 หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Vetiver Seedlings Multiplication in Rice Husk Amended Soil and Crops Performance on Erosion-Prone Hillside under Vetiver Buffer Strips) ผู้เขียน: Effi om Oku, Ambrose Aiyelari, Olajire Fagbola, Ayuk Essoka สื่อสิ่งพิมพ์:pdf AbstractVetiver 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. |
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:Effi om Oku, Anthony Iwara, Ekaette Ekukinam สื่อสิ่งพิมพ์:pdf AbstractMicronutrients 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. |