Search Result of "Oku, N"

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ผลงานตีพิมพ์ในวารสารวิชาการ

Maklamicin, an Antibacterial Polyketide from an Endophytic Micromonospora sp.

ผู้แต่ง:ImgIgarashi, Y, ImgOgura, H, ImgFurihata, K, ImgOku, N, ImgIndananda, C, ImgDr.Arinthip Thamchaipenet, Associate Professor,

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Researcher

ดร. งามผ่อง คงคาทิพย์, ศาสตราจารย์

ที่ทำงาน:ภาควิชาเคมี คณะวิทยาศาสตร์ บางเขน

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Researcher

ดร. อรินทิพย์ ธรรมชัยพิเนต, รองศาสตราจารย์

ที่ทำงาน:ภาควิชาพันธุศาสตร์ คณะวิทยาศาสตร์ บางเขน

สาขาที่สนใจ:Biology and Molecular Genetics of Streptomyces and related genera, Genetics and Biosynthetic Pathway of Polyketide Antibiotics, Combinatorial Biosynthesis, Endophytic actinomycetes: plant growth regulating agents and bioactive compounds

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ที่มา:วิทยาสารเกษตรศาสตร์ สาขา วิทยาศาสตร์

หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Predictability of Philip and Kostiakov Infiltration Models under Inceptisols in the Humid Forest Zone, Nigeria)

ผู้เขียน:ImgEffiom Oku, ImgAmbrose Aiyelari

สื่อสิ่งพิมพ์:pdf

Abstract

Knowledge of the infiltration of water into a soil is very important for efficient soil and water management and conservation, especially when the water supply is through rainfall. For efficient irrigation water management, once field infiltration values are constant and the curve established for a particular soil, it is possible to determine during irrigation how long it will take to infiltrate a certain amount of water. Ring infiltrometer measurements were carried out at 10 m intervals down a 5% Inceptisol toposequence of 100 m length in a humid forest in southern Nigeria. The aim was to determine the infiltration capacity of the soil with slope positions and to fit the infiltration data into the Philip and Kostiakov infiltration models in order to quantify the hydrological behavior of the soil and the ability of these models to predict infiltration into the Inceptisols of a humid forest. The nonlinear least square procedure was employed to determine the parameters of the models—namely, the transmissivity and sorptivity of Philip’s model and the initial infiltration and the index of soil sorptivity reflecting the rate of declining infiltration capacity of Kostiakov’s model. The results indicated that the initial infiltration and cumulative infiltration ranged from 2.0 to 7.50 cm min-1 and from 84.90 to 555.20 cm after 6 h of elapsed time, respectively. The coefficient of determination was near unity indicating the models were a good fit for data and could be used to predict infiltration for the studied soil. Transmissivity values ranged from 0.14 to 1.29, putting the soil conductivity class between ‘very slow’ and ‘slow’. Sorptivity was very high with values in the range 1.20 to 8.08. The index of sorptivity of soil ranged from 0.65 to 0.88 indicating fairly high soil sorptivity and the initial infiltration of Kostiakov’s model ranged from 0.03 to 1.09. Goodness of fit was used to compare the measured and predicted infiltration values and showed that 10% and 50% disparities existed for initial infiltration and 30% and 70% disparities for cumulative infiltration under Philip’s and Kostiakov’s models, respectively. It can be deduced that Philip’ s model was more suitable than Kostiakov’s model for predicting water infiltration in Inceptisols of the humid forest zone of Nigeria.

Article Info
Agriculture and Natural Resources -- formerly Kasetsart Journal (Natural Science), Volume 045, Issue 4, Jul 11 - Aug 11, Page 594 - 602 |  PDF |  Page 

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ที่มา:วิทยาสารเกษตรศาสตร์ สาขา วิทยาศาสตร์

หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Variability in Soil Properties Along an Udalf Toposequence in the Humid Forest Zone of Nigeria)

ผู้เขียน:ImgEffiom Oku, ImgAyuk Essoka, ImgEunice Thomas

สื่อสิ่งพิมพ์:pdf

Abstract

Uniform soil management without any knowledge of the variability of soil properties could result in some parts of an agricultural field receiving insufficient inputs, while other parts receive an excess. Profile soil samples were collected and analyzed for some physico-chemical properties along an Udalf toposequence and their variability assessed. Soil pH was consistently least variable along the toposequence and at all depths. Highly variable properties on the upper slope (crest) included Ca, Mg, Na, K, and P; on the middle slope (hill slope) they were K, organic C, N, silt and clay; and on the foot slope (valley floor) they were Mg, organic C, available P, EA, silt and clay. Moderately variable properties were: C. electrical conductivity (EC), effective cation exchange capacity (ECEC), bulk density, clay, gravimetric moisture, volume wetness and degree of saturation on the upper slope; Mg, Na, EC, and ECEC, base saturation, sand, bulk density, gravimetric moisture and volume wetness on the middle slope; and on the foot slope Ca, N, EC, ECEC, base saturation, bulk density, gravimetric moisture, volume wetness and degree of saturation were moderately variable. The use of bulk samples randomly collected to determine soil properties should be minimized. Large soil sample sizes are needed for soil property studies along the toposequence, as most properties varied from highly to moderately variable. Uniform soil management along the toposequence should be avoided.

Article Info
Agriculture and Natural Resources -- formerly Kasetsart Journal (Natural Science), Volume 044, Issue 4, Jul 10 - Aug 10, Page 564 - 573 |  PDF |  Page 

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ที่มา:วิทยาสารเกษตรศาสตร์ สาขา วิทยาศาสตร์

หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Vetiver Seedlings Multiplication in Rice Husk Amended Soil and Crops Performance on Erosion-Prone Hillside under Vetiver Buffer Strips)

ผู้เขียน:ImgEffi om Oku, ImgAmbrose Aiyelari, ImgOlajire Fagbola, ImgAyuk Essoka

สื่อสิ่งพิมพ์:pdf

Abstract

Vetiver buffer strips hold back soil on cultivated hillsides. A major constraint in their adoption is the low availability of seedlings for the establishment of buffer strips. Two experiments were conducted. In the fi rst, vetiver grass strip spacing (VGSS) at 5, 15, 25 m and farmers’ practice (FP) (no soil conservation measures used) were established as treatments on erosion plots sited on a cultivated hillside with a view to identifying the VGSS that would best increase crop yields. In the second experiment, 0, 25, 33.33, 41.67 and 50 t.ha-1 of rice husk were applied as soil organic nutrient enhancer to identify the rice husk rate that would maximize vetiver seedling multiplication on degraded soil. A traditional crop mixture of maize and cassava was introduced on mounds. Maize grain yield was signifi cantly infl uenced by VGSS and FP. Maize yields were 18.7, 8.7 and 11.6% higher on VGSS at 5, 15 and 25 m, respectively than on the FP plot. Maize dry matter accumulation between the VGSS and FP plots were signifi cantly different. Fresh cassava tuber yields were signifi cantly infl uenced by VGSS. Fresh cassava tuber yields were; 36.6, 12.2 and 13.2% higher on the VGSS at 5, 15, and 25 m, respectively, than on FP. The signifi cant benefi cial effect of VGSS in increasing crop yields on the cultivated hillside was evident. The farmer’s fi eld soil used for the vetiver multiplication was degraded having a sand fraction of 886 g.kg-1 of soil and a clay fraction of 40 g.kg-1. The soil was naturally very low in calcium and effective cation exchange capacity, low in organic carbon, nitrogen, magnesium and sodium and medium in potassium. Plant nutrient analysis of the rice husk used in amending the soil showed that it was high in available phosphorus and potassium, and medium in organic carbon and nitrogen. Vetiver tillers increased with the application rate of rice husk. A rice husk rate at 33.33 t.ha-1 could be the optimum rate of application as there was no signifi cant tiller increase beyond this rate.

Article Info
Agriculture and Natural Resources -- formerly Kasetsart Journal (Natural Science), Volume 046, Issue 2, Mar 12 - Apr 12, Page 151 - 161 |  PDF |  Page 

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ที่มา:วิทยาสารเกษตรศาสตร์ สาขา วิทยาศาสตร์

หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Evaluation of Vetiver Grass Buffer Strips and Organomineral Fertilization for the Improvement of Soil Physical Properties)

ผู้เขียน:ImgEffiom Oku, ImgOlajire Fagbola, ImgPaul Truong

สื่อสิ่งพิมพ์:pdf

Abstract

Soil erosion still remains the major cause of deterioration of soil physical qualities on cultivated lands worldwide. A study was carried out on erosion plots at the Teaching and Research Farm of the University of Ibadan, Nigeria to assess soil physical properties after five years of using vetiver grass buffer strips (VGBS) and organomineral fertilizer (OMF) with bare soil on which farmers had planted without soil conservation measures as the control. Samples were analyzed for water stable aggregates (WSA), mean weight diameter (MWD), bulk density, porosity and particle size distribution. The cone index (CI) was also assessed. Infiltration values were fitted to Philip’s and Kostiakov’s models. Results showed that the amount of WSA for the VGBS and OMF plots was the same (64%) and on the bare soil was 54%. The MWD on the VGBS plot was 6.11% higher than on the OMF plot and 19% higher than on bare soil. The bulk density for the bare soil was 4% higher than that of the VGBS plot. Porosity values for the VGBS and OMF plots were the same, being 8% higher than the bare soil plot. The CI was 15.7% and 7% lower on the VGBS and OMF plots, respectively, compared to the bare soil. Cumulative and initial one-minute infiltration increased by 39.4% and 35%, respectively, on the VGBS plot when compared with the bare soil. Hydraulic conductivity increased by 41.7% on the VGBS plot when compared with bare soil. The initial capacity of the soil to accept water increased on the VGBS plot by 19% over the OMF plot and 39% over the bare soil plot. The index of soil sorptivity (reflecting rate of decline of infiltration capacity) was the same for the VGBS and OMF plots and 21.78% higher than for the bare soil plot. The use of vetiver grass buffer strips on erosion-prone cultivated fields over the years could act as a source of organic fertilizer, improving soil physical properties.

Article Info
Agriculture and Natural Resources -- formerly Kasetsart Journal (Natural Science), Volume 045, Issue 5, Sep 11 - Oct 11, Page 824 - 831 |  PDF |  Page 

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ที่มา:วิทยาสารเกษตรศาสตร์ สาขา วิทยาศาสตร์

หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Effects of Age of Rubber (Hevea brasiliensis Muell Arg.) Plantation on pH, Organic Carbon, Organic Matter, Nitrogen and Micronutrient Status of Ultisols in the Humid Forest

ผู้เขียน:ImgEffi om Oku, ImgAnthony Iwara, ImgEkaette Ekukinam

สื่อสิ่งพิมพ์:pdf

Abstract

Micronutrients are required by plants in minute quantities. Literature on the micronutrient status of soils sustaining rubber plantations in the humid forest zone of southern Nigeria is not readily available where a study was carried out on Ultisols to examine the status of manganese (Mn), iron (Fe), Copper (Cu) and zinc (Zn) in rubber plantations aged 7, 16, 39 and 41 yr. A grid sampling method was used to collect soil samples from fi ve quadrats of 10 m ? 10 m in each of the plantation plots. For each plot, fi ve surface (0–15cm) soil samples were randomly collected and composited. The soil samples were analyzed for pH, organic carbon (OC), organic matter (OM), nitrogen (N), Mn, Fe, Cu and Zn. Data were analyzed using analysis of variance and Pearson’s correlation. The soils were strongly acidic (pH 4.0–4.4). The OC status was rated as very low (below 2%) in all the plantation soils. In addition, the OM was rated as low under the trees at 7, 16, and 39 yr whereas, for the 41 year-old plantation, it was rated as high. The Mn and Zn contents were rated as low for the 16, 39 and 41 year-old rubber plantations, whereas they were rated as medium under the 7 year-old rubber plantation. The Mn, Fe and Cu contents varied signifi cantly (P < 0.01 to P < 0.05) with the age of trees, while Zn did not vary (P > 0.05) among the rubber plots. The fertility rating of Fe was toxic or excessive in all the plantations and the levels of Cu were rated high. The results showed that the contents of Zn, Fe, Cu and Mn in the soils decreased with increasing age of rubber plantation. The Mn content was rated as high, medium, medium and low in the 7, 16, 39 and 41 year-old plantations, respectively. The Fe contents were rated as high whereas the Cu contents were rated as medium. With the exception of the 7 year-old plantation, where Zn was rated as medium, the Zn contents were below the critical limits for crop production, with soils in the 16, 39 and 41 year-old rubber plantations benefi ting from its application. The low values of soil pH across the rubber plantation plots did not signifi cantly favour the increase in selected micronutrient levels in the soil. To improve the levels of micronutrients in the rubber plots, it is recommended that biomass burning should be discouraged during replanting as it strips the soil of these nutrients. The use of organo-mineral fertilizer combined with inorganic fertilizers is recommended. Care must be taken not to apply Mn in excess. A rubber-based agroforestry system, as opposed to rubber monocultures is recommended as it would improve the micronutrient levels of the soils in the plantation.

Article Info
Agriculture and Natural Resources -- formerly Kasetsart Journal (Natural Science), Volume 046, Issue 5, Sep 12 - Oct 12, Page 684 - 693 |  PDF |  Page 

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ที่มา:วิทยาสารเกษตรศาสตร์ สาขา วิทยาศาสตร์

หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Green Structure for Soil and Water Conservation on Cultivated Steep Land)

ผู้เขียน:ImgEffiom Oku, ImgAmbrose Aiyelari, ImgPaul Truong

สื่อสิ่งพิมพ์:pdf

Abstract

A study was conducted on a farmer’s field on a 35 % slope in the humid forest zone, Nigeria on the use of a green structure that performed some engineering functions on cultivated steep lands to help curtail soil and water losses. Treatments consisted of a vetiver grass strip as a green buffer structure at different surface spacings of 5, 15, 25 m with no vetiver as the control and were laid out in a randomized complete block design with three blocks. Twelve erosion plots each measuring 50 m long and 3 m wide were used for the study. The plots were planted with cassava and maize in a simple crop mixture. The runoff, soil loss and crop yield were assessed under the four treatments. The rainfall lost as runoff with no vetiver (control plot) was 24.8 % compared to 7.7, 11.5 and 11.6% lost on the green structure plots at spacings of 5, 15 and 25 m, respectively. Soil loss on the no vetiver plot was 40 times higher than the acceptable soil loss limit of 12 t.ha-1 yr-1 for the tropics, whereas the soil loss on plots under vetiver at spacings of 5, 15 and 25 m was 1.4, 6.8 and 6.5 times higher than the acceptable limit. The maize grain yield and the fresh cassava tuber yield were significantly lower in the control plots and highest with the 5 m spacing. A vetiver strip as a green structure was more effective at a spacing of 5 m as it reduced soil and water losses and increased crop yield. This spacing was also adequate for traditional pre- and post-farming activities.

Article Info
Agriculture and Natural Resources -- formerly Kasetsart Journal (Natural Science), Volume 048, Issue 2, Mar 14 - Apr 14, Page 167 - 174 |  PDF |  Page