Full Terms & Conditions of access and use can be found athttp://www.tandfonline.com/action/journalInformation?journalCode=lcss20

Download by: [Abu El-Eyuoon Amin] Date: 10 May 2017, At: 11:04

Communications in Soil Science and Plant Analysis

ISSN: 0010-3624 (Print) 1532-2416 (Online) Journal homepage: http://www.tandfonline.com/loi/lcss20

Impact of Corn Cob Biochar on Potassium Statusand Wheat Growth in a Calcareous Sandy Soil

Abu El-Eyuoon Abu Zied Amin

To cite this article: Abu El-Eyuoon Abu Zied Amin (2016) Impact of Corn Cob Biochar onPotassium Status and Wheat Growth in a Calcareous Sandy Soil, Communications in Soil Scienceand Plant Analysis, 47:17, 2026-2033, DOI: 10.1080/00103624.2016.1225081

To link to this article: http://dx.doi.org/10.1080/00103624.2016.1225081

Accepted author version posted online: 18Oct 2016.Published online: 18 Oct 2016.

Submit your article to this journal

Article views: 65

View related articles

View Crossmark data

Impact of Corn Cob Biochar on Potassium Status and WheatGrowth in a Calcareous Sandy SoilAbu El-Eyuoon Abu Zied Amin

Soils and Water Department, Faculty of Agriculture, Assiut University, Assiut, Egypt

ABSTRACTA pot experiment was conducted to investigate effects of biochar producedfrom corn cobs on some chemical properties and potassium status in acalcareous sandy soil. The addition of biochar to this soil resulted insignificant increases (P ≤ 0.05) in the soil pH, organic matter (OM), solublepotassium, and available potassium. The soil potential buffering capacity ofpotassium (PBCK) significantly increased with adding the biochar to thecalcareous sandy soil. Significant increases were also occurred in the activityratio of potassium at equilibrium (ARKeÞ with the applying the biochar to thissoil. Moreover, biochar additions gave significant increases in the labile poolof K �ΔKoð Þ value of the calcareous sandy soil. The fresh and dry weight aswell as potassium content of wheat plants grown in the calcareous sandysoil significantly increased with biochar additions.

ARTICLE HISTORYReceived 29 July 2015Accepted 1 June 2016

KEYWORDSBiochar; calcareous; growth;potassium; quantity-intensity; wheat

Introduction

The calcareous sandy soils suffer from many problems such as their low content of the necessaryplant nutrients, the formation of a crust soil surface when drought, and their low water holdingcapacity. OM as well as chemical and organic fertilizers should be added to these soils to compensatethe insufficiency of their fertility and to improve their unusual chemical and physical properties.However, find an alternative method to reduce the use of chemical fertilizers in these soils is toconvert plant wastes and crop residues into biochar to improve soil fertility as well as some physicaland chemical characteristics of these soils.

Biochar as a black carbon or a charcoal is produced from the pyrolysis of biomass process in theabsence of oxygen or the presence of partial oxygen (Esposito 2013; Jha et al. 2010; Joseph et al. 2010;Woolf et al. 2010). Many researchers found that the additions of biochar to soils led to enhance thesoil fertility and crop productivity. Biochar applications also cause increases carbon sequestrationand decreases in greenhouse gas emissions (Chan et al. 2008; Glaser, Lehmann, and Zech 2002;Lehmann, Gaunt, and Rondon 2006; Oguntunde et al. 2004). In addition, Novak et al. (2009) foundthat the additions of biochar to a loamy sand soil caused an increase in the soil pH. Charcoalapplications to some different textured soils resulted in an increase in the soil pH from 5.4 to 6.6(Mbagwu and Piccolo 1997). Moreover, adding the biochar to soils led to an increase in the soilcation exchange capacity (CEC) (Lehmann et al. 2003; Liang et al. 2006). Lehmann et al. (2003) alsoindicated that the application of charcoal to the soil improved the soil available potassium. Thisstudy aims to use the biochar produced from corn cops as a source of potassium in a calcareoussandy soil and to improve some chemical properties of this soil as well as to affect the Q/I parametersof soil potassium.

CONTACT Abu El-Eyuoon Abu Zied Amin abueleyuoon@gmail.com Soils and Water Department, Faculty of Agriculture,Assiut University, P.O. Box: 71526, Assiut, Egypt.Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/lcss.© 2016 Taylor & Francis

COMMUNICATIONS IN SOIL SCIENCE AND PLANT ANALYSIS2016, VOL. 47, NO. 17, 2026–2033http://dx.doi.org/10.1080/00103624.2016.1225081

Materials and methods

Pot experiment

An open-air pot experiment was conducted to investigate effects of biochar produced from corn cobson some chemical properties and potassium status of a calcareous sandy soil as well as on wheatplants grown in this soil. A sample of a calcareous sandy soil was collected from the surface layer (0–30 cm), El-Ghorieb Experimental Station Farm, Assiut University, Assiut, Egypt. This soil wasclassified as a Typic Torripsamments according to US Taxonomy. Some physical and chemicalproperties of this soil are shown in Table 1. The chemical properties of biochar produced from corncobs are shown in Table 1. After biochar production being his crushed process and passed through a2 mm sieve. The collected soil sample was air-dried, crushed, and passed through a 2-mm sieve.Plastic pots containing 1 kg of this soil in a randomized complete block design where biochar wasadded to the soil was used. Biochar was applied at treatment levels 0, 20, 40, and 60 Mg/ha soil andmixed with the soil in the pots. Each treatment had three replications. Then, the moisture content ofall soil in the pots was kept at the field capacity level for 20 days with turning over of the soil in potsevery 2 days during this period. Wheat seeds were sown in all pots on 14 January 2015 and irrigatedwith tap water. After germination, the plants in each pot were thinned to 4 plants and the moisturecontent was kept at the field capacity level. Nitrogen was added with the irrigation water at a level of200 kg N/ha as ammonium nitrate (33.5%N) in two equal doses after 15 and 40 days from sowing,respectively. Wheat plants were harvested after 2 months from sowing and the total fresh shootweight in each pot (Mg/ha) was estimated. The plants were washed with distilled water and oven-dried at 70°C and then the total dry matter weight for each pot (Mg/ha) was recorded. Soil sampleswere taken from each pot after the harvest. The collected soil samples were air dried, crushed, passedthrough a 2 mm sieve, and analyzed for the physical and chemical properties.

Chemical analysis

The soil pH was determined in a 1:1 of a soil to deionized water suspension by a glass electrode(Jackson 1973), while the pH of biochar was measured in a suspension of a 1:2.5 ratio. The electricalconductivity (EC) of the soil was measured in a 1:1 of a soil to water extract using an EC meter(Hesse 1998), while the EC of biochar was measured in an extract of 1:5 ratio. Available potassium(ammonium acetate (NH4OAC)-extractable K) was extracted using 1 M ammonium acetate

Table 1. Some physical and chemical properties of the soil under study and biochar producedfrom corn cobs.

Soil

Property ValueSand (%) 87.2Silt (%) 6.0Clay (%) 6.8Texture Loamy sandO.M (g kg−1) 0.8CaCO3 (g kg−1) 247.2EC (dS/m) 4.11pH 8.11Olsen-P (mg kg−1) 9.15Soluble K (mg kg−1) 96.74NH4OAC-extractable K (mg kg−1) 408.26

BiocharOM (g kg−1) 937.3EC (dS/m) 3.58pH 9.67Olsen-P (mg kg−1) 192.10Soluble K (g kg−1) 6.05NH4OAC-extractable K (g kg−1) 10.05

COMMUNICATIONS IN SOIL SCIENCE AND PLANT ANALYSIS 2027

(NH4OAC) at pH 7, and potassium (K) in the extract was determined using the flame photometrymethod (Jackson 1973). The soluble potassium was determined in a soil extract of a 1:1 ratio byflame photometer, while the soluble potassium in biochar was determined in an extract of a 1:5 ratio.The OM in the soil was determined using the Walkley–Black method (Jackson 1973) while the OMin the biochar was determined using the loss-on-ignition method.

Quantity/intensity of potassium

The quantity/intensity of potassium was carried out by adding 50 ml of 10 mM calcium chloride(CaCl2) solutions containing various concentrations of potassium [0, 0.2, 0.4, 1, 2 and 4 mmole/lfrom potassium chloride (KCl)] to 5.00 g of soil sample in bottles. Then, the soil suspensions wereshaken for 2 hours and allowed to equilibrate for 22 hours. The suspension samples were filtered andthe supernatants were analyzed for potassium, calcium, and magnesium, the potassium was mea-sured using the flame photometer while calcium plus magnesium were determined by titration usingethyline-diamine tetra acetic acid (EDTA) solution.

The activity ratio for K or the intensity (I) factor (ARK) was calculated from the measuredconcentrations of K and calcium (Ca) + magnesium (Mg) in the supernatant solutions afterequilibrium according to Evangelou and Blevins (1988) as follows:

ARK ¼ aK

ðaCaþMgÞ1=2

where a ion activity, ai ¼ Ciγi, Ci, concentration of ion after equilibrium and γi, activity coefficient,determined according to the Davies equation (Sposito 2008):

log γ ¼ �0:512 z2I1=2

1þ I1=2� 0:3I

� �

where z is the valence of ion and I is the ionic strength. The ionic strength (I) of a supernatantsolution after equilibrium was calculated from the Griffin and Jurinak (1973) equation according toLindsay (1979) as follows:

I ¼ 0:013 EC

where the EC is electrical conductivity dS:m�1ð Þ of the supernatant solution after equilibrium.The quantity factor (Q) or ±ΔK is the amount of potassium that was lost or gained by the soil

after equilibrium. It is calculated by the subtraction between initial and final equilibrium potassiumconcentrations.

Statistical analysis

The data were statistically analyzed and the means were compared using the least significantdifference (LSD) values at a 5% level of significance. The statistical analysis that was conducted inthis experiment was done using the MSTAT program according to Steel and Torrie (1982).

Results and discussion

Soil chemical properties

Biochar additions to the calcareous sandy soil resulted in a significant increase (P ≤ 0.05) in the soilpH (Table 2). These additions raised the soil pH from 8.15 (control) to 8.31 at the 60 Mg/ha level ofbiochar. Many researchers indicated that the application of biochar to the soils led to increase thesoil pH (Berek 2014; Glaser, Lehmann, and Zech 2002; Lehmann and Rondon 2006). The increase inthe soil pH after biochar additions is due to the fact that the biochar contains calcium, magnesium,

2028 A. EL-EYUOON A. Z. AMIN

and potassium salts as carbonates and oxides forms, which they in turn have the ability to besolubilized in soil solution (Gaskin et al. 2010; Glaser, Lehmann, and Zech 2002; Joseph et al. 2010).Chan et al. (2008) found that the application of biochar increases the soil pH from 5.0 to 6.6. Thereis no a clear effect of biochar on the EC of this soil. On the contrary, the application of coal char tothe soil resulted in a significant increase in the EC of the soil (Oguntunde et al. 2004). Biocharapplications to this soil caused significant increases in the OM. These additions enhanced the soilOM from 0.077% (control) to 0.193% at the 60 Mg/ha level of biochar. Nigussie et al. (2012) foundthat the addition of biochar to the soil significant increases in the OM. The results showed significantincreases in the available phosphorus (Olsen-P) of the calcareous sandy soil with adding biochar(Table 2). The addition of biochar to the calcareous sandy soil caused an increment of the availablephosphorus from 8.31 mg/kg (control) to 10.43 mg/kg at the highest addition level of biochar. Soilavailable phosphorus increases after biochar addition is attributed to the high P content of biochar.Charcoal amendments to soils were reported to increase the soil available P (Glaser, Lehmann, andZech 2002; Oguntunde et al. 2004).

Soluble and available soil potassium

The soluble and available soil potassium significantly increased (ρ ≤ 0.05) with increasing thebiochar levels (Table 2). The addition of biochar to the calcareous sandy soil caused an incrementof soluble potassium from 100.4 mg/kg for the control treatment to 232.7 mg/kg at a level of 60 Mg/ha of biochar and an increase in the available potassium of this soil from 421.3 mg/kg at controltreatment to 740.6 mg/kg at the highest level of biochar (60 Mg/ha). However, the soluble andavailable potassium in the soil significantly increased with all addition levels of biochar even whenlow levels were added. This indicates that biochar is able to improve the available soil nutritionalstatus of potassium because the biochar from corn cobs contains free nutrient cations such aspotassium and do not volatilize after the burning process during production of biochar. Theapplication of charcoal to soil also was found to significantly increase the availability of base cationssuch as potassium (Gaskin et al. 2008; Glaser, Lehmann, and Zech 2002; McElligott 2011).

Q/I ratio parameters of potassium

The parameters of Q/I ratio of potassium are shown in Figure 1. The potential buffering capacity ofpotassium (PBCK) of this soil was obtained from the slope of the linear portion of the Q/I curve(Figure 2). It significantly increased with the biochar addition to the calcareous sandy soil (Table 3).The increase in the PBCK in this soil due biochar applications was from 1.685 (control) to2.679 cmole.kg–1.mole–1/2.l1/2 at highest addition level of biochar accounting for 59% of the originalpotential buffering capacity for K of this soil. The potential buffering capacity of potassium (PBCK)of the soil expresses the soil ability to supply potassium the soil solution (intensity) due to the loss ofpotassium from the soil or its uptake by the plants, which is related to the CEC of the soil (Tan2011). A high PBCK value indicates that the soil enough available potassium for plants, while a lowPBCK means that the soil is in a need of K fertilization. The PBCK in some Nigerian soils ranged

Table 2. Effect of biochar on pH, EC, soluble K and available K of the calcareous sandy soil.

BiocharTreatment

pH(1:1)

EC(dS/m)

O.M.(%)

Olsen-P(mg/kg) Soluble K(mg/kg)

NH4OAC-extractable K(mg/kg)

Control 8.15c 4.26a 0.077b 8.31b 100.4d 421.3d20 Mg/ha 8.17c 4.15a 0.117b 9.78a 144.3c 542.8c40 Mg/ha 8.23b 4.35a 0.123b 10.14a 187.1b 663.2b60 Mg/ha 8.31a 4.10a 0.193a 10.43a 232.7a 740.6a

The means, which have the same letter of the alphabet for each factor, do not significantly differ using LSD test at probability of 5%.

COMMUNICATIONS IN SOIL SCIENCE AND PLANT ANALYSIS 2029

from 0.06 to 2.00 cmole.kg−1.mole−1/2.l1/2 (Idigbor et al. 2009). Liang et al. (2006) indicated that thebiochar had higher ability for cation adsorption and maintenance than the OM because of its largersurface area and the higher negative surface charge. In addition, McElligott (2011) showed thatadding biochar to the soil led to increase in the CEC and exchangeable potassium of the soil.

The activity ratio of potassium in soil solution at equilibrium ðARKe Þ value is ameasure of the availability

or the intensity of labile K in the soil. The ARKe value was obtained when the value of ΔK = 0 and at the

intersection with the X-axis for the linear portion of the Q/I curve (Figure 2). Significant increases in theARK

e were recorded with applying biochar to the calcareous sandy soil (Table 3). The addition of biochar to

Figure 1. A typical Quantity/Intensity (Q/I) plot according to Evangelou (1986).

y = 1.685x - 0.103

R2

= 0.854 y = 2.148x - 0.151

R2

= 0.916

y = 2.300x - 0.187

R2

= 0.896

y = 2.679x - 0.234

R2

= 0.919

-0.25

-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.00000 0.02000 0.04000 0.06000 0.08000 0.10000 0.12000

Control

20 Mg/ha

40 Mg/ha

60 Mg/ha

ARK(mole.l-1)

±-1

)

Figure 2. Biochar effects on Q/I relationships of soil potassium.

Table 3. Effect of biochar on the Q/I ratio parameters of the calcareous sandy soil.

BiocharTreatment

PBCK

(cmole.kg−1.mole−1/2.l1/2) ARKe (mole.l−1) � ΔKo(cmole.kg−1)

Control 1.685c 0.061d 0.103d20 Mg/ha 2.148b 0.070c 0.151c40 Mg/ha 2.300b 0.081b 0.187b60 Mg/ha 2.679a 0.087a 0.234a

2030 A. EL-EYUOON A. Z. AMIN

this soil caused the ARKe value to raise from 0:061 controlð Þ to 0:087mole:l�1 at the highest addition level of

biochar (60 Mg/ha) accounting for 43% of the initial ARKe of this soil. Sparks and Liebhardt (1981) found

that the ARKe value ranged from 0.020 to 0.058mole:l�1 in the surface layer of the sandy loam soil. In some

calcareous soils, the ARKe value was reported to be varied between 0.0014 and 0.028 mole:l�1 (Samadi

2006). The ARKe values of the studied soil were greater than 0.01 mole/l, indicating that the adsorption of

potassium occurs on the mineral planar surfaces as a non-specific adsorption. Sparks and Liebhardt (1981)suggested that if the ARK

e is greater than 0.01 mole/l, the potassiumwill be adsorbed on the planar surfaces.The � ΔKo value which is a measure of the exchangeable K or the labile pool of K in the soil and

represents the non-specifically adsorbed potassium in the soil. The non-specific adsorption of Koccurs on the planar surfaces of soil minerals (Tan 2011). The � ΔKo value is calculated from theintercept of the linear portion with y-axis of the Q/I curve (Figure 2). Significant increases werefound in the � ΔKo value of the calcareous sandy soil with biochar additions (Table 3). Biocharadditions to the calcareous sandy soil increase its � ΔKo value from 0.103 (control) to 0.234 cmole.kg−1 at the highest addition level of biochar representing 127% of the normal � ΔKo value of thissoil. These increases in the � ΔKo value indicate that potassium is released to the soil solution dueto adding corn cobs biochar that has a high content of potassium. The values of � ΔKo ranged from0.044 to 2.5 cmole.kg−1 in some calcareous soils (Samadi 2006).

Fresh weight, dry weight and potassium content of wheat plants

Biochar additions to the calcareous sandy soil caused significant increases (P ≤ 0.05) in the fresh anddry weight of wheat plants (Table 4). Improved fresh and dry weight of wheat plants because ofadded biochar to this soil under study, fresh weight of wheat plants increased from 1.26 (control) to2.48 Mg/ha at the highest addition level of biochar while the dry weight raised from 0.51(control) to1.14 Mg/ha at highest addition level of biochar. Applying biochar at a level of 60 Mg/ha to this soilresulted in increases in the fresh and dry weight of wheat plants of 96.8 and 123.5%, respectively,compared to the control treatment. The improvement in the growth of wheat plants in this soilbiochar additions may be attributed the improvement in the physical properties of the soil, such asthe degree of aeration. In addition, biochar is considered a reserve for many plant nutrients. Esposito(2013) found that the application of biochar to the soil significantly enhanced the plant growthcompared to the control.

The results obtained from this experiment also showed a significant increase in the potassiumcontent in wheat plants with applying biochar compared to the control treatment. Potassium contentin the wheat plants increased from 1.14 mg/kg to 1.49 g/100 g of plant for (control) with adding thehighest level of biochar. Increase the potassium content within the plant is due to increase theamount of available potassium in the soil by adding biochar.

Conclusion

An application of the biochar produced from corn cobs to the calcareous sandy soil led to increase inthe availability of soil and in the soil potential buffering capacity of potassium. Since biochar

Table 4. Effect of biochar on fresh weight, dry weight and potassium content of wheat plants.

BiocharTreatment

Fresh weight(Mg/ha)

Dry weight(Mg/ha)

K content(g/100 g)

Control 1.26c 0.51c 1.14c20 Mg/ha 1.64b 0.75b 1.24bc40 Mg/ha 1.69b 0.79b 1.31b60 Mg/ha 2.48a 1.14a 1.49a

COMMUNICATIONS IN SOIL SCIENCE AND PLANT ANALYSIS 2031

produced from biomass can sequester carbon in the soil for hundreds to thousands of years.Accordingly, the biochar can be used as a source of potassium substitute for potassium chemicalfertilizers. Moreover, biochar additions improve some physical properties of the soil. Therefore, it isrecommended to use biochar that is produced from corn cobs in the newly reclaimed calcareous andsandy soils.

Acknowledgments

The author offers sincere thanks and appreciation to Prof. Dr. M.A. El-Desoky, Professor of Soil Sciences, Departmentof Soils and Water, Faculty of Agriculture, Assiut University, Egypt, for his linguistic correction of this manuscript.

References

Berek, A. K. 2014. Exploring the potential roles of biochars on land degradation mitigation. Journal of Degraded andMining Lands Management 1 (3):149–158.

Chan, K. Y., L. Van Zwieten, I. Meszaros, A. Downie, and S. Joseph. 2008. Using poultry litter biochars as soilamendments. Australian Journal of Soil Research 46:437–444. doi:10.1071/SR08036.

Esposito, N. C. 2013. Soil nutrient availability properties of biochar. M.Sc. Thesis, The Faculty of Cal Poly StateUniversity, San Luis Obispo, USA.

Evangelou, V. P. 1986. The influence of anions on potassium quantity-intensity relationships. Soil Science Society ofAmerica Journal 50:1182–1188. doi:10.2136/sssaj1986.03615995005000050018x.

Evangelou, V. P., and R. L. Blevins. 1988. Effect of long-term tillage systems and nitrogen addition on potassiumquantity-intensity relationships. Soil Science Society of America Journal 52:1047–1054. doi:10.2136/sssaj1988.03615995005200040028x.

Gaskin, J. W., R. A. Speir, K. Harris, K. C. Das, R. D. Lee, L. A. Morris, and D. S. Fisher. 2010. Effect of peanut hull andpine chip biochar on soil nutrients, corn nutrient status, and yield. Agronomy Journal 102:623–633. doi:10.2134/agronj2009.0083.

Gaskin, J. W., C. Steiner, K. Harris, K. C. Das, and B. Biben. 2008. Effect of low-temperature pyrolysis conditions onbiochar for agricultural use. Transactions of the American Society of Agricultural and Biological Engineers 51(6):2061–2069.

Glaser, B., J. Lehmann, and W. Zech. 2002. Ameliorating physical and chemical properties of highly weathered soils inthe tropics with charcoal - a review. Biology and Fertility of Soils 35:219–230. doi:10.1007/s00374-002-0466-4.

Griffin, R. A., and J. J. Jurinak. 1973. Estimation of activity coefficients from the electrical conductivity of naturalaquatic systems and soil extracts. Soil Science 116:26–30. doi:10.1097/00010694-197307000-00005.

Hesse, P. R. 1998. A textbook of soil chemical analysis. Delhi, India: CBS Publishers & Distributors.Idigbor, C. M., D. O. Asawalam, E. U. Onweremadu, and B. N. Ndukwu. 2009. Potassium quantity-intensity

relationship of fauna modified soils of Abia State. International Journal of Sustainable Agriculture 1 (2):49–52.Jackson, M. L. 1973. Soil chemical analysis. Englewood Cliffs, NJ, USA: Prentice-Hall, Inc.Jha, P., A. K. Biswas,, B. L. Lakaria, and A. S. Rao. 2010. Biochar in agriculture - prospects and related implications.

Current Science 99 (9):1218–1225.Joseph, S. D., M. Camps-Arbestain, Y. Lin, P. Munroe, C. H. Chia, J. Hook, L. Van Zwieten, S. Kimber, A. Cowie, B. P.

Singh, J. Lehmann, N. Foidl, R. J. Smernik, and J. E. Amonette. 2010. An investigation into the reactions of biocharin soil. Australian Journal of Soil Research 48:501–515. doi:10.1071/SR10009.

Lehmann, J., J. P. Da Silva, C. Steiner, T. Nehls, W. Zech, and B. Glaser. 2003. Nutrient availability and leaching in anarchaeological Anthrosol and a Ferralsol of the Central Amazon basin: Fertilizer, manure and charcoal amend-ments. Plant and Soil 249:343–357. doi:10.1023/A:1022833116184.

Lehmann, J., J. Gaunt, and M. Rondon. 2006. Bio-char sequestration in terrestrial ecosystems- a review. Mitigation andAdaptation Strategies for Global Change 11:395–419. doi:10.1007/s11027-005-9006-5.

Lehmann, J. and M. Rondon. 2006. Bio-char soil management on highly weathered soils in the humid tropics. In BiologicalApproaches to Sustainable Soil Systems, eds. N. Uphoff, A. S. Ball, E. Fernandes, H. Herren, O. Husson,M. Laing, C. Palm, J.Pretty, P. Sanchez, N. Sanginga, J. Thies, 517–530. Boca Raton, FL, USA: CRC Press.

Liang, B., J. Lehmann, D. Solomon, J. Kinyangi, J. Grossman, B. O’Neill, J. O. Skjemstad, J. Thies, F. J. Luizao, J.Petersen, and E. G. Neves. 2006. Black carbon increases cation exchange capacity in soils. Soil Science Society ofAmerica Journal 70:1719–1730. doi:10.2136/sssaj2005.0383.

Lindsay, W. L. 1979. Chemical equilibria in soils. New York, USA: John Wiley & Sons.Mbagwu, J. S. C., and A. Piccolo. 1997. Effects of humic substances from oxidized coal on soil chemical properties and

maize yield. In The role of humic substances in the ecosystems and in environmental protection, eds. J. Drozd, S. S.Gonet, N. Senesi, and J. Weber, 921–925. Wroclaw, Poland: IHSS, Polish Society of Humic Substances.

2032 A. EL-EYUOON A. Z. AMIN

McElligott, K. M. 2011 Biochar amendments to forest soils: Effects on soil properties and tree growth. M.Sc. Thesis,College of Graduate Studies, University of Idaho. Moscow, Idaho, USA.

Nigussie, A., E. Kissi, M. Misganaw, and G. Ambaw. 2012. Effect of biochar application on soil properties and nutrientuptake of lettuces (Lactuca sativa) grown in chromium polluted soils. American-Eurasian Journal of Agricultural &Environmental Sciences 12 (3):369–376.

Novak, J. M., W. J. Busscher, D. L. Laird, M. Ahmedna, D. W. Watts, and M. A. S. Niandou. 2009. Impact of biocharamendment on fertility of a southeastern coastal plain soil. Soil Science 174:105–112. doi:10.1097/SS.0b013e3181981d9a.

Oguntunde, P. G., M. Fosu, A. E. Ajayi, and N. Van De Giesen. 2004. Effects of charcoal production on maize yield,chemical properties and texture of soil. Biology and Fertility of Soils 39:295–299. doi:10.1007/s00374-003-0707-1.

Samadi, A. 2006. Potassium exchange isotherms as a plant availability index in selected calcareous soils of WesternAzarbaijan Province, Iran. Turkish Journal of Agriculture and Forestry 30:213–222.

Sparks, D. L., and W. C. Liebhardt. 1981. Effect of long-term lime and potassium applications on quantity—Intensity(Q/I) relationships in sandy soil. Soil Science Society of America Journal 45:786–790. doi:10.2136/sssaj1981.03615995004500040022x.

Sposito, G. 2008. The Chemistry of Soils, 2nd ed. New York: Oxford University Press.Steel, R. G. D., and J. H. Torrie. 1982. Principles and procedures of statistics a biometrical approach. New York, USA:

Mc Graw Hill Book Company.Tan, K. H. 2011. The Principles of Soil Chemistry, 4th ed., Boca Raton, FL: CRC Press.Woolf, D., J. E. Amonette, F. A. Street-Perrott, J. Lehmann, and S. Joseph. 2010. Sustainable biochar to mitigate global

climate change. Nature Communications 1:1–9. doi:10.1038/ncomms1053.

COMMUNICATIONS IN SOIL SCIENCE AND PLANT ANALYSIS 2033