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Clearance of the Scarp Zone and intensification of farming in the Valley Zone

The most important factor in the rapid economic growth of the Pa Sak valley since the Second World War has been, as stated at the beginning, the improved transport conditions due to road construction. In 1942, a strategic link road leading through the Pa Sak valley (laterite) to Lomsak was completed. However, the decisive improvement came when the asphalt highways were completed in the early 1960s. The market town to Lomsak, formerly the terminal point for river-barge transport on the Pa Sak river and thus the traffic and market centre for the upper Phetchabun valley region, was able to expand even more because it was now situated at the crossroads of the two new highways. As a result, it became the market and supply centre for the surrounding, rapidly expanding farming region. Around Lomsak, an intensification of traditional irrigated lowland cultivation was initiated, whereas in the outer regions new areas were being cleared for dry-land cultivation.

It became technically feasible to introduce double cropping (tobacco, vegetables, and mung beans) in the areas directly surrounding Lomsak in 1962, when the traditional irrigation system was considerably improved by the Royal Irrigation Department. In 1985, this irrigation system covered an area of 1,680 ha. In the same year, a second project was completed that will allow for another 1,280 ha. However, both systems are located in the middle of the valley and are fed by the Pa Sak river, which means that villages in front of the scarp zone are not connected. Nevertheless, it was possible to introduce double cropping into the rice area of these villages owing to the innovation of ground water irrigation by dug or tube wells and motor pumps. The introduction and expansion of contract tobacco growing in the upper Phetchabun valley served as the economic basis for more intensive use of the rice fields. (1972 saw the introduction of the burley variety by an American company and Turkish tobacco was promoted in 1977 by other companies.) At the same time, high input/high return vegetable crops spread, mainly along the Pa Sak river.

The area irrigated by ground water in the whole Lomsak district consists of approximately 7,200 ha (1985) scattered over the valley region and constituting 27 per cent of the total rice field area. In addition, the two state irrigation systems cover an area of 2,960 ha (constituting 11 per cent of the total growing area), which means that almost 40 per cent of the wet-rice area can be double cropped. The double cropping areas are identical to the fertile, lower alluvial soils of the Pa Sak river and its tributaries, which make up most of the older rice land and have a high ground water table. They are surrounded on a slightly higher elevation by wet-rice fields with impounded rainfall. These rice fields have been carved out of dry terraces and are of recent or very recent origin. In this way, the rice growing areas have been considerably expanded since the early post-war years. For example, three families in Bung Nam Tao were able to gain approximately 10 ha of new rice land as recently as 1980-1982 by levelling scrub forest areas (with the aid of a caterpillar tractor). Rice is grown in these more recently established fields only with impounded rainfall and gives considerably lower yields (2.53.0 t/ha) than rice in those areas with gravity irrigation and alluvial soils (4.5-5.0 t/ha).

Farm holdings in the study community range from 1 to 2.5 ha of wet-rice land. The great majority of families are self-sufficient in rice production and a number of them regularly produce surpluses for sale. The family-owned rice area does not consist of a single plot but is generally split into two or three fields at different locations. Normally, part of the family rice land is situated in the irrigated alluvial section and the other part consists of rice fields with impounded rainfall. This fragmentation of holdings is typical of traditional wet-rice growing areas and can be explained by the tradition of dividing up the land among offspring for generations.

It seems that in Bung Nam Tao the large majority of families have at least one plot in the rice area which is suitable for double cropping and therefore they could and did take advantage of the income opportunities provided by growing a cash crop after the rice crop.

At the same time cash crop growing was expanding in parts of the valley wet-rice area, the scarp zone was also being opened up for dry-land cash crop cultivation by the same farmers. In the mid- and late-1960s, farmers from Bung Nam Tao and neighbouring villages were already experimenting with maize on the high terraces and the scarp foothills, but due to the shallow and poor soils, cultivation was abandoned after a few years.

In the early 1970s, the villagers began with the clearance of the whole scarp zone-a process which became more intense in the years from 1973 to 1975. The economic incentives provided by high maize prices lead to a rapid expansion of maize cultivation in the whole country, particularly in the maize belt. At the same time (1973-1976), the political climate was generally favourable for forest clearance, because the government in Bangkok, facing pressure from farmers' unions and demonstrators calling for immediate agricultural reforms and the redistribution of land to the landless, was only too pleased to find a safety valve in land clearing and could not or would not run the risk of aggravating the tense situation in the rural areas by preventing pioneer settlers from finding a new livelihood in the forest areas.

Within a period of only 10 years, the whole scarp zone was almost completely cleared for maize cultivation. Only a few steep upper slope areas and the lower scarp zone (200400 m) were not included. In the latter, farmers abandoned attempts at growing maize after only two to three years due to greatly decreased yields. This zone manifests much more unfavourable soil conditions because the parent sandstone material allowed for the development of only shallow, stoney soils, poor in mineral nutrients. Furthermore, the area receives much less rain since it is shadowed by an 800-1,000 m mountain range. For both of these reasons, the natural vegetation covering differs enormously from that in higher parts of the scarp. Degraded, dry dipterocarp forest is found up to an elevation of 350 to 400 m, whereas the natural vegetation of the higher areas consists of dry evergreen forest or rich mixed deciduous forest (no teak). Soils in the middle and upper scarp area, originating from volcanic-andesitic tuff, are extremely deeply weathered, show a dark humus colour, and are obviously very rich in minerals.

As in other areas of forest clearing and land colonization, the preceding lumber phase also made clearance much easier here. The farmers were not faced with any areas of primary forest that could only be cleared with a great deal of effort but found wellcleared areas with relatively easy access from the lumber tracks.

With family labour, 1 ha on average could be cleared per year-with the help of paid workers, some farmers were in a position to clear more. The size of holdings ranges from 5 to 15 ha, generally in the form of a single plot. The field pattern of the scarp maize area is reminiscent of a central European "Waldhufendorf." The scarp zone is in turn divided by smaller streams into V-shaped valleys, each of which was cleared almost exclusively by villagers originating from the respective communities at the beginning point of the valley, so that each wet-rice village cleared its own adjacent dry-land area. This is the reason the process of land clearance here was not accompanied by any important conflicts arising from land distribution. The plots have their narrow edge along the track on the valley floor and then stretch upwards along the slope to the ridge. As a rule, plot boundaries are naturally marked by small rivulets. The farmers have built their temporary shelters at the bottom end of their plots along the road. Their shelters resemble more their permanent houses in the villages than temporary field huts, which is largely due to the fact that part of the family labour force spends a considerable amount of its time here.

Since the farmers work both dry-land and wet-land (double cropped) areas, their labour budget has become extremely tight. Labour peaks, which occur particularly in the large dry-land cultivation areas, can only be coped with by hiring off-farm labour and through the partial mechanization of the work process. The peak labour period in dry-land cultivation is during the preparation of the land in February and March. Approximately 70 to 80 per cent of the area is ploughed by tractors. The remaining areas are steep slopes which have to be prepared by manual labour. To accomplish this, most farmers hire seasonal labourers from the north-east. These people work in teams of five to ten and are paid according to the area the whole group covers. The labourers are also farmers coming from poor subsistence ricegrowing areas in Khon Kaen and Chaiyaphum provinces, where only a single rice crop a year is possible. (Thus they do not constitute a class of rural landless itinerant workers as can be found on Java or in Latin America.) Manual and mechanical land preparation costs are almost the same; however, it is much more difficult and time-consuming to organize and supervise manual land preparation. In the years when the north-east has a good rice crop, farmers can also experience difficulties in finding a sufficient work-force.

Maize has been grown continuously in the study area for about 10 years now. In addition, many farmers grow mung beans as a catch crop, which, despite the low input (no land preparation is necessary), is usually restricted to a partial area since the family labour force is needed when the rice harvest begins down in the valley.

When asked about yields (3-4 t/h), farmers complained that they have suffered a decrease over the last two to three years, although the decrease is estimated to be only 20 to 30 per cent below the highest yields received. There is a general consensus of opinion that yields increased immediately after tractor ploughing was introduced and the land was sufficiently cleared of stumps and roots to make its use possible (normally three to four years after clearance). However, this short improvement turned into a disadvantage after several years of cropping. In contrast to the areas worked by hand, tractor-ploughed areas show a higher rate of general decrease in yield. This coincides with the observation that erosion is much higher on tractor-ploughed slopes.

The practice of downhill ploughing has led to severe soil erosion. Steeper slopes have had to be abandoned in the last three to four years since small landslides and deep gullies have made ploughing impossible. These areas soon become covered with Ya Kha grass (Imperata cylindrica), which is too difficult to remove by hoe and manual labour, and are therefore no longer tilled. In this way some farmers have lost 20 to 30 per cent of their workable land to Ya Kha grass and steadily deepening gullies.

However, the main problem for the whole zone appears to be the extent of soil erosion. Although the high rate of chemical weathering and the extremely deep soils have, up to now, prevented the complete loss of top soil on the upper slopes in the scarp zone, villagers have reported an increasing occurrence of flash floods in the last year or two after the first heavy monsoon rains. These floods and the amount of transported eroded material are becoming more pronounced and frequent, causing heavy damage to the village and surrounding rice field areas. As a result, it is necessary to clean and repair weirs and irrigation channels much more frequently.

The majority of farmers are only just becoming aware of the problems involved in the present land-use system in the scarp area, because they have not yet been confronted by a decrease in farm income. A certain careless attitude towards upland resources seems to result from the fact that this area is largely regarded as a supplement from which extra income may be made and not as a resource from which the family has to make its living, as was and still is the case in the lowland wet-rice area. Farmers can only be expected to undertake soil conservation measures, which would mean a temporary drop in income but which are absolutely necessary in the mid- and long-term in order to maintain soil stability, whenever they receive official title deeds for their upland areas. As an incentive to adapt land use to ecological needs (e.g. cultivation along contour lines), it would be possible for the government to promote the shift from a system of permanent rain-fed cultivation to a system of perennial tree crops by providing those farmers who are willing to undertake the change with title deeds for their upland areas.

A more ecologically balanced land-use system in the scarp zone could consist of a zone of vegetable growing in the proximity of the valley floor, followed by an intermediate level of orchards intercropped with annual plants, such as maize and leguminous plants, and finally a reforested upper zone with fast-growing cash crop wood species.


Development in the valley-scarp zone was characterized by both the intensification of land use in the existing wet-rice area (e.g. double cropping) and, simultaneously, the introduction of commercial dry-land cropping in the adjoining scarp area. It is important to note that farms in general did not specialize either in lowland or in upland production but undertook both to intensify production in the traditional wet-rice area and take up commercial dry-land cultivation. Consequently, the acreage per farm increased considerably, resulting in pronounced labour peaks which could hardly be managed by the family labour force alone and by traditional farming techniques. For example, a typical family of the area, having cultivated 1.5 ha of wet rice formerly, will now cultivate an additional irrigated second crop (tobacco, vegetables, groundnuts, or mung bean) in the dry season and, in the scarp area, grow about 8 ha of maize normally followed by about 2 ha of mung beans as a catch crop.

The cultivation of such an increased area per farm was only possible by changes in the whole farm management system, based on innovations such as partial mechanization of ploughing, harvesting, and transport in both rice and dry-land cultivation (single-axle tractor, rice thresher, and, in maize growing, contract disc-plough, maize picker, and pick-up truck). Buffaloes, kept as draught animals in the traditional farming system, have vanished almost completely within just a few years. This mechanization had to be complemented by off-farm labour as offered by the seasonal migration work-force of the poor rice growing areas of the north-east.

Another crucial factor in commercial dry-land cultivation by small- to middlesized farms is the problem of paying in advance for inputs such as contract ploughing and offfarm labour. Since the farmers of the study area hold full title deeds to their wet-rice lands, they are in a favourable position compared to many farmers in other cash crop areas of Thailand, who do not have title deeds to their land and thus have no access to formal credits from the Bank of Agriculture at low interest rates. As a result, farmers in the research area are among those who could profit from the government's efforts to improve the system of agricultural credit during the last few years.

As far as individual farm incomes are concerned, the clearance of the scarp zone and the integration of cash crop dry-land cultivation into the existing farming system has proven extremely successful and has resulted in the doubling, if not trebling, of incomes. This is evidenced in the appearance of the whole village, where many new, large houses are to be found. Not only did some well-to-do families benefit, but a large majority of the population was able to take advantage of this development. Moreover, differences in income do not seem to have increased, as very often happens when agricultural production undergoes commercialization. In fact, here the reverse seems to be true.

From an ecological point of view, this positive development appears to have been made at the expense of the sensitive scarp-valley ecosystem, which has been put at considerable risk and is also in danger of threatening agricultural production in the valley zone.

The problem we are faced with is finding and successfully implementing a landuse system for the scarp zone which is economically attractive to the farmer and can at the same time conserve the overall high agricultural potential of this zone for the future.


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Institute of Population Studies, Chulalongkorn University. 1981. Migration in relation to rural development: Self-help land settlement in Thailand. ASEAN Population Programme, Bangkok.

Kheoruenromne, I. 1982. "Landforms, soils and potential land use in upper Pasak river basin, central highland, Thailand." In First International Symposium on Soil Geology and Landforms-lmpact on Land Use Planning in Developing Countries, Bangkok.

Moormann, F. R., and S. Rojanasoonthon. 1972. The soils of the Kingdom of Thailand: Explanatory text of the general soil map. Report SSR-72A, Soil Survey Division, Department of Land Development, Bangkok.

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Scholten, J. J., and C. Siriphant. N.d. Soils and land forms of Thailand. Report SSR-97, Soil Survey Division, Department of Land Development, Bangkok.

Uhlig, H., ed. 1984. Spontaneous and planned settlement in Southeast Asia. Institute of Asian Affairs, Hamburg, and Giessener Geographische Schriften, Vol. 58, Hamburg.

World Bank. 1980. Thailand: Toward a development strategy of full participation. A World Bank country study. East Asia and Pacific Regional Office, The World Bank, Washington, D.C.

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