Malaysian Society of Soil Science

Abstract
Arable land in Peninsular Malaysia is dominated by highly weathered infertile soils which are taxonomically classified as Ultisols. The production of non-acid tolerant sweet corn on these acidic Ultisols is known to be negatively affected by soil acidity and/or Al³⁺ toxicity. However, to some extent, corn is able to defend itself against Al³⁺ toxicity and/or H⁺ stress. For Al³⁺ toxicity problem, the defence mechanism is along this line. The positively-charged Al³⁺ is attracted to the negatively-charged root surface of the sweet corn. When the Al³⁺ touches the surface of the root, the corn plant reacts instantly to release oxalic acid that chelates the Al³⁺. By this mechanism some of the Al³⁺ at the solution-root interface will be deactivated by the organic acid and rendered unavailable for uptake by corn. The chelation of Al³⁺ occurring in soil solution by this mechanism is a crucial step to help sustain the production of corn growing on the Ultisols. For sustainable corn production, the pH of the Ultisols has to be raised to a level above 5.3 by liming or other agronomic means. In the final analysis, Al³⁺ activity in the soil solution is less than the critical level of 10 μM. The low productivity of the Ultisols can be overcome by applying EFB-biochar at a rate of 10 t biochar/ha, which is an economically viable agronomic practice.

Abstract
Erosion and landslides that occur in volcanic areas of Indonesia are crucial problems that cannot be overcome completely. This study was designed to determine the ability of different plant types to reduce water runoff and soil erosion and improve soil physical properties. Soil samples were taken from landslide-prone areas in Patamuan, West Sumatra. Plots created from steel plates of 1.5 × 0.5 × 0.3 m in dimension and set at 22° angle, were placed in the greenhouse and a rain simulator was used to irrigate the plots. The experiment was a completely randomised design with three replications. The plant types were Tithonia shrub, vetiver, king grass and Napier grass. Results showed that runoff and soil erosion were reduced from 93 to 74 liter/m², and from 1.03 to 0.17 kg/m², respectively. Planting Tithonia decreased runoff while Napier grass reduced soil erosion. Soil moisture content at field capacity increased from 14% to 20%, and macropores from 31% to 41%; however there was a decrease in micropores from 17.5% to 14%. King grass increased root density (RD) and root area ratio (RAR), but reduced the relative soil particle detachment rate (RSD). King grass and vetiver had a positive impact on reducing both runoff and soil erosion.

Abstract
Soil termiticide treatment is a fundamental method to control termite population and infestation by creating a continuous barrier surrounding the structures. Dissipation of termiticides depends on half-life, degradation rate, leaching activity, and storage method. The use of termiticides without understanding their fate would lead to environmental contamination. This study determined the degradation rate and half-life of three commercially available termiticides (bifenthrin, fipronil, and imidacloprid) in soils having different textures, a sandy loam and loamy sand, under a laboratory setting. The remaining termiticides in the soils were extracted and analysed using an Ultra-Performance Liquid Chromatography (UPLC) system. It was found that bifenthrin had the highest half-life (166.88 days) and the lowest degradation rate (4.28ppm/day), compared to fipronil (56.05 days and 5.43 ppm/day) and imidacloprid (50.02 days and 5.46 ppm/day). On account of the high half-life, lower degradation rates, and good soil bonding capacities, fipronil and bifenthrin are recommended as termite control in this study. These features make fipronil and bifenthrin termiticides suitable for buildings environmental protection.

Abstract
Statistical and spatial approaches have been used to determine the relationship between in-situ resistivity, soil moisture content and pH. These are done to establish the extent to which resistivity measurements can be used in mapping selected soil properties. Soil resistivity measurements were taken via a Wenner array platform having an electrode spacing of 8 cm. Soil samples were taken at 0–3 cm depth. The samples were analysed for moisture content and pH. Clayey sand and sand textural classes were deduced from resistivity values (210–750 ohm-m and >750 ohm-m respectively). Moisture content values were classified in conjunction with texture as unavailable water (UW) and available water (AW). pH values were classified as moderately acidic (5.2 – 6.0), slightly acidic (6.1 – 6.5) and neutral (6.6 – 6.9). A moderate inverse relationship was observed between resistivity and moisture content. The spatial correlation between resistivity-derived textural classes and moisture content classes was 62%. Resistivity was also found to be inversely correlated with pH. Spatially, higher resistivity zones were abundantly associated with moderately acidic pH zones, while lower resistivities correlated with slightly acidic to neutral pH zones – thereby bringing the spatial association between resistivity and pH to 60%. The pilot/plot-scale study concluded that to a satisfactory extent, in-situ soil resistivity measurements can be adopted as a complimentary tool for selected soil properties mapping.

Abstract
The crater environment of Ratu Crater, Tangkuban Parahu Volcano was largely shaped by chemical processes that occurred in the geothermal centre in the form of fumarole and solfatar. A range of five representative profiles were identified in the toposequences of the crater i.e. A (toeslope), B, D (backslope), G and J (summit). Soil samples were physically, chemically, and mineralogically analysed. Mineralogical analysis showed that the sand fraction of heavy minerals (specific gravity> 2.87) were opaque, augite, and hipersten, while light minerals (specific gravity< 2.87) were volcanic glass, zeolite, andesin, labradorite, bitownite and rock fragments. Extraction with oxalate and pyrophosphate showed Profile D (backslope) to contain the highest mineral content of allophane (1.414%), imogolite (0.391%), and ferrihydrite (2,091%). The lowest content was found in Profile A (toeslope), which had a smaller content than Profile J (summit). XRD analysis results (no treatment) showed that all profiles of A, B, D, G, J had almost the same reflection pattern consisting of calcite (3.03 Å), cristobalite (4.04 Å), feldspar (3.1-3.25 Å, gibbsite (4.85 Å), kaolinite (7.1 Å) and quartz (3.34, 4.27 Å). XRD analysis (Mg+glycol) of the profiles showed each profile to be mostly dominated by non-crystalline minerals (amorphous); however Profile J (Summit) and Profile A (toeslope) were dominated by crystalline minerals that had been developed from amorphous minerals, i.e. mineral 2:1 (smectite and chlorite) and mineral 1:1 (halloysite and kaolinite).

Abstract
Fertilisation plays a major role in growth and dry matter yield of forage. A field experiment was conducted over two planting seasons on the same site to determine the effect of different fertilisers on growth of corn and soybean and dry matter yield of mixed forage. Six fertiliser treatments with three replications were arranged in randomised complete block design. The treatments were 100% chemical fertiliser (NPK), 100% poultry manure (PM), 50% PM, combined application of 50% PM with biofertiliser, sole biofertilser and untreated (control). The results in the first season showed that 100% NPK produced the highest dry matter yield (13.83 t ha^-1) but in the second season, 100% PM produced a similar dry matter yield (9.91 t ha^-1) with 100% NPK (9.84 t ha^-1). Sole biofertiliser produced the same yield as 50% PM. The results indicate that 100% PM at the rate of 6.3 t ha^-1 significantly increased dry matter yield of mixed forage.

Abstract
An experiment was conducted to determine the effects of free-living diazotrophs on the growth and root colonisation of pak choi. Free-living diazotrophs were isolated from soil samples obtained from the selected areas of the university campus. The isolation method used Jensen’s liquid (N-free medium) and a spectrophotometer to determine diazotrophic bacterial growth and check the level of turbidity, respectively. Bacteria that grew in the N-free liquid medium were assumed to be diazotrophs. Three diazotrophic strains were selected from the isolation in the N-free liquid medium for a pot experiment. Growth of the strains in the Jensen’s liquid medium was an indicator for selection of strains in this study. The level of turbidity was compared with that of the control. Results showed that shoot biomass was significantly affected by the diazotrophs. Plants inoculated with Bacterium 3 produced significantly larger shoots (F_2.35 = 2.10, P < 0.001) than those grown with Bacterium 1, 2 and 0 (uninoculated). However, the fresh weight of root and root colonisation analyses were unaffected by treatment. The plants did not grow well and were stressed for most of the experiment. The combined effects of autoclaving and nutrient limitation possibly adversely affected plant health. Nevertheless, plants grew sufficiently well for the experiment to be continued and for testing the efficacy of the bacteria.

Abstract
Crude petroleum oil is a rich source of hazardous materials that can cause soil and water pollution which can be treated by natural biodegradation processes. The aim of this study was to isolate and identify native oil degrading microorganisms from a petroleum-contaminated soil. The study was conducted at Changanassery, Kottayam district in Kerala, India. A total of six bacterial and four fungal strains were isolated from the samples. Isolated bacterial strains were Pseudomonas aeruginosa, Bacillus subtilis, Pseudomonas spp, Bacillus spp and Staphylococcus aureus. Fungal isolates were identified as Aspergillus niger, Aspergillus spp, Aspergillus flavus, Pencillium spp. It was observed that these organisms were able to utilize and degrade crude oil constituents.

Abstract
Conversion of natural forests into monoculture oil palm plantations may result in detrimental effects on soil microbial population and the physical properties. In this study, data on soil microbial populations and soil chemical properties were collected from three different areas namely, undisturbed secondary forest (USF), disturbed secondary forest (DSF) and oil palm cultivated area (OP) at three different sampling times (June 2012, January 2013, June 2013). Results showed that microbial populations were significantly affected by location and time of sampling. The OP had the highest populations of bacteria (6.57 log₁₀cfu g^-1 soil) and fungi (5.57 log₁₀cfu g^-1 soil) in June 2013. Population of phosphate-solubilising bacteria was consistently low at the OP compared to that in the secondary forests (USF and DSF) at all sampling times. Most of the soil chemical properties were affected by time changes. Soil moisture was higher in the secondary forests (USF and DSF) in June 2012 and June 2013. Total C (4.09%) and N (0.31%) were higher in USF compared to DSF and OP in January 2013. The findings demonstrate that cultivation of oil palm did not diminish the overall microbial population and physico-chemical properties of the soil. However, differences in soil attributes between the secondary forests (USF and DSF) and oil palm OP denote that oil palm cultivation did have some adverse effects on soil microbial population.

Abstract
The respiration of microorganisms in soil is one of the indexes of microbial activity of the soil. However, it is known that soil microbial respiration has decreased due to heavy use of chemical fertilisers and lack of organic matter in the soil. Hence, this study was carried out to measure the effects of different types of vermicompost on microbial respiration. The study was conducted in a completely randomized design with four replications in 2014 in the laboratory of Soil Science, College of Agriculture and Natural Resource, Gonbad Kavous University, Iran. Treatments consisted of different mixtures of vermicompost with soil and without soil that were produced from different manures. The results showed that the type of vermicompost with soil and without soil had a significant effect on microbial respiration. The most and least microbial respiration rates were observed in 50% cow manure + 50% potato and in 25% straw + 75% horse manure, respectively, when tested without mixing with soil. Means comparison of microbial respiration in treatments by 50% composition (vermicompost + soil) showed that the lowest and highest rates of microbial respiration was in 25% straw + 75% horse manure with 735 mg carbon per kg composition and 75% straw + 25% poultry manure at 1934 mg carbon per kg composition respectively. Our study found that vermicompost increased the organic matter of soil and created a good environment for microorganisms to live in the soil.

Abstract
Soursop (Annona muricata L.) has been increasingly cultivated in Malaysia. In view of the importance of the crop, there is a need to understand the effects of agronomic management such as NPK fertiliser application and the inoculation of arbuscular mycorrhizal fungi (AMF) on soursop growth and nutrient uptake. Therefore, this study aimed to determine the effects of AMF and fertiliser on the growth and nutrient uptake of soursop seedlings. The experiment was conducted under glasshouse condition in UPM, Serdang, Selangor, Malaysia using completely randomised design (CRD) with five treatments which comprised AMF inoculations with full and half dose of NPK 15:15:15 fertilisation. The treatments were: T1- Control (without AMF and NPK fertiliser); T2- AMF only; T3- AMF with 50% NPK fertiliser; T4- AMF with full amount (100%) NPK fertiliser; and T5- full amount (100%) NPK fertiliser only (without AMF). Plant growth, soil microbial population AMF development, ‘nutrient’ status of the plants and soils were determined after the 8^th week of planting. Soursop seedlings grown in soils treated with 100% NPK 15:15:15 fertiliser (T5) had the highest chlorophyll content, root volume, N uptake and soil N and K. Surprisingly, inoculation of AMF (T2) had similar effects to that of NPK 15:15:15 fertiliser (T5) on plant P uptake. Mycorrhizal spore production even at low numbers (66 spores/10 g soil) indicated probable symbiotic interaction with soursop seedling roots at the nursery stage.