Chapter 2. Agro-ecological zones

Malaysia has a total land area of 339 733 km², consisting of two geographical regions (West or Peninsular Malaysia and East Malaysia). These regions are separated by the South China Sea. Their climatic and agro-ecological environments are somewhat different despite their belonging to the same warm humid tropics classification. The two regions are therefore described separately.

Malaysia characteristically experiences heavy rainfall (2 540 mm p.a. and above), average daily temperatures of 21-32°C and a humidity averaging about 85 percent. The seasonal variation in solar radiation is low, resulting in an annual difference in day length of only 2 minutes along the equator and 49 minutes in northern regions. In consequence, there is a year round day length of 12.5 hours (Nieuwolt, 1982).

About 72 percent of Malaysian soils are Ultisols and Oxisols, which are acidic and highly weathered (International Board for Soil Research and Management -IBSRAM, 1985). This has implications for phosphate fertilizer use due to fixation. This problem is dealt with through the biennial addition of about 2 to 4 t/ha of limestone (Shamshuddin et al., 1992).

The major regions characteristically have similar rainfall patterns, lengths of growing period and thermal patterns during the growing season. There are, however, exceptions in certain highland areas such as the Cameron Highlands, Pahang, where crops such as tea and strawberries, that do well in cool environments, are grown.

Data on crop areas and production in Malaysia are based on classification by state and not on the agro-ecological zones (AEZ). Therefore, the data presented in this report are on a state basis and, in some cases, on a regional basis (West and East Malaysia). There is a broad spectrum of crops grown throughout the country but the predominance of crops in terms of area and production varies from state to state depending on the crops' suitability to local conditions. This is reflected in the ranking of crops as suitable (A) and marginally suitable (B) as shown in Table 2 in the form of a matrix for all the states of Malaysia.

TABLE 2
Matrix of suitable and marginally suitable crops recommended for cultivation in States of Malaysia

A = Suitable; B = Marginally suitable

WEST OR PENINSULAR MALAYSIA

West or Peninsular Malaysia has an area of 131 587 km² (13.16 million ha), of which 8.10 million ha is arable. It consists of twelve administrative states namely Perlis (the smallest), Kedah, Pulau Pinang, Perak, Selangor, Federal Territory (included in Selangor), Negeri Sembilan, Melaka, Johor, Pahang (the largest), Terengganu, and Kelantan. The area as a whole is composed of 80 percent lowland and 20 percent highland (Lim and Chan, 1993). The AEZs of West Malaysia are shown in Figure 1. Figure 2 shows the major soil groups of Malaysia.

FIGURE 1
Agro-ecological regions of Peninsular Malaysia

Source: Adapted from Nieuwolt et al., 1982.

FIGURE 2
Dominant soil map of Malaysia

Original scale 1:5 million
Source: DSMW - FAO/UNESCO.

Knowledge about the soils on which fertilizers are to be applied is important for better fertilizer management and use efficiency. In Malaysia as a whole, there are three groups of lowland soils considered as problem soils, namely the sandy soils (Beach ridge [bris] and tin-tailings), peat and acid-sulphate soils. These soils usually require specific amendments for successful agricultural use. In Peninsular Malaysia and Sabah, about 155 400 and 40 400 ha of bris soils exist respectively (Thomas, 1966). In 1995, the total area of tin-tailing areas in Peninsular Malaysia was estimated to be approximately 200 000 ha. It is estimated that tin-tailing areas in Peninsular Malaysia are expanding at a rate of 4 000 ha annually (Aziz, 1995), which gives an estimated area of 236 000 ha in 2004.

There are approximately 2.4 million ha of peat in Malaysia, of which 0.8, 1.5 and 0.1 million ha are located in West Malaysia, Sarawak and Sabah, respectively.

The problems of the loss of applied fertilizer by leaching are serious on sandy and peat soils. Farmers adopt appropriate management practices, such as split application according to crop requirements. For the acid soils, the main problem as regards fertilizer use is phosphate fixation. This is dealt with by lime amendment and the direct application of phosphate rocks.

EAST MALAYSIA

East Malaysia consists of two states: Sarawak (123 466 km²) in the southwest and Sabah (73 711 km²) in the northeast. The total arable land areas of Sarawak and Sabah are of 5.31 and 2.15 million ha respectively. The mean annual rainfall in Sarawak is between 2 500 and 5 000 mm, and is fairly well distributed, with no month below 100 mm (Andriesse, 1968). Similar rainfall conditions exist in Sabah, which is moist and wet throughout the year, especially towards the interior, a few rain shadow areas being an exception.

The characteristics of the AEZ's and the soils of Sarawak, including their agricultural suitability, are summarized in Table 3. Most of Sabah has very steep land. The major soils include Fluvisols and Gleysols (S1), Lithosols, Regosols and Cambisols (S3), Luvisols and Nitosols (S5), Acrisols and Ferralsols (S6) and Histosols (S7). The codes in parenthesis represent equivalent groups proposed by Panabokke (1979). The S3 soils group includes all the shallow soils of the highlands and the Regosols of the alluvial plains and is therefore the most extensive. This is followed by the S6 group, which constitutes the major agricultural soils. Groups S1 and S5 are less extensive; the S1 group is extensively cultivated with paddy and the S5 with dry land crops. Group S7 is mainly peat, occurring in relatively large blocks, and is used largely for commercial pineapple production. Large areas of S7 are now being opened up for oil-palm and sago. Sarawak's AEZ's are shown in Figure 3. They comprise twelve classes.

FIGURE 3
Agro-ecological regions of Sarawak

Source: Department of Agriculture, Sarawak.

TABLE 3
Summary of the characteristics of the AEZ of Sarawak