale Livelihoods and Natural Resources Management in Marginal Areas,” 29-30 October 2003, United Nations University, Tokyo, Japan.

Caldwell, J.S., Sukchan, S., On-ok, W., Satravaja, C., Ogura, C., Yamamoto, Y., Prapin, P. 2002. Farmer perceptions of water availability, erosion, and yield relationships in rainfed paddy and upland fields on two transects in a watershed in Nong Saeng Village, Khon Kaen Province, Thailand. JIRCAS Journal 10: 31-41.

Caldwell, J.S., Sukchan, S., Ogura, C., On-ok, W., and Prabpan, M. 2004. Participatory strategic dike reinforcement in Nong Saeng Village, Khon Kaen Province, Thailand. pp. 253-258 in M. Mihara and E. Yamaji (eds.), Participatory Strategy for Soil and Water Conservation. Institute of Environmental Rehabilitation and Conservation, Tokyo, Japan.

Hamada, H., Moroizumi, T., Watabe, H., Srisuk, K., and Hasegawa, S. 2005. Groundwater in Nong Saeng. Pp. 32-39 in M. Oda, O. Ito, and J. Caldwell (eds.), Increasing Economic Options in Rainfed Agriculture in Indochina through Efficient Use of Water Resources, Khon Kaen, Thailand.

Lacombe, G. 2003. Compréhension des strategies d’adaptation à la varibilité des pluies en riziculture inondée par la modélisation. Mémoire de DEA. Université de Montpellier II, France; CIRAD/IRRI, Bangkok; et Université d’Ubon Ratchathani, Thailand.

Oda, M., Sukchan, U., and Caldwell, J. 2005. Farmers begin to invent water saving cultivation in Northeast Thailand. International Farming Systems Association (IFSA) Global Learning Opportunity Symposium, Rome, Italy (forthcoming).

Ogura, C, Sukchan, S., Suzuki, K., and.Caldwell, J. 2005. Paddy use and status of water resources in a first order watershed in a sandy soil area of Northeast Thailand. Paper to be presented at the Symposium, “Management of Tropical Sandy Soils for Sustainable Agriculture”, Khon Kaen, 28 November – 2 December, 2005 (forthcoming).

Office of Soil Survey & Land Use Planning. 2002. Problem soils for economic crops in Thailand (map). Land Development Department, Bangkok, Thailand.

Ruaysoongnern, S., and Suphanchaimart, N. 2002. Land use patterns and agricultural production systems with emphasis on changes driven by economic forces and market integration. Pp. 67-77 in S.P. Kam et al. (eds.), Natural Resource Management Issues in the Korat Basin of Northeast Thailand. IRRI, Manila, Philippines.

Srisuk, K., Prayut, C., and Hamada, H. 2005. Determination of safe yield by groundwater modeling in Nong Saeng subwatershed. Pp. 75-82 in M. Oda, O. Ito, and J. Caldwell (eds.), Increasing Economic Options in Rainfed Agriculture in Indochina through Efficient Use of Water Resources, Khon Kaen, Thailand.

Sukchan, U., Caldwell, J.S., N. Suphanchaimat, I. Phaowphaisal, S. Sukchan, M. Oda, and Prasop Verakornphanich. 2005. Forming a farmer experimental group to develop technology for integrated farming in Northeast Thailand. International Farming Systems Association (IFSA) Global Learning Opportunity Symposium, Rome, Italy (forthcoming).

Suzuki, K., Goto, A., Mizutani, M., and Sriboonlue, V. 2003. Simulation model of rainfed rice production on sloping land in Northeast Thailand. Paddy and Water Environment 1(2): 91-97.

Suzuki, K., Yamamoto, Y. and Sukchan, S. 2005. Hydrological modeling in small watersheds. Pp. 17-23 in M. Oda, O. Ito, and J. Caldwell (eds.), Increasing Economic Options in Rainfed Agriculture in Indochina through Efficient Use of Water Resources, Khon Kaen, Thailand.

Wongwiwatchai, C., and Paisancharoen, K. 2002. Soil and nutrient management of some major field crops in the Korat Basin of Northeast Thailand. Pp. 127-136 in S.P. Kam et al. (eds.), Natural Resource Management Issues in the Korat Basin of Northeast Thailand. IRRI, Manila, Philippines.

Yuvaniyama, A. 2001. Management of problem soils in the northeast of Thailand. Pp. 147-156 in S.P. Kam et al. (eds.), Natural Resource Management Issues in the Korat Basin of Northeast Thailand. IRRI, Manila, Philippines.


1 The Rainfed Agriculture Project is a collaborative effort of the Japan International Research Center for Agricultural Sciences (JIRCAS), several Departments in the Ministry of Agriculture & Cooperatives, Thailand, and Khon Kaen University, Khon Kaen, Thailand.

1 Rainfed Agriculture Project, Japan International Research Center for Agricultural Sciences (JIRCAS), Khon Kaen, Thailand.
2 Soil Survey Laboratory, Land Development Department, Khon Kaen, Thailand.
3 Department of Agricultural Environment Engineering, NIRE, JAPAN.

Farming systems in the sandy area of the Thua Thien Hue Province,
 central Vietnam. Survey of socio-economic situation and constraints
identified by farmers

Pham K.T.1, T.T.H. Hoang1, N.D. Hoang1, D.H. Le1, D.H. Nguyen1, T.D. Nguyen1,
M.H. Nguyen 1, D.N. Le 1, Q.H. Pham2, Ph. Lebailly3, F. Francis3, E. Haubruge3,
C.L. Bragard4 and J.E. Dufey4

Keywords: Sandy soils, smallholders, animal production, crop production, farming systems, Central Vietnam


The Thua Thien Hue Province situated in Central Vietnam encompasses 5,054 km2 with a population of about 1.1 million people. The total cultivated area is 84,000 ha of which approximately 66,000 ha are soils classified as having a sandy texture. This sandy area is located along the coast and is the most densely populated of the province. The research aims at evaluating various aspects of the present situation including socio-economic aspects and farming systems on these light textured soils of this province. Using an interview-based questionnaire, a survey was conducted in villages by staff members of the Hue University of Agriculture and Forestry. Data were collected among 145 households in four districts of the coastal area of the Thua Thien Hue Province. The results show that hostile climate, poor quality of soils, lack of technical knowledge and experience in agricultural production of smallholders on sandy soils are major constraints that limit crop yields and induce a deficit in nutritive value of animal feed. Low income of farmer’s households is an obvious consequence of this unfavourable situation. Our results also indicate that the present animal and cropping systems on sandy soils of Thua Thien Hue include a high diversity of local varieties of plants and local breeds of animals. Options for possible improvement of techniques will be suggested. This research is being conducted in the framework of a Vietnam-Belgium joint project towards a sustainable agricultural development in this area, mainly through the better use of organic resources within farming systems, and by integrated pest and disease management.


Sustainable agriculture is a subject of great interest and lively debate over years in many parts of the world. According to Honeyman (1991), sustainable production is a combination of production techniques that enhance profit and improve the area’s environ­mental and socio-economic condition. Descriptive observation studies on smallholder farming systems have been conducted in Solomon Island (De Fredrick, 1977). Integrated or mixed farming systems, crop and livestock are interdependent elements (Amir and Knipscheer, 1989).

Vietnam is an agricultural country with over 80% population living in rural areas and their livelihoods are mainly based on agriculture. Similarly, in Thua Thien Hue Province, farmers rely chiefly on farm production for their livelihoods while off-farm activities are under developed. Their life is still difficult and not easily changed. The situation is worse in sandy areas, where soil conditions are clearly not suitable for an efficient agriculture. Fortunately, local people own diverse resources of plant varieties and animals breed, which can be more efficient (thanks to low inputs) and more sustainable (due to less chemical use) agriculture.

A detailed survey was conducted to identify potentials and constraints in farming systems of the coastal sandy area in Thua Thien Hue Province. This research should provide reliable information for identifying options for improving farming systems namely by optimizing organic matter recycling, which is a key problem in tropical light textured soils.


Interviewee’s selection

Interviewees (145 families) were selected from seven villages of the four coastal districts of Thua Thien Hue Province (Phong Dien, Quang Dien, Phu Vang, and Phu Loc; see Figure 1), after allocating households into three income groups: rich, with income >200,000 Vietnamese dông (VND), i.e. some 10 euros or 13 US$, per person per month, average with income from 140,000 to 200,000 VND, and poor with income less than 140,000 VND. These groups of farmers were categorized by village or hamlet chairpersons, who could make the best income estimation of their villagers. To make sure that one interviewee correctly met the selection criterion, a double check for eligibility at start of an interview was done.

Figure 1. Map of Thua Thien Hue Province, with boundaries of districts (names in capital) and location of the targeted villages (names in lower-case)

Management of Tropical
Sandy Soils for Sustainable

Data collection and analysis

Information was collected using a questionnaire with oral interviews. This questionnaire covered various aspects of farming systems such as: family size, land and labor resources, crop and livestock production, organic matter utilization, etc. The education level of household heads was also surveyed as well as encountered pests and plant diseases. Income of households was estimated from animal and crop production, and from off-farm activities. Collected data were statistically analyzed using SPSS software (version 11.0).

Results and discussion

The main economic features of interviewed families are showed in Table 1. The family size averages 7.5 persons, often including 2 or 3, and sometimes 4, generations. On average, one family owns only 0.9 ha of farming land. But that area varies according to income level. The rich family has about 1.14 ha, while figures for average and poor families are 0.87 and 0.58 ha respectively. Large families and small farm sizes create increasing issues associated with population pressure at the family and community levels. In addition, soil type and quality (Table 2) do not adequately support farmers for sufficient crop production. Indeed, in the field plots cultivated by the 145 interviewed farmers, i.e. some 500 plots, sandy soils (white or yellow sand) represent 80% of the land and, according to farmers’ opinion more than 40% are of bad or very bad quality. Farmers hardly expect high income from their crop and animal production. In the last decades, marginal arable land and high population pressure together resulted in splitting farmland from generation to generation, which caused many social problems and some farmers have become landless in the process.

The house is an important property of farmers in rural areas. Among the 145 visited households, we found that the type of houses show marked difference sbetween rich and poor farmers (Figure 2). There are about 5% poor households who have no house.

Table 1. Mean values and coefficients of variation (CV) for different characteristics and income sources of the 145 surveyed farms in Thua Thien Hue Province


Mean values


No of persons per family



Farmland size per family (m2)



No of ruminants per farm (heads)



No of pigs per farm (heads)



No of poultry per farm (birds)



Total income per farm



(millions VND/year)


Crop income per farm



(millions VND/year)


Animal income per farm



(millions VND/year)


Other income per farm



(millions VND/year)


Table 2. Texture and quality of soils (percentage of cultivated land) as evaluated by farmers in Thua Thien Hue Province

Soil texture









Soil quality




Very bad





Pests and plant diseases reported in Table 3 reflect another constraint on agricultural production in the surveyed area. All four main crops (rice, cassava, sweet potato, and groundnut) are affected by many different types of insects and diseases, which, according to local people, are very important and, unfortunately, highly widespread. This situation is likely related to optimal climate conditions for pathogen development, and to fragility of crops grown on poor soils as well.

Figure 2. Characteristics of houses of 145 selected families in Thua Thien Hue Province as a fonction of estimated income classe

Management of Tropical
Sandy Soils for Sustainable

Table 3. Major pests and plant diseases observed by farmers of Thua Thien Hue Province and damages caused to main crops (+ + + : very widespread and very important; + + : widespread and important; + : locally important)

Scientific Name

English name

Local name

Distribution & damage level for plants




Sweet potato 


Major insects


Cnaphalocrocis medinalis

Leaf folder

sau cuon la nho

+ + +

Scirpophaga incertulas W.

Yellow stem bore

Sau duc than 2 cham

+ +


5 vach dau nau +

C. polychrysus

5 vach dau den +

Spodoptera litura

sau keo + + + +

Melanilis leda ismene

sau buom mat ran

Oxya sp. chau chau lua +

Nilaparvata lugens

ray nau + + + + + +

Nephotettix spp.

ray xan duoi den


Sogatella furcifera

ray lung trang +

Leptocorisa oratorius

bo xit dai ++

Spodoptera litura

Taro caterpila Sau khoang + + + + + + + + +

Agrotis ipsilon

Black cutworm Sau xam + +

Helicoverga armigera

Cotton bollworm

Sau xanh + + + + + + + +

Lamprosema diemenalis

Soybean leaffolder

Sau cuon la + + + + + +

Heliothis spp.

Leaf-eating caterpillar

Sau rom + +

Aphis craccivora

Groundnut aphid

Rep muoi hai lac

+ + +

Epicauta gorhami M.

Blister beetle Ban mieu + + +

Tetronichus bimacerlatus

  Nhen do + + +

Cylas formicarius fabricius


Bo ha khoai lang


Omphisa anastomosalis


Duc la khoai lang


Major deseases


Pyricularia oryzae

Dao on lua + +

Rhizoctonia solani K.

kho van + + +

Cercospora oryzae M.

Dom nau + + +

Grain discoloration

  + + +

Mycosphaerella arachidis

Early leaf spot

dom nau lac + + +

M. berkelevii

Later leaf spot

dom den lac        

Aspergillus niger

Collar rot, seed rot

heo ru goc, thoi hat

+ + +

Puccinia arachidis

Rust gi sat + + +

Peanut stripe virus

Groundnut stripe

la kham vang + + +

Ralstonia solanacearum

Bacteria wilt of potato

heo ru tai xanh

+ + +

Table 4. Average yield, with standard deviation (SD), of main crops as reported by the 145 interviewed farmers in Thua Thien Hue Province


Average yield ± SD
Rice 4.30 ± 0.12
Cassava  11.36 ± 0.23
Sweet potato 2.67 ± 0.46
Groundnut 1.38 ± 0.03

As a consequence of these natural constraints, crop yield is generally low as compared to other areas of Vietnam (Table 4). For instance, rice yield (one or two crops per year) is only 4.3 tonnes per hectare per year according to farmers’ information, compared to some 10 tonnes per hectare per year in the Red River and Mekong deltas. Consequently, household food sufficiency is not ensured in Thua Thien Hue Province.

In animal husbandry, it was found that the number of heads per ha of cultivated land is 4.1 pigs, 38.4 poultry and 4.4 ruminants. Breeds are mainly indigenous with high adaptability to local unfavourable climate and poor nutrition. They require less input compared to improved breeds so they are preferred by farmers. The survey revealed high diversity in livestock species: 15 indigenous mammals and avian breed are raised in the region. The same situation was found for farmed vegetation, which consists of more than 40 plant varieties. These diverse bio-resources offer a good foundation for future development of agriculture toward sustainable, profitable and ecological approach.

As in many traditional systems, farmers in this area try to exploit all organic products (Table 5). Beside conventional agricultural byproducts such as straw and leftovers after crop harvest, some local people use other organic sources such as lagoon/seaweeds and hyacinth to improve soil fertility and to feed animals. Figure 3 presents the rate of organic manure utilization on different crops. However, a great number of interviewed farmers expressed their preference for using chemical fertilizers (urea and NPK fertilizers) instead of organic manure because they can bring immediate profits with respect to crop yield.

Management of Tropical
Sandy Soils for Sustainable

Figure 3. Rate of utilization of organic manure on different crops in the surveyed farms of the four coastal districts of Thua Thien Hue Province

Table 6 shows the average annual income from crop production and animal husbandry for the smallholders selected in the four districts. We calculated that the total output per hectare and per year ranges from 9.3 to 13.4 millions VND, which is very low compared to 40 to 50 millions VND per hectare per year in Habac, Hanoi or Thai Binh Provinces. According to the data presented in Table 1, plant production, animal husbandry, and off-farm activities account for 41.5%, 37.6%, and 20.9% of mean total income. The variation of those proportions with family classes (rich, average, poor) is shown in Figure 4.

Table 5. Utilization of organic resources in the 145 surveyed farms (+ + + : widespread use; ++ : medium use; + : local use only)

Organic resources


Rice straw 

Groundnut stem & leaves

Sweet potato stem & leaves

Cassava leaves


Lagoon seaweed 

Animal waste  

Burned on the field +
Returned to soil +++ ++ ++ ++ + ++ ++
Animal feed +++ ++ +++ + +
Fish feed + + +
Litter +++ + +
Mushroom substrate +
Family fuel +++ ++ + +

Table 6. Estimated annual revenue per hectare and per year from crop and animal productions in the selected farms of the 4 coastal districts of Thua Thien Hue Province

Mean estimated revenue ± SD
millions VND/ha/year





Phong Dien 6.33 ± 0.29 7.06 ± 1.15 13.39 ± 0.72  
Quang Dien 7.02 ± 0.61 5.88 ± 0.52  12.90 ± 0.56 
Phu Vang 5.94 ± 1.76 4.40 ± 0.49 10.34 ± 1.12  
Phu Loc 3.19 ± 0.63 6.08 ± 0.92 9.27 ± 0.77

Figure 4. Relative income sources of the surveyed households in Thua Thien Hue Province as a function of their estimated living standards

Management of Tropical
Sandy Soils for Sustainable

Table 7. Problems and constraints perceived by farmers and possible tracks for solution in their opinion

Problems and constraints

Solutions suggested by local villagers

Poor condition sandy soil
Lack water in dried season and flood in rain season

They have no effective solution at moment Call for support to solve problem

Lack of water in dry season and floods in rainy season Irrigation not available, cropping mainly based on rainfall

Call to invest in irrigation system
Improve service quality of existing irrigation

Lack of technical knowledge and experience for agriculture Scientific research not yet applied in agriculture
Not suitable use of chemicals

Want attending practical courses on crop and animal production

Plant production
High diversity of plant varieties but low yield and economic income Plant varieties are not pure and yield is not stable
Gardens with large area but low revenue

Want to have new plant varieties with high yield and better adaptation to sandy soil Supply fruit plant with high economic value Ask for assistance in using organic manure and chemicals effectively

Animal production
Small scale and low benefit
Lacking pure breed
Low nutritive value of food
Poor housing condition
Lack experience of husbandry and management

Want for training in animal husbandry Supply pure breed with high performance

Pests and diseases of plants and animals
Very frequent occurrence leading to decreasing yield and quality of product Too many kind of pesticides, difficulties to select and use them

They have no effective solution

Labour and capital resource
Labour in excess, lacking jobs
Lack of capital to invest for production and professional education
Lack of experience for capital resource management and use

Call support of capital and education on management

Poor road system in rural area, not convenient for transporting materials from home to field, products from field to home and to market

Call to invest to improve local road and transportation system

Low farm gate price Lack of price stability

Ask for price control
Farm gate price not forced by middle-men

Population pressure
Farmers leave villages to find job in city
Free immigration

Improve life quality
Improve education condition and health care for
women and children

Farmers were asked to identify the constraints responsible for their fragile economic situation and to suggest possible solutions to alleviate these constraints (Table 7). Obviously, many factors contribute to poverty of family farmers, including natural limitations due to soils and climate, farming characteristics and socio-economic organization.


To improve soil fertility and food production, in sandy area, the locally available organic resource should be employed and appropriately used in system VAC (Garden, fish-pond and Animal husbandry). Some new varieties of cassava, groundnut can be introduced to increase yields of root plants.

Net garden system can be applied to reduce temperature and water evaporation as well as prevent the damage by pest and insect for vegetable production to improve income for farmers in this area.


As a conclusion, our survey stresses on the need of an integrated approach to improve living standards of rural smallholders in Thua Thien Hue Province and in Central Vietnam in general, as compared to other regions of Vietnam with more favourable natural and socio-economic conditions. Scientific, technical, social and economic research involving all aspects of farming systems (soil-plant-animal-human interactions) and wider environment is a great challenge for researchers and public authorities.


This research and development project is supported by the “Commission Universitaire pour le Développement” (CUD) in charge of the cooperation activities carried out by the universities of the French Community of Belgium.


Amir, P., and Knipscheer, H.C. 1989. Conducting on-farm animal research: Procedures and Economic analysis. Winrock International Institute for Agriculture Development and International Development Research Centre. Singapore National Printers Limited. pp. 143-162.

De Fredrick, D.F. 1977. Pig production in the Solomon Island. I: Village pig production. Tropical Animal Health and Production, 9, 113-123.

Honeyman, M.S. 1991. Sustainable swine production in the U.S. corn belt. American Journal of Alternative Agriculture 6(2), 63-70.

1 Hue University of Agriculture and Forestry, 24 - Phung Hung, Hue City, Vietnam, [email protected]
2 National Institute for Soils and Fertilizers, Chem - Tu Liem, Hanoi, Vietnam.
3 Faculté Universitaire des Sciences Agronomiques de Gembloux, Passage des Déportés 2, 5030 Gembloux, Belgium.
4 Université Catholique de Louvain, Faculté d’Ingénierie Biologique, Agronomique et Environnementale, Croix du Sud 2/10, 1348 Louvain-la-Neuve, Belgium.

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