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.
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