Radziah Othman | UPM - Universiti Putra Malaysia (original) (raw)
Papers by Radziah Othman
Compost Science & Utilization, 2013
ABSTRACT The present study was conducted at the Composting Unit, Universiti Putra Malaysia to det... more ABSTRACT The present study was conducted at the Composting Unit, Universiti Putra Malaysia to determine the physico-chemical changes, microbial dynamics, and enzyme activities during microbial composting of rice straw at different pH conditions. Different treatments comprising of composting substrates (A), substrates with microbial consortium (B), substrates, microbial consortium, and acetic acid (C), substrates, microbial consortium, and sodium hydroxide (D) were used to enhance the composting process of rice straw. In inoculated treatments, the temperature increased rapidly to higher than 50°C by day 5 and remained above 40°C up to day 17, while in the control the temperature increased slowly and peaked (46°C) at day 9 and remained above 40°C until day 23. The results showed that biodegradation was at its maximum in microbial-infused treatments within 14–21 days as indicated by profiles of pH, reduction of C/N ratio, lignocellulolytic (lignin peroxidase, endoglucanase, and exoglucanase) enzyme activities, and lignocellulose bioconversion. After day 21, the C/N ratio of microbial-infused treatment without any pH adjustment (B) was reduced to 17.5 from an initial value of 29.2 suggesting that there were no additive effects of pH adjustment during the microbial composting of rice straw.
Water supply is the most important factor which influences growth and yield of rice. An experimen... more Water supply is the most important factor which influences growth and yield of rice. An experiment was conducted at rain shelterhouse, Universiti Putra Malaysia to evaluate the effect of water stress at different growth stages on Malaysian commercial rice variety MR220. Treatments used in this study were: 1. flooding, 2. field capacity, 3. field capacity at panicle initiation stage, 4. field capacity at active tillering stage and 5. field capacity at first flowering stage. Number of tillers, panicles, spikelets, filled grains, length of panicles and yield were significantly reduced under filled capacity condition. Field capacity at active tillering stage also reduced number of tillers and panicles per plant, spikelets per plant, filled grains percentage, panicle length, and yield thus indicating that MR220 is sensitive to water stress especially at active tillering stage.
ABSTRACT Soybean (Glycine max) is one of the most important legume crops which fix atmospheric ni... more ABSTRACT Soybean (Glycine max) is one of the most important legume crops which fix atmospheric nitrogen in symbiotic association with bacteria through nodules. A study was conducted to investigate the effect of molybdenum and pre-inoculation of Rhizobium on biological nitrogen fixation and yield of soybean under drip irrigation system. A total of six treatments were used in this experiment which included control, 1 kg of Mo/ha, 1.5 kg of Mo/ha, 10 kg of Mo/ha, Rhizobium isolate UPMR020, UPMR020 + 1 kg of Mo/ha, UPMR020 + 1.5 kg of Mo/ha, UPMR020 + 10 kg of Mo/ha. Application of 1kg of Mo/ha along with bacterial inoculum produced the highest (51) nodules per plant. This treatment also produced the highest nodule's weight (199 mg/plant) and plant dry weight (72 g/ plant). Application of 1 kg of Mo/ha in association of UPMR020, produced significantly high yield (29.46 g/plant) compared to control which produced only 9.15 g/plant, thus indicating the potential of this treatment to be used for soybean with drip irrigation system.
Compost Science & Utilization, 2014
Microbial fortified organic amendment in chili cultivation may affect plant development and disea... more Microbial fortified organic amendment in chili cultivation may affect plant development and disease suppression. Microbial infused rice straw compost, commercial rice straw compost, and fungicide Benomyl for chili (Capsicum annum L.) cultivation and control of Sclerotium foot rot were studied under glass house condition. Chili seed cv. Kulai were sown in the Sclerotium rolfsii infested and non-infested soil. After two weeks, five healthy seedlings were transplanted into planting bags. Growth performance and development of disease symptoms associated with S. rolfsii foot rot infection were assessed. Applying microbial infused rice straw compost increased seed germination and plant growth, and suppressed development of foot rot compared to using commercial rice straw compost and the Benomyl. A higher disease reduction (84.6%) occurred with 15 Mg·ha −1 microbial infused rice straw compost (62.7%), followed by Benomyl (53.8%), and 15 Mg·ha −1 commercial rice straw compost (46.2%). Application of microbial infused rice straw compost at 15 Mg·ha −1 yielded optimum seed germination and seedling establishment, plant growth, and disease suppression. Microbial infused rice straw compost is a good alternative to chemical fungicide in controlling Sclerotial disease in chili. * * * * * Shown is the significant interaction only. † NS: nonsignificant; * * : significant at P ≤ 0.01, ANOVA. * T 1 = Control; T 2 = 7.5 Mg·ha −1 microbial infused rice straw compost; T 3 = 15.0 Mg·ha −1 microbial infused rice straw compost; T 4 = 7.5 Mg·ha −1 Best Flora compost; T 5 = 15.0 Mg·ha −1 Best Flora compost; and T 6 = Benomyl @ 0.55 kg·ha −1 . † Means within columns followed by the same letter are not significantly different, 5% level of probability, least significant difference (LSD) test.
American Journal of Agricultural and Biological Science
Biofertilizer is a relatively safer, environmentally friendly and cost-effective approach as an a... more Biofertilizer is a relatively safer, environmentally friendly and cost-effective approach as an alternative to reduce chemical fertilizer usage. The selection of bacterial strains with multiple beneficial characteristics are important to maximize the effectiveness on the host plant. Due to aforementioned interest, several Plant Growth-Promoting Rhizobacterial (PGPR) and rhizobial strains were isolated from rice and legume roots, respectively, at four locations in Malaysia namely Universiti Putra Malaysia (UPM), Serdang, Selangor; Besut, Terengganu; Tunjung, Kelantan and Sik, Kedah. Bacterial isolations were undertaken to select the best isolates which exhibit multiple beneficial effects to the rice plant and a total of 205 bacterial strains were isolated and categorized as follows; 94 rhizospheric and 107 endophytic bacteria from rice roots, one rhizobial strain from soybean and three from Mimosa pudica. These isolates were screened for their abilities to fix N 2 and solubilize phosphate; 52 were positive for both tests. The selected isolates were then tested for IAA production and other biochemical tests such as potassium solubilization, hydrolyzing enzymes (cellulase and pectinase) and iron siderophore productions. Four isolates, namely UPMB19 (rhizospheric PGPR from Tunjung, Kelantan), UPMB20 (endophytic PGPR from Besut, Terengganu), UPMR30 (rhizobia from soybean) and UPMR31 (rhizobia from Mimosa) were selected for subsequent plant inoculation tests with UPMB10, a PGPR isolated from oil palm root, as the reference strain. Based on 16S rDNA gene sequencing, these bacterial strains were identified under several genera: Lysinibacillus, Alcaligenes, Bradyrhizobium, Rhizobium and Bacillus, respectively. Results of plant inoculation test indicated that UPMB19 significantly enhanced the seedling height at the early growth stage (7 days after transplanting, DAT) which could be attributed to the higher N 2 fixation rate of this strain as compared to the other strains, except UPMB20. UPMB10 and UPMR31 also showed significant effects with increased seedling height and Total Dry Weight (TDW) at the later stage (14 DAT) possibly due to the higher bacterial population and IAA produced as observed in the residual nutrient solution without addition of fertilizer-N. This study has successfully demonstrated the effectiveness of locally isolated PGPR and rhizobial strains with multiple beneficial characteristics on early growth and vigor of rice seedlings under controlled condition. The result proved to be a vital information in the development of a liquid biofertilizer for rice; thus further studies will be done to evaluate the effectiveness of these isolates under glasshouse and field conditions on growth, tillering and yield of rice.
Compost Science & Utilization, 2014
The physical and chemical parameters were monitored for seven weeks during Trichoderma/Aspergillu... more The physical and chemical parameters were monitored for seven weeks during Trichoderma/Aspergillus inoculated rice straw composting at various pH levels. Three treatments (A, B, and C) were inoculated with lignocellulolytic microbial consortium (Aspergillus niger, F44 and Trichoderma viride, F26) and three were un-inoculated (D, E, and F). pH of the starting materials was amended to 5.75 (A and D), 6.75 (B and E), and 7.75 (C and F) with either acetic acid or sodium hydroxide. Three typical phases of temperature were observed both in inoculated and un-inoculated treatments during composting: mesophilic phase, thermophilic phase, and followed by cooling and maturation phase. The bioconversion were maximum in Trichoderma/Aspergillus inoculated treatments within 14-21 days as indicated by the profiles of electrical conductivity, bulk density, total carbon and nitrogen, and germination index. After day 21, the germination index of Trichoderma/Aspergillus inoculated treatment (B) without any pH amendment was increased to 74.5 indicating the maturity of compost and suitability for field application.
This research report is about the potential of coconut coir dust (CD) amended with oil palm frond... more This research report is about the potential of coconut coir dust (CD) amended with oil palm frond (OPF) compost soilless growing media for cauliflower cultivation. Five different soilless growing media comprising of CD alone and as mixtures of CD and peat [CDP]; CD and OPF compost A (CDC a ); CD and OPF compost B (CDC b ); CD and OPF compost C (CDC c ) were evaluated in a tropical humid planthouse. The treatment CDC a provided optimum plant growth conditions of cauliflower throughout the growing period due to superiority in physiological traits (stomatal conductance, photosynthesis rate and chlorophyll content in leaves) and higher rate of nutrients uptake resulting maximum total dry mass production thereby economic yield i.e., production of biggest curd (302 g/plant). Moreover, Plants grown on CDC a media mature six days earlier than the control plants. Therefore, plants grown in soilless growing medium, CDC a might suitable growing medium for commercial cultivation of cauliflower in tropical conditions.
International Journal of Botany, 2008
Soil and Sediment …, Jan 1, 2011
Bioremediation Journal, 2012
The bioleaching experiment was conducted for the removal of heavy metals from mine tailings. A fu... more The bioleaching experiment was conducted for the removal of heavy metals from mine tailings. A fungal strain was isolated from the gold mine tailings and it has been identified as Aspergillus fumigatus based on its 18S rDNA analysis. Bioleaching using A. fumigatus was carried out in bioleaching step processes (one-step and two-step) at various tailings concentrations (1%, 2%, 4%, and 8% [w/v]). In the one-step bioleaching process where fungi were cultivated in the presence of the tailings, concentration of oxalic acid was the highest among the organic acids produced. On the other hand, in the two-step bioleaching process where the metabolic products of fungal growth, which have been separated from its biomass, were used, citric acid was dominant. In the one-step process, the highest As (62%), Fe (58%), Mn (100%), and Zn (54%) removals were observed at the lowest tailings concentration (1%). The removal of Pb at 1% tailings concentration in the one-step process was 56%, whereas 88% removal was achieved in the two-step process where citric acid was dominant. In general, heavy metals removal efficiency decreased with increased tailings of the concentration in both bioleaching processes. This study shows the possibility of using A. fumigatus to bioleach hazardous heavy meals from gold mine tailings.
The degradation and leaching of napropamide were compared between Beach Ridges Interspersed with ... more The degradation and leaching of napropamide were compared between Beach Ridges Interspersed with Swales (BRIS) soil samples, and the same soil samples amended with 20 mg ha À1 of either chicken dung (CD) or palm oil mill effluent (POME). The effects of removing dissolved organic carbon (DOC) from the soil samples on napropamide degradation and leaching were also studied. The addition of CD and POME to BRIS soil increased the napropamide half-life values to 69 and 49.5 days, respectively. Sterilization of the soil samples resulted in partial inhibition of napropamide degradation in all soil samples. The half-lives of napropamide in BRIS soils receiving 0, 20, 100, and 200 mg kg À1 of DOC derived from CD were 43, 46.2, 53.4, and 63 days, respectively. The napropamide half-lives in soil samples treated with 0, 20, 100, and 200 mg kg À1 of DOC derived from POME were 43, 49.2, 57.7, and 69 days, respectively. However, in the sterilized soil samples, there were no significant effects of adding DOC derived from either CD or POME on napropamide half-lives. Incorporating either CD or POME decreased napropamide leaching and total amounts of napropamide remained in the soil columns after two pore volumes of water has been leached were higher in the amended than the non-amended soil. The CD was more effective in decreasing napropamide leaching than the POME. There were no effects of DOC on napropamide leaching in all soil treatments.
A study was conducted at Universiti Putra Malaysia to determine the effect of phosphate-solubiliz... more A study was conducted at Universiti Putra Malaysia to determine the effect of phosphate-solubilizing bacteria (PSB) and organic acids (oxalic & malic) on phosphate (P) solubilization from phosphate rock (PR) and growth of aerobic rice. Four rates of each organic acid (0, 10, 20, and 30 mM), and PSB strain (Bacillus sp.) were applied to aerobic rice. Total bacterial populations, amount of P solubilization, P uptake, soil pH, and root morphology were determined. The results of the study showed significantly high P solubilization in PSB with organic acid treatments. Among the two organic acids, oxalic acid was found more effective compared to malic acid. Application of oxalic acid at 20 mM along with PSB16 significantly increased soluble soil P (28.39 mg kg −1 ), plant P uptake (0.78 P pot −1 ), and plant biomass (33.26 mg). Addition of organic acids with PSB and PR had no influence on soil pH during the planting period. A higher bacterial population was found in rhizosphere (8.78 log 10 cfu g −1 ) compared to the nonrhizosphere and endosphere regions. The application of organic acids along with PSB enhanced soluble P in the soil solution, improved root growth, and increased plant biomass of aerobic rice seedlings without affecting soil pH.
Bioremediation Journal, 2012
Soil & Sediment Contamination, 2011
Beach Ridges Interspersed with Swales (BRIS) is a sandy soil and in Malaysia it is found exclusiv... more Beach Ridges Interspersed with Swales (BRIS) is a sandy soil and in Malaysia it is found exclusively in the east coast of Peninsular Malaysia. It is a marginal soil because of its low nutrient and water-holding capacity. However, with proper management and organic ...
Compost Science & Utilization, 2013
ABSTRACT The present study was conducted at the Composting Unit, Universiti Putra Malaysia to det... more ABSTRACT The present study was conducted at the Composting Unit, Universiti Putra Malaysia to determine the physico-chemical changes, microbial dynamics, and enzyme activities during microbial composting of rice straw at different pH conditions. Different treatments comprising of composting substrates (A), substrates with microbial consortium (B), substrates, microbial consortium, and acetic acid (C), substrates, microbial consortium, and sodium hydroxide (D) were used to enhance the composting process of rice straw. In inoculated treatments, the temperature increased rapidly to higher than 50°C by day 5 and remained above 40°C up to day 17, while in the control the temperature increased slowly and peaked (46°C) at day 9 and remained above 40°C until day 23. The results showed that biodegradation was at its maximum in microbial-infused treatments within 14–21 days as indicated by profiles of pH, reduction of C/N ratio, lignocellulolytic (lignin peroxidase, endoglucanase, and exoglucanase) enzyme activities, and lignocellulose bioconversion. After day 21, the C/N ratio of microbial-infused treatment without any pH adjustment (B) was reduced to 17.5 from an initial value of 29.2 suggesting that there were no additive effects of pH adjustment during the microbial composting of rice straw.
Water supply is the most important factor which influences growth and yield of rice. An experimen... more Water supply is the most important factor which influences growth and yield of rice. An experiment was conducted at rain shelterhouse, Universiti Putra Malaysia to evaluate the effect of water stress at different growth stages on Malaysian commercial rice variety MR220. Treatments used in this study were: 1. flooding, 2. field capacity, 3. field capacity at panicle initiation stage, 4. field capacity at active tillering stage and 5. field capacity at first flowering stage. Number of tillers, panicles, spikelets, filled grains, length of panicles and yield were significantly reduced under filled capacity condition. Field capacity at active tillering stage also reduced number of tillers and panicles per plant, spikelets per plant, filled grains percentage, panicle length, and yield thus indicating that MR220 is sensitive to water stress especially at active tillering stage.
ABSTRACT Soybean (Glycine max) is one of the most important legume crops which fix atmospheric ni... more ABSTRACT Soybean (Glycine max) is one of the most important legume crops which fix atmospheric nitrogen in symbiotic association with bacteria through nodules. A study was conducted to investigate the effect of molybdenum and pre-inoculation of Rhizobium on biological nitrogen fixation and yield of soybean under drip irrigation system. A total of six treatments were used in this experiment which included control, 1 kg of Mo/ha, 1.5 kg of Mo/ha, 10 kg of Mo/ha, Rhizobium isolate UPMR020, UPMR020 + 1 kg of Mo/ha, UPMR020 + 1.5 kg of Mo/ha, UPMR020 + 10 kg of Mo/ha. Application of 1kg of Mo/ha along with bacterial inoculum produced the highest (51) nodules per plant. This treatment also produced the highest nodule's weight (199 mg/plant) and plant dry weight (72 g/ plant). Application of 1 kg of Mo/ha in association of UPMR020, produced significantly high yield (29.46 g/plant) compared to control which produced only 9.15 g/plant, thus indicating the potential of this treatment to be used for soybean with drip irrigation system.
Compost Science & Utilization, 2014
Microbial fortified organic amendment in chili cultivation may affect plant development and disea... more Microbial fortified organic amendment in chili cultivation may affect plant development and disease suppression. Microbial infused rice straw compost, commercial rice straw compost, and fungicide Benomyl for chili (Capsicum annum L.) cultivation and control of Sclerotium foot rot were studied under glass house condition. Chili seed cv. Kulai were sown in the Sclerotium rolfsii infested and non-infested soil. After two weeks, five healthy seedlings were transplanted into planting bags. Growth performance and development of disease symptoms associated with S. rolfsii foot rot infection were assessed. Applying microbial infused rice straw compost increased seed germination and plant growth, and suppressed development of foot rot compared to using commercial rice straw compost and the Benomyl. A higher disease reduction (84.6%) occurred with 15 Mg·ha −1 microbial infused rice straw compost (62.7%), followed by Benomyl (53.8%), and 15 Mg·ha −1 commercial rice straw compost (46.2%). Application of microbial infused rice straw compost at 15 Mg·ha −1 yielded optimum seed germination and seedling establishment, plant growth, and disease suppression. Microbial infused rice straw compost is a good alternative to chemical fungicide in controlling Sclerotial disease in chili. * * * * * Shown is the significant interaction only. † NS: nonsignificant; * * : significant at P ≤ 0.01, ANOVA. * T 1 = Control; T 2 = 7.5 Mg·ha −1 microbial infused rice straw compost; T 3 = 15.0 Mg·ha −1 microbial infused rice straw compost; T 4 = 7.5 Mg·ha −1 Best Flora compost; T 5 = 15.0 Mg·ha −1 Best Flora compost; and T 6 = Benomyl @ 0.55 kg·ha −1 . † Means within columns followed by the same letter are not significantly different, 5% level of probability, least significant difference (LSD) test.
American Journal of Agricultural and Biological Science
Biofertilizer is a relatively safer, environmentally friendly and cost-effective approach as an a... more Biofertilizer is a relatively safer, environmentally friendly and cost-effective approach as an alternative to reduce chemical fertilizer usage. The selection of bacterial strains with multiple beneficial characteristics are important to maximize the effectiveness on the host plant. Due to aforementioned interest, several Plant Growth-Promoting Rhizobacterial (PGPR) and rhizobial strains were isolated from rice and legume roots, respectively, at four locations in Malaysia namely Universiti Putra Malaysia (UPM), Serdang, Selangor; Besut, Terengganu; Tunjung, Kelantan and Sik, Kedah. Bacterial isolations were undertaken to select the best isolates which exhibit multiple beneficial effects to the rice plant and a total of 205 bacterial strains were isolated and categorized as follows; 94 rhizospheric and 107 endophytic bacteria from rice roots, one rhizobial strain from soybean and three from Mimosa pudica. These isolates were screened for their abilities to fix N 2 and solubilize phosphate; 52 were positive for both tests. The selected isolates were then tested for IAA production and other biochemical tests such as potassium solubilization, hydrolyzing enzymes (cellulase and pectinase) and iron siderophore productions. Four isolates, namely UPMB19 (rhizospheric PGPR from Tunjung, Kelantan), UPMB20 (endophytic PGPR from Besut, Terengganu), UPMR30 (rhizobia from soybean) and UPMR31 (rhizobia from Mimosa) were selected for subsequent plant inoculation tests with UPMB10, a PGPR isolated from oil palm root, as the reference strain. Based on 16S rDNA gene sequencing, these bacterial strains were identified under several genera: Lysinibacillus, Alcaligenes, Bradyrhizobium, Rhizobium and Bacillus, respectively. Results of plant inoculation test indicated that UPMB19 significantly enhanced the seedling height at the early growth stage (7 days after transplanting, DAT) which could be attributed to the higher N 2 fixation rate of this strain as compared to the other strains, except UPMB20. UPMB10 and UPMR31 also showed significant effects with increased seedling height and Total Dry Weight (TDW) at the later stage (14 DAT) possibly due to the higher bacterial population and IAA produced as observed in the residual nutrient solution without addition of fertilizer-N. This study has successfully demonstrated the effectiveness of locally isolated PGPR and rhizobial strains with multiple beneficial characteristics on early growth and vigor of rice seedlings under controlled condition. The result proved to be a vital information in the development of a liquid biofertilizer for rice; thus further studies will be done to evaluate the effectiveness of these isolates under glasshouse and field conditions on growth, tillering and yield of rice.
Compost Science & Utilization, 2014
The physical and chemical parameters were monitored for seven weeks during Trichoderma/Aspergillu... more The physical and chemical parameters were monitored for seven weeks during Trichoderma/Aspergillus inoculated rice straw composting at various pH levels. Three treatments (A, B, and C) were inoculated with lignocellulolytic microbial consortium (Aspergillus niger, F44 and Trichoderma viride, F26) and three were un-inoculated (D, E, and F). pH of the starting materials was amended to 5.75 (A and D), 6.75 (B and E), and 7.75 (C and F) with either acetic acid or sodium hydroxide. Three typical phases of temperature were observed both in inoculated and un-inoculated treatments during composting: mesophilic phase, thermophilic phase, and followed by cooling and maturation phase. The bioconversion were maximum in Trichoderma/Aspergillus inoculated treatments within 14-21 days as indicated by the profiles of electrical conductivity, bulk density, total carbon and nitrogen, and germination index. After day 21, the germination index of Trichoderma/Aspergillus inoculated treatment (B) without any pH amendment was increased to 74.5 indicating the maturity of compost and suitability for field application.
This research report is about the potential of coconut coir dust (CD) amended with oil palm frond... more This research report is about the potential of coconut coir dust (CD) amended with oil palm frond (OPF) compost soilless growing media for cauliflower cultivation. Five different soilless growing media comprising of CD alone and as mixtures of CD and peat [CDP]; CD and OPF compost A (CDC a ); CD and OPF compost B (CDC b ); CD and OPF compost C (CDC c ) were evaluated in a tropical humid planthouse. The treatment CDC a provided optimum plant growth conditions of cauliflower throughout the growing period due to superiority in physiological traits (stomatal conductance, photosynthesis rate and chlorophyll content in leaves) and higher rate of nutrients uptake resulting maximum total dry mass production thereby economic yield i.e., production of biggest curd (302 g/plant). Moreover, Plants grown on CDC a media mature six days earlier than the control plants. Therefore, plants grown in soilless growing medium, CDC a might suitable growing medium for commercial cultivation of cauliflower in tropical conditions.
International Journal of Botany, 2008
Soil and Sediment …, Jan 1, 2011
Bioremediation Journal, 2012
The bioleaching experiment was conducted for the removal of heavy metals from mine tailings. A fu... more The bioleaching experiment was conducted for the removal of heavy metals from mine tailings. A fungal strain was isolated from the gold mine tailings and it has been identified as Aspergillus fumigatus based on its 18S rDNA analysis. Bioleaching using A. fumigatus was carried out in bioleaching step processes (one-step and two-step) at various tailings concentrations (1%, 2%, 4%, and 8% [w/v]). In the one-step bioleaching process where fungi were cultivated in the presence of the tailings, concentration of oxalic acid was the highest among the organic acids produced. On the other hand, in the two-step bioleaching process where the metabolic products of fungal growth, which have been separated from its biomass, were used, citric acid was dominant. In the one-step process, the highest As (62%), Fe (58%), Mn (100%), and Zn (54%) removals were observed at the lowest tailings concentration (1%). The removal of Pb at 1% tailings concentration in the one-step process was 56%, whereas 88% removal was achieved in the two-step process where citric acid was dominant. In general, heavy metals removal efficiency decreased with increased tailings of the concentration in both bioleaching processes. This study shows the possibility of using A. fumigatus to bioleach hazardous heavy meals from gold mine tailings.
The degradation and leaching of napropamide were compared between Beach Ridges Interspersed with ... more The degradation and leaching of napropamide were compared between Beach Ridges Interspersed with Swales (BRIS) soil samples, and the same soil samples amended with 20 mg ha À1 of either chicken dung (CD) or palm oil mill effluent (POME). The effects of removing dissolved organic carbon (DOC) from the soil samples on napropamide degradation and leaching were also studied. The addition of CD and POME to BRIS soil increased the napropamide half-life values to 69 and 49.5 days, respectively. Sterilization of the soil samples resulted in partial inhibition of napropamide degradation in all soil samples. The half-lives of napropamide in BRIS soils receiving 0, 20, 100, and 200 mg kg À1 of DOC derived from CD were 43, 46.2, 53.4, and 63 days, respectively. The napropamide half-lives in soil samples treated with 0, 20, 100, and 200 mg kg À1 of DOC derived from POME were 43, 49.2, 57.7, and 69 days, respectively. However, in the sterilized soil samples, there were no significant effects of adding DOC derived from either CD or POME on napropamide half-lives. Incorporating either CD or POME decreased napropamide leaching and total amounts of napropamide remained in the soil columns after two pore volumes of water has been leached were higher in the amended than the non-amended soil. The CD was more effective in decreasing napropamide leaching than the POME. There were no effects of DOC on napropamide leaching in all soil treatments.
A study was conducted at Universiti Putra Malaysia to determine the effect of phosphate-solubiliz... more A study was conducted at Universiti Putra Malaysia to determine the effect of phosphate-solubilizing bacteria (PSB) and organic acids (oxalic & malic) on phosphate (P) solubilization from phosphate rock (PR) and growth of aerobic rice. Four rates of each organic acid (0, 10, 20, and 30 mM), and PSB strain (Bacillus sp.) were applied to aerobic rice. Total bacterial populations, amount of P solubilization, P uptake, soil pH, and root morphology were determined. The results of the study showed significantly high P solubilization in PSB with organic acid treatments. Among the two organic acids, oxalic acid was found more effective compared to malic acid. Application of oxalic acid at 20 mM along with PSB16 significantly increased soluble soil P (28.39 mg kg −1 ), plant P uptake (0.78 P pot −1 ), and plant biomass (33.26 mg). Addition of organic acids with PSB and PR had no influence on soil pH during the planting period. A higher bacterial population was found in rhizosphere (8.78 log 10 cfu g −1 ) compared to the nonrhizosphere and endosphere regions. The application of organic acids along with PSB enhanced soluble P in the soil solution, improved root growth, and increased plant biomass of aerobic rice seedlings without affecting soil pH.
Bioremediation Journal, 2012
Soil & Sediment Contamination, 2011
Beach Ridges Interspersed with Swales (BRIS) is a sandy soil and in Malaysia it is found exclusiv... more Beach Ridges Interspersed with Swales (BRIS) is a sandy soil and in Malaysia it is found exclusively in the east coast of Peninsular Malaysia. It is a marginal soil because of its low nutrient and water-holding capacity. However, with proper management and organic ...