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- ItemOpen AccessSlope-soil Relationships on an Aberrant Toposequence in Ife Area of South Western Nigeria: Variabilities in Soil Properties(Faculty of Agriculture, University of Ife, 1985) Okusami, T. A.; Oyediran, G. O.Soils located on the upper-slope segment of a toposequence were studied to observe their properties and evaluate thc slope-soil variabilities thereof. In addition, the soils were classified. This toposequence has no middle-slope soils that normally occupy physiographic units between those soils formed in upper slope in-situ materials and Gambari series (Smyth and Montgomery, 1962). The soils studied occupy summit but crestal position (FBI), the lower crestal position (FB2), and the physiographically slightly sloping lower upper-slope segment (FB3, FB4 and FB6) of the landscape. They are located on 2%, 5%, 3%, 2.5% and 3% slopes respectively. All the soils belong to Iwo series with the greatest soil morphological variabilities expressed in the BC, and in C horizons. : Typically, the surface horizons (0-30cm) range from dark yellowish brown (10 YR 314 or 414 to dark brown (7.5 YR 518). A typical B horizon is strong brown (7.5 YR 518) with a depth range of 35-95cm. Soil physical and chemical properties mostly show statistically insignificant differences between soils located on different physiographic/slope positions. However, there are significant differences in chroma between FB3, FB4 profiles and others. Significant differences exist between some of the soil profiles for their silt content. Soils are mostly in the strongly acid to extremely acid range. Exchangeable Mg is the least variable (C.V. of 9.1%) of the exchangeable cations. These soils are classified as Paleustults in the USDA system with an equivalent of Ferric Acrisols and Ferric Lixisols in the FAO-Unesco system.
- ItemOpen AccessHydromorphism - Its Definition and Correlation between Three Major Classification Systems with Reference to West Africa(Faculty of Agriculture, University of Ife, 1985) Okusami, T. A.Hydromorphic soils may be defined simply as any wetland soil that will not support crops (or plants), with aerobic edaphic requirements, during the peak of the groundwater recharge. The influence of the water-table is largely controlled by the texture of the profile. This is of significance because the capillary fringe of any water-table may be as saturated as those horizons under the water-table, and this tends to increase the height of the groundwater. A depth of 100 cm. to a saturated zone is suggested as the depth below which a pedon ceases to become aquic or show features associated with hydromorphism that could limit the environment to anaerobic crops. For a general landuse purpose, a probable depth of 150 cm. is suggested as the depth beyond which a pedon ceases to become hydromorphic. Because hydromorphism does not preclude those soil forming processes peculiar to the well-drained upland soils, classification as outlined in Soil Taxonomy (USDA) could be appropriate for the classification of hydromorphic soils. The aquic prefix points to the influence of the water regime on the pedogenesis and properties of the soils concerned. Attempt at correlating the three systems, viz. USDA, FAO - UNESCO and French was made.
- ItemOpen AccessCompaction and Moisture Suction Effects on Soil Strength and Crop Emergence(Faculty of Agriculture, University of Ife, 1985) Aina, P. O.; Fapohunda, H. O.; Idowu, J.Laboratory studies were conducted to determine the effects of four levels of soil compaction and five moisture suctions on the relationship between penetrometer soil strength and emergence of maize and cowpea seedlings for five contrasting soils of Western Nigeria. Compaction (bulk density) and moisture suction accounted for 75-- 88% of observed variation in soil strength and affected seedling emergence at specified soil strengths. The effect of compaction or moisture suction on the relation of seedling emergence to soil strength depended on 5oil and crop species. The rate of cowpea seedling emergence, which was about two-thirds that of maize, was more adversely affected by compaction than by high moisture suction. Cowpea emergence ceased when soil strengths exceeded 8 kg/cm2 in the clay loam or 10 kg/cm2 in the sandy clay loam and sandy loams, while corresponding values for maize were 14 kg/cm2 for the clay loam and 18 kg/cm2 for the other soils
- ItemOpen AccessResponse of Two Lowland Rice Varieties to N, P and a Combination of Other Nutrients in a Flooded Soil(Faculty of Agriculture, University of Ife, 1984) Obi, A. O.; Adepetu, J. A.A 4x3x2x2 factorial experiment was conducted to evaluate the effects of N, P and a combination of some other nutrients on grain yields of two rice varieties under hydromorphic soil conditions, in the &forest of southern Nigeria. The low yielding variety (IR-20) responded better to fertilizer application than the higher yielding variety (OM). The best rates of N and P application to both rice varieties in this flooded soil were 60kg N/ha and 25kg N P/ha. Yield response to a combination of l00kg K, 40kg Mg, 5kg Cu, 2kg Zn and 2kg Fe per ha was significant during both years of cropping. Yield response to NP, and the combined application of the other nutrients were greater during the second than the first year of cropping.
- ItemOpen AccessMicronutrient Concentration of Okra (Hibiscus esculentus) Leaves and Fruits as Influenced by Nitrogen Fertilization(Faculty of Agriculture, University of Ife, 1981) Aduayi, E. A.The influence of nitrogen fertilization on leaf and fruit micronutrient composition of okra plants, was studied in field trials from 1975 to 1977. Leaf-Fe was higher at the vegetative stage than at the flowering and fruiting stages of growth. Its concentration decreased steadily at the vegetative stage as nitrogen rates increased, but the converse occurred at the flowering and fruiting stages. Similar effects were noticed in leaf-Mn. The highest Mn, Cu and Zn accumulations in the leaves were observed at fruiting. Leaf-Cu was low at all stages of growth relative to other micronutrients. Fruit-Fe and Mn were generally low compared to the leaf concentration, while fruit-Cu and Zn were almost as high as the leaf concentration.