Malaysian Society of Soil Science

Abstract
Knowing peat characteristics and its microstructure is of grave importance to agriculturists, engineers and developers. This paper aimed to determine the degree of humification of tropical peat in the state of Sarawak, Malaysia. The peat under study was extracted from Sarawak and the degree of humification was determined based on its physical properties. Data was collected using seven parameters based on the American Society for Testing and Materials (ASTM) and British Standard (BS) method while peat assessment was done using the scanning electron microscope (SEM). The micrograph of peat shows colloidal granular particles with no visible hollow cellular connections. Our findings show that the peat index properties reflect the effect of decomposition and influence of fabric composition on its geotechnical properties. The degree of humification was successfully identified as H7. This implies that the peat sample is highly decomposed in the subsurface. Further research using X-Ray diffraction should be able to correlate the degree of humification with the shear strength of the peat to obtain a better understanding of peat’s microstructure.

Abstract
Inadequate availability of nutrients and leaching losses due to water table fluctuations is a serious concern in oil palm cultivation on tropical peat land. The objectives of the study were to determine peat subsidence and leaching losses of N, P, K, Mg, Ca, Cu, and Zn from tropical peat soil under cultivation of oil palm seedlings at different water table depths. The study was conducted using cylindrical lysimeters with five water table depths namely, 25, 40, 55, 70, and 85 cm from the soil surface. The experimental layout was a Randomised Completely Block design. Leachate from each lysimeter was collected after a rainfall event to determine the leaching loss of nutrients. The highest water table depth (25 cm) from the soil surface showed the highest nutrient leaching losses, and the lowest water table depth (85 cm), showed the highest subsidence and lowest nutrients leaching losses. Plant growth was highest under the 55 cm water table depth, and the lowest under the highest and lowest water table depths of 25 and 85 cm. The 55 cm water table depth was the best for oil palm growth because the active root zone of oil palm is within the 60 cm soil depth.

Abstract
Sustainable soil management is essential for maintaining proper soil health for future production of crops. A comparative study was carried out at Dumuria soil series in Khulna district to observe the current fertility and physical changes of soils over a period of time due to different land use. Soil physical (soil texture, water holding capacity, bulk density and total porosity) and chemical properties (Nitrogen (N), Phosphorous (P), Potassium (K), Sulphur (S), soil organic matter (SOM), soil organic carbon (SOC) along with cation exchange capacity (CEC), sodium absorption ratio (SAR), exchangeable sodium percentage (ESP), base saturation percentage (BSP) and % salt properties were determined. Except for the control, all the soils had silt loam texture. Water holding capacity varied from (33.57 ± 3.3 to 55.57 ± 5.2)% and all soil indicated good porosity (average 47 ± 5.59)%. Soil pH (5.96 to 7.4) indicated that the soils were neutral to alkaline in nature and had an average salt percentage (0.11% ± 0.05). The SOM was higher in natural vegetative soil (2.45 ± 0.46)% and decreased over the period of land use for cultivation. In terms of ESP and SAR, 50 to 10 years cultivated soil showed the highest value and a significant difference was observed among the treatments (p ≤ 0.05). For BSP, 100 to 50 years cultivated soil showed the highest value and uncultivated soil showed the lowest value and was statistically insignificant among treatment (p ≤ 0.05). Overall observation showed that long term land use resulted in a significant decline in soil quality. So, sustainable soil management should be incorporated in the development of suitable agricultural management such as the use of organic matter or incorporate organic mixed with inorganic fertilizer and adaptation of soil conservation farming. Proper strategies should be adopted to seek a sustainable solution that better addresses of soil fertility management.

Abstract
Physical properties and various compounds of soil structure are reflected in different soil properties which affect the hydraulic properties of soil and consequently the flow of water and movement of contaminants. Therefore, this study was conducted to measure physical and hydraulic properties in different structures of Silakhore Bala plain located in Lorestan province of Iran. The study was conducted under laboratory conditions on nine undisturbed soil columns with three different structures of granular, blocky and massive with three replications for each column in a completely randomised design with different structures of the soil as the main factor. Physical parameters like soil particle size distribution, bulk density, total porosity, mean weight diameter and also hydraulic parameters like saturated and unsaturated hydraulic conductivity and the number of water-conducting active pores in each column were measured. Chemical properties including organic matter content were measured too in different soil samples. The results showed that soil structure had a significant effect on physical and hydraulic parameters. Due to higher organic matter content, porosity and stability of the structure, granular soils had the highest value of for saturated and unsaturated hydraulic conductivity compared to blocky and massive structures. Soils with massive structure had the weakest structure in terms of physical and hydraulic properties.

Abstract
Residual nitrate nitrogen in a soil profile is influenced by agricultural practices such as fertilisation, irrigation and cultivation. In this study, the effects of different tillage methods and timing on corn yield were investigated in relation to soil penetration resistance and variation of nitrate nitrogen (NO₃-N) through a vertisol soil depth. A field experiment was carried out with three different tillage times (Fall-at the end of October, Early-at the middle of May; and Late-at the end of May) and tillage methods (mouldboard, chisel and direct drilling) in the Black Sea Agricultural Research Institute in 2011. Nitrate nitrogen values in 0-20, 20-40 and 40-60 cm soil layers were measured for the six different soil sampling times using the potentiometric method. Corn yield values generally decreased when the first soil tillage time when mould board and chisel applications were delayed or were made at the end of May. The fall tillage treatment with mouldboard had the highest corn yield (61.1 Mg/ha) while the lowest yield value (30.9 Mg/ha) was found with the direct drilling treatment. Generally, late tillage timing at the end of May reduced corn yield due to changing soil structure with reducing penetration resistance, increasing macroporosity and nitrate leaching in the soil profile. In conclusion, fall season soil tillage using mouldboard in clay soils is suggested to achieve optimum plant growth soil conditions resulting in high corn yield, and because of nitrate leaching, it also results in beneficial effects on conservation of water pollution.

Abstract
The morphological, physical and chemical characteristics of three toposequences were studied in order to offer suggestions on soil management systems that would increase crop production in South-eastern Nigeria. The study was conducted at the upper slope, middle/lower slope, and valley bottom on three parent materials, namely, basement complex (BC), sandstone and sandstone/shale. The Ap horizon was generally shallow. A hue of 7.5YR typified the landscapes, and colour value ranged from light-brown to brown. Low chroma in the matrix and high value mottles were common in the valley bottom. The soil profiles were similar in soil structure and consistency, generally weak, medium sub-angular blocky and friable topsoil to very sticky and very plastic subsoil. Sand was the dominant particle-size fraction. Soil texture was either sandy loam or loamy sand overlying sandy clay or sandy clay loam. Soil density varied with the soil profiles. Macropores were generally greater than 50% of total pore space. Saturated hydraulic conductivity (Ksat) was 2.16, 1.50 and 1.28 cm h^-1 in the respective toposequences. Water stable aggregates >2.0 mm averaged 28.8%, 26.5% and 33.5%, while >0.5 mm averaged 52.1%, 60.1% and 51.5%, respectively in the topographic positions of the toposequences. The soil profiles were slightly acidic. Soil organic C, averaged over all toposequences was 11.6, 12.5 and 10.5 g kg^-1, while available phosphorus was 9.32, 6.77 and 20.04 m kg^-1, respectively. Similarly, CEC averaged 7.21, 10.61 and 12.48 cmol kg^-1, while base saturation was 45.4%, 67.8% and 78.6%, respectively. Based on the soil characteristics, three soil management units (SMU) were identified as SMU A (Upper slope), SMU B (Middle/lower slope) and SMU C (Valley bottom). The corresponding soil management systems (SMS) are dry land farming with agroforestry and planted fallow in SMU A, wetland and dry land farming in SMU B, and wetland, and wetland/dry land farming in SMU C. These SMUs and SMS will facilitate the use of the soils on the slopes and lead to an increase in crop production and farmers’ income in the study area and other areas with similar soil and ecological conditions. These SMS are being recommended for use by agricultural extension agents to assist farmers cultivate their sloping lands in a more efficient and productive manner.

Abstract
In recent years, there has been significant regression of the Aleppo pine forest massif in the semi-arid areas of Algeria which is the last barrier against desertification. Several studies on the effects of climate and anthropogenic practices have been undertaken to identify the limiting factors but no study in the region deals with the effects of soil properties. In this work, we studied the quality of soils in a pine forest of Aleppo, Western Algeria by comparing their physico-chemical and biological parameters in order to characterise these soils and to identify the main limiting and degrading factors of their quality. The results of this study showed that the forest soils in this area were alkaline but not salty with a presence of limestone. They had a balanced texture homogeneous moisture with the colour varying from reddish brown to reddish maroon. The C/N ratio was moderately low indicating that these soils release some nitrogen despite being rich in organic matter. Microbial activity in these soils was moderately low as a function of nitrogen availability to ensure good carbon mineralisation. This study has shown that the soils of Aleppo pine forests in semi-arid zones are fragile and generally characterised by heterogeneous properties that are very sensitive to the influence of environmental factors (climate and human). This may result in the deterioration of physico-chemical and biological quality of the soils over a long-term consequently changing them into arid soils.

Abstract
Rice hull and saw dust at rates of 3, 6 and 9 t ha^-1 (designated as T1, T2 and T3 for rice hull and T4, T5 and T6 for saw dust, respectively) were applied separately to Bajoa and Dumuria soils to evaluate their reclamation potentiality of salinity through estimation of physico-chemical attributes of the soils. The pH of both soils was not significantly influenced by the amendments. The EC values of both the soils were significantly (p≤0.05) decreased and the reductions were more pronounced in the Bajoa soil. The values of sodium adsorption ratio (SAR) were found to decrease for all the treatments in both the soils and followed the order of T6 > T3 > T5 > T2 > T4 > T1 in the Bajoa soil and T2 > T3 > T6 > T1 > T5 > T4 in the Dumuria soil. Sodium removal efficiency was reduced significantly (p≤0.05) at the highest dose (9 t ha^-1). The treatments showed significant (p≤0.01) effects on exchangeable cations at different periods of incubation. During the incubation, the concentration of Na showed a remarkable decrease while K, Ca and Mg concentrations showed an increasing trend in both soil types.

Abstract
Pteris vittata L. has been demonstrated to absorb heavy metals, especially arsenic (As) from the soil. The interaction of As (V) and phosphate in the ferns that hyperaccumulate As is essential. Therefore, a glasshouse study was conducted to investigate the effect and interactions of phosphate in different forms at varying rates on biomass and uptake of As by Pteris vittata L. grown in naturally organic As-rich soil. P. vittata was grown in soil subjected to 9 treatments including control (0 P treatment) and four different rates of P in solid form of Triple Superphosphate (TSP) and liquid form of potassium dihydrogen phosphate (KH₂PO₄) at 12.5, 25, 50 and 75 kg P ha^-1. Results showed a significant (P≤0.0001) increase in frond biomass compared to non-amended soil, whereas the biomass of roots showed no significant (P>0.05) difference in all treatments. The concentration of As in the fronds ranged from 29 to 157 mg kg^-1 with the highest uptake of As being 0.71% in TSP, while in KH₂PO₄, it was 0.331%, almost half the rate in TSP. The application of P has been shown to increase the phyto-availability of arsenic in soil, resulting in a positive response on P.vittata As uptake, that is, TSP performed better compared to KH₂PO₄ in terms of As uptake and plant growth. It is postulated that the increase in As uptake was accompanied or more likely a synergism by the addition of phosphate.

Abstract
The advent of the green revolution, characterised by intensive use of chemical fertilisers, has contributed significantly to degradation processes in the low activity clay mineral tropical soils. This has led to recent campaigns to use organic fertilisers. The use of phospho-compost, which is a phosphorus (P) fortified compost as an amendment on P-deficient tropical soils is relatively new in Nigeria and information on its production, especially on the P fortification method that assures nutrient quality and environmental safety, is scanty. This study evaluated the effects of P fortification and methods on phospho-compost nutrient quality and phytotoxicity effects on maize seedling performance. Two carbon sources (sawdust (SD) and rice bran (RB)), poultry manure (PM), Gliricidia sepium (GL) leaves and bone meal (BM) (phosphorus fortifier) were mixed in 1:3:0.125:0.125 (60:180:7.5:7.5 kg feedstock mix) ratio under two bone meal (phosphorus) fortification methods: Co-composting (BMC) and post-stability fortification (BMP) methods were used to prepare four phospho-composts, SD+PM+GL+BMC, SD+PM+GL+BMP, RB+PM+GL+BMC, and RB+PM+BMP, following a standard procedure. Two bone meal unfortified sawdust (SD+PM+GL) and rice bran (RB+PM+GL) based composts were included for comparison. Data were taken on pH, electrical conductivity, P, calcium (Ca), magnesium (Mg), manganese (Mn) and iron (Fe) contents of the cured compost. Data on maize seed germination and root elongation percentages were used for estimation of germination index of maize in each compost extract. Data were analysed by descriptive statistics and multidimensional analysis (MDA) was computed to rank the properties of the composts for use on tropical acid soils. Phosphorus fortification improved pH, electrical conductivity and P content of composts. The post-stability phosphorus fortification method, however, was superior in increasing pH (8%), P (223%), Ca (139%), Mg (15%) and germination index of maize (64%) and reducing Mn (23%) and Fe contents (68%) compared to the co-composting phosphorus fortification method. The MDA results showed a decreasing ranking order of the composts for use on tropical acid soils as SD+PM+GL+BMP > SD+PM+GL+BMP > RB+PM+GL > SD+PM+GL > SD+PM+GL+BMC > RB+PM+GL+BMC. Post-stability bone meal fortification method is thereby recommended for use in the production of high quality and environmentally safe phospho-compost.

Abstract
Arbuscular mycorrhizal fungi (AMF) play a significant role in enhancing soil health, nutrient uptake and availability in soils. This research aimed to determine the status of indigenous AMF on an intensively cultivated agricultural soil ecosystem (chili rhizosphere) and a natural forest ecosystem in Garut district, well known as a central chili producer in West Java. High tillage of agricultural soil may lead to destruction of the soil microbial community in general, therefore a forest ecosystem representing an untilled natural soil was used as a comparison Soil sampling was done in transects with the length of an ordinate point in every 100 m on chili cultivated areas and in the natural forest soil ecosystem of Gunung Putri. Five composite soil samples (0-20 cm depth) from each ecosystem were taken based on coordinate points. The number of indigenous AMF spores and roots colonisation was determined and mycorrhiza species were identified using a molecular analysis of the AMF DNA. The research results revealed that number of AMF spores in the chili rhizosphere soil was greater than in the natural forest soil. However, the degree of mycorrhizal colonisation in the rhizosphere under both ecosystems was not significantly different. The indigenous Glomus etunicatum was identified to be the dominant species in both soil ecosystems. Further research needs to investigate the potential of this indigenous AMF that could develop as biofertilizer for cultivation of chili.

Abstract
Several biofertiliser microorganisms are subjected to gamma-irradiation for mutagenesis to improve capabilities of N₂ fixation and P solubilisation, and also to satisfy biofertiliser market demands. The effects of gamma-irradiated Acinetobacter calcoaceticus on N and P uptake of choy sum or green mustard (Brassica chinensis) were investigated in a greenhouse experiment. Eight bacteria isolated from compost, soil and plants which were to be used as biofertilisers were gamma irradiated at 50–400 Gy and screened for the best N-fixing and P-solubilising mutants. The gamma-irradiated A. calcoaceticus M100/200 mutant showed higher N₂ fixation and phosphate solubilisation than those of the wild-type in vitro. The selected mutant (M100/200) and wild-type (M100) A. calcoaceticus were then tested on green mustard in a greenhouse experiment. N, P and K contents in soil, as well as pH, were determined using a soil nutrient analyser. Urea and rock phosphate were used as nitrogen and phosphate sources, respectively. Two-week-old seedlings were treated with biofertiliser (mutant or wild type) with either N or P source alone or in combination. The control treatments comprised of biofertiliser or N or P source alone (positive control) and without treatment (negative control). Crops were harvested after 2 months. Fresh and dry weight, height, chlorophyll content, leaf area and total N and P in the tissue of the crops were measured. Mutant M100/200 with N and P source treatment or with P source only showed superior growth and nutrient uptake in comparison to those of the samples given other treatments in the greenhouse experiment. Nitrogen input did not enhance growth, whereas phosphorus input and administration of phosphate solubiliser increased plant growth indirectly through a better rooting system. Green mustard inoculated with mutant strain demonstrated better nutrient uptake in a greenhouse experiment than those inoculated with the wild type.

Abstract
Saline soils can be developed for the cultivation of food crops such as rice. Despite offering this potential, the utilisation of saline soils is limited by its physical, chemical and biological properties. These barriers can be amended through the application of azolla compost and biofertilisers. In this research, combinations of azolla compost and biofertiliser consortia were assessed to identify the best treatment for rice plants grown in soil at various salinity levels. showed that the application of azolla compost and biofertiliser increased the phosphate solubilising bacteria (PSB) population and the dry weight of rice dry cultivated in a saline soil. The salinity treatment of 2-6 mm hos cm^-1 influenced PSB population and rice dry weight. An ncreasing level of salinity decreased PSB population and rice dry weight.

Abstract
Pesticides are chemicals that are widely used in the agricultural sector to control pests in the environment. Lambda cyhalothrin is an insecticide that belongs to a group of pyrethroids. As lambda cyhalothrin is persistent in the soil, there is an urgent need to take remedial measures to control environmental pollution. In this study, the ability of bacteria to degrade lambda cyhalothrin from a paddy field was evaluated. Tolerance of bacterial isolates was tested at different concentrations. Among the ten different genera, isolate Pseudomonas sp designated as GMMC1 was found to tolerate pesticides up to 500 ppm and was selected for further degradation studies. GMMC1, lambda-cyhalothrin degrading bacterium identified by Sequence BLAST analysis,was isolated from the paddy crop soil and found to be the dominant bacteria which tolerates pesticide. Results of a phylogenetic analysis of GMMC1 found it to be closely related to Pseudomonas fluorescens. Pseudomonas fluorescens (GMMC1) isolate as appears to be the best short term choice for bioremediation of pesticide-contaminated agricultural fields.

Abstract
An experiment was conducted to study the impact of water logging and addition of organic amendments on green house gas (GHG) emissions in a saline soil. The treatments comprised of water levels maintained at three levels viz., complete saturation, 10 cm and 15 cm below the soil surface. Organic amendment at the rate of 7.5 t ha^-1 was added. Gas samples were collected at periodic intervals and analysed. The results revealed that CO₂, N₂O and C₂H₂ emissions were lower under a water logged condition and were found to be higher at water levels 10 cm / 15 cm below the soil surface. There was an increase in emissions from 100 to 400 mg kg^-1 at 7 days after incubation (DAI). Methane emission was found to be higher in completely saturated soil. Soils at 10 cm water level and amended with the organic material registered a higher value of soil microbial biomass – C of 1320 mg kg^-1. Emissions of GHG were enhanced with the addition of organic material. This suggests that lack of C substrate is the dominant limitation for GHG emissions on saline soil. Lower q CO₂ values in water logged soils indicate low microbial activity.