Influence of agricultural activity on soil morphological and physicochemical properties on sandy beach ridges along the east coast of Peninsular Malaysia

Abstract

Along the east coast of Peninsular Malaysia, beach ridges are formed with interspersed swales, which are referred to locally as beach ridges interspersed with swales (BRIS). Although BRIS soils are regarded as problematic lowland soils for agriculture because of their very sandy texture and concomitant infertility, agricultural activities in such soils have been recently increasing. This study was conducted to characterize the BRIS soils and to evaluate the influence of agricultural activities on soil characteristics and fertility. Three 1-km transects from the shoreline running inland were established; two transects passed through the experimental farm of Cherating Station of the Malaysian Agriculture Research Development Institute while the other transect passed through an adjacent remnant forest. The soils located close to the shoreline and that further inland were classified as Typic Quartzipsamments and Typic Haplohumods, respectively. The soils had a very high sand content, occasionally exceeding 95%, were acidic and had low cation exchange capacity (CEC) values. While soil organic matter was the determining factor for cation exchange capacity, the regression slope of CEC against soil carbon in the Bhs horizon of the Spodosols was different from that in the other horizons. Because the effective CEC value was much lower than the CEC value, the development of the negative charges on variable-charge surfaces seemed to be largely restricted under acidic conditions. For the Spodosols, the levels of aluminum (Al) and iron (Fe) oxides extracted with acid ammonium oxalate and those oxides with dithionite-citrate-sodium bicarbonate were negligible in the A to E horizons, but they showed sharp peaks in the Bhs horizons. Agricultural activities affected the soil in three ways. First, the A horizon of the farm soil had lower amounts of total carbon (C) and nitrogen (N) compared with the forest, suggesting insufficient input of plant litter to sustain original levels of soil organic matter. Second, although the levels of pH, and exchangeable calcium (Ca) and magnesium (Mg), were higher in the farm soil than the forest, exchangeable potassium (K) was occasionally not detected despite fertilizer application. This finding might be due to the preferential adsorption of divalent cations over monovalent K on the variable negative charges on soil organic matter surfaces as well as limited development of the charge sites in the sandy soil. Finally, the Spodosols under agricultural land use had the highest peak of available phosphorus (P) in the Bhs horizon despite its low level in the overlying A and E horizons. While phosphate is known to be immobile relative to other anions, our finding suggest the downward translocation of mineral P from fertilizer and its retention in the Bhs horizon. Based on the findings, soil organic matter was very important in BRIS soil. Increasing organic matter levels of the soils can improve soil fertility through enhancing cation exchange capacity and the resulting increase in basic cations.

Soil morphological and chemical properties in homegardens on sandy beach ridges along the east coast of Peninsular Malaysia

“…The topography in the village is relatively flat, and leveling for housing had been seldom conducted. The flat topography seems to be common for the BRIS in this district (Khairul et al 2017).…”

“…On the other hand, on the BRIS on the east coast of the Malay Peninsula where substantial settlement is believed to have started since the eighteenth or nineteenth century, the soils used for homegardens have not yet been investigated. During the survey in our previous study (Khairul et al 2017), we found that homegarden soils were dark in color down to the deep layers, suggesting a preferable soil condition for plant growth. This finding may provide a clue to help develop sustainable and ecofriendly systems for agriculture in BRIS soils.…”

“…1) and contains fruit tree lots such as Cocos nucifera (coconut), Manilkara zapota (ciku in Malaysia), Anacardium occidentale (cashew nut), and Averrhoa carambola (starfruit), and pasture lots with grasses such as Brachiaria humidiocola (koronivia grass). Detailed information about the farm was provided in our previous paper (Khairul et al 2017). For the fruit trees, chemical fertilizers (200 g each of Christmas Island rock phosphate, magnesium sulfate, and ground magnesium limestone) and organic amendments (1 or 2 kg of oil-palm empty fruit bunches and palm oil mill sludge) were applied upon planting.…”

“…BRIS accounts for 1.23% (162,000 ha) of the total land area of Peninsular Malaysia (Zahari et al 1982). The soils located close to the shoreline and those inland wards are reported to be classified as Typic Quartzipsamments and Typic Haplohumods, respectively, in the USDA system (Okubo et al 2003;Roslan et al 2010;Khairul et al 2017). Unlike other regions, the BRIS land in the Malay Peninsula has been settled and used for agriculture, although the soil is recognized as problematic lowland soil for farming, as well as peat swamp soil and acid sulfate soil.…”

“…Although many agronomic studies have been conducted to help increase crop production through improving fertilizer schemes (Abdul-Hamid et al 2009;Hanafi et al 2010;Che Lah et al 2011), knowledge of BRIS soils is still limited to fundamental aspects such as their formation process (Okubo et al 2003;Roslan et al 2010). In our previous study, we investigated the influence of farming activities on the soil characteristics, comparing an experimental field of the Malaysian Agriculture Research Institute (MARDI) with the adjacent remnant forest (Khairul et al 2017). We showed that agricultural activities even with a well-managed system in the experimental farm caused an obvious reduction in soil organic matter in the A horizon and excessive loss of nutrients from the soils.…”