Phosphorus Speciation in Soils of Contrasting Lithologies in Imo State, Southeastern Nigeria

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B.U. Uzoho & E.T. Jaja Federal University of Technology

ABSTRACT

Phosphorus speciation provides useful information about the dominant P fractions in soils and their availability for plant nutrition and environmental sustainability. Chemical P fractions (H2O, 0.5 M NaHCO3, 0.1 M NaOH, 1.0 M HCl and H2SO4-P) in soils of contrasting lithologies in Imo State, Southeastern, Nigeria were determined using sequential extraction technique. Also, P fractions were correlated with selected soil properties using correlation analysis. Mean water, NaHC03, NaOH, HCl and -1 H2S04-P in soils of various lithologies varied as 0.11, 0.15, 0.36, 0.07 and 0.14 mg kg respectively in decreasing order of NaOH > NaHCO3 = H2SO4 > H2O > HCl for the top soil. Also, mean concentrations -1 were 0.12, 0.14, 0.36, 08 and 0.17 mg kg for water, NaHCO3, NaOH, HCl and H2SO4-P respectively P in a decreasing order of NaOH > H2SO4 > NaHCO3 > H2O > HCl for the subsoil. Averaged over lithologies, NaOH-P was higher while averaged over chemical fractions, concentrations in Coastal Plain Sands were better than other lithologies at both soil depths. Chemical P fractions correlated with selected soil properties especially sand, silt, clay, pH, ECEC, clay, OM and exchangeable Al, Ca and Mg. In general, amorphous and crystalline Fe and Al oxides/hydroxides, in addition to clay minerals and organic P compounds associated with NaOH-P dominated P chemistry of the soils.

Keywords: phosphorus, speciation, lithologies, sequential extraction, southeastern and nigeria. Classification: FOR Code: 050399 Language: English

LJP Copyright ID: 824568 ISBN 10: 1537586327 ISBN 13: 978-1537586328

London Journal of Research in Science: Natural and Formal 380U Volume 18 | Issue 1 | Compilation 1.0

© 2018. B.U. Uzoho & E.T. Jaja. This is a research/review paper, distributed under the terms of the Creative Commons Attribution- Noncommercial 4.0 Unported License http://creativecommons.org/licenses/by-nc/4.0/), permitting all noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Phosphorus Speciation in Soils of Contrasting Lithologies in Imo State, Southeastern Nigeria

α σ B.U. Uzoho & E.T. Jaja ______

I. ABSTRACT II. INTRODUCTION Phosphorus speciation provides useful Phosphorus is essential for the nutrition of most information about the dominant P fractions in biological organisms including animals, microbes soils and their availability for plant nutrition and and plants and associated with the eutrophication environmental sustainability. Chemical P of surface and grouwater systems (Rydin et al., fractions (H2O, 0.5 M NaHCO3, 0.1 M NaOH, 1.0 2011; McMahon and Read, 2013; Wang et al., M HCl and H2SO4-P) in soils of contrasting 2013; Dapeng and Yong, 2014). Its reactivity, lithologies in Imo State, Southeastern, Nigeria solubility and availability vary depending on the were determined using sequential extraction dominant chemical fractions present in soils and technique. Also, P fractions were correlated with sediments (He et al., 2010; Camelo et al., 2015). selected soil properties using correlation analysis. Mean water, NaHC03, NaOH, HCl and Chemical P fractions have been operationally H2S04-P in soils of various lithologies varied as defined as water, 0.5M NaHC0 , 0.1 M NaOH, 1 M 3 -1 0.11, 0.15, 0.36, 0.07 and 0.14 mg kg HCl and H2S04 soluble fractions. Water soluble or respectively in decreasing order of NaOH > Resin extractable P fraction refers to the inorganic

NaHCO3 = H2SO4 > H2O > HCl for the top soil. P in soil solution or the weakly adsorbed on Also, mean concentrations were 0.12, 0.14, 0.36, oxy-hydroxide or carbonates that is very mobile or -1 08 and 0.17 mg kg for water, NaHCO3, NaOH, readily available and thus easily lost through plant HCl and H2SO4-P respectively P in a decreasing and microbial uptake or leaching and runoff. The order of NaOH > H2SO4 > NaHCO3 > H2O > HCl 0.5 M NaHCO fraction constitutes the weakly 3 for the subsoil. Averaged over lithologies, adsorbed inorganic Pi or easily hydrolysable of Research in Science: Natural and Formal NaOH-P was higher while averaged over organic Po compounds such as ribonucleic acid chemical fractions, concentrations in Coastal and glycerophosphates, 0.1 M NaOH extractable Plain Sands were better than other lithologies at fraction includes inorganic Pi that is associated both soil depths. Chemical P fractions correlated with amorphous and crystalline Al and Fe with selected soil properties especially sand, silt, oxyhydroxides and clay minerals or organic Po London Journal clay, pH, ECEC, clay, OM and exchangeable Al, associated with organic compounds like humic Ca and Mg. In general, amorphous and and fulvic acids while the 1 M HCl fraction crystalline Fe and Al oxides/hydroxides, in consists of the fraction that is associated with addition to clay minerals and organic P carbonates (Solomon et al., 2002). Availability of compounds associated with NaOH-P dominated these P fractions has been indicated to vary from P chemistry of the soils. potential to none availability (Mehmood et al, 2015). Keywords: phosphorus, speciation, lithologies, sequential extraction, southeastern and nigeria. Concentrations of various P fractions in soils and Author α: Dept of Soil Science & Technology, Federal sediments could be estimated using sequential University of Technology, Owerri. extraction procedures, which involves the σ: Dept of Plant Science & Biotechnology, Rivers State extraction of the readily available or weakly University of Science and Technology, Portharcourt.

© 2018 London Journals Press Volume 18 | Issue 1 | Compilation 1.0 27 adsorbed P fractions first using mild extractants (Al-P and Fe-P) was reported dominant in soils and then the non-readily or unavailable fractions derived from silicate and mixed silicate-carbonate subsequently with more stringent extractants. For parent materials (Prietzel et al., 2016). instance, the order for P fractions using the fractionation procedure proposed by Hedley et al. Soils of southeastern Nigeria are underlain by (1982) and modified by Tiessen and Moir (1993) different parent materials that affect their has been reported to be an increasing sequence of properties. Presently, interests on P studies in the soils have been concerned with the P sorption water or resin, 0.5 M NaHCO3, 0.5 M NaOH, 1 M hot concentrated HCl and residual P fractions characteristics, organic and inorganic P status and (Buehler et al., 2002). P fertility management (Uzoho and Oti, 2005; Uzoho et al., 2014). There appears to be a dearth Several factors especially physicochemical of information on the status of P chemical forms properties of soils and sediments influence in soils of the various lithologies. Such concentration of chemical P forms (Dharumarajan information could be useful in understanding P and Sigh, 2016). According to Jalali and Tabar dynamics of the soils and the adoption of (2011), the degree of P association with different appropriate P management technologies for chemical forms strongly depends on soil efficient crop production and environmental physicochemical properties. It has been noted that sustainability. The objectives of this study were to in Western Plain Rajasthan soils, India, all P determine P speciation of soils of contrasting

fractions except HCl (Ca-P) and H2S04 (red P) P lithologies in Southeastern Nigeria and their fractions were affected by soil OC, EC, ECEC and correlation with selected soil physicochemical silt + clay fractions (Devra et al., 2014). Also, properties. increased HCl (Ca-P) and decreased NaOH (Al-P and Fe-P) P fractions have been reported with III. MATERIALS AND METHODS increased pH in subtropical soils of India (Amaresh, 2010) and subtropical soils of Iran 2.1 Study Location (Adhami et al., 2013). Besides HCl-P that was The study locations were Amuruo, Bende, related with exchangeable Na and Mg and Ihiagwa, Oguta and Okigwe representing five H2S04-P with exchangeable Ca and CaC03, there different lithologies (Imo clay shale, Bende- was no significant correlation between P forms of Research in Science: Natural and Formal Ameke shale, Coastal Plain Sands, Alluvium and and soil properties in Western Iranian Calcareous false bedded sandstone) in southeastern, Nigeria. soils under different land uses (Jalali and Tabar, 0 1 0 1 Amuruo lies between Latitudes 5 4 8 and 5 5 3 N 2011). 0 1 0 1 and Longitudes 7 20 and 7 2 5 E and underlain 0 1 by Imo Clay Shale, Bende between Latitudes 5 2 5 Distribution of P chemical forms varies with soil

London Journal 0 1 0 1 0 1 and 5 5 2 N and Longitudes 7 28 and 7 4 5 E and lithologies (Camelo et al., 2015; Mehmood et al., 2015; Prietzel et al., 2016). It has been indicated over Bende/Ameke Shale, Ihiagwa (Latitudes 50 1 0 1 0 1 0 1 21 and 5 2 7 N and Longitudes 7 02 and 7 1 5 E ) that in calcareous vertisols and aridisols of Northern Jordan, HCl-P fraction dominated due and underlain by Coastal Plain Sands, Oguta 0 1 0 1 0 1 to the calcareous nature of the parent materials (Latitudes 5 4 2 and 5 4 6 N and Long. 6 47 0 1 (Rawajfih et al., 2010). Also, high HCl-P (Ca-P) and 6 4 9 E ) over Alluvium and Okigwe (Latitudes 0 1 0 1 0 1 0 has been reported in alkaline soils derived from 5 4 5 and 6 0 0 N and Longitudes 7 15 and 7 1 45 E ) and over False bedded Sandstone. Soil types basic and ultrabasic rocks while high NaOH–P fraction was noted in acidic soils over sandstone of the locations consisted of Eutric Tropofluvent and shale parent materials (Amaresh, 2010). (Oguta), Arenic Kandiudults (Ihiagwa and Furthermore, in a study of P speciation of western Okigwe) and Typic Dystrudepts (Amuruo and soils of the temperate zone using wet-chemical Bende), with the climax vegetations varying as fractionation and Xane spectroscopy, NaOH-P rice (Oritza Sativa) and Oil palm (Elaeis

Phosphorus Speciation in Soils of Contrasting Lithologies in Imo State, Southeastern Nigeria

28 Volume 18 | Issue 1 | Compilation 1.0 © 2018 London Journals Press guinensis) in Amuruo, Cocoa (Theobroma cacao) 2600 rpm. The contents were decanted into a 10 and Cassava (Manihot utilis) in Bende and ml polyethylene bottle. Cassava (Manihot Spp) in Ihiagwa, Oguta and 0.5 NaHC03 –P fraction (F2) Okigwe. Farming and trading in addition to fishing and quarrying in Oguta and Okigwe Residue from F1 above was extracted with 10 ml respectively constituted the dominant economic 0.5 M NaHC0 for 16 hrs, centrifuged at 2600 activities in the locations. Climatic conditions of 3 rpm for 15 mins and the supernatant decanted the locations include a mean annual rainfall range into a 10 ml polyethylene bottle. of between 1900-2600 mm, mean daily 0 temperature of 26-33 C and relative humidity of 0.1M NaOH – P fraction (F3) between 75-85%, characteristic of the humid tropical zone of southeastern, Nigeria (IPEDC, Residue from F2 above was extracted with 10 ml 2006). 0.1M Na0H for 16 hrs, centrifuged for 15mins at 2600 rpm and then decanted into a 10 ml 2.2 Sample Collection, Preparations and polyethylene bottle. Laboratory Analyzes 1.0 M HCl- P fraction (F4) Soil samples were collected from generic horizons Residue from F3 was extracted with 10 ml 1.0 M of profile pits dug on each of the five study HCl for 16 hrs and centrifuged at 2600 rpm for 15 locations. A total of forty five (45) soil samples mins. The supernatant was decanted into a10 ml were collected and air dried, sieved using a 2 mm polyethylene bottle. diameter mesh and the fine earth soil fractions (< 2 mm) stored ready for laboratory analyzes. H2S04- P fraction Routine analyses using standard methods were conducted on subsamples of the fine earth soil Finally, residue from F4 was digested with 10 ml fractions. Particle size was determined after H2S04 in a digestion block after which it was dispersion with calgon (Gee and Or, 2002), OM allowed to cool before centrifugation for 15 mins using wet oxidation method (Nelson and at 2600 rpm. The supernatant was then decanted Sommers, 1996), Exchangeable cations, ECEC and into a 10 ml polyethylene bottle. pH (Thomas, 1996), available P (Olsens, 1982) of Research in Science: Natural and Formal and total N (Bremner, 1996). 2.4 Statistical Analysis Data generated from the different P fractions were 2.3 Phosphorus fractionation subjected to Analysis of Variance (ANOVA) and Phosphorus fractionation was conducted on the means separated using least significant difference

top and subsoil samples of the soil profiles. The (LSD) at 5% probability. Also correlation between London Journal topsoil was taken as soils from the topmost depth P fractions and selected soil properties was while the subsoil was that from the remaining determined using correlation analysis. All horizons of the profile. Sequential extraction statistical analyses were conducted using Genstat using the procedure outlined by Hedley et al. statistical package (Buysse, 2004). (1982) was employed for the P fractionation process. The procedure included as follows: IV. RESULTS AND DISCUSSION 3.1 Soil Characterization Water Soluble-P fraction (F1) Soils were dominantly sandy with the degree Subsample (1 g) of fine earth soil fraction was depressed with profile depth exception being shaken with 10 ml de-ionized water in a centrifuge Amuruo and Bende. Differences in soil textures tube for 16 hrs and then centrifuged for 15 mins at were related to the lithologies, with soils over

Phosphorus Speciation in Soils of Contrasting Lithologies in Imo State, Southeastern Nigeria

© 2018 London Journals Press Volume 18 | Issue 1 | Compilation 1.0 29 Coastal Plain Sands, Alluvial and sandstone differences in leaching losses of the topsoil that sandier than the shale. Soils of Coastal Plain was heavier in the former than the later Sands and sandstone parent materials have been lithologies. It has been reported that water soluble reported to be skeletal and coarse textured (Uzoho P constitutes the fraction that is readily available et al., 2014). Exchangeable cations, ECEC, N and in soil solution and thus easily lost through P were low and decreased with soil depths as the leaching (Mehmood et al., 2015). In the soils OM. High concentration of soil OM and plant studied, water soluble P was significantly nutrients in the surface soil depth could be (P < 0.05) correlated with soil ECEC (r = -0.50), ascribed to the increased accumulation of plant exchangeable Mg (r = -0.39), OM (r = -0.38) and litter. Linear relationship between soil OM and silt (r = 0.61) but not with clay (-0.33), plant nutrients confirms early observations that exchangeable Al (r = 0.17), Ca (r = 0.22) and pH fertility of tropical soils depends on their organic (r = - 30) (Table 4). matter contents (Uzoho et al., 2007). In general, Sodium bicarbonate P fraction (NaHC03-P) low nutrient concentration of the soils could be -1 ranged between 0.11-0.21 (mean = 0.15 mg kg ) ascribed to the high OM oxidation and base leaching due to the high intense tropical rainfall. equivalent to 11.70-23.53% (mean = 19.27%) of Soils were acidic and ascribable to the intense total P in the topsoil (Table 2) and 0.13- 0.15 -1 (mean = 0.14mg kg ) equivalent to 10.49-27.48 leaching of basic cations (Uzoho et al., 2007; 2014). (mean = 17.71%) of total P in the subsoil (Table 3) of various lithologies. Variation amongst 3.2 Phosphorus Fractions lithologies was low in the topsoil (CV = 29.80%) but uniform in the subsoil. Shale (Bende and Phosphorus fractions varied and differed with soil Amuruo) was significantly (LSD 0.05) better than lithologies. Water soluble P ranged between 0.02- the other lithologies in both top and subsoils -1 0.15 (mean = 0.11 mg kg ) equivalent to 2.13-17.74 exception being alluvium (Oguta) that was similar (mean = 13.46%) of total P in the topsoil (Table 2) to shale (Bende) in the subsoil. Sodium -1 and 0.01-0.18 (mean = 0.12mg kg ) equivalent to bicarbonate P fraction constitutes the weakly 1.90-17.97 (mean = 12.35%) total P in the subsoil adsorbed inorganic Pi or easily hydrolysable depths (Table 3) of the various lithologies. organic Po compounds like ribonucleic acid and Variation in concentration amongst lithologies glycerophosphates (Solomon et al., 2002). Thus of Research in Science: Natural and Formal was low with a coefficient of variation (CV) of shale (Bende) was better in both the top and 9.5% and 7.70% in the top and subsoil depths subsoil depths with much of the P exchangeably respectively. In the topsoil, shale (Amuruo) was held. There was significant (P < 0.05) correlation significantly (LSD 0.05) higher than others while between NaHC03-P and soil OM (r = 0.52), pH sandstone (Okigwe) was the least (Table 2) (r = 0.45), exchangeable Mg (r = 0.41), London Journal whereas Coastal Plain Sands (Ihiagwa) was exchangeable Ca (r = 0.65) and ECEC (r = 0.41) significantly better and with shale (Amuruo) being but none with exchangeable Al (r = -0.04), clay (r the least in the subsoil (Table 3). Low = 0.26), sand (r = -0.24) and silt (r = -0.26) concentration in the topsoil for the sandstone (Table 4). parent material could be ascribable to its skeletal nature and associated leaching, runoff and uptake by plant as well as low retention capacity whereas the large value in the topsoil of shale (Amuruo) parent lithology could be due to the high retention

capacity. Similarly, high and low accumulations in the subsoil of Coastal Plain sands (Ihiagwa) and shale (Amuruo) respectively could be due to the

Phosphorus Speciation in Soils of Contrasting Lithologies in Imo State, Southeastern Nigeria

Location/PM Depth Sand Silt Clay OM N l P (H20) Ca Mg K Na ECEC mg Cm g kg-1 cmol kg-1 kg-1 Bende (Shale) 0-8 809.60 20.00 170.40 12.40 0.10 4.55 5.91 3.41 0.40 0.45 0.23 7.49 8-15 553.60 36.00 410.40 9.00 0.20 4.13 5.06 2.17 0.20 0.15 0.13 4.75 15-27 845.60 44.00 110.40 3.80 0.20 3.36 4.97 1.43 0.10 0.15 0.10 2.38 Amuruo(Shale) 0-7 869.60 20.00 110.40 21.70 0.10 4.90 6.48 3.35 0.10 0.37 0.20 7.00 7-14 611.60 18.00 370.40 19.70 0.20 3.50 6.26 2.41 0.80 0.33 0.60 7.26 14-28 689.60 20.00 290.40 17.20 0.30 2.73 5.98 2.43 0.80 0.37 0.08 5.28 Okigwe (Sandstone) 0-8 850.40 24.00 125.60 16.60 0.30 6.30 6.05 0.25 0.14 0.26 0.03 6.68 8-16 809.60 40.00 150.40 10.30 0.20 5.60 6.02 0.25 0.24 0.22 0.01 12.72 16-30 840.60 29.00 130.40 3.40 0.20 5.67 5.39 0.27 0.34 0.28 0.01 21.90 Ihiagwa (Coastal plain Sands) 0-15 893.60 30.00 70.40 15.90 0.20 4.69 5.90 0.51 0.10 0.24 0.04 4.49 15-30 865.60 24.00 110.40 18.30 0.20 5.95 5.86 0.33 0.26 0.26 0.03 8.35 30-45 879.60 10.00 110.40 11.40 0.20 3.43 5.67 0.53 0.12 0.26 0.04 6.95 Oguta (Alluvium) 0-15 919.60 50.00 30.40 8.30 0.30 6.86 5.82 0.59 0.40 0.35 0.01 2.94 15-30 865.60 84.00 50.40 7.20 0.20 4.34 5.73 0.49 0.42 0.30 0.03 2.14 30-45 855.20 100.00 44.80 6.60 0.20 3.50 5.43 0.67 0.20 0.33 0.03 3.63

Table 2: Absolute and Relative P Fractions in Top soils of Varying Lithologies

-1 A. Absolute P Fractions (mg kg ) Location/PM H20 0.5 M NaHC03 0.5 M NaOH 0.1 M HCl H2S04 Total Amuruo (Shale) 0.15 0.20 0.27 0.09 0.14 0.85 Bende (Shale) 0.11 0.21 0.13 0.06 0.11 0.62 Ihiagwa (Coastal plain Sands) 0.13 0.14 0.53 0.06 0.13 0.99 Oguta (Alluvium) 0.14 0.11 0.37 0.07 0.15 0.84 of Research in Science: Natural and Formal Okigwe (Sandstone) 0.02 0.11 0.52 0.09 0.20 0.94 LSD 0.05 0.02 0.09 0.02 0.02 0.08 0.02 % CV 9.50 29.80 3.00 12.10 29.70 1.30 B. Relative P Fractions (%)

Amuruo(Shale) 17.65 23.53 31.76 10.59 16.47 London Journal Bende (Shale) 17.74 33.87 20.97 9.68 17.74 Ihiagwa (Coastal plain Sands) 13.13 14.14 53.53 6.06 13.13 Oguta (Alluvium) 16.67 13.10 44.05 8.33 17.86 Okigwe (Sandstone) 2.13 11.70 55.32 9.57 21.28 PM = Parent material

Phosphorus Speciation in Soils of Contrasting Lithologies in Imo State, Southeastern Nigeria

-1 A. Absolute P Fractions (mg kg ) Location/PM H 0 0.5 M NaHC0 0.5 M NaOH 0.1 M HCl H S0 Total 2 3 2 4 Amuruo (Shale) 0.01 0.14 0.15 0.08 0.13 0.51 Bende (Shale) 0.16 0.15 0.38 0.08 0.12 0.89 Ihiagwa (Coastal plain Sands) 0.18 0.13 0.60 0.08 0.25 1.24 Oguta (Alluvium) 0.09 0.15 0.34 0.08 0.13 0.79 Okigwe (Sandstone) 0.14 0.13 0.32 0.08 0.21 0.88 LSD 0.05 0.02 0.00 0.09 0.00 0.02 0.13 % CV 7.70 0.00 13.70 0.00 12.80 1.30 B. Relative P Fractions (%) Amuruo (Shale) 1.96 27.48 29.40 15.67 25.52 Bende (Shale) 17.97 16.85 42.70 6.06 13.47 Ihiagwa (Coastal plain Sands) 14.51 10.49 48.30 6.45 20.17 Oguta (Alluvium) 11.40 18.98 43.00 10.12 16.45 Okigwe (Sandstone) 15.92 14.76 36.40 9.10 23.86 PM = Parent material

Table 4: Simple Correlation between P fractions and selected Soil Properties

Soil P Fractions Properties 0.5 M H 0 0.5M NaOH 0.1 M HCl H S0 2 NaHC0 2 4 3 Clay -0.33 0.26 -0.23 -0.57 -0.54 ECEC -0.50 -0.41 0.44 0.51 0.20 Exchangeable Al 0.17 -0.04 0.28 -0.39 -0.29 Exchangeable Ca 0.22 0.65 -0.32 -0.06 -0.49

of Research in Science: Natural and Formal Exchangeable Mg -0.39 0.41 -0.78 -0.34 -0.46 pH -0.30 0.45 -0.82 0.34 -0.51 Sand 0.28 -0.24 0.20 0.61 0.50 Silt 0.61 -0.26 0.34 -0.25 0.54 OM -0.38 0.52 -0.77 0.11 -0.72 London Journal

Ranges of NaOH-P associated with Fe/Al and subsoils respectively, but with the later higher -1 oxy-hydroxide were 0.13-0.53 (mean = 0.36 mg than the former. In both top (0.53 mg kg ) and -1 -1 kg ) equivalent to 20.97-53.53 (41.13%) and sub soils (0.60 mg kg ) , concentrations were -1 0.15-0.60 (mean = 0.36 mg kg ) equivalent to significantly (LSD 0.05) higher in Coastal Plain 29.40-48.30 (39.96%) total P in the top (Table 2) Sands (Ihiagwa) than the other lithologies and subsoils (Table 3) of the various lithologies probably due to its high acidity. It has been respectively. Concentrations for the topsoil were reported that Al and Fe-P extractble with NaOH very low compared to values obtained for increased under high acidity due to high P calcareous soils of Jordan (Rawajfih et al., 2010). precipitation and retention by Al and Fe Variations amongst various lithologies were low, (Amaresh, 2010). Soil properties especially ECEC with CV’s equivalent to 3 and 13.70% in the top (r = 0.44), exchangeable Mg (r = -0.78), pH

Phosphorus Speciation in Soils of Contrasting Lithologies in Imo State, Southeastern Nigeria

32 Volume 18 | Issue 1 | Compilation 1.0 © 2018 London Journals Press (r = -0.82) and OM (r = -0.77) correlated Variability amongst lithologies was low, with CV’s significantly (P < 0.05) with NaOH-P while its equivalent to 29.70 and 12.80% in the top and relationship with clay contents (r =-0.23), silt subsoils respectively and with the former better (r = -0.34), sand (r = 0.20), exchangeable Al than the later. Concentrations were significantly -1 (r = 0.28) and exchangeable Ca (r = 0.34) was not (LSD 0.05) better in sandstone (0.20 mg kg ) and -1 significant. It has been reported that in Coastal Plain Sands (0.25 mg kg ) than other sub-tropical soils of Iran, NaOH-P was not lithologies in the top and subsoils respectively. significantly correlated with OM, clay, sand and Concentrations were seriously correlated with soil silt but with pH (Adhami et al., 2013) and thus OM (r = -0.72), sand (r = 0.50), silt (r = 0.54), pH corroborated the observations for the soils (r = -0.51), exchangeable Mg (r = -0.46), studied. exchangeable Ca (r = -0. 49) and clay (r = -0.54) but not with ECEC (r = 0.20) and exchangeable Al Concentrations of HCl-P ranged between (r = -0.29). -1 0.06-0.09 (mean = 0.07mg kg ) equivalent to 6.06-10.59 (mean = 8.85%) in the topsoil and Total P obtained as the summation of all P -1 extremely low when compared with ranges of fractions ranged between 0.62-0.99 (0.85mg kg ) -1 -1 522-1089 mg kg for calcareous Vertisols and and 0.51-1.24 (mean = 0.86 mg kg ) in the top Aridisols of Jordan (Rawajfih et al., 2010). and subsoils respectively, with variability amongst Amongst lithologies, variation was very low in the lithologies low (CV = 1.30%) at both depths. topsoil with a CV equivalent to 12.10%. Also, in Coastal Plain Sands was significantly better in the -1 -1 the topsoil, shale (Amuruo) and sandstone top (0.99mg kg ) and subsoils (0.86 mg kg ) (Okigwe) were better than the other parent while shale was the least in both top (0.62 mg -1 -1 materials. In the subsoil, concentrations were kg ) and subsoils (0.51 mg kg ) . High content of similar amongst parent materials and with mean Coastal Plain Sands could be attributed to a high values equivalent to 0.08 mg kg-1 indicating that inorganic fertilizer application or accumulation of Ca-P extractble by NaOH was similar in the organic materials. Mean values obtained at both subsoil of these acidic soils. High HCl-P (Ca-P) soil depths were low relative to a range of -1 -1 has been reported in high alkaline calcareous soils 181.1-439.15 mg kg (mean = 310.13 mg kg ) for (Amaresh 2010; Rawajfih et al., 2010). There was deep tropical soils of varying parent materials and significant correlation (P < 0.05) between HCl-P altitudes, ascribable to high degree of weathering of Research in Science: Natural and Formal and Clay (r = -0.57), ECEC (r = 0.51), and leaching Ameresh, 2010). exchangeable Al (r = -0.39) and sand (r = 0.61) but none with exchangeable Ca (r = -0.06), Mg In general, mean absolute P fractions averaged (r = -0.34), pH (r =-0.34), silt (r = -0.25) and over lithologies decreased in the order total (0.85) > NaOH (0.36) > NaHCO3 = H2SO4 (0.15) > H2O OM (r = 0.11). It has been noted that in London Journal sub-tropical soils of Iran, HCl-P correlated (0.11) > HCl (0.07) in the topsoil and NaOH (0.36) > H2SO4 (0.17) > NaHCO3 (0.14) > H2O significantly with pH and CCE (Adhami et al. 2013) contrary to observation obtained for the (0.12) > HCl (0.08) in the subsoil. This showed soils studied. that NaOH-P was best while HCl-P the least at both soil depths of the various lithologies. Similar

Residual or H2S04-P ranged between 0.11-0.20 observation has been reported for sub-tropical -1 (mean = 0.15 mg kg ) equivalent to 13.13-21.28 Iranian soils (Adhami et al., 2013) and some (mean = 17.30%) total P in the topsoil (Table 2) Southwestern Ethiopian soils (Melese et al., 2015) -1 and 0.12-0.25 (mean = 0.17 mg kg ) equivalent to ascribable to the dominance of Al /Fe-oxides, old 13.47-25.52 (mean = 19.89%) total P in the subsoil age, high acidity and advanced weathering stage -1 (Table 3). Mean subsoil (0.17 mg kg ) (Ameresh, 2010; Melese et al., 2015). Kolahchi concentration was better than topsoil (0.15 mg and Jalali (2012) obtained high HCl-P or Ca-P in -1 kg ) probably due to high leaching losses. calcareous soils, high in Ca, Mg and CaCO3.

Phosphorus Speciation in Soils of Contrasting Lithologies in Imo State, Southeastern Nigeria

© 2018 London Journals Press Volume 18 | Issue 1 | Compilation 1.0 33 Concentration of total P was higher in the top 6. Camelo, D.L, Joao, C.K, Roberto, F. N, than subsoils as have been reported for some Marcelo, M.C and Vinicio, C.L. 2015. Southwestern Paraná State, Brazil soils under Sequential Extraction of Phosphorus by varying tillage practices (Tales et al.,2012) and Mehlich-1 and Ion Exchange Resin from B Southwestern basin of Dian lake, China soils Horizons of Ferric and Perferric Latosols (Zhang and Li, 2016). (Oxisols). R. Bras. Ci. Solo, 39: 1058-1067. 7. Dapeng, L and H.Yong 2014. Distribution of V. CONCLUSIONS added phosphorus in sediment under intermittent conditions. Environmental Phosphorus fractions in soils of the various Engineering and Management Journal 13 (10): lithologies varied and decreased in the order 2593-2600.

NaOH > NaHCO3 = H2SO4 > H2O > HCl and 8. Devra, P, S.R. Yadav and I.J. Gulati 2014. NaOH > H2SO4 > NaHCO3 > H2O > HCl in both Distribution of different phosphorus fractions top and subsoils respectively. The NaOH-P was and their relationship with soil properties in higher averaged over lithologies while P western plain of Rajasthan. Agropedology 24 concentrations in Coastal Plain Sands were better (01): 20-28. averaged over P fractions at both soil depths. Soil 9. Dharumarajan, S and S.K.Singh 2016. properties especially sand, silt, clay, OM, Variation of soil properties and phosphorus exchangeable Al, Ca, Mg, ECEC and pH affected fractions in three cropping systems of lower concentrations of the various P fractions. Indo-Gugetic Alluvial Plain. African Journal of Agricultural Research 9(24): 1878-1886. REFERENCES 10. Gee, G., W. and Or, D. (2002). Particle size analysis. In: Dane, J. H. and G. C. Topps 1. Adhami, E, H.R. Owliaie, R. Molavi, M. Rezaei (eds.). Methods of soil analysis, Part 4. Rashti 2, and M. Esfandbod 2013. Effects of Physical methods. Soil Sci. Soc. Am. Book soil properties on phosphorus fractions in Series No.5, ASA and SSSA, Madison, WI.pp, subtropical soils of Iran. Journal of Soil 255 – 293. Science and Plant Nutrition, 2013, 13(1), 11-21. 11. He, Z, H. Zhang, G. S. Toor, Z. Don, C. W. 2. Amaresh, Das 2010. Effect of varying parent Honeycutt, B. E. Haggard and M. S. Reiter materials and altitude on phosphorous

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Phosphorus Speciation in Soils of Contrasting Lithologies in Imo State, Southeastern Nigeria

34 Volume 18 | Issue 1 | Compilation 1.0 © 2018 London Journals Press use. Journal of. Plant Nutrition & Soil Science. from coastal Baltic Sea sediments as estimated 2011, 174, 523–531. from sediment profiles, Estuarine, Coastal and 15. Kolahchi, Z and M. Jalali 2012. Speciation of Shelf Science, 92, 111–117. phosphorus in phosphorus-amended and 24. Solomon, D, J. Lehmann, T. Mamo, F. leached calcareous soils using chemical Fritzsche and W. Zech 2002. Phosphorus fractions. Polish Journal of Environmental forms and dynamics as influenced by land use Studies 21(2): 395-400. changes in the sub-humid Ethiopian 16. McMahon, K.D and E.K Read 2013. Microbial highlands. Geoderma 105: 21–48. contributions to phosphorus cycling in 25. Thomas, G. W. 1996. Soil pH and soil acidity eutrophic lakes and wastewater. Annual in: Sparks, D. L. (Ed.), Methods of soil Review of Microbiology, 67: 199–219. analysis, Part 3, Chemical methods. Soil 17. Melese, A, H. Gebrekidan, M. Yli-Halla and B. Science Society of America and American Yitaferu 2015. Phosphorus Status, Inorganic Society of Agronomy, Madison, Wisconsin, Phosphorus Forms, and other Physicochemical USA, pp. 475-490. Properties of Acid Soils of Farta District, 26. Tales T, D. R. dos Santos, J. Kaminski and A. Northwestern Highlands of Ethiopia. Applied Calegari 2012. Forms of Inorganic Phosphorus and Environmental Soil Science 2015: 1-11. in Soil under Different Long Term Soil Tillage 18. Mehmood. A, M. S. Akhtar, K. S. Khan, A. Systems and winter Crops. R. Bras. Ci. Solo, Khalid, M. Imran and S. Rukh 2015. 36: 271-281. Relationship of Phosphorus Uptake with Its 27. Tiessen, H and J.O. Moir 1993. Fractions in Different Soil Parent Materials. Characterization of available P by sequential International Journal of Plant and Soil Science extraction. Soil sampling methods of analysis. 4(1): 45-53. Canadian Society of Soil Science. Boca Raton: 19. Nelson, D.W. and L.E. Sommers 1996. Total Lewis Publishers. pp. 75–86. carbon, organic carbon, and organic matter, 28. Uzoho, B.U and N.N. Oti. Phosphorus in: Sparks, D. L. (Ed.), Methods of soil adsorption characteristics of selected analysis, Part 3, Chemical methods. Soil Southeastern Nigerian soils. Agro-Sci. J. Agric. Science Society of America and American Food, Environ. Ext. 2005, 4(1): 50-55. Society of Agronomy, Madison, Wisconsin, 29. Uzoho, B.U, N.N.Oti and A.Ngwuta 2007.

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Phosphorus Speciation in Soils of Contrasting Lithologies in Imo State, Southeastern Nigeria