An Assessment of Physico-Chemical Properties of Soils In Selected Vegetable Farms Around Sokoto Metropolis

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1 Nigeria Journal of Soil and Environmental Research Nig. J. Soil & Env. Res. Vol. 10: 2012, Department of Soil Science, Faculty of Agriculture, Ahmadu Bello University, Zaria, Nigeria An Assessment of Physico-Chemical Properties of Soils In Selected Vegetable Farms Around Sokoto Metropolis 1 2 Abdulkareem*¹, J. H., A. A. Abdullahi, M. Audu ¹Department of Soil Science, Faculty of Agriculture/Institute for Agric Research, Ahmadu Bello University Zaria P.M.B 1044, Zaria, Nigeria. ²Department of Soil Science and Agricultural Engineering, Faculty of Agriculture, Usmanu Danfodiyo University Sokoto, Nigeria. ABSTRACT The physico-chemical properties of soils in selected vegetable farms around Sokoto metropolis were investigated wi e objective of assessing e level of e physico-chemical properties as well as e differences among different locations and deps. Girabshi and Kofar Kware areas of vegetable crop production were randomly selected in e metropolis. Soil samples were collected at 0-15, and cm deps, in all possible combinations making six treatments which were laid down in a Randomised Complete Block Design (RCBD) replicated 3 times. Particle size analysis, soil ph, total N, available P, organic C, CEC, and exchangeable K, Ca and Mg were determined. The soils in e areas were predominantly sandy, sandy loam to loamy sand. The difference in total N and organic C were significant (P<0.05) wi respect to location, Girabshi had higher content of bo N and organic C wi values of and 0.1g kg- respectively. Total N and CEC were also significant (P<0.05) wi respect to dep, cm dep was highest in total N followed by e 0-15 cm. Though not significant bo organic C and available P also showed slight decrease wi dep. The highest CEC was obtained at e top soil (0-15 cm) gradually decreased wi dep. Keywords: physico-chemical properties, vegetable production, soils, INTRODUCTION Soil is essential for e development of most plants providing physical support and nutrients. Plants are anchored in e soil by eir roots. Nutrients dissolve in soil water which is necessary for e plants grow. Soils contain various organic matters, including dead minerals from plants and animals as well as organisms at choose to live in soil. Soil is a store of various nutrients such as carbon and nitrogen which plays an important role in e global nutrient cycles in hydrological cycles and atmospheric system (Hiscox, 2004). Plant nutrients are e chemical elements and compounds required for plant grow. They are obtained from weaering materials, precipitation, atmosphere, biological activity and decomposition. Major reserves of ese nutrients in e soil are held in e clay-humus complex where humus combines wi clay particles. This is very important for soil fertility as e clay and humus bo supply nutrients for plant grow. Humus is e form of organic matter at is ultimately incorporated into e soil and is referred to as true organic matter. Nitrogen is e most critical element to plant grow an all oer nutrient elements wi total amount in e soil ranging from 0.2 to 2.5g kg-¹ of soil. (Brady and Weil, 1999) Sulphur on e oer hand has a range of about 1.8 to 5.4 g kg-¹ depending on e organic matter content of e soil and it occurs basically in ree forms in e soil; organic form, inorganic and gaseous or elemental form (Brady and Weil 1999). In e soil, phosphorus as a nutrient occurs in two forms; organic and inorganic forms. (Hiscox, 2004; FAO, 2002, Brady and Weil 1999) Vegetables are important sources of vitamins, minerals and dietary fibre and are low in fat and calories (Anon., 2004). They are also e main sources of nitrogen in diets of many Nigerians accounting for about 65-75% of e total intake (Onyeson and Okoh, 2006; Czamiecka- Skubina and Golaszewska, 2001).

2 An Assessment of Physico-Chemical Properties of Soils In Selected Vegetable Farms Around Sokoto Metropolis 85 Vegetables are grown in various environments ranging from city window boxes and home gardens to large commercial farms. Most vegetable species rough careful selection of varieties can be grown widely in diverse environments. Growers must still be careful however, to choose varieties adapted to eir particular soil and climates. Most of e common vegetables grown in Nigeria have been developed in temperate regions but some have been adapted to e tropics (Anon., 2004). This study was conducted wi e objective of assessing e physico-chemical properties of soils in selected vegetable farms around Sokoto metropolis wi a view of determining eir difference wi deps and locations. MATERIALS AND METHODS Study Area The study was conducted wiin Sokoto metropolis. Sokoto is located between latitude 13º 03' to 14º 02'N and longitude 05º 14' to 06º 16'E, 80 km sou of e Rima and Sokoto Rivers. It falls wiin e Sudan savannah zone wi two major seasons, a short rainy season and a long dry season. The rain is erratic and small in quantity wi a mean of about 500mm to 800 mm from e nor increasing towards e sou which lasts from May to October wi an uneven distribution and a peak in August (Anborg, 1988). The dry season consist of cold dry spell (Harmattan) roughly from November to January followed by a hot dry spell from February to April (Singh and Babaji, 1989). Low humidity, high temperature and solar radiation due to clear skies are some of e climatic conditions. The minimum and maximum temperatures in e area are 15ºC and 40ºC respectively (Anborg, 1988). The area is intensively cultivated and has started experiencing serious decline in agricultural productivity (Noma et al., 2009) Sample Collection and Preparation Soil samples were collected during e dry season from two randomly selected locations among ose intensively cultivated vegetable crops in e study area. Girabshi falls in e western part of Sokoto metropolis (L1) and Kofar Kware in e nor eastern part of e metropolis (L2). The samples were taken at a dep of 0-15 (D1), (D2) and 30-60cm (D3). The samples were taken in all possible combinations making six treatment combinations (S1D1, S1D2, S1D3, S2D1, S2D2, S3D1, S3D2, S3D3) which are laid down in a Randomised Complete Block Design (RCBD) replicated 3 times using farmers fields. A total of six fields ree for each location. Composite samples were taken for all treatment combinations, a total of 18 soil samples. The samples were taken to e laboratory, air dried, ground using porcelain capped pestle and mortar and sieved rough 2mm sieve after which were later subjected to analyses. Soil Analyses Some of e physico-chemical properties of e samples analysed include particle size distribution, organic C, total N, available P, exchangeable bases, soil ph and CEC. Particle size analysis was carried out using Boyoucos hydrometer meod as described by Gee and Bouder (1986). The textural class was determined using USDA soil textural triangle. Soil ph was determined wi a glass electrode ph meter 1:2 soil: water ratio (Bates, 1954). Total N was determined using micro-kjedahl meod as described by Nelson and Sommers (1982). Available P by Bray No. 1 Meod (Bray and Kurtz, 1945) and exchangeable bases were determined for calcium and magnesium using EDTA titration meod as described by Devis and Freitas (1970) and potassium using flame photometery (Rich, 1965). Figure 1: Map of Nigeria showing Sokoto state Statistical Analyses The data obtained were subjected to analysis of variance (ANOVA) to compare e locations and e different deps. Where F values were significant, treatment means were separated using Duncan Multiple Range Test (DMRT). The statistical analyses were performed using SAS (1998).

3 86 Abdulkareem, J. H., A. A. Abdullahi, M. Audu RESULTS AND DISCUSSION Figure 2: Map of Sokoto state showing study location Table 1 shows e results of e particle size distribution of e soils. The soils were sandy loam to loamy sand in bo e locations and deps which explains Jones and Wild (1975) report at e cultivated soils of e savannah region of West Africa are predominantly loamy sand to sandy loam in nature depending upon e location. Results of e soil chemical analyses are shown in Table 2. The organic C was very low and total N was high. There was no significant difference between Girabshi and Kofar Kware in all e chemical properties except for total N and organic C. Girabshi had higher content of Total N, - average values of 3.97 and 0.61 g kg ¹ for organic C in - Girabshi against 3.52 and 0.31 g kg ¹ for Kofar Kware, respectively. This could be attributed to possible higher rate of application of organic and inorganic N fertilizers or excessive irrigation water (Mc Neal et al., 1995) by Girabshi farmers relative to ose of Kofar Kware. This might have led to higher accumulation of bo total and nitrate-n beyond e uptake of e vegetable crops, which could eventually lead to low N efficiency, high nitirogn content in plants and environmental contamination (Hong et al., 2007; Halvorson et al., 2005). The variation among different deps in total N was also significant (P<0.05). The cm dep has higher total N content (4.32 g kg-¹) closely followed by 0-15 cm dep, indicating high total N content in e upper horizons (0-30 cm) which could be linked to higher level of N at e topsoil compared to lower deps (30-60 cm). This was supported by e findings of Brady and Weil, 1999 and Wild, For obvious reasons such may be as a result of higher accumulation of organic matter and its mineralization by micro organisms applied organic and inorganic N fertilizers from where it leaches down e profile. The organic C, available P and exchangeable bases (potassium, calcium and magnesium) were low. Even ough ere is no significant difference between e two locations and deps except for CEC where ere is significant difference (P<0.05) in e deps. Absolute values indicate slightly higher contents of e parameters in Girabshi and e topsoil, decreasing down e profile for similar reasons proffered for total N. The ph was slightly alkaline wiin e range of and was not significant between e two locations and among deps.

4 An Assessment of Physico-Chemical Properties of Soils In Selected Vegetable Farms Around Sokoto Metropolis 87 Table 1: Particle size distribution of soils of vegetable farms in Giabshi and Kofar Kware areas of Sokoto metropolis Location Dep Samples %Sand %Silt %Clay Textural (cm) Class Girabshi SL '' SL '' S Kofar Kware '' LS '' S '' LS Girabshi SL '' SL '' SL Kofar Kware '' LS '' LS '' LS Girabshi SL '' SL '' LS Kofar Kware '' S '' LS '' LS LS- Loamy Sand, SL-Sandy Loam and S- Sand Table 2: Some chemical properties of soils of vegetable farms in Girabshi and Kofar Kware areas Treatments Total N Organic C Available P ph K Ca Mg CEC g kg** g kg** mg kg** Cmol kg** Location Girabshi 3.92a 0.61a Kofar Kware 3.52b 0.31b SE* Signficance * * NS NS NS NS NS NS Dep 0-15 cm 3.65b cm 4.32a cm 3.27c SE* Signficance * NS NS NS NS NS NS * LXD NS NS NS NS NS NS NS NS *Significant (P<0.05), NS Not significant (P>0.05). Means on e same column and treatment having same letter are not significant, L & D; Location & Dep This is e ph range wiin which nitrification takes place (Tisdale and Nelson, 1975) during which N content of soil increases rapidly (Onyeson and Okoh, 2006). CONCLUSION The soils of e study areas had slightly alkaline ph, high total N, low organic C, exchangeable bases, available P and CEC. There was no significant difference in bo locations and deps for organic C, available P and

5 88 Abdulkareem, J. H., A. A. Abdullahi, M. Audu exchangeable bases. There was a significant difference in total N, and organic C, between e locations wi Girabshi having higher values an Kofar Kware and CEC in e deps. There was also significant difference among e deps in total N wi a decrease in dep, ough not consistent indicating possible danger of N leaching and accumulation down e profile. A check for indiscriminate application of bo organic and inorganic N fertilizers is erefore recommended. REFERENCES Anborg, T. (1988). Where Savannah turns into desert. International Rural Development Center Swedish University of Agricultural Sciences and Rural Development studies. N o. 2 4., Uppsala. pp Anonymous, (2004). Soil Management. Microsoft Encarta (DVD). Microsoft Corporation. Bates, R. C. (1954). Electrometric ph determination. John Wiley and Sons Inc. New York pp Brady, N. C. and R. R. Weil (1999).The nature and properties of soils. 12 edition. Prentice-Hall Inc. Simon & Shuster A viacon company Upper Saddle River, New Jercy 881pp. Bray, R. H. and L. T. Kurtz (1945). Determination of total, organic and available phosphorus in soils. Soil Sci. 59: Czamiecka-Skubina, E. and K. Golaszewska (2001). Nitrate and Nitrite in Vegetables. Wageningen, The Neerlands: Center for Agricultural Publishing and Documentation. Devis, J. and F. Freitas (1970). Physical and Chemical Meods of Soil and Water Analysis. Soil Bulletin No. 10 Food and Agricultural Orgnization (FAO) Rome. FAO, Food and Agricultural Organization (2002). Fertilizers and eir use. National Special Program on Food Security, Abuja, Nigeria. Gee, G. W. and J. W. Bouder (1986). Particle Size Analysis in Aklate (ed) Meods of Soil nd Analysis 2 ed. No. 9 ASA Inc SSA Madison, Washington D. C. pp Halvorson, A. D., R. F. Florett and M. E. Bartolo (2005). Corn response to N fertilizer in a soil wi a high residual N. Agron J. 97: Hiscox, J. (2004). Soil Management. Microsoft Encarta (DVD). Microsoft Corporation. Hong, N., P. C. Scharf, J. G. Devis (2007). Economically optimum nitrogen rate reduces soil r e s i d u a l nitrate. J Environ. Qual. 36: Jackson, M. L. (1962). Soil Chemical Analysis. IITA. Manual Series No. 170pp. Jones, M. I. and A. Wild (1975). Soils of West African S a v a n n a h. T h e m a i n t e n a n c e a n d improvement of eir salinity. Technical Communication No. 55 of e Commonweal Bureau of Soils, Harpeden, UK. Commonweal Agriculture Bureau (CAB), Farnham Royal, UK., pp: McNeal, B. L., C. D. Stanley, W. D. Graham, P. R. Culrea, D. Downey and J.F. Greigton (1995). Nutrient loss trends for vegetable and citrus fields in west Florida: I. Nitrate. J. Environ. Qual. 25: Nelson, D. W. and L. E. Sommers (1982). Total carbon, organic carbon and organic matter. P: In: A. L. Page et al., (ed.) Meods of Soil nd Analysis. Part 2. 2 ed. Monogr. 9 ASA and SSSA Madison, W. Noma, S.S., A. A. Abdullahi, M. Yakubu, M. Audu, A. U. Dikko and N. M. Danmowa ( ). Impact of climatic change on soil properties and Agricultural Productivity in Sokoto, Norwest rd Nigeria. Proceedings of e 23 Annual National Conference of Farm Management Association of Nigeria, December, Onyeson, I. and P. N. Okoh (2006). Qualitative analysis of nitrate and nitrite contents in vegetables commonly consumed in Delta state, Nigeria. British J of Nutri. 96, Rich, C. L. (1965). Elemental Analysis by Flame Photometry in Meod of Soil Analysis A. M. Soc. Agron. C. A. Black (ed.) No. 9 part 2 pp SAS (1998). The GLM Procedure. In SAS/STAT User's Guide, Release 6.12 ed. SAS Inst., Cary, W. I. Singh, B. R. and G. A. Babaji (1989). Characteristics of Soils in Dundaye District. The Soils of e University Dry Land Farm. Niger. J. Basic Appl. Sci. 3:7-16 Tisdale, S. L. and W. L. Nelson (1975). Soil fertility and rd fertilizers. 3 ed. Macmillan publishers, London. Pp Wild, A. (1988). Plant nutrients in soil: Nitrogen in soil conditions and plant grow. A Wild (ed). 11 edition. Longman Group UK. Pp