Malaysian Society of Soil Science

Abstract
A degraded area in Forest Research and Education (FRE) Wanagama 1 was successfully rehabilitated with Gliricidia sepium, a fast growing pioneer species capable of producing a great amount of organic matter, and which facilitates the development of a shallow clay soil. Since rehabilitation, this area has received minimal human disturbances, and is thus a suitable area for studying soils developed on/or in association with limestone parent material. Such studies, which are rather limited, contribute to knowledge on soil development in the tropics. Soil samples from six plots representing two different stand ages (44 and 28 years old) of G. sepium, three slope positions, and soil depths were collected and analysed for selected physical, chemical and mineralogical properties. Results of this study showed that the soil is dark brown to very dark grey in color, contains a high amount of organic matter, is pH neutral to alkaline and is dominated by clay particles which mainly consist of smectite; the soil can therefore be classified as Vertisols. The smectite-dominated soil is developed from dissolution and subsequent precipitation of limestone parent materials. Soil forming factors, namely monsoonal climate, dense vegetation which causes builtup of soil organic matter content, and terracing were responsible for the formation processes.

Abstract
The BX-1 system (consisting of the BX-1 media and RB 900 tube) is a new planting system introduced by a private company to replace the growth of plants in soil-filled polybags. Different irrigation systems influence plant growth differently. The main objective of this study was to compare and determine the best of three water irrigation systems: overhead sprinkler (SPR), drip (DRP) irrigation, and the capillary wick (WCK) system, for the BX-1 system. The test crop was water spinach (Ipomoea reptans), and the performance of these three irrigation systems was compared with one another in terms of their effects on plant growth, amount of water and nutrient losses via leaching, water productivity and water use efficiency. The field experiment was carried out under a rain shelter at Field No. 15, Agrobio Complex, Universiti Putra Malaysia (2 59’ 4.96” N, 101 44’ 0.70” E), for 5 weeks from July to August, 2014. The experimental layout was the RCBD with the treatments being the three irrigation systems with three replications per treatment. Each experimental unit was planted with 20 water spinach plants. Results from the study showed that the capillary wick system produced the least leachate volume and nutrients loss. In terms of growth, the WCK system gave the highest growth for roots dry weight and leaf area. This was because the WCK treatment had the lowest amount of leachate and nutrient losses, so it had the highest nutrient content in the plant for N, P, and K. but there was no difference (p>0.05) in the Ca and Mg content. WCK also had the highest water use efficiency, but there was no difference in water productivity between the three treatments. WCK consumed the highest amount of water (but had least water wastage) to produce the highest amount of roots biomass and leaf area compared to DRP and SPR treatments. Thus, it is suggested that the WCK system be used with the BX-1 system as it was found to be the most effective irrigation system.

Abstract
Carbon sequestration is the process of transferring atmospheric carbon dioxide into the soil and storing it securely so it is not immediately re-emitted into the atmosphere. A thorough understanding of carbon and nitrogen sequestration in various profile horizons would be helpful to comprehend carbon and nitrogen cycling from a pedological perspective. The quantity of carbon and nitrogen sequestered at different horizons of the soil profile pit was investigated. Results showed that the mean organic carbon content of the soils varied from 6.81 to 37.75 g kg^-1. The organic carbon content of the individual horizon varied substantially within the profiles. Carbon and nitrogen sequestration capacities of the soils varied from 3142.60 – 7643.25 g C m^-2, 101.33 – 503.55 g N m^-2 and increased with horizon thickness in all the soil profiles. Bulk density has significant positive relationship with the amount of carbon sequestered in the soil. The results of regression analysis showed that with the effect of horizon thickness, bulk density and organic carbon on carbon sequestration, the regression coefficient of determination (R2) was 0.693 (p<0.001). On N sequestration versus horizon thickness, bulk density and total nitrogen, it was found that 67% of the variation (significant at p<0.001) in soil nitrogen sequestration capacity was due to the aforementioned independent variables in soil.

Abstract
Understanding the distribution of various fractions of micronutrients in soils is important for effective and efficient management of soils for optimum crop production and environmental conservation. Distribution of various Zn fractions in soils of different parent materials (coastal plain sands, alluvium, false bedded sandstones and Imo clay shale) in Imo State, South-eastern Nigeria was evaluated using sequential extraction procedure, comprising six fractions: water soluble, exchangeable, specifically sorbed/CO₃ bound, Fe-Mn bound, organic matter (OM) bound and residual bound. Soil samples were sequentially extracted and the various Zn fractions determined using atomic absorption spectrophotometer. Also, various Zn fractions were correlated to selected soil properties. On average value basis, zinc fractions in mg/kg decreased in the order of residual bound (0.695) > Fe-Mn oxide bound (0.598) > specifically sorbed/CO₃ bound (0.454) > exchangeable (0.241) > water soluble (0.209) > OM bound (0.143) in soils of Coastal Plain Sands; specifically sorbed/CO₃ (0.408) > water soluble (0.378) > exchangeable (0.375) > residual bound (0.250) > OM bound (0.217) > Fe-Mn oxide bound (0.121) in soils of alluvium; specifically sorbed/CO₃ bound (0.581) > residual bound (0.560) > Fe-Mn oxide bound (0.464) > OM bound (0.402) > exchangeable (0.283) > water soluble (0.182) in soils of false bedded sandstones; and residual (1.163) > specifically sorbed/CO₃ bound (1.086)> exchangeable (0.587) > Fe-Mn oxide bound (0.389) > OM bound (0.364) > water soluble (0.154) in soils of Imo clay shale. Available zinc concentrations were low and varied among the soils of different parent materials in a decreasing order of alluvium (0.753 mg/kg) > Imo clay shale (0.741 mg/kg) > false bedded sandstones (0.464 mg/kg) > coastal plain sands (0.449 mg/kg) while total zinc concentrations were in decreasing order of Imo clay shale (3.742 mg/kg) > falsebedded sandstones (2.471 mg/kg) > coastal plain sands (2.340 mg/kg) > alluvium (1.749 mg/kg). Zn fractions correlated among each other and with pH, OM, ECEC, available P, Ca and clay.

Abstract
The objective of the present study was to evaluate the potential of persulfate (PS) oxidant in the presence of mineral siderite (SI) for remediation of fuel oil contaminated soils. Clay and sandy soils were selected as representative soils which were spiked with 5000 mg fuel oil per kilogram of dry soil. The effects of controlling factors such as different persulfate concentrations (100 - 500 mM), siderite concentrations (0.1 - 0.5 g), pH (3 - 9), and temperature (20 - 60°C) were also investigated. The results indicated that in clay and sandy soil samples, the highest total petroleum hydrocarbon (TPHs) degradation was observed in the following condition: pH = 3, soils temperature = 60°C and PS/Fe (II) molar ratio = 400 mM/0.4 g and 300 mM/0.3 g in clay and sandy soil, respectively. Based on our findings, using persulfate oxidation in the presence of siderite as an activator is a promising technique to remediate soil contaminated by petroleum hydrocarbons.

Abstract
One of the problems of the modern world is global warming. Agriculture, after industry, is a source of production of greenhouse gases (GHGs). However, suitable agricultural management practices will enable the reduction in emission of GHGs from fields. The objective of this research was to determine the effect of organic matter such as filter mud, bagasse, manure, poultry and biochar on the production of GHGs in a wheat-corn-wheat rotation semi-arid area of south-western Iran from December 2011 to May 2013. The results from this study show there is a fluctuation in production of CH₄, CO₂ and N₂O with the change in seasons, with this behaviour being related to temperature and moisture changes of the season. There were significant differences between treatments and control with more emission from soil after adding organic matter. A comparison of the treated soils showed that biochar had the lowest emissions of CO₂ and N₂O besides experiencing increased immobilisation of CH₄ by the soil for eighteen months.

Abstract
Greenhouse gas emissions have increased during the last century due to human activities such as agricultural practices, fossil fuel burning and industrial practices. However, the formation of greenhouse gases, in particular N₂O or CO₂ is strongly controlled by both soil temperature and soil moisture. A laboratory experiment was conducted to assess the response of grassland and arable soils with regard to N₂O and CO₂ flows and mineral nitrogen concentration; soils were exposed to various drying- rewetting cycles at different gravimetric water contents (θwt) under controlled conditions for a duration of 60 days. In total, four treatments were conducted: soils under continuously moist conditions (control) at 32% θwt; soils received short drying rewetting cycles (SDWC) of between 32 to 21% θwt; soils exposed to medium drying rewetting cycles (MDWC) of between 32 to 18% θwt and a treatment with long drying rewetting cycles (LDWC) of between 32 to 5% θwt. Short, medium and long drying-rewetting cycle treatments went through 6, 4 and 2 drying-rewetting cycles (DWC) (0.1, 0.07 and 0.03 drying-rewetting frequencies). Soil samples (you should mention the different soils used for analysis here in the abstract) were analysed for NH₄⁺ and NO₃^- at the different stages of incubation in order to compare changes over time. Soils reduced N₂O-N flow in the long drying-rewetting treatments. For the grass soil, the short drying-rewetting cycle treatment yielded the highest cumulative N₂O flow (325 μg kg^-1). In arable soil, however, the long drying-rewetting cycles receiving treatment released 69% less N₂O-N flow as compared to the other treatments. For the CO₂-C flow, soils showed differing patterns, with the shortly dried-rewetted cycle treatment of grass soils yielding the highest (130 μg kg^-1) cumulative flow that was 25% higher than LDWC. Drying-rewetting cycles (DWC) on grass soils had no effect. The stressed treatments emitted only 19% higher CO₂-C flow than the control. The treatment with 5% (θwt) successfully reduced N₂O-N flow in grassland and arable soils. Soil net nitrogen mineralisation (NNM) and nitrification (NNN) rates of arable soils were significantly higher than in grass soils.

Abstract
Agricultural and industrial activities contribute most to pollutants found globally, and bioremediation of these pollutants is being intensely sought. We have isolated a molybdenum-reducing bacterium from agricultural soil for bioremediation purposes. The bacterium was grown in low phosphate medium supplemented with molybdate in a microplate format. The molybdenum-reducing bacterium was then further screened for amide-degrading properties. The bacterium was able to use acrylamide as a source of electron donor for reduction, and was able to grow on acrylamide, acetamide and acetonitrile. The growth parameters obtained according to the modified Gompertz model were lag periods of 0.468, 0.979 and 1.53 d and maximum specific growth rates of 1.165, 0.932, 0.842 d^-1 for acrylamide, acetamide and acetonitrile respectively. Optimal conditions for molybdate reduction included glucose, pH between 6.0 and 6.8, temperature between 25°C and 34°C, and phosphate and molybdate concentrations between 5 and 7.5 mM and 10 and 20 mM, respectively. The Mo-blue exhibited a unique absorption spectrum closely resembling a reduced phosphomolybdate. Mo-blue production was inhibited by the heavy metals copper, mercury, silver, chromium and cadmium. The bacterium was identified as Bacillus sp. strain Zeid 14. The bacterium will be very useful for bioremediation of sites contaminated with molybdenum and amides.

Abstract
This study was aimed at assessing soil enzyme activities in the Beas River bed for the pre-monsoon, post-monsoon and winter seasons. Soil samples were collected in triplicates from four sites for each season and analysed for 21 soil characteristics. The soil enzymes assessed were urease, catalase, polyphenol oxidase (PPO) and invertase. The hypothesis tested was that the enzyme activities are determined by soil characteristics and other environmental variables. Data were analysed using analysis of variance, multiple comparison test, cluster analysis, principal component analysis, stepwise multiple linear regression analysis and artificial neural networks. It was concluded from the study that maximum soil urease, PPO and invertase activities occurred during the winter season. There were two factors underlying the enzyme activities: factor-1 for urease and catalase, and factor-2 for PPO and invertase. Urease activity was increased to a maximum by the phosphate content of the soil, an important component of animal excreta. Ni and Cu are the prosthetic groups of urease and PPO which contributed a maximum to the activities of the respective enzymes.

Abstract
A laboratory study was conducted to examine the effects of organic and inorganic cultivation on soil biological processes and biodiversity. Five soil samples from each of the organic manure treated fields and inorganic fertiliser treated fields from two different states, Tamil Nadu and Madhya Pradesh, in India were examined. The soil types were either black cotton or loamy soil. Two other soil samples from a fallow area of Indore, Madhya Pradesh, India were also included for nutrient status and biodiversity comparison. Soil organic carbon, nitrogen, phosphorus, and potassium levels and soil enzymes that reflected soil microbial activity, such as dehydrogenase, beta glucosidase, phosphatase and nitrate reductase, were estimated. Inorganic soils had the lowest organic carbon content (4.5 g kg^-1) compared to the highest (12.2 g kg^-1) in organic soils. Similarly, soil phosphatase, glucosidase and dehydrogenase activities were higher by 26%, 28% and 21%, respectively, in organic soils. Randomly Amplified Polymorphic DNA (RAPD) profiles of soil DNA indicated microbial richness in organic soil as it had a low Jaccard’s similarity coefficient of 0.577 vs 0.703 in inorganic soil. Soil microbial diversity and dynamics were found to be greater in the organic system of cropping. These findings suggest that these could be used as potential indicators for soil health.

Abstract
Potassium-solubilising microbes (KSM) are microbes that are able to solubilise different kinds of potassium compounds and make their potassium ions available to plant growth. This study undertook to: (1) isolate KSM from soil samples, (2) evaluate their ability to solubilise not-easily soluble potassium sources, and (3) evaluate the effect of selected KSM on the growth of sorghum. KSM were isolated from soil samples taken from agricultural land, ex-tin mining land, and ex-gold mining land. KSM isolates were further selected according to (1) pathogenic characteristics, (2) a potassium solubility index on solid medium, (3) ability of KSM to solubilise not-easily soluble potassium sources in liquid medium, and (4) ability of KSM to stimulate sorghum growth. The best selected KSM were characterised by using molecular analysis. Results showed that KSM isolated from ex-mining land have better ability to solubilise feldspar than KSM from agricultural land. KSB2 and KSB6 isolates have the best ability to stimulate sorghum growth. KSB2 has 97.8% similarity with Achromobacter xylosoxidans, and KSB6 has 99% similarity with Burkholderia cepacia.

Abstract
Empty fruit bunch (EFB) biochar is being used as soil amendment to improve soil productivity of infertile soil for enhanced plant growth. Tropical soil is generally unfertile unit, low organic matter, plant nutrients, acidic and low microorganisms that affect crop production. Addition of biochar such as empty fruit bunch (EFB) could improve the soil fertility. Laboratory and glasshouse studies were conducted to determine the effect of EFB biochar and nitrogen-fixing bacteria Stenotrophomonas sp. (Sb16) on soil microbial communities, enzyme activity, chemical properties and growth of sweet corn. Five rates of EFB biochar (0, 0.25, 0.5, 0.75 and 1%) were applied to soil either with or without bacteria Sb16 and incubated for 40 days under laboratory condition. Sweet corn were grown in pots containing 6 kg soil and applied with five rates of EFB biochar (0, 5, 10, 15 and 20 t/ha) with or without bacteria Sb16. The experiment was arranged in Randomized Complete Block Design (RCBD), with 5 replications. Results of laboratory study showed that combination of EFB biochar at 0.5% without inoculation and 0.25% with bacteria Sb16 in both soil, significantly increased populations of soil bacteria, fungi, actinomycetes and N₂-fixing bacteria (NFB), enzymes (urease, acid phosphatase and fluorescein diacetate (FDA) hydrolysis activity), and soil chemical properties (pH, organic carbon, total N, available P and exchangeable K, Ca and Mg). The glasshouse experiment showed that application of EFB biochar at 5 t/ha with bacteria Sb16 significantly (p<0.05) improved growth of corn (shoot and root biomass, root length, root volume, plant height, leaf chlorophyll content and nutrient uptake). Addition of higher EFB biochar to soil negatively affected all the observed parameters. The studies showed that application of EFB biochar at 5 t/ha or 0.25% with N2-fixing bacteria Sb16 and 10 t/ha or 0.5% without bacteria inoculation improved corn growth and the quality of soil for sustainable corn production.

Abstract
Oil palm frond (OPF) contains high lignin and cellulose which leads to environmental problem. With an appropriate composting management, OPF have a potential as organic compost that can be applied as soil amendment to promote rubber plant growth. This study was aimed to observe the characteristic of OPF composting process and to investigate the optimum dose of OPF-based compost to promote rubber plant growth. The study was carried out by analysis of OPF composting process and application test of the compost as media amendment of rubber planting material. Composting temperature of the chopped OPF (3 to 5 cm), reached ambient temperature on day 75 with C/N ratio of 15.32. The highest percentage of compost particles-size distribution was > 4.75 mm in size. Generally, the quality of OPF-based compost has met the minimum standard of Indonesian National Standard for compost quality, except for K₂O content. The application test revealed that treatment of 20% compost + 80 % subsoil was the optimum dose to increase rubber plant growth compared to other treatments. The final cation exchange capacity (CEC) value of control decreased compared to the initial value, on the contrary, the CEC value of compost added media increased along with increased doses of compost. Media amended with compost also increase P, K, Ca, and Mg contents compared to control.