Characteristics, Classification And Management Of Inland Valley Bottom Soils For Crop Production In Subhumid Southwestern Nigeria

Inland valley bottoms (IVBs) on basement complex in sub-humid southwestern Nigeria were studied for water-table (WT) dynamics, and physical and chemical characteristics for their classificationand management needs for crop production. The IVBs are generally small in size. About 64% of the IVBs averaged 0.78 ha while 36% averaged 1.69 ha. The dry season WT was 0 – 40 cm deep in 22%, 40 – 70 cm in 27% and 70 – 120 cm in 50% of the IVBs. These, corresponding to fluxial, high WT and very poorly drained IVBs (WT class 1), phreatic, medium and poorly drained IVBs (WT class II), and pluvial, low WT and imperfectly drained IVBs (WT class III), respectively. Clay and silt fractions are irregularly distributed in the soils but generally higher in the topsoil. Soil texture is highly variable both within and among the WT regimes, but while WTI and WTIII IVBs have loam or clay loam over sandy clay loam, WT II IVBs has silt loam over clay loam or sandy clay loam. Hydraulic conductivity (Ks) averaged 2.43 cmh-1 in the top 60 cm and 0.59 cmh-1 at lower depth in WT1 IVBs. The corresponding average values in WTII are 4.43 cmh-1 and 1.16 cmh-1, and 4.14 cmh-1 and 0.77 cmh-1 in WT III. Organic C and effective CEC are moderately high, and the basic cations comprised more than 90% of the adsorption complex. The soils were classified as AquicEndoaquepts, (WTI), Typic Endoaquepts and Aeric Typic Endoaquepts (WT III). Low input technologies for intensive uses of the IVBs consist in adapting farming to the wet condition by adopting the rice culture, or adopting a system of shallow drain-ditches with mound-tillage tosimultaneously lower the WT and increase the rooting depth during the dry season. Equally, moundtillage can be used to grow a toposequence of crops with decreasing tolerance for excessive wetness from the base to the apex. Occasional fertilizer supplementation and mulching will be needed toconserve the soils and sustain high crop yields when the IVBs are transformed into intensive agro ecosystem

Physical fertility of degraded acid sands in South-eastern Nigeria

We evaluated the physical fertility of degraded and undegraded acid sands in Akwa Ibom State, South-eastern Nigeria. The soils were similar in texture, being predominantly sandy, averaging 90.1% in degraded and 89.9% in undegraded soil. Bulk density averaged 1.50g/cm3 and 1.45g/cm3, while macropores averaged 0.215cm3/cm3 and 0.228cm3cm3 respectively. Saturated hydraulic conductivity averaged 1.43m/d in degraded and 3.25m/d in undegraded soil. Water stable aggregates (WSA) > 2.0mm diameter averaged 31.6% in degraded and 51.2% in undegraded soil, while plant available water capacity averaged 5.94cm/cm and 10.3cm/cm, respectively. Organic C average 0.80% in degraded and 1.59% in undegraded soil. The respective average values of the infiltration characteristics are: sorptivity, 18.0mm min-½and 20.6mm min-½; transmissivity, - 3.0mm min-1 and 2.57mm min-1; infiltration rate at 1 minute, 9.0mm min-1 and 13.0mm min-1, and at 2h, 5.42mm min-1 and 8.33mm min-1; and cumulative intake 650.0mm and 884.0mm. The lower values of the measured properties in degraded compared with undegraded soil indicate the loss of physical fertility in the former. Nigerian Journal of Soil Science Vol. 15 2005: 102-10

Infiltrationn characteristics and soil physico-chemical properties of wetland in Akwa Ibom state, Southeastern Nigeria

No Abstract. Nigerian Journal of Soil Science Vol. 16 (1) 2006: pp73-7

Spatial Variability of Particle Sizes of Coastal Plain Sands Soils of Southeastern Nigeria

Geostatistical analysis facilitates site-specific farming, soil and sanitary landfill management, sustainability and health. The objectives of this study were to assess the extent of variability, spatial dependence and structure of soil particle sizes, pedological and management implications in the coastal plain sands soils of southeastern Nigeria. Surface (0 – 15cm) and subsurface (15 – 30cm) soil samples were collected at 10m2 intervals (rigid grid nodes) in a 100m by 100m plot at the one year fallowed portion of Teaching and Research / Commercial Farm of University of Uyo, in Use Offot, Uyo, Nigeria. A total of 100 samples were collected for each depth. Coefficient of variation (CV) of silt: clay ratio (SCR), silt, fine and coarse sand (surface) were highly variable at both soil depths, while coarse sand of subsurface soil was least variable (13.8%). Spatial dependence of the variables ranged from strong to moderate. The moderately spatially dependent variables included fine sand (36.7%), coarse sand (48.7%) on the surface, and SCR (33.7%) on the subsurface, while the remaining variables were strongly spatially dependent. Pearson correlation coefficients between the semivariances of the two depths showed significance in 52.8% of the entire relationships compared to 19.4% observed on the measured values of the particle sizes. Stronger spatially dependent variables correlated with more variables compared to the moderately spatially dependent variables. It was observed that most of the kriged maps produced displayed similarity in the sedimentation or depositional characteristics which now followed the depositional effect of the massive erosive forces. Kriging may combine correlation and spatial dependence to facilitate site specific farming, soil and sanitary landfills management, knowledge of pedogenesis and sustainability in the coastal plain sands soils.Keywords: coastal plain sands, spatial structure, soil variability, particle sizes, pedogenesi

Influence of bush fallow on the physical and chemical quality of acid sands in South-eastern Nigeria

This paper reports the effect of bush fallow on the physical and chemical properties of acid sand soils in Akwa Ibom State, South-eastern Nigeria. It shows that the bush fallow period is drastically reduced. About 30.0% of the farmers cultivate their lands after 4-year fallow, 26.0% after 1-year fallow, while 13.3% cultivate after 3 and 7-year fallow. The soils were sandy in texture and bulk density averaged less than 1.40g/cm3 among the fallow ages. Non-capillary porosity averaged more than 40% among the fallow ages. Hydraulic conductivity varied from moderately rapid to rapid, while available water capacity was generally lower than 7cm3/15cm depth. Water stable aggregates > 2mm diameter were low, averaging less than 30.0% among the fallow ages. The soils were slightly acidic, and organic carbon content was generally low averaging between 1.90% and 2.24% among the fallow ages. Effective CEC was lower than 6 Cmol/kg, and base saturation was higher than 50%. The fallow ages were statistically similar in the measured parameters. Management practices that will enhance soil productivity are suggested. Nigerian Journal of Soil Science Vol. 15 2005: 96-10

Effect Of Tillage And Mulching Practices On Soil Properties And Growth And Yield Of Cowpea (Vigna unguiculata (L), Walp) In Southeastern Nigeria.

This paper reports the field evaluation of the effect of tillage [tilled (MT) and untilled, (NT)], mulching material [Panicum maximum (p) and Chromolaena odorata (c)] and mulching method [incorporated (b), surface (s) and no mulch (o)] on soil properties and growth and yield of cowpea (Vigna unquiculata) in 2000 and 2001 cropping seasons, in Akwa Ibom State, Southeastern Nigeria. The study was a three-factor factorial in randomize complete block (RCB). The soil in 2000 and 2001 was strongly acidic. Organic C increased by about 83.6% at harvest in 2000 and declined by 16.4% in 2001. Available P declined by about 15.9% in 2000 and 59.6% in 2001. Base saturation increased by 9.6% in 2000 and decreased by 6.8% in 2001. Tillage and mulching practices improved water-stable aggregates >2mm by 16.6% in 2001. Bulk density was similar between MT and NT in 2000, but significantly lower (