Climate Change

Read more/Download

Abstracts & Full Texts: Vol. 13, April 2009

Abstracts & Full Texts: Vol. 13, April 2009

Effect of Dolomitic Limestone and Gypsum Applications on
Soil Solution Properties and Yield of Corn and
Groundnut Grown on Ultisols
A study was conducted to determine soil solution properties and relative tolerance of corn and groundnut plants to soil acidity. Corn followed by groundnut was planted on Ultisols one month after lime or gypsum was incorporated into the topsoil. Soil samples were collected after corn and groundnut harvest. Soil solutions were extracted by the immiscible replacement method of soil water with fluorocarbon trichlorofluoroethane. Results showed that total Al, inorganic Al, Ca, and Mg concentrations were erratically affected by the treatments. However, total Al values were indicated to be high when solution pHs were low, especially at treatments with low amounts of lime or high amounts of gypsum. It appeared that Ca released from the dissolution of gypsum had replaced Al in the exchange  complex,  causing  the  high  concentrations  of  Al  in  the  solution.  Solution pH, corresponding to 90 % relative yields of corn and groundnut, were 4.7 and 4.3, respectively. This means that groundnut is more tolerant to soil acidity than corn. Liming Ultisols at low rates may be necessary for groundnut cultivation. For corn cultivation, the liming rate is 2 t ha-1, which supplies adequate amounts of Ca and Mg for the growth of corn plants.

Chemical Characteristics of Representative High Aluminium
Saturation Soil as Affected by Addition of Soil Amendments
in a Closed Incubation System



Soil acidity is one of the main factors that limits profitable and sustained agricultural production. This study examined the performance of selected amendments in improving soil fertility of acidic tropical soils. The best two acidic tropical soils from Malaysia, Batu Anam and Durian, were selected to represent acid soils from Colombia while the five soil amendments selected were ground magnesium limestone (GML), magnesium carbonate (MgCO3), gafsa phosphate rock (GPR), gypsum, and kieserite. They were incubated in a closed incubation system for two months. The measured parameters were soil pH, exchangeable aluminium (Al), exchangeable cations, and available P. The treatments were organised in a factorial completely randomised design (CRD) with three replications. There was a significant  difference in response among soils, amendments, rates and their interaction effects for the different soil parameters evaluated, with GML giving a high soil pH (0.339) effect and amelioration of the exchangeable Al (-0.838 cmolc/kg) per ton applied. MgCO3 and GPR gave similar effects in neutralising exchangeable Al (~ -0.6 cmolc/kg) per ton ha-1 with a slight increase in soil pH (0.1 unit). Kieserite and Gypsum had a significant effect on amelioration of aluminum (~ -0.16 cmolc/kg) in Batu Anam soil. GML was the most cost-effective amendment in increasing soil pH and neutralising Al at USD$ 118.5 per cmolc/kg of Al.

Earthworm Populations and Cast Properties in the Soils of
Oil Palm Plantations
Oil palm plantations generate a substantial amount of agricultural by-products, such as oil palm empty fruit bunches (EFB) and fronds. These by-products are commonly recycled in the oil palm plantations in order to obtain plant nutrients through decomposition. Information on earthworm species and populations and their cast properties in oil palm plantations in different soil types and oil palm tree ages is still lacking. The population and diversity of earthworms, casts and soils were surveyed in 10 m transects using 5 of 25 cm2 quadrat. In all sampling sites, only an endogeic species, Pontoscolex corethrurus Müller discovered. The earthworm population densities were influenced by the age of the oil palm trees and soil types. Under similar soil types and different oil palm ages, the earthworm population densities were inversely related. Four major factors which dictated the heterogeneity of earthworm population in oil palm plantation were: (i) food and soil physical habitat, (ii) exchangeable calcium, (iii) pH, and (iv) exchangeable potassium as determined by principal component analysis (PCA). The earthworm population was positive significantly related to the CEC and exchangeable Ca in the soil (R2=0.66*, n=100). With the exception of the soil C:N ratio, all other soil chemical properties (pH, C, N, total P, plant available P, total K, total Mg, CEC, exchangeable- K, Ca and Mg) were significantly correlated with the earthworm cast properties. Available P was 509 % higher in casts than in the surface soil (r=0.63*, n=100). The cast CEC and exchangeable Ca were strongly correlated with the soil CEC and exchangeable Ca in soil. However, the increase in CEC and exchangeable Ca were 67 and 98%, respectively. The earthworm population was highly correlated with soil CEC and exchangeable Ca.

 Production of Hydrolytic Enzymes in Rice (Oryza sativa L.) Roots Inoculated with N2-Fixing Bacteria
An experiment was conducted to determine the production of hydrolytic enzymes endoglucanase (EG) and endopolymethylgalacturonase (EPMG) in rice (Oryza sativa L.) roots inoculated with N2-Fixing bacteria. Screening for hydrolytic enzymes by N2-Fixing bacteria, using the plate method showed that nine out of 12 bacterial strains were positive for carboxymethylcellulose (CMC) and pectin reactions. Three of the isolates, Sb34, Sb41 and Sb42 were inoculated to MR219 rice seedling. The bacterial population and the production of hydrolytic enzymes were monitored for 45 days of plant growth. The scanning (SEM) and transmission electron microscopy (TEM) were used to observe bacterial colonization on plant roots. In general, the populations of inoculated diazotrophs were higher in the rhizosphere than the endosphere. There were significant effects of different diazotrophs inoculations on the rice rhizosphere and endosphere populations. Plants inoculated with diazotrophs showed significantly higher specific enzyme activities and soluble proteins compared to the non-inoculated control. SEM and TEM observations revealed the abilities of the diazotrophs to colonize the surfaces and interior of the roots. Inoculation significantly increased root growth of rice with substantial increase in root length, volume and surface area in the inoculated plants.

Agronomic Characteristics and Proline Accumulation of
Iranian Rice Genotypes at Early Seedling Stage under
Sodium Salts Stress
Momayezi, M.R., Zaharah, A.R., Hanafi, M.M. &Mohd Razi, I.
Salt composition can affect rice (Oryza sativa L.) growth at germination and early seedling stages. The response of eleven rice genotypes to sodium salt compositions (NaCl and Na2SO4 with the ratio of 1:1, 2:1 and 1:2 molar concentrations) and concentrations (2.5, 5.0, 7.5 and 10 dS m-1 salt concentrations) was investigated in the laboratory for 10 days. Effects due to salinity, genotype, and their interaction were observed for most of the measured parameters during the germination and early seedling stages. Mean germination time increased and germination index decreased with increasing salt stress. Measured agronomic characteristics were influenced by salinity stress with the extent differing with salt treatments. The 2:1 molar ratio compared to the other salt compositions showed the greatest effect on rice germination. The results also confirmed that Cl-  toxicity effects decreased as SO42- increased in the solution. There was a non-significant relationship between water content and proline accumulation. The anion associated with Na+ may play a functional role in the responses of rice seedlings and the degree of proline synthesis in stressed plants. According to mean germination time and germination index, Tarom-e-Hashemi and Shirodi can be classified into salt sensitive and salt tolerant groups, respectively.

Composting Oil Palm Wastes and Sewage Sludge for Use In
Potting Media of Ornamental Plants
The use of oil palm wastes, particularly the empty fruit bunch (EFB), frond and trunk as compost are now receiving greater attention by researchers. Currently, these organic waste materials have not been fully utilized on a large scale, either agriculturally or industrially, for manufacture of useful by-products. Another organic waste that needs to be appropriately disposed of in Malaysia is the sewage sludge. Co-composting these waste materials could potentially convert these wastes into value added product. The objective of this study was to determine the best formulation using oil palm wastes and sewage sludge in producing a composted material to be used as a potting media in horticulture. Composting different oil palm wastes with sewage sludge was carried out in the glasshouse using a polystyrene box. Shredded oil palm wastes (EFB, frond and trunk) were mixed with sewage sludge in 3 different ratios (1:0, 3:1 and 4:1 ratio) and adjusted to 60% moisture content. Based on the temperature, C/N, NH4+ -N and NO3- - N + NO2- -N patterns of the oil palm wastes added with sludge during composting, the EFB, frond and trunk added with sludge composts seemed to perform similarly.However, due to the small volume of compost, the temperature did not sustain > 45ºC because of dissipation of the heat. Oil palm trunk with sewage sludge at 4:1 ratio was found to be the most optimum compost as potting media for ornamental plants because of its texture suitable for potting media, not stringent or stiff, had high nutrient contents (2.05 % N, 0.640 % P, 1.39 % K, 0.705 % Ca, 0.229% Mg), pH 6.2 and low C/N ratio, 19.

Modelling the Spatial and Temporal Change in Diffusion
Rates of Molasses in Sand Medium
E.G. Goh & I. Athira

Diffusion is one of the important parameters in groundwater study. In a relatively slow moving groundwater, diffusion could be a dominant factor in transporting contaminants between liquid-solid interface and liquid-liquid interchange. The diffusion coefficient of dissolved substance is normally tabulated as a constant value, irrespective of the influence of space and time. In this study, molasses was taken as a dissolved organic carbon (DOC) representation, and it was injected into a basin filled with porous medium (sand) in which it was allowed to diffuse horizontally and vertically in space and time. Diffusion coefficient was determined from first and second Fick’s law, in which the later model was solved with polynomial equation. Diffusion coefficient was observed with respect to changes in space and time. A large fluctuation of diffusion coefficient was more apparent at the initial stage of diffusion. Changes of DOC concentration eventually stabilized after a longer time period. Diffusion coefficient from second Fick’s law was found to be more informative than the first Fick’s law. From graphical observation, four types of concentration-distant relation curve were proposed to classify an observed relation of concentration and distant.

Effects of Nitrogen and Phosphorous Fertilisation on Nitrous
Oxide Emission and Nitrogen Loss in an Irrigated Rice Field
M.T. Iqbal

Nitrous oxide is an important greenhouse gas which contributes to stratospheric ozone destruction, but still little is known about emission of this trace gas from paddy rice fields treated with N and P fertilisation and how it is affected by irrigation. Therefore, a field experiment was conducted to measure nitrous oxide (N2O) emissions and nitrogen loss through the emission from irrigated rice fields treated with different nitrogen and phosphorous fertilisers. Emissions of nitrous oxide (N2O) were measured by the closed chamber method during the vegetative period (6 July to 8 August) of the paddy plant in ShuangQiao farm in the northern part ofZhejiangProvince in the Southeast coastal area of China. Jia-9312 rice variety was used for rice cultivation. Treatments of five nitrogen rates (0, 90, 180, 270, 360 kg N ha-1) and three phosphorous rates (0, 40 and 60 kg P ha-1) were laid out in a randomised block design with 3 replications in 45 plots. Submerging the rice field by continuous flooding irrigation at 7 cm depth up to maturity caused a remarkable reduction in N2O emission. First and second peaks of emission were observed immediately after basal and top dressing of fertiliser addition due to nitrification and denitrification process. The study indicates that 180 kg N ha-1 incorporation with 40 kg P ha-1 may be practised in mitigation of N2O emissions from irrigated paddy rice fields. The amount of total N2O emission from different N and P treatments ranged from 431.89 to 1181.21 g N ha-1 which was a N loss of 0.10 to 1.18% through emission of applied nitrogen.

 Sorption-Desorption Study of a Herbicide 2,4-Dichlorophenoxyacetic Acid on Acidic Tropical Soils  Akma, N.M.H., Samsuri, A.W., Ainie, H.K. & Rosenani, A.B.

The sorption and desorption of 2,4-dichlorophenoxyacetic acid (2,4-D) was evaluated on different soils with different range of organic matter content. The batch equilibrium technique under laboratory condition was used to determine the sorption/desorption behavior of 2,4-D in 4 different soil orders of Malaysia viz Histosols (peat), Inceptisols (Selangor and Briah) and Ultisols (Rengam and Serdang) and Oxisol (Munchong). Sorption data were fitted to the linear and Freundlich equations. The values of Kd and Kf ranged from 1.35 to 35.26 and 2.70 to 42.04, respectively. Highest sorption was observed in peat soil and the lowest was in Rengam soil. According to the sorption and desorption results, organic matter and clay seemed to be the most important factor influencing the sorption capacity of 2,4-D. Thus, the contributions of organic matter were evaluated by comparing changes in 2,4-D of sorption before and after organic matter removal. After organic matter was removed from the soils, the Kd values for sorption by Selangor and Munchong, which were calculated from linear and Freundlich equations, decreased by 26.7 % and 28.0 %, respectively. This revealed that soil organic matter greatly influenced the 2,4-D sorption. Based on their sorption capacity, the soils can be ranked in the following decreasing order: Peat> Selangor> Munchong> Briah> Serdang> Rengam Soil series.

Abstracts & Full Texts: Vol. 12, April 2008

Abstracts & Full Texts: Vol. 12, April 2008

Geochemical Distribution of Elements at Lipad and Tabin Mud Volcanoes, Sabah
A study was conducted to determine the chemical characteristics of mud volcanoes at Lipad and Tabin situated at Tabin Wildlife Reserve.  Both areas comprise of inner zone (with absence of vegetative cover) and outer zone (with vegetative cover).  The concentrations of Fe and Mn at the inner zone for both volcanoes ranged from 17390-24800 mg/g and 497-941 mg/g respectively.  The total concentrations of Mg, Na, Ca and K were highest at the inner zones ranging from 3653-6088 mg/g, 1543-19472 mg/g, 291-2875 mg/g and 722-2428 mg/g, respectively.  The concentrations of these elements at 200 m away from the periphery of the inner zone decreased to 588-1448 mg/g, 41-139 mg/g, 0.9-30 mg/g and 256-632 mg/g, respectively.  The element distribution decrease in the outer zone could be associated with the degree of mud volcanoes activity.  The concentrations of trace elements such as Zn, Cu, Cr, Pb, Co, Ni and Cd were of the same order of magnitude (<100 mg/g) with no apparent trend between inner and outer zones.  This indicates that the degree of mud volcanoes activity does not influence the distribution of trace elements.

 Hydrophobicity of Soils Formed over Different Lithologies

Using a free survey technique and special analytical methods, wettability of soils derived from different parent materials in central Southeastern Nigeria were investigated in 2005. Resulting soil data were subjected to Analysis of Variance (ANOVA) using PROC Mix-model of SAS, and some soil properties were regressed to identify leading predictors of soil hydrophobicity in the study area. Soil hydrophobicity varied among the soil groups and horizons (p<0.05) in response to differences in soil properties. Soil moisture, organic matter, clay, sand, sodium saturation were good predictors of soil hydrophobicity in soils of the study site although at varying levels of prediction and parameter combinations. Accuracy of predictions was very high. Further studies involving detailed sampling, increasing parameter combinations and geostatistical analysis should improve the quality of models used to study soil hydrophobicity in the study area.


Effects of Anthropogenic Disturbance on Soil Microbial Biomass C, N and P in a Tropical Rainforest Ecosystem of Assam, Northeast India

 The effect of anthropogenic disturbance on soil microbial biomass C, N and P dynamics in a tropical rainforest ecosystem of Northeast India was studied in undisturbed, moderately disturbed and highly disturbed stands.  Tree species richness in the community was drastically reduced due to disturbance, from 82 species in the undisturbed stand to 13 species in the highly disturbed stand. Soil organic C, total Kjeldahl nitrogen and P concentration was low in the disturbed stands compared to the undisturbed stand. With the increase in disturbance, the microbial-biomass C, N and P decreased significantly (P>0.001) because of lower inputs of organic matter to the soil. Microbial biomass C, N and P ranged between 226-1060 µg g-1, 27-92 µg g-1 and 15-52 µg g-1, respectively, in the undisturbed and highly disturbed stands. The seasonal pattern of microbial biomass C, N and P was influenced by the variation of soil moisture and temperature, with maximum during winter and minimum during the  rainy season. There were significant positive relationships among microbial biomass C, N and P and SOC, TKN and P concentration.  Destruction of above ground vegetation by selective logging and clear felling caused a significant reduction in microbial biomass in the disturbed stands.


Organic Matter, N and P Dynamics of Fine and Coarse Roots in Humid Subtropical Forest Ecosystem Exposed to Disturbance in Meghalaya, Northeast India

Standing fine (<2mm diameter) and coarse (>2mm diameter) root mass production, N And P accumulation, and turnover rate were studied in two pairs of protected and disturbed stands of a subtropical humid forest to examine the response of below-ground parts to mild disturbance caused by above-ground vegetation by humans.   Disturbance of mild intensity caused significant reduction in biomass accumulation and production of fine and coarse roots. The fine root (540-754 gm-2) and coarse root (307-387 gm-2) mass was higher in the protected stands, declining (fine root: 422-466 gm-2, coarse root: 247-305 gm-2) significantly in the disturbed stands. The total annual root production was also higher in the protected stands (1102 -1242 gm-2) than in the disturbed stands (890-940 gm-2).  Live roots (biomass) showed a higher N and P concentration than the necromass (dead root mass).  Nutrient concentration was higher in the fine roots compared to the coarse roots.  N and P accumulation in the roots was high (N = 99 - 132 kg ha-1, P =5 - 8 kg ha-1) in the protected stands and low (N = 76 - 85 kg ha-1, P= 4 -7 kg ha-1) in the disturbed stand.  The total input of N to the soil by roots ranged from 121-132 kg ha-1 in the protected stands to 96-100 kg/ha in the disturbed stands, whereas  P input was 5 to 7 kg ha-1 in all the stands. The study reveals that roots play a significant role in maintaining the organic matter, Nitrogen and P status of the soil and is influenced by soil conditions and vegetation   characteristics.  Soil and vegetation are affected due to disturbance, which in turn affects mass, production, N and P concentration and their accumulation in the roots. These results are discussed in the present paper and the information should help further understanding of the fragility of subtropical humid forest ecosystems.

 Carbon and Nitrogen Stocks of the Central Clay Plane: Irrigated versus Rain-fed Vertisols
Mitigation of atmospheric CO2 concentration and ensuring national food security could be achieved by increasing carbon sequestration in the soil. We estimated soil organic C and N sequestered in the long- (79 years), medium- (46 years) and short-term (22 years) crop rotation systems of cotton (Gossypium hirsutum), sorghum (Sorghum bicolor), groundnut (Arachis hypogaea), wheat (Triticum aestivum) and fallow in Vertisols, both irrigated and rain-fed, of the semi-arid tropics of Sudan.  Total C pool, comprising soil organic and inorganic C for the entire profile (0 - 0.90 m) of irrigated Vertisols was estimated to be 142, 174 and 99 t ha-1 C for the short-, medium- and long- term cultivation, respectively. Under irrigated soils, organic C made up 31 to 71% of the total C stored in the profile compared to 63 to 73% under rain-fed Vertisols. It was estimated that about 25% was lost from total profile (0 - 0.9 m) C as CO2 after about 79 years of cultivation (0.414 t C ha-1yr-1) of the Gezira cotton scheme. Similarly, loss from organic C was estimated at 29% with a rate of 0.208 t C ha/yr. Total profile (0 - 0.9 m) N under short- and medium-term cultivation (6.74 – 7.79 t  ha-1) was significantly higher than that under long-term cultivation (5.05 t N ha-1). However, cropping system had no significant effect on total N (an average of 8.0 t ha-1) under rain-fed Vertisols. About 65 to 68% of total profile N was found below the plough layer (0 – 0.3 m). Since Vertisols are heavy clay soils, reducing tillage operations, an alternative management practice (for example, using cover crops during fallow periods and retaining crop residues in situ) would help in reducing C loss in one of the largest cotton schemes in Africa.  


Enhancing Rice Establishment in Anaerobic Direct Seeding Through Control of Weedy Rice

A glasshouse and field trial was conducted to investigate the effects of pre-treated rice seeds on cultivated rice and weedy rice establishment in direct seeding planting system. Treatments applied were wet seeding (T1) and water (anaerobic) seeding at 10 cm flooding depth (T2). In the glasshouse trial, water seeding significantly reduced weedy rice seedling emergence almost three-fold compared to control; the usage of pre-treated seeds in both seeding methods significantly increased the viability of cultivated rice compared to weedy rice. The weedy rice population was significantly decreased (32%) in the water seeding plot compared to wet seeding at 90 DAS in season 2/04 in the field. The water seeding technique also profoundly reduced weedy rice population by about 50% at both 60 and 90 days after sowing (DAS) the following season (season 1/05) compared to wet seeding.   The use of pre-treated seeds for the anaerobic direct seeding technique had an advantage on seedling vigour that out- competed the growth of weeds, and increased rice seeds viability.

Amelioration of Cheringa Acid Sulfate Soil and Screening of Acidity-Salinity Tolerant Rice Varieties in a Simulation Study
A simulation study was conducted to evaluate the effects of basic slag (BS10: basic slag 10 t ha-1  and BS20: basic slag 20 t ha-1), aggregate size (A20: aggregate sizes of soil less than 20 mm and A30: aggregate sizes of soil, 20-30 mm) and groundwater depth (Gw0: no influence of groundwater and Gw50: groundwater beneath 50 cm of the soil surface) in pre-leached Cheringa acid sulfate soil (Typic Sulfic Halaquept) in relation to the production and screening of the acidity-salinity tolerance of 18 rice cultivars. The results obtained from the study showed that the physico-chemical properties of the pre-leached acid sulfate soil were strongly (p=0.05) influenced by the application of basic slag, aggregate size and maintenance of groundwater depth. Among the individual treatments, the application of BS20 ranked first with regard to the reclamation of soil and production of rice, followed by Gw50 > A30. The average soil data of all the treatments at post harvesting of rice cultivars were increased by 1.6 units for soil pH(water: 1:2.5) and 34 to 1803%  for the contents of N, P, Ca and Mg, while the saturations of Fe, Al and Na were decreased by 24 to 88% compared with the initial soil.  The maximum quantity (6.9 t/ha) of rice grain was attained by the local (Cox’ Bazar) Kajashail, followed by the Bangladesh rice (BR) line 5828-11-1-4 (6.7 t ha-1) > BR 23 (6.6 t ha-1).  Among the rice varieties, the BR lines were found to be the most effective for rice production in the soil, followed by the local varieties > BR varieties > international rice (IR) varieties. Almost similar and significant (p=0.05) effects were observed for plant height, tiller production, straw yield and yield components of the rice cultivated in the soil.

  Characterization of Malaysian Sewage Sludge and Nitrogen Mineralization  in Three Soils Treated with Sewage Sludge
Studies to determine the chemical composition of sewage sludges produced in Malaysia and potentially mineralisable nitrogen (No) and mineralization rate constant (k) of sewage sludge in three Malaysian soils are reported.  The sludges collected from ten wastewater treatment plants in Malaysia were acidic in nature and the N, P, K, Ca and Mg contents were variable. The heavy metal (Pb, Cd, Cu, Mn and Ni) concentrations of the sludges, except for Zn, were below the European Union Maximum permitted level in sludges. In an incubation study, three topsoils of Bungor, Jawa and Serdang series were treated with three rates (0, 140 and 420 kg N ha-1) of dewatered sewage sludge and incubated about 60% of the water holding capacity for 12 weeks. Mineralization of N exhibited a slow initial rate, followed by a rapid increase in rate in week 4 to 8. Accumulation of mineral N ranged from 50.5 to 147.6 mg kg-1 soil.  Bungor and Jawa series had higher N mineralization than Serdang series. Sludge added at 420 kg N ha-1 resulted in the highest concentration of net mineralised N. Values of potentially mineralisable N, (No), and mineralization rate constant, (k), ranged from 23.4 to 137.5 mg N kg-1 soil and 0.036 to 0.082 week-l, respectively. It was concluded that N mineralization of the sewage sludge treated soils was dependent on the application rate of sludge and soil type.

 Concentrations and Chemical Forms of Heavy Metals in Some Ultisols in Johore, Peninsular Malaysia
The concentrations of heavy metals in soil are associated with biological and geochemical cycles and are influenced by anthropogenic activities such as agricultural practices, industrial activities and waste disposal. A total of 36 surface soil samples (Typic Kandiudult, Rengam Series) were collected from some major vegetable growing areas developed over granite. Twelve soils from areas not cultivated with vegetables but also developed over granite were also sampled for background values. The pseudo-total heavy metals, (Cu, Pb, Zn and Ni) were determined by the aqua-regia method. Chemical properties such as pH, organic carbon and CEC were also analysed. Some selected cultivated soil samples (24 of Ultisols and 12 of background soils) were analysed for chemical partitioning using a modified Tessier’s procedure (F1: exchangeable fraction, F2: fraction bound to organic matter, F3: fraction bound to amorphous iron oxides and F4: residual fraction). Mean values of the total heavy metals for the cultivated soils are Cu (23.3 mg kg-1), Pb (18.0 mg kg-1), Zn (49.4 mg kg-1) and Ni (6.0 mg kg-1). Comparison of these values to the contents in the background soils show that Cu and Zn have significantly increased. However, all these values are below the contaminated levels established for the country’s agricultural soil limits (95th percentile). From the partitioning study, the general trend in the Ultisols for Pb and Ni is residual > oxalate >exchangeable>organic. For Zn and Cu, the oxalate extractable phase is highest followed by the residual phase. Zinc and Pb contents in the soils are also positively correlated with the pH of the soil.

Malaysian Journal of Soil Science (MJSS) MJSS Vol. 11, April 2007 MJSS

Malaysian Journal of Soil Science (MJSS)

MJSS Vol. 11, April 2007
Effects of Lime and Fertiliser Application in Combination with Water Management on Rice (Oryza sativa) Cultivated on an Acid Sulfate Soil


Acid sulfate soils are widespread along the coastal plains of theMalay Peninsula, with some being cultivated with rice. Following farmers’ practices, rice yields are very low due to low pH and prevailing adverse condition such as Al and/or Fe toxicity. A study was conducted in a glasshouse to determine the effect of lime and fertilizer application in combination with water management on rice cultivated on an acid sulfate soil, using MR 219 rice variety as the test crop. The soil used was Typic Sulfosaprists. The results showed that soil pH increased from 4.27 to 4.93 by applying 4 t GML/ha, thereby reducing Al and/or Fe toxicity. In this treatment, exchangeable Ca increased from 1.28 to 3.13 cmolc/kg soil, which is above the rice Ca requirement. The increase in exchangeable Ca also reduced Al toxicity. Fertliser or fertiliser in combination with lime affected rice production significantly. Rice yield was negatively correlated with acid-extractable Fe. Additionally, rice yield increased with increasing pH and Ca. The best yield of 14.15 t/ha was obtained for treatment with 4 t/ha lime together with 120 kg N/ha + 16 kg P/ha +120 kg K/ha. This shows that liming together with prudent fertilizer management improves rice production on an acid sulfate soil.

Effects of Nitrohumic Acids Derived from Low Grade Coal of Sarawak on Aggregate Stability of Loamy Sand and Clay Loam


Humic acids are commonly used to improve the aggregate stability of soils; however, it is not popular in this region. In this paper, low grade coal from Mukah was used as the source of nitrohumic acids and the effects of the nitrohumic acids on the aggregate stability of loamy sand (83.5% sand, 16.4% clay) and clay loam (31% sand, 37% clay) were investigated. Nitrohumic acids were prepared with nitric acid pretreatment and extracted with acid base fractionation. On loamy sand and clay loam, six application rates of nitrohumic acids (0.00, 0.05, 0.10, 0.50, 1.00 and 10.00 g/kg) and 5 wetting and drying cycles were used to assess the changes in the aggregate stability. Results showed that the aggregates stability of loamy sand was improved with nitrohumic acids amendment. For a clay loam sample, the aggregate stability was instead reduced. Nevertheless, there was an upper limit (0.10 g/kg) where the aggregate stability was improved or alleviated. In conclusion, the effect of nitrohumic acids on aggregate stability is dependent on soil type.

Effect of Organic-based and Foliar Fertilisers on Cocoa (Theobroma cacao L.)  Grown on an Oxisol in Malaysia


The Malaysian cocoa industry is facing many problems due to cocoa being grown on marginal soils, such as Ultisols and Oxisols. These soils are generally acidic, low in basic cations and also low in soil cation exchange capacity. A field study was undertaken to investigate the effect of organic- based and foliar fertilisers on soil fertility improvement, the growth of matured trees, yield and quality of cocoa grown on an Oxisol in Malaysia . The treatments (with four replications) consisted of T1: NPK (fertiliser) (control), T2: organic-based fertiliser + NPK. T3: foliar + NPK, T4: foliar + Ca-foliar + NPK and T5: organic-based fertiliser + foliar + Ca-foliar + NPK applied on approximately 5-year-old cocoa plants located at the Malaysian Cocoa Board Experimental Station, Jengka, Pahang. The results showed that the combination of these fertilisers gave negative response on the growth, yield and quality of cocoa. For clone PBC 130, T2 (organic-based fertiliser + NPK) gave greater pod weight compared to other treatments. Manganese toxicity is possibly the most limiting factor observed in this study. 


Arbuscular Mycorrhizal Inoculation and Phosphorus Mobility in Phosphorus-Fixing Sweetpotato Soils


Phosphorus (P) mobility in three P-fixing (laterite, red and sandy) sweetpotato soils in relation to inoculation with arbuscular mycorrhizal (AM) fungi Glomus microcarpum has been studied through a pot culture trial for two seasons. In all the inoculated soils, irrespective of season, the sweetpotato plants had a comparatively high rate of colonisation. However, increased P level in the soil tended to decrease colonisation. Percentage root colonisation increased with days after planting (DAP) while, the spore density in the root-zone soil decreased with DAP. Soil P availability varied between inoculated and uninoculated treatments and different soil types. In general, inoculated treatments showed a low soil P availability but the rate of removal of P from soil to plant tissue was more in mycorrhiza inoculated treatments in both the seasons and at different DAP. The rate of removal of P by mycorrhizal plants was maximum in laterite and sandy soils at all DAP. Mycorrhizal inoculation did not give any added benefit on soil P release and fixation in the soil types studied.

Relationship between Metals in Vegetables with Soils in Farmlands of Kuching, Sarawak

(Full Text-pdf-0.56MB)

The accumulation of Fe, Zn. Cu, Mn. Co md Pb in vegetables was investigated in two farmlands, Siburan and Beratok at Kuching, Sarawak. Leafy and fruit vegetable samples were collected and analysed for metal content using the acid wet digestion method. Topsoil samples (0-30 cm) were characterised for pH, organic matter, particle size, nitrogen content, phosphorus content and heavy metals. Leafy vegetables accumulated higher amount of metals compared to fruit vegetables. Metals were determined at the highest concentrations in leaves of kale at Beratok compared to other plant parts. No clear pattern of metal uptake in different parts was observed for green mustard and white mustard. Essential metals, Fe, Zn and Cu, were generally high in the vegetables. Pb levels in the vegetables analysed (dry weight basis) exceeded slightly the level recommended by the Malaysian food Act 1983. Atmospheric deposition and gas emissions from traffic were the contributing factors for Pb contamination since Pb displayed a tendency to accumulate in leaves compared to other parts of the vegetables. Element concentration in the soils differed between sampling sites. Correlation analysis yielded a significant relationship between Zn concentrations in soils and vegetables (n= 15, r= 0.86, P = 0.001) and moderate correlation for Cu (r=0.55, P<005) and Pb (r= 0.65, P<0.05).

Characterisation and Composting of Tannery Sludge


Tannery industries create serious environmental problems especially in terms of polluting organic effluent and hazardous solid waste as a result of hides and skin processing. It is very important that tannery waste in the form of sludge is managed in an environmentally sound manner. This study focuses on the characterisation of tannery sludge and its development as a composting material. The results show that electrolytic conductivity (EC) of the compost was 2.0 mS cm-1, pH 6.6 and C/N ratio of 16. Total concentrations of chromium, zinc, copper, lead, and cadmium in dry compost were reduced and complied with the standards of the Canadian limits, thus classifying them excellent for making the compost suitable for use as a fertiliser and soil conditioner. The compost characteristics indicated that it was mature, and the germination index for Chinese cabbage was 82.5 %, which may suggest absence of phytotoxic compounds.

Domestic Sewage Sludge Application to an Acid Tropical Soil: Part III. Fractionation Study of Heavy Metals in Sewage Sludge and Soils Applied with Sewage Sludge


Soil fractionation studies of heavy metals can provide insight into their solubility and chemical reactivity in terms of labile and non-labile pools of these metals. The fractionation of cadmium (Cd), copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn) in domestic sewage sludge, soil, soil applied with (NH4) 2SO4 and soil applied with sewage sludge was studied after the first and third maize cycles. The second cycle did not give significant yield results because of the dry period during this cycle. The correlation between different forms of heavy metals in the soil and content in maize grain was also investigated. Fractionation of heavy metals in sewage sludge showed that most soil metals were associated with the less soluble or non-labile soil moieties (carbonate, Fe-Mn oxides, organic and residual fraction). The dominant form of all heavy metals was the residual form (non-phytoavailable form) except for Cu. Leaving the residual fraction aside, Cd and Pb were dominant in exchangeable (labile pool) form, Ni in carbonate form and Zn in Fe-Mn oxide form. For the untreated and treated soils, the residual fraction was also the dominant fraction except for Cd and Pb. The organic form is the dominant form for Cu in sludge treated soil. In general, the percentage of water soluble content was less than 5%. Also, in general, there was no significant difference between the different metal fractions of the inorganic fertiliser treatment compared to the control, except for exchangeable Pb and Zn associated with Fe-Mn oxide fraction. The addition of sewage sludge tended to shift the solid phase forms of the metals away from the residual to the Fe-Mn oxide form. Significant correlations were only obtained between Cd content in maize grain and the organic forms in soil (n=30, r =0.378, and p <0.05), Ni content in grain with total metal in the soil (n=30, r= 0.406, p<0.O5) and between Cu content in maize grain and the carbonate. Fe-Mn oxide and organic forms in soils (n=30, r= 0.475, p<001; n=30. r=0.539, p<0.01; and, n=30, r=0.545, p<0.01, respectively).