Towards Sustainable Land use through Land Evaluation : A Case Study of Muaklek, Thailand

Towards Sustainable Land ues through Land Evaluation : A Case Study of Muaklek, Thailand

Rajendra Prasad Shrestha and Apisit Eiumnoh
Yokohama National university
Institute for Environmental Science and Technology Hodogaya-ku,
Tokiwadai 156, Yokohama 240, Japan
Elgene 0. Box
STARISERD. Asian Institute of Technology
G.P.O. Box 2754, Bangkok 10501, Thailand

Abstract
The suitability of land for four major crops, viz., maize, cassava, fruit orchards and pasture was assessed in the Muaklek area of Thailand. The procedure followed was in accordance with Food and Agriculture Organization (FAG) Framework for Land Evaluation. Field surveys were also conducted to supplement with the socio-economic information and ground truthing. Vector based GIS (ARC/INFO) was used to analyze the spatial data. Simple benefit/ cost ratio analysis was performed to appraise the , economic returns of the selected crops. The study exhibited that the present land uses are not in accordance with the land :- qualities. i. e. land are put under cultivation despite its unsuitability. The study demonstrates the need of conducting land .evaluation in which socio-economic elements are to be considered in particular and also the application of Remote Sensing and GIS as useful planning tools.

1.0 Introduction
Thai agricultural production has been experienced to have fast growth in the past. But in the recent past (1983-93), it has been reported that the annual growth of paddy and .maize production is negative, -.0.2 and -2 .1% , respectively, however , annual growth of cassava and total milk production has increasedby 1 and 15% respectively (FAG, 1994). Share of agriculture in GDP has fall down from 26% in 1970 to 12% in 1992. The increase in agricultural imports (16.5%) is more than double of the export increase (7%) between 1982 and 1992. Despite this declining situation of agricultural production, total agricultural land in the country is reported to increase from 37.4% in 1982 to 39.4% in 1992. This articulates the situation of lower land ~ utilization. Subsistence crop farming dominates agriculture in Thailand. Since the cropping system utilized by the people reflects ,. short term economic goals, such systems are not necessarily environmentally sound (McGregor and Barker, 1991).33.7 percent ~ of the total agriculture land in Thailand are degraded due to improper utilization of marginal land and poor management I: practices (Dent, 1989).

Emphasis on "sustainability" has arisen because of increasing worldwide concern about environmental degradation and " various related processes, such as, soil erosion and degradation, and loss in genetic biodiversity , which are known to have adverse effects on agricultural productivity .Land, being the scarce resource and basis of production, raising land productivity in stock terms is more important than flow terms for the fuller utilization of land. Land be best conserved if utilized it based on its ,supporting capacity for cultivation. Hence, there is the need of agronomically sensible and technically appropriate solutions to revitalize these degraded pieces of land and the eventual environmental conservation. It is on this premise that this study was carried out to determine the potentials of the land for cultivation of four. important crops assessing land qualities, social and economic parameters With the purposes of both rehabilitation the land quality and conserve the environment.

2.0 The Study Area
The study area, Muaklek, situated in the central highlands of Thailand, is characterized by a rolling and sloppy terrain. The climate of the area is tropical Savannah with an annual mean maximum temperature of32.7° C, mean minimum of 20.4° C, average humidity of 79.45% and an annual rainfall of 1,050 mm. There is a sharp decline in the crop area since 1992 for all major crops (Figure 1). The study area is the largest production area of modern dairy farming in the country (Hirunruk, 1973), but shortage of livestock fodder is the most pressing problem.

Figure 1. Change in Area Coverage for Different Crops in Muaklek.
Population density accounts to 48.4 and 93.3 persons/ sq. kIn. of the total and cultivated area, respectively. A .) significant majority (88.5%) of the working population are engaged in agriculture. On the basis of land holding, the proportion . ( of marginal farmers (land holding < 4 ha), small (4-8 ha), medium (8-16 ha) and large ( >16ha) were 35.2,24.1, 16.6 and 24.1%, respectively (Shrestha, 1993). The majority of the area is under crop farming and maize is the principle crop (Figure 2). : Orchard and livestock production are important farming businesses which are gradually replacing the crop farming. Water is a.; scarce resource in the area. The major sources of water for drinking and household uses are underground water and collected rain water. Dipterocarpus sp. is the dominant forest species. Besides, Leucaena leucocephala as fodder species, it has also been -M, extensively used in the new forest plantation area.

Figure 2. Land Use of Muaklek , Thailand.
3.0 Methodology
The FAD Framework for Land Evaluation was adopted to conduct this study. The basic source materials used for spatial analysis of suitability classification were: soil map (scale, 1:100,000), topographic map (1:50,000), geological map 19';c (1:250,000) and meteorological data. Land use were interpreted from Landsat TM film (1:500,000) of 14 December 1989 using Procom II. The principal process involved in land suitability classification is matching the land use requirements and limitations. with land qualities. The main physical parameters considered for the spatial analysis were soil texture, effective soil depth, : surface runo.f1 permeability, soil pH; organic matter, cation exchange capacity, available phosphorus and potassium, slope, bedrock type and rainfall. Slope classes were generated from the topo map. Similarly, bedrock types were generated from the geological map. Information on other parameters were acquired from the existing secondary sources. Limitation concept combined with parametric classification approach was employed for performing physical suitability analysis. Proper weightage as per the land use requirement (LDD, 1992) for the selected crops were given to the different classes of individual parameter considered which were encoded into a digitized GIS coverage. Similarly, after proper rating of the every attribute of other maps, viz., land use, slope and geological, their respective weightage were also encoded in their individual GIS coverage's. Suitability analysis was performed following a linear combination approach by overlaying all the coverage's in vector-based GIS (ARC/INFO). A field survey was also conducted to collect socio-economic information and for ground truthing. Besides evaluating the soil suitability for the selected crops, the cost and return for each crop was also appraised through Benefit/ Cost , analysis to see their economic feasibility

4.0 Results and Discussion

4.1 Land Suitability Classification
The process of land suitability classification involves appraising and grouping of specific types of land in terms of their absolute or relative suitability for a specified kind of use (FAG, 1976). The suitability map produced distinguishes four different classes for the crop production, viz., highly suitable (S2), moderately suitable (S2), marginally suitable (S3), and not suitable (N) on the basis of level of limitations associated. In the "not suitable" (N) class, no further distinction between "currently not suitable" ( N 1 )and "permanently not suitable" (N2) was made, because this group constitutes natural vegetation and built-up areas. It was also observed during the field survey that some of the area with greater slope gradient are heavily eroded resulting into unsuitable for the crop cultivation. Since it is neither feasible to correct soil limitations nor is it economically feasible, these area can only be rehabilitated by protecting the top soil with vegetation cover. Based on the physical parameters, the study area have been delineated according to suitability classes for maize, cassava,orchard growing and pasture production. Such land suitability classes which are basically physical suitability are presented in Table 1.

Table 1. Soil Suitability for Maize, Cassava, Orchard and Pasture.

Suitabilty class	Maize		cassva		orchard		Pasture
Suitabilty class	Area(ha)	%	Area(ha)	%	Area(ha)	%	area(ha)	%
Highly suitable	1,226.6	11.3	2,101.6	19.4	3,320.0	30.6	3,496.2	32.2
Moderately	3,139.6	28.9	2,033.2	18.7	2,592.8	23.8	2,359.2	21.7
Marginally suitable	1,472.8	13.5	1,083.7	10.0	203.0	1.9	479.1	4.4
Not suitable	5,011.0	46.3	5,631.5	51.9	4,734.0	43.6	4,515.5	41.7
Total	10,850.0	100.0
Existing landuse (% of total)	4,9991.0	46.0	54.3	0.5	434.0	4.0	119.4	1.1

Land suitability for maize: Compared to existing land use under maize (46% ), spatial analysis showed that as much as 11.3% of the total area are highly suitable for maize production. Likewise, 28.9 and 13.5% are of moderate and marginal suitability, respectively and the area under not suitable category is 46.3%.

Land suitability for cassava: Land suitability for cassava was evaluated because of the fact that the cassava was found to be the second crop after maize in terms of area coverage for the interviewed farmers. However, the cassava land use during 1989 was very insignificant (0.5%), it implies that the cultivation of cassava is increasing over time. As it is generally believed that cassava is usually grown in rather less fertile soils, it indicates that the soil fertility is decreasing over time and maize is being replaced due to loss of soil fertility .The SI' S2 and S3 category for cassava production accounted 19.4, 18.7 and 10%, respectively.

Land suitability for orchard: Nearly one third (30.6%) area was found highly suitable for orchard growing where as 23.8 and 1.9% area were classified as moderate and marginal suitability.

Land suitability for pasture: For the pasture suitability, the proportion of the area under SI' S2 and SJ category accounted to 32.2,21.7 and 4.4%, respectively.

Looking at the spatial representation of the suitability classes for the selected crops ( Figure 3), it is understood that the SI class is shared for all the crops in particular location with better land quality.

Figure 3. Land Suitability for the Selected Crops.
4.2 Agricultural Land Use and Management Practices
Although maize and cassava are the major crops grown in the area, their productivity of 2.05 and 5.18 ton per ha., respectively were very low compared to the average productivity of Muaklek district. The Multiple Cropping Index (MCI) of 2.4, 2.1, 1.2 and 1.1 were found for marginal, small, medium and large category fanners, respectively with an average MCI of 1.5. Majority of the farmers have adopted the monoculture/ monocropping system due to insufficient soil moisture and poor soil status. Level of management differs according to the resources affordability of the farm categories.

4.3 Farm Income and Expenditure
18.5% of the households were found having an annual income of less than 50,000 Baht (1 US$ = 25 Baht) , whereas, 13% were found having more than 400,000 Baht per annum, nevertheless, the earning from livestock was the major source of income (60% of the total income) for all farm categories. Second major source of income (25% of annual total income) was non-farm activities. The share in income from the crop constituted the least (15%) for all farm categories (Shrestha, 1993). In relation to household expenditure, expenses on livestock fanning accounted a major share (60%) of total annual expenditure of a farm household followed by expenditure on household consumption and domestic use (28%) and crop farming (12%) (Shrestha, 1993).

At this point, it is clear that the livestock production system is an important subsystem in the area. Considering this r along with the area to be the largest dairy production area, it will be desirable to discuss this aspect in rather detail.

4.4 Livestock Production System and Condition of Grazing Lands
The average livestock holding is 21.3 Tropical Livestock Unit (TLU). Cattle is the major species, however, buffalo, ..goat and pig are also being raised by the farmers relatively in small number. Livestock holding, however, is positively correlated with land holding size, livestock unit per unit of land holding is found in the same fashion as cropping index which articulates r" that the smaller category farmers are more dependent on the public natural resources, such as grazing lands, waste land, roadside and fallow fields to graze their livestock. Outside source of paddy straw serves as the major livestock feed. The assessment of ~ grazing capacity is important for assigning an optimal animal stocking rate to pasture land as well as regulating the conservation .efforts. The grazing practices existing in the area are uncontrolled, particularly in the communal land. Private fallowland and community owned land are accessed to anyone for livestock grazing. In general. speaking, the average condition of the grazing lands was observed to have 50 to 60% grass cover and above 60% utilization closely grazed under 1 cm. The legumes composition is less than 15%.

4.5 Environmental Impact
It was observed that people are enough cognizant of the environmental degradation and the various factors responsible for degradation. Even then, the continuous exploitation of the resources is not yet stopped, it may be because of the fact that there are no alternative resources available and people are forced to make use of it for their survival. It was revealed that there , were negative impacts on all attributes, both on farmland and non-farm land. An index value of -0.76 indicated that the impact was most intense on soil moisture and water availability followed by soil erosion (-0.57) and soil fertility (-0.52), and least intense on vegetation change (-0.11 ).

4.6 Gross Margin Analysis
Gross Margin Analysis (GMA) was performed to appraise the economic feasibility of maize, cassava, orchards and pasture. Unlike other crops, it was difficult to calculate the return from pasture since there were no detail production statistics : available. Herein, the productivity was estimated to be 25.0 tons of green matter per ha. (Tumwasorn et al, 1992). Beside the price of forage, the market value for all other crops was taken into account to calculate the gross return. Since there was no r market price available per unit of cut forage, the price of one kilogram was estimated based on the price of paddy straw valuing ; its Dry Matter (DM) content. None of the respondents were paying any type of rent or tax for the land they cultivate. However, renting a ha. of land can cost equivalent to US $ 31.25 to 45, an additional cost US$ 31.25 per ha., as an opportunity cost, was included to calculate the total cost of production for pasture.

The analysis considered the total cost and return per crop. The maximum net return per ha. was from orchard with US$ 157.62 (Table 2). Other important crops were pasture, maize and cassava with a net return of US$ 91.25,47.35, and 16.38, respectively. In the case of orchard farming, only the operating cost was considered. In the long run, the return could be lower when the fixed cost is taken into consideration. Similarly, except for fruit crops, the benefit-cost ratio for pasture (1.45:1) was higher than that for maize (1.25: 1) and cassava (1.04:1), which are the dominant crops of the study area.

Table 2: Cost and Return of Selected Crops.

Crop	Cost/ha			Return/ha		B/C ratio]
Crop	TVC	FC	TC	Gross	Net	B/C ratio]
Cassava	360.94	4.46	365.40	381.45	16.38	1.04
Maize	175.92	4.95	180.87	227.28	47.35	1.25
Pasture	169.33	35.54	204.87	296.12	91.25	1.45
Orchand	116.60	1.09	117.67	272.21	157.62	2.31

Note: Cost and Return in US $. TVC= Total Variable Cost, FC= Fixed Cost, TC= Total Cost (TVC+FC), B/C ratio = (Gross return -TC)

5.0 Conclusions and Recommendations
The crop production systems of the study area is basically a "low input-low output" system which obviously may not be sustainable from both economic and ecological perspectives because the production is decreasing over time due to reduced , soil fertility and soil moisture. On the other hand, the area is the largest dairy farming producer in Thailand. However, the acute shortage of feed results in the high cost of milk production because the majority of livestock feed, especially paddy straw, has to be purchased from other parts of the country .The overall pasture condition of existing grazing lands is also. not satisfactory in terms of grazing capacity .The area also has great potential for orchard farming because of Its suitable physiography . Since, the area with better land quality for crop production is very limited, with due consideration of these fundamental factors, various land use alternatives are proposed in the process of appraising alternatives (Figure 4) which will be viable in terms of rehabilitating the land and environmental quality and best economic use as well.

Figure 4. Proposed Agricultural Land Use Planning for the Study Area.
Nearly half of the area are to be left untouched in its natural state. Maize, other upland crops and orchard are recommended on about 10% area for each. Orchard/pasture integration, pasture alone and cassava are recommended on 8.1,5.4 and 2.8% area, respectively. 6.6% of the area which are heavily eroded needs immediate conservation measures. Such scheme would not only solve the problem of shrinking land availability but also assist maintain the productivity of the ecosystem.

References

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FAO. 1976. A Framework for Land Evaluation. International Institute for Land Reclamation and Improvement, The Netherlands.
FAG. 1983. Guidelines: Land Evaluation for Rainfed Agriculture. FAG Soils Bulletin, No.52, Rome.
FAG/RAPA. 1994. Selected Indicators of Food & Agriculture Development in Asia-Pacific Region, 1983-93, Bangkok.
Hirunruk, V. 1973. A Case Study of Twenty Dairy Farms in Muaklek, Thailand. Master's Thesis, Faculty of Economics, Thammasat University , Bangkok.
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