ABSTRACT Variability in soil properties is a critical element across wide areas of researches especially in several aspects of agriculture and environment including sewage disposal and global climate change. Particle size fraction (sand, silt, and clay), effective cation exchange capacity, base saturation, pH, organic carbon, total nitrogen, carbon nitrogen ratio, available phosphorus, exchangeable bases (calcium, magnesium, sodium, potassium) and acidity are frequently used in agriculture for soil management. The objective of this study therefore was to identify soil management factors from these set of 15 soil properties and spatial distribution of representative soil management properties. The study was carried out in the University of Uyo Teaching and Research Farm measuring 8.19 hectares in University of Uyo Annex, Uyo in Akwa Ibom State of Nigeria. Nine and ten traverses were made horizontally and vertically respectively at 40 meters intervals. A total of 58 soil samples were collected at 0 - 15 cm depth on the grid nodes of the traverses. Particle size distributions, exchangeable bases and acidity, effective cation exchange capacity (ECEC), available phosphorus (avail. P), base saturation (BS), organic carbon, total nitrogen, carbon nitrogen ratio (CNR) and pH of the samples were determined in the laboratory. Coefficient of variation indicated that 26.6% of the soil properties (sand content, pH, CNR and sodium) were least variable, 40.1% comprising silt, clay contents, ECEC, base saturation, phosphorus and magnesium were moderately. Whereas 33.3% of the soil properties comprising clay content, organic carbon, total nitrogen, exchangeable Ca, K and acidity (i.e.) were highly variable. There were significant correlation (p < 0.05) in 26.6% of the soil properties, the strongest negative significant (p < 0.01) correlations were between sand and clay (r = –0.85), exchangeable acidity and base saturation (r = –0.85), whereas the strongest positive significant correlations were between ECEC and Ca (r = 0.80), Ca and BS (r = 0.74), organic carbon and total nitrogen (r = 0.80). Principal component analysis indicated the existence of six factors including mineralogical or weathering, soil organic matter, cation exchange activity, soil texture, and dispersion and soil phosphorus based on either management or pedological considerations. Semivariance statistics showed that sand and clay contents, ECEC, BS and total N were moderately (≥25.7% ≤47.3%), while silt content, pH, organic carbon, CNR, avail. P, exchangeable Ca, Mg, Na and acidity (≥0.18% ≤22.8%) were strongly spatially dependent. The variability observed was primarily incident upon factors of soil formation. Therefore, the utilization of spatial structure of organic matter and texture factors in the management of nutrient and soil water will facilitate planning of crop production scheme on coastal plain sands soils.
Cite this paper
nullJ. Obi and B. Udoh, "Identification of Soil Management Factors from Spatially Variable Soil Properties of Coastal Plain Sands in Southeastern Nigeria," Open Journal of Soil Science, Vol. 1 No. 2, 2011, pp. 25-39. doi: 10.4236/ojss.2011.12004.
 P. C. Robert, R. H. Rust and W. E. Larson, “Precision Agriculture, Proceeding International Congress, 3rd Agronomy Society of America and Soil Science Society of America,” Madison Wisconsin, Madison, 1996.
 T. R. Green, T. Makoto and H. Kooi, “Potential Impact of Climate Change and Human Activities on Surface Water Resources,” Vadose Zone Journal, Vol. 6, No. 3, 2007, pp. 531-532.
 J. D. Phillips, “Development of Texture Contrast Soils by a Combination of Bioturbation and Translocation,” Catena, Vol. 70, No. 1, 2007, pp. 92-104.
 D. R. Neilsen, Wendrothe and M. B. Parlandge, “Opportunities for Examining on-Farm Soil Variability: In Site Specific Management for Agricultural Systems, Agronomy Society of America and Soil Science Society of America,” Madison Wisconsin, Madison, 1995, p. 152.
 M. K. Shukla, B. K. Slater, R. Lal and P. Cepuder, “Spatial Variability of Soil Properties and Potential Management Classification of a Chernozemic Field in Lower Austria,” Soil Science, Vol. 169, 2004, pp. 852-860.
 J. C. Obi and A. O. Ogunkunle, “Influence of Termite Infestation on the Spatial Variability of Soil Properties in the Guinea Savanna Region of Nigeria,” Geoderma, Vol. 148, No. 3-4, 2009, pp. 357-368.
 F. C. James and C. E. McCulloch, “Multivariate Analysis in Ecology and Systematic Panacea or Padora’S Box?” Annual Reviews Ecological System, Vol. 21, 1990, pp. 129-166. doi:org/10.1146/annurev.ecolsys.21.1.129
 M. Duffera, J. G. White and R. Weisz, “Spatial Variability of Southeastern U. S. Coastal Plain Soil Physical Properties: Implication for Site Specific Management,” Geoderma, Vol. 137, No. 3-4, 2007, pp. 327-339.
 A. G., Ojanuga, G. Lekwa and F. O. R. Akamigbo, “Survey, Classification and Genesis of Acid Sands. In: Acid sands of Southeastern Nigeria,” Soil Science Society, No. 1, 1981, pp. 1-7.
 G. E. K. Ofomata, “Actual and Potential Erosion in Nigeria and Measures for Control. In: Acid sands of southeastern Nigeria,” Soil Science Society, No. 1, 1981, pp. 151-165.
 PP. I. Ogban and I. O. Ekerette, “Physical and Chemical roperties of the Coastal Plain Sands Soils of Southeastern Nigeria,” Nigerian Journal of Soil Research, Vol. 2, 2001, pp. 6-14.
 SLUS-AK, “Soils and Land Use Survey of Akwa Ibom,” Government Printers, Uyo, 1989, p. 603.
 G. W. Gee and J. W. Bauder, “Particle Size Analysis. p. 404-407. In: A. Klute (ed.) Methods of Soil Analysis. Part 1. 2nd Edition, AgronMonogr. No. 9, Agronomy Society of America and Soil Science Society of America,” Madison Wisconsin, Madison, 1986.
 J. M. Bremner and C. S. Mulvaney, “Total nitrogen. Methods of Soil Analysis. Part II, 2nd Edition. Page, A. I. Ed. Agronomy Monograph. No. 9, Agronomy Society of America and Soil Science Society of America,” Madison Wisconsin, 1982, pp. 595-624.
 D. W. Nelson and I. E. Sommer, “Total Carbon, Organic Carbon and Organic Matter. Methods of Soil analysis. Part II, 2nd Edition. Page, A. I. Ed. Agronomy Monograph. No 9, Agronomy Society of America and Soil Science Society of America,” Madison Wisconsin, Madison, 1982, pp. 961-1010.
 E. O. McLean, “Soil pH and lime requirement. In Methods of Soil Analysis, Part II. A. L. Page (ed.), ASA Monogr. No. 9,” Madison Wisconsin, Madison, 1982, pp. 199-223.
 A. Mehlick, “Mehlick 3 Soil Test Extractant: A Modification of Mehlick 2,” Communications in Soil Science and Plant Analysis, Vol. 15, No. 12, 1984, pp. 1409-1416.
 J. M. Anderson and J. S. I. Ingram, “Tropical Soil Biology and Fertility,” A Handbook of Methods, 2nd Edition, CAB International, 1993. p. 221.
 Soil Survey Staff, “Keys to Soil Taxonomy,” United States Department of Agriculture, Natural Resources Conservation Services, 10th Edition, 2006, p. 331.
 S. S.Shapiro and M. B. Wilk, “An Analysis of Variance test for Normality,” Biometrika, Vol. 52, 1965, pp. 691- 710.
 SAS Institute, “SAS Systems for Information Delivery for Windows,” Release 6.12. SAS Institute, Cary, NC, 1996.
 T. B. Parkin and J. A. Robinson, “Anslysis of Lognormal Data,” Advances in Soil Sciences, Vol. 20, 1992, pp. 193-325. doi:org/10.1007/978-1-4612-2930-8_4
 C. A. Cambardlla, T. B. Moorman, J. M. Novak, T. B. Parkin, D. L. Karlan, R. F. Turco and A. E. Konopka, “Field Scale Variability of Soil Properties in Central Iowa Soils,” Soil Science Society of American, Vol. 58, No. 5, 1994, pp. 1501-1511.
 C. T. Haan, “Statistical Methods in Hydrology,” Iowa State University Press, Ames, 1997.
 R. A. Johnson and D. W. Wichern, “Applied Multivariate Statistical Analysis, Prentice Hall,” Eaglewood Cliffs, New Jersey, 1992.
 S. Sharma, “Applied Multivariate Techniques,” John Wiley and Sons, New York, 1996.
 B. B. Trangmar, R. S. Yost and G. Uehara, “Application of Geostatistics to Spatial Studies of Soil Properties,” Advances in Agronomy, Vol. 38, 1985, pp. 45-94.
 T. C. Bailey and A. C. Gatrell, “Interactive spatial data analysis,” Addison Wesley Longman, UK, 1998.
 A. B. McBratney and M. J. Pringle, “Estimating Average and Proportional Variograms of Soil Properties and Their Potential Use in Precision Agriculture,” Precision Agricul Ture, Vol. 1, No. 2, 1999, pp. 219-236.
 S-Plus, “S-Plus SpatialStats User’s Manual for Windows and Unix. Data Analysis Product Division, MathSoft,” Seattle, Washington, 1997.
 A. G. Journel and C. J. Huijbregts, “Mining Geostatistics,” Academic Press, London, 1978.
 P. Goovaerts, “Geostatistics for Natural Resources Evaluation,” Oxford University Press, New York, 1997.
 M. David, “Geostatistics Area Reserve Estimation,” Elsevier Science Publisher, Amsterdam, 1977.
 I. Clark, “Practical geostatistic,” Applied Science Publisher, London, 1979.
 J. Iqbal, J. A. Thomasson, J. N. Jenkins, P. R. Owens and F. D. Whisler, “Spatial variability analysis of soil physical properties of alluvial Soils,” Soil Science Society of American, Vol. 69, No. 4, 2005, pp. 1338-1350.
 M. K. Shukla, R. Lal and M. Ebinger, “Principal Component Analysis for Predicting Biomas and Corn Yield under Different Land Uses,” Soil Science, Vol. 169, 2004b, pp. 215-224.
 L. P. Wilding, “Spatial Variability: Its Documentation, Accommodation, and Implication to Soil Surveys. In Soil spatial Variability. D. R. Nielsen and J. Bouma (eds). Pudoc,” Wageningen, The Netherlands, 1985, pp. 166- 194.
 T. O. Ibia, G. S. Effiong, P. I. Ogban and J. C. Obi, “Relationship between Phosphorus Forms and Parent Materials in Soils of Southeastern Nigeria,” Acta Agronomica Nigeriana, Vol. 8, No. 2, 2008, pp. 104-112.
 J. D. Shaw, E. C. S. Packee and C. L. Ping, “Growth of Balsam Poplar and Black Cottonwood in Alaska in Relation to Landform and Soil,” Canada Journal of Soil Resources, Vol. 31, 2001, pp. 1793-1804.
 R. L.Voortman, J. Brouwer and P. J. Albersen, “Characterization of Spatial Soil Variability and Its Effect on Millet Yield on Sudano-Sahelian Coversands in SW Niger. Staff Working Paper. WP-02-02,” Centre for World Food Studies, The Netherlands, 2002.
 O. O. M. Olatunji, A. O. Ogunkunle and A. O. Tabi, “Influence of Parent Material and Topography on Some Soil Properties in Southwestern Nigeria,” Nigerian Journal of Soil and Environmental Research, Vol. 7, 2007, pp. 1–6.
 E. G. Gregorich, M. R. Carter and B. H. Ellert, “Towards a minimum data set to assess soil organic matter quality in agricultural soils,” Cananda Journal of Soil Science, Vol. 74, No. 4, 1994, pp. 367-385.
 C. A. Seybold, R. B. Grossman and T. G. REinsch, “Predicting Cation Exchange Capacity for Soil Survey Using Linear Model,” Soil Science Society of American Journal, Vol. 69, No. 3, 2005, pp. 856-853.
 Z. M. Souza, J. M. Júnior and G. T. Pereira, “Spatial Variability of the Physical and Mineralogical Properties of the Soil from the Areas with Variation in Landscape Shapes,” Brazilian Archives Biology Technology, Vol. 52, No. 2, 2009, pp. 305-316.
 F. E. Botros, T. Harter, Y. S. Onsoy, A. Tuli and J. W. Hopmans, “Spatial Variability of Hydraulic Properties and Sediments Characteristics in a Deep Alluvial Unsaturated Zone,” Vadose Zone Journal, Vol. 08, 2009, pp. 276-289. doi:org/10.2136/vzj2008.0087