Logistic Regression to Predict Termite Occurrences with Environmental Variables in Primary Forest and Oil Palm Ecosystem: The Case Study in Sabah, Malaysia

AbstractThe aim of this research was to study the relationship between presence of termite and environmental variables in primary forest and adjacent oil palm plantation located in Sabah province, Malaysia. Termite sampling was conducted with manually dug and sorted soil pits (25cm × 25cm × 10cm) at a minimum extent of 64 m and lag of 2 m. Logistic regression technique was used to analyze the collected data. In general, termite species richness and relative abundances are lower in oil palm plantation in comparison with primary forest. The result showed that probability of termite occurrences in primary forest are mainly related to dead woods, trees and non-predatory ants. Likewise, probability of termite occurrences in oil palm plantation was affected with the appearance of dead woods, pruned stacked fronds, non- predatory ants and earthworms. This result indicated that pruned stacked fronds and dead woods play an important role of recovery of termite assemblages in oil palm plantation

Soil characteristics in an oil palm field, Central Pahang, Malaysia with special reference to micro sites under different managements and slope positions

Within an oil palm field, different micro sites are established for fertilizer application (weeded circle), organic matter addition (frond heap) and operation paths (harvest path). This study reports the soil characteristics on an oil palm field with special reference to the micro sites as well as slope positions. For this study purpose, a second generation oil palm field (average slope gradient of 8°) with 10 years old oil palm was selected. The soils (Typic Hapludox) could be generally characterized by acidic nature and low levels in exchangeable bases with high aluminum activity. Soil properties were significantly or tended to be different at the depth of 0-5 cm and 5-10 cm in terms of micro sites; total carbon (T-C), total nitrogen (T-N), exchangeable magnesium (Mg) and exchangeable calcium (Ca) contents were higher at the frond heap. On the other hand, higher amounts of available phosphorus were accumulated in the weeded circle due to fertilizer application. Meanwhile, between different slope positions, non-distinct soil particles movement was observed and no evidence of soil erosion was found

Nutrient status of frond heaps and the underlying soils at an 18-year-old oil palm field in Central Pahang, Malaysia

In oil palm plantation, palm fronds are pruned off upon fruit bunch harvest and heaped up in-between palm trees, which is called as a frond heap. This study examined the amounts of nutrients contained in frond heaps and their influence on the underlying soil fertility at an 18-year-old oil palm field in Central Pahang, Malaysia. Based on biomass measurement and nutrient analysis, the amounts of C, N, P, K, Ca, and Mg in the frond heaps were estimated to be 697, 11.8, 0.810, 18.9, 8.05, and 2.73 g m-2, respectively. Meanwhile, the surface soils below the frond heaps showed higher levels of pH, EC, total C, N, exchangeable Ca, Mg, and K than those at harvest path, which is operation path for workers to harvest, while available P was more accumulated at weeded circle, to which fertilizer is applied under the palm canopy. These tendencies were more obvious compared with our previous study conducted at a 10-year-old field located in the same region. This study reveals that the nutrients released from decomposing frond heaps could contribute to build-up of the major nutrients except for P in the underlying soils to be recycled by palm trees

A comparative study of the use of organic carbon and loss on ignition in defining tropical organic soil materials

Organic soils or Histosols or peats as they are commonly referred to, are characterized by the presence of large amounts of organic soil materials (OSM), which is commonly quantified by the Walkley and Black (1934) (WB) method to determine the soil organic matter (SOM) using a correction factor of 1.724. SOM of Histosols is also identified through a combustion (loss on ignition, LOI) or elemental C-analysis (with a carbon-nitrogen-sulfur (CNS) analyzer with combustion and gas density detector). These methods were established using temperate and boreal peat deposits and here we demonstrate that tropical peat deposits require a modified approach. Typical SE-Asian tropical lowland peat pedons from rain forest and oil palm settings were sampled and the material analysed using a CNS analyzer, WB-C and LOI. The ratios for LOI:CNS-C for the 20 samples yielded values between 2.00-3.09 with a mean of 2.50 while the LOI:WB-C ratio yielded values from 1.75 to 2.58 with a mean of 1.94. A comparison of these values for topsoils and subsoils showed mean ratios (LOI:WB-C) of 1.94 and 1.89 for topsoils and subsoils, respectively. The forest samples had higher LOI:WB-C ratios than the subsoils from oil palm settings (1.94 vs 1.84). These values suggest that the standard factor of 1.724 to correct OSM to SOM for tropical soils is untenable. The values to convert CNS and WB-C values of tropical topsoils/subsoils to SOM or LOI should be 2.5 or 1.9, respectively. Our results indicate a significant difference in the soil organic carbon (SOC) of tropical lowland peats depending on the method used

Classification, genesis and characterization of spatial variability of soils derived from sedimentary rocks in Malaysia / Wong Mum Keng

In Malaysia, soils derived from sedimentary rocks are extensively used for agricultural purposes with oil palm and rubber being the main use. This study was carried out to determine the variability of physicochemical properties and classification of soils developed on sedimentary rocks under different ecosystems over natural forest and agriculture land. Therefore, three related studies were set up for this purposes. This first study focused on describing, sampling and analyzing physicochemical properties of twenty-five representative soil profiles taken from six study sites with different rainfall regimes spread across Malaysia. The soils are classified into 19 subgroups with qualifiers according to the World Reference Base for Soil Resources, 13 subgroups according to the USDA Soil Taxonomy and 15 subgroups according to the Malaysian Soil Taxonomy. Soil macronutrients contents were generally higher in the forest ecosystems followed by rubber plantations and finally oil palm plantations. From the principal component analysis(PCA) projection, it was found that soil physicochemical properties and microhabitats form an associative relationship. For the different agricultural and natural sites that have distinctive weathering condition and soil utilization, a comprehensive strategy is needed for maximizing the release of inorganic nutrients from sedimentary rocks and retaining them in bioavailable forms in the soil for sustainable crop production and ecosystem services. The second study focused on characterizing soil physiochemical properties of six soil profiles located along an altitudinal gradient (900 – 1900 m a.s.l.) developed from sedimentary parent rocks on Mount Alab, Sabah. The soils of the highest topographical position consisted of soils with a thin organic surface horizon, while the soils of the lower parts of the topographical positions were Inceptisols and finally Ultisols. All six pedons showed remarkable variability in morphological, physiochemical and clay mineralogical properties depending on the variations of the parent material. Field observations, soil physiochemical as well as clay mineralogical results of this study provide useful baseline information for soil conservation purposes in the tropics. The third study focus on quantifying the spatial variability of soils physicochemical properties in an oil palm plantation. Two study sites on oil palm plantation were chosen by soils that derived from similar parent material (sedimentary rock) with different soil series (Bungor and Chat series) characteristics. Soil samples were collected for surface (0-15 cm) and subsurface horizons (15-30 cm) from three management zones including weeded circle, harvest path and frond heap using a grid system. Leaf samples of front 17 were sampled from selected palms. Soil nutrients were higher at weeded circle and front heap as compare with harvest path in Bungor study site. On the contrary, different management zones of Chat study site shown less prominent differences in soil nutrients. This suggested that soil physical properties mainly soil texture plays an important role in determining spatial distribution pattern of soil nutrients. The outcomes from the spatial study can help to improve estate management strategies such as adapting a fertilizer application program that is more sitespecific based on the nutrient requirement to replenish the nutrient depleted from the soils

Impact of agricultural land use on physicochemical properties of soils derived from sedimentary rocks in Malaysia

In Malaysia, soils derived from sedimentary rocks are extensively used for agricultural purposes with oil palm and rubber being the main dwellers. In order to understand the environmental impact of these perennial crops planting, the variability of physicochemical properties of 25 representative soils derived from sedimentary rocks under different ecosystems (agriculture land and natural forest) at six study sites spread across Malaysia was examined. Among the soil physicochemical properties, total soil organic carbon, total nitrogen, and fertility level were found to be generally higher in the forest ecosystems followed by rubber plantation and finally oil palm plantations. Likewise, projection of principal component analysis showed an associative relationship between soil physicochemical properties and microhabitats. Finally, this study showed that soils from different agricultural and natural sites, but derived from similar sedimentary rocks, had distinctive weathering conditions and soil properties. Therefore, site-specific field management according to soil type, soil management techniques as well as fertilizer strategies are required to maximize crop production and to sustain ecosystem services. The output of this study will enable farmers to improve their crop yield via the selection of suitable crops cultivation based on soil characteristics