Malaysian Society of Soil Science

Abstract
Ultisols of the tropics are characterised by low crop productivity, severe degradation and variability in their properties due to inappropriate land use practices and seasonal changes. Knowledge of variability in soil properties is important for precision farming, adequate food production and environmental modeling. The major objective of this study was to evaluate the effect of season and land use on the studied properties. The experiment was factorially arranged in randomised complete block design (RCBD), with season, month of sampling and land use, serving as factors. Data were analysed using analysis of variance (ANOVA) and significant means were separated using least significant difference at 5% probability level. Bare fallow had the lowest shear strength (119.62 kN m^-2), water stable aggregates (WSA) (33.34 %), soil organic matter (13.95 g kg^-1), and bulk density (1.40 g cm^-3). Soil under bush fallow had the highest shear strength (136.95 kN m^-2) and WSA (38.00%), and the least silt content (89.35 g kg^-1). The shear strength, organic matter and aggregate stability varied moderately (C.V = 16.89, 20.26 and 38.43%, respectively). Significant interactions between the season and land use were noted in organic matter content only. Seasonal variations affected shear strength, organic matter, and bulk density significantly (P = 0.05).

Abstract
The aim of this study was to use simple genetic algorithm (SGA) as a an inverse method to fit Haverkamp constitutive functions, implemented in Richards' water flow equation, to volumetric water content data to predict a globally-optimum set of input parameter values. For the purpose of comparison, bat algorithm (BA) was also implemented. Both SGA & BA were coded in FORTRAN to solve Richards' equation. The Haverkamp constitutive functions were used to govern the relationships between hydraulic properties. Richards' equation was approximated by a finite-difference solution and was used to simulate water infiltration into Yolo light clay. Uncertainties in the input parameters were subjected to global sensitivity analyses (GSA) to determine the sensitivity indices and interactions between parameters by previous studies. Additionally, GSA was used to determine the input parameter that was responsible for the greatest uncertainty in the simulation results. In this study, the optimum population size was found to be 50, and the SGA was able to reproduce the water infiltration front, provided that data points of water content at saturation and residual levels were used in the prediction. Under extreme conditions where the uncertainties in the input parameter values were significant, a larger population size (greater than 50) would be required to obtain reasonable simulation results. The SGA was found able to generate comparable results to the bat algorithm at a population size of 50.

Abstract
Moisture transport in porous media is a fundamental subject in soil physics and civil engineering and therefore it is necessary to understand its mechanisms and processes involved. In this paper, the isothermal moisture diffusion, is estimated with gravimetric method for loamy sand, silty loam and clay loam soils. The basis of the method is to measure the amount of water absorbed by the small soil columns with different heights as a function of time. To evaluate the accuracy of the obtained diffusivity data they were compared with those obtained from Bruce-Klute method. Considering calculated logarithmic RMSE between two mentioned methods, it was confirmed the gravimetric technique may be more reliable to estimate the isothermal moisture diffusivity especially in finer texture soils. Moreover, this technique is quite simple and may be carried out with minimum laboratory facilities. Moreover, the results showed that the gravimetric method somewhat underestimated moisture diffusion D(ɵ) as compared to Bruce-Klute method, and the difference between the two methods increased with increasing at moisture content which will be discussed in the current paper.

Abstract
Invasions by exotic plants and the establishment of plantations have been associated with the enrichment of plant nutrients in the soil. The first aim of this study was to examine soil physic-chemical properties of the Acacia mangium plantation and the nearby undisturbed heath forest (HF) at the Andulau Forest Reserve, Sungai Liang, Brunei. The second aim was to determine the most influential soil properties that accounted for the most variation in the Acacia plantation and HF plots. A total of six pairs of 20 m × 20 m plots were established along two parallel transects (260 m each) in the Acacia plantation (6 plots) and the HF (6 plots). Each of the twelve plots were subdivided into four 10 m × 10 m subplots and one soil core (0 – 15 cm depth) was sampled in each subplot. Soil pH, gravimetric water content (GWC), organic matter (OM), organic layer depth, texture and nutrient concentrations were determined for each soil core. Significantly higher total Ca concentrations and organic layer depth were found in the soils of the HF than in the Acacia plantation. However, the Acacia plantation soils had significantly higher total N concentrations than the HF soils. Non-native A. mangium trees have the ability to change the soil physico-chemical properties to improve their growth. Total Ca concentration and GWC were the most influential soil properties in the HF, whilst for the Acacia plantation plots, pH was most influential. Studying soil properties of both native forests and plantations of exotic species provides insights into how non-native plants changes soil properties in ways different from native plant species.

Abstract
A high purity germanium detector (HPGe) which is a low background gamma-ray spectrometry system, was used for radioactivity measurement of soils from Habiganj District of Bangladesh to establish a radiation map within this area as a baseline record for future studies. The radioactivity concentration levels of ²³⁸U (Ra_eq), ²³²Th and ⁴⁰K were measured in soil samples. From the measured specific activities of the above three natural radionuclides, the radium equivalent activity (Ra_eq), the external hazard index (H_ex), the external gamma absorbed dose rate and the annual effective dose were calculated in this study. The activity concentration levels were found to be in the range of 5 to 19 Bq kg^-1 for ²³⁸U (Ra_eq), 7 to 38 Bq kg^-1 for ²³²Th, and 93 to 392 Bq kg^-1 for 40K with mean values of 11, 22 and 227 Bq kg^-1, respectively. No ¹³⁷Cs was found in this study. Radium equivalent activity (Ra_eq), gamma absorbed dose rate, external hazard index (H_ex) and annual effective dose values were found to be 59 Bq kg^-1, 28 nGy h^-1, 0.162 and 33 µSv, respectively, which indicates that the study area is radiologically safe for human beings.

Abstract
Suitability evaluation of soils derived from three different parent materials in the Owerri agricultural zone for maize and groundnut cultivation was done using the Food and Agricultural Organization of the United Nations’ (FAO) conventional method. Data were obtained from six pedons, two from each parent material. The results showed that despite climatic factors, soil depth, topography, and base saturation, there was no one highly suitable (S1) land for maize and groundnut cultivation. The organic carbon contents of the soils derived from Imo clay shale were highly suitable (S1) for groundnut cultivation. Soils derived from alluvium and coastal plain sands were only moderately suitable (S2) for groundnut cultivation. Generally, the soils derived from the three different parent materials were moderately suitable (S2) for maize production when their carbon contents matched the organic carbon requirement of the crop. In view of the aggregate suitability ratings, the major constraint for both groundnut and maize cultivation in the soils was soil fertility (f). Though not currently suitable (N) for groundnut and maize cultivation, the soils can still produce increased and sustainable crop yield if the appropriate husbandry practices are adopted, with particular reference to phosphate fertilizer application.

Abstract
Amendment of high pH soils with elemental sulphur (S) can result in a reduction of ammonia (NH₃) emissions following a local decrease in the soil ammonium concentration and pH. Two laboratory experiments were conducted to determine how the application rates of elemental S impacted urea transformations. Urea was surface applied at a rate of 1652 mg per kg of Bintang Series soil that was incubated with different rates of elemental S (0, 0.5, 1 and 2 g S kg^-1 of soil) for three months. The results showed that with the application of elemental S, volatilisation losses decreased quadratically to 30.42% of applied nitrogen (N), for the highest S rate, indicating that as more elemental S was added to the soil, a lesser fraction was lost as NH₃. Cumulative NH₃-N emissions were closely related to initial soil pH (r = 0.62**) and ammonium concentration (r = 0.74**). NH₃ volatilisation was the major pathway for the loss of N from surface applied urea and sulphur coated urea in Bintang Series soil. However, acidification of the soil by elemental S reduced NH₃ volatilisation by 50% as compared to the control. The NH₃ volatilisation pattern in soil treated with different rates of S was the same, but the addition of 2 g S kg^-1 soil delayed NH₃ volatilisation for four days. It should be noted that NH3 hydrolysis in Bintang Series soil was fast and only 1.6 days were needed for the disappearance of 50% of of the urea.

Abstract
A field experiment on sugar beet (Beta Vulgaris L.) grown in saline soil was carried out during the 2014 growing season to study the effect of potassium (K) fertilisation rates of 0, 100, 150 and 200 kg ha^-1 and foliar spray of salicylic acid (SA) solution of 1000 mg L^-1 (sprayed twice at the rate of 1200 L per ha each time) on yield, quality, nutrient contents, and uptake. The application of 200 kg ha^-1 of K in combination with salicylic acid foliar spray gave the highest root length, root diameter, shoot and root yield, sucrose, juice purity percentage, gross sugar yield and possible extractable white sugar, nitrogen (N), phosphate (P) and K content and uptake. The highest increase in sucrose (20%) as well as possible extractable white sugar (184%) were obtained by the addition of 200 kg ha^-1 of K in combination with salicylic acid foliar spray. The K, sodium (Na) and α-amino N contents in sugar beet decreased with the application of K with SA foliar spray. The highest values of K, Na and α-amino N contents were observed in the non-treated plants. K, N and α-amino N contents decreased by 48.5%, 68% and 76.6%, respectively, when treated with 200 kg ha^-1 of K with the addition of SA spray.

Abstract
Field experiments were carried out for three consecutive years to evaluate the effect of the interaction of potassium and sodium on foliar nutrient concentration, quality and quantity of coconut, grown in an acidic Ultisols in Kerala, India. The treatments comprised of different levels of potassium (K) as muriate of potash and sodium (Na) (common salt), either alone or in combination. The results showed that interaction between K and Na did not exert a significant effect on the foliar concentrations of nitrogen (N), phosphorous (P) and magnesium (Mg) as against K, Na and calcium (Ca). Full or partial omission of K for >2 years had a negative impact on nut yield, but this could be corrected by application of equal proportions of K and Na, which resulted in an increase in nut yield. The interaction between K and Na did not exert a significant effect on the quality of the kernel as indicated by biochemical characteristics. The treatments receiving K with Na registered a higher content of K and sugar in coconut water, but Na content was highest in full K treatment. Significant differences were not observed between treatments for pH, total mineral, and vitamin C content of the coconut water. The treatments studied could be beneficial to farmers cultivating coconut in acidic soils the world over.

Abstract
Peat, when used as a growing medium, must be optimally managed to improve its soil chemical properties. One alternative to increasing soil pH and available nutrient is by applying coastal sediment and salted fish waste which are easily obtained and relatively inexpensive. This study examined the effect of different amounts of coastal sediment and salted fish waste on nutrient uptake and production of maize on the peatlands of West Borneo (West Kalimantan). One control and three dosing regimes were tested on three types of peatlands as follows: (1) control case (farmers’ standard practice without additional dosing); (2) 20 Mg ha^-1 of coastal sediment + 0.75 Mg of salted fish waste ha^-1; (3) 40 Mg ha^-1 of coastal sediment + 1.5 Mg of salted fish waste ha^-1; and (4) 60 Mg ha^-1 of coastal sediment + 2.25 Mg of salted fish waste ha^-1. The peatlands that were improved were Typic Haplohemist, Typic Sulfisaprist and Typic Haplosaprist. A combination of 40 Mg ha^-1 of coastal sediment and 1.5 Mg ha^-1 of salted fish waste was found to be the best dosing regime for each peat type, increasing nutrient uptake (N, P and K) and improving the production of maize. Typic Haplosaprists (13.36 Mg ha^-1) was found to have the highest maize production, followed by Typic Haplohemists (13.06 Mg ha^-1) and Typic Sulfisaprists (12.96 Mg ha^-1).

Abstract
A pot experiment was conducted under greenhouse conditions to assess the impact of three halophyte species, Atriplex halimus, Atriplex lentiformis, and Atriplex amnicola, coupled with or without gypsum, on salt accumulation from excessive saline-sodic soil from the Sahl El-Tina plain, North West coast of Sinai, Egypt. All halophyte species ameliorated the soil at the end of their growth. Soil salinity and sodicity decreased particularly when combined with gypsum. Soil salinity decreased from 51.2 (initial soil salinity) to 8.10, 12.10, 10.14, 4.10, 7.10 and 5.14 mS/cm using A. halimus, A. amnicola, A. lentiformis, A. halimus + gypsum, A. lentiformis + gypsum, and A. amnicola + gypsum, respectively. Sodium adsorption ratio (SAR) decreased from 31.1 to 4.10, 5.01, 4.58, 2.91, 3.84 and 3.26, whilst exchangeable sodium percentage (ESP) decreased from 35.9 to 4.83, 6.19, 5.56, 3.07, 4.44 and 3.59 using A. halimus, A. amnicola, A. lentiformis, A. halimus + gypsum, A. lentiformis + gypsum, and A. amnicola + gypsum, respectively. The most efficient treatments that enhanced soil characteristics were A. halimus + gypsum, followed by A. amnicola + gypsum, A. lentiformis + gypsum, A. halimus, A. amnicola, and A. lentiformis.

Abstract
Ethylenediaminetetraacetic acid (EDTA) is an effective chelating agent in removing heavy metals from contaminated soils, although extraction efficiency depends on many factors. Moreover, extraction of heavy metals by low molecular weight organic acids (LMWOAs) of citrate, oxalate, and acetate is likely to be more representative of the available fraction to plants. This study examined the potential of these two chelating agents to decontaminate a calcareous soil (with a total heavy metal concentration of 80.6 mmol kg^-1) from the zinc-lead smelting plant area in Zanjan Province, Iran. This was carried via 12 successive washings of soils with 0.01 M concentration chelating agent. For EDTA and citric acid, the orders of extraction efficiency of heavy metals (in decreasing order) were found to be lead (Pb) > zinc (Zn) > cadmium (Cd), and Zn > Pb > Cd, respectively. Oxalic acid removed more Zn than Cd. Acetic acid removed more Cd than Zn. Neither showed any efficiency for Pb removal. Therefore, EDTA and citric acid were efficient extraction agents for Pb and Zn, respectively. However, both of these agents were unable to efficiently remove Cd from the soil, even at high concentrations. This study found that chelating agents showed different efficiencies in removing a variety of heavy metals from contaminated soils and more than one chelating agent may be necessary to optimise cleanup efforts.

Abstract
Interactions between the arbuscular mycorrhizal fungus (AMF) Glomus mosseae and two soil yeasts (Saccharomyces cerevisiae and Candida sake) and their effects on faba bean plants were studied in a pot experiment in sterile, phosphorus (P) deficient soil. These organisms interacted synergistically when added consecutively at 2-week intervals, where sporulation, root infection with G. mosseae and the populations of either soil yeast species were significant with dual inoculation, especially when soil yeast species were inoculated for two weeks prior to sowing. Plant shoot dry weight, uptake of nitrogen (N) and P by the shoots, as well as nodulation and nitrogenase activity of faba bean roots were improved by inoculation with either G. mosseae or the two soil yeast species. Soil yeast species S. cerevisiae was more effective than C. sake. Dual inoculation was more effective on growth, nutrition nodulation and nitrogenase activity than individual inoculation.