Jpn. J. Trop. Agr. 50(4): 183-189, 2006

Evaluation of Degradation of Agricultural Soils Associated with Brick Burning in Selected Soil Profiles in the Eastern Region of

Md. Harunor Rashid KHAN*, Md. Khalilur RAHMAN2,A.J.M. Abdur ROUF3, Yoko OKI1 and Tadashi ADACHI1

1 Graduate School of Environmental Science, Okayama University 2 Department of Soil, Water and Environment, Faculty of Biological Sciences, University of , Dhaka 1000, Bangladesh 3 Ministry of Science and Information & Communication Technology, Bangladesh Secretariat, Dhaka 1000, Bangladesh

Abstract Degradation of agricultural soils associated with brick burning (400 to 1000•Ž) was examined based on profile studies of burnt (soil around brick kilns) and unburnt (agricultural land) soils in the Cox's Bazar and districts,

Chittagong division, , division and Dhaka and districts, Dhaka division. The pH values of the unburnt soils increased as a function of the soil depth, except for the sub-soils in Cox's Bazar, where the values decreased. Burning of soils significantly (p•…0.05) increased the average pH (8%) and EC values (520%). The average sand content of the soil profiles increased by 245%, while the silt and clay contents decreased by 42 and 36%, respectively. The average losses associated with the burning of agricultural soils were amounted to 66% for organic matter, 67 to 90 and 27 to 73% for available and total N, P, K and S, respectively. This deterioration of soil fertility throughout the 1 m deep profile in the area affected by brick factories covering 5000 ha led to a loss of large amounts of nutrients from the soils and to environmental degradation, along with contributing to changes in the global climate.

Key Words: Brick factory, Environmental degradation, Soil fertility

brick kilns in some cases tend to be shifted after 10 to Introduction 15 years due to the lack of agricultural topsoils nearby. Land degradation leading to declines in soil The abandoned kilns are then used for building houses quality and world food security is due to natural or for local fisheries, etc. However, in these areas, processes and anthropogenic activities (Eswaran, agricultural land is being lost. Blum (2002) stated that 1999). Soil degradation and environmental pollution to address the challenges faced by soil science in the are serious problems in the world today, because of 21st Century, the soil scientists should pay much their adverse effect on agriculture. More than 97% of attention to soil use, management and its benefits to the world food originated from land rather than from human societies along with societal and environmental the oceans and other aquatic systems. Three-quarters issues of soils. Therefore, the prevention of soil of the world soil degradation occur in tropical areas, degradation to promote sustainable agriculture is where over 100 million people are facing a total loss of essential. Brick kiln is one of the principal agents of productivity from their land and about 62% of global topsoil degradation and environmental pollution in soil degradation has taken place in Asia and Africa Bangladesh (Khan et al., 2004). Every year, brick kilns (Dowdeswell, 1998). About 7% of the total land area are not only destroying large areas of lands through (13,391 km2) of Bangladesh is experiencing land brick burning but also reduce the production of degradation (Eswaran et al., 1993). Although the total mango, rice, etc. due to excessive dusting during crop area affected by brick kilns in Bangladesh has not pollination. Brick burning not only alters the physico- been determined, bricks are made by collecting soils chemical properties and habitats of the nearby soils from a depth of about 1 to 2 m in agricultural land but also contributes to the pollution of environments which extended over about 5000 ha during the 1998-99 and ecosystems. The topsoil nutrient elements and soil period in different pockets of brick fields (Rahman and biota are destroyed through brick burning. The Khan, 2001). These affected areas are expanding adverse effects, including expansion and intensity, the rapidly due to the increase in brick production. The factors involved and/or affected by brick kilns should

Received Oct. 5, 2005 be analyzed. Accordingly, as a part of coordinated Accepted Sept. 16, 2006 studies on soil degradation and environmental pollution *Corresponding author Okayama 700-8530, Japan in different regions of Bangladesh, Khan et al. (2004) [email protected]. evaluated the lands in the Northwestern part of the 184 Jpn. J. Trop. Agr. 50 (4) 2006 country and characterized the soils (0-15 cm depth) in Materials and Methods terms of acidity, land suitability for particular crops and fertilizer use. Simultaneously, they reported that the Five agro-ecological zones in the eastern regions brick kilns are exerted considerable effects on the of Bangladesh, including Dhaka, Sylhet and Chitta- concentrations of oxides of C and N in the atmosphere gong divisions were studied for the assessment of the through soil burning. However, the findings were impact of brick kilns on the degradation of agricultural different from those in the present study. Moreover, topsoils. The sites were selected based on the climatic the present study was carried out in another region, conditions, soil type and fertility status, geographic considering the agro-ecological influences and impacts position and land use (Table 1). Five man-made profiles of burning of soils up to a depth of 100 cm. It is of each burnt soil obtained by staking the soils in open essential to investigate the contribution of soils to the air at the boundary or periphery of brick kilns were release and/or fixation of greenhouse gases (IUSS, studied. They consisted of remnants in the brickfields

2002) . However, studies on these aspects are scanty and had been subjected to heating at 400 to 1000•Ž and the inhabitants of urban areas, who have been temperatures. The unburnt soils profiles consisted

adversely affected by brick manufacturing, are urgently mostly soils in agricultural lands from where the seeking ways and methods to prevent topsoil degradation topsoils (1 to 2 m depth) had been removed, depending and preserve the environment. Against this back- on soil quality, for brick production. The studies were ground, the objective of the present study was to carried out during the dry seasons of 1998 to 1999. Pits evaluate the degradation of agricultural soils associated approximately 1.5 m deep were dug for each burnt and with brick burning and possible hazards to environment unburnt natural soil at a distance of about 0.5 km from in various soils and under different climatic conditions. the brick kilns where the topsoils had usually been

Table 1 Description of study sites in the eastern region of Bangladesh

Sources: Fertilizer Recommendation Guide (BARC,1997), *Hussain (1992; based on FAO/UNESCO legend), #AEZ=Agro-ecological zone, OM*1=Organic matter, and WHC*2=Water-holding capacity. Khan et al.: Degradation of agricultural soils associated with brick burning 185

collected. From the agronomic point of view, the Schlichting and Blume (1966). Total P content was topsoils to a depth of 100 cm are very important in determined by the yellow color method (Jackson, terms of nutrient dynamics and degradation of soil 1973), S content was determined after the development fertility. Accordingly, the soils in each profile were of turbidity (Klute, 1986) and the total K content was sampled and analyzed at intervals of 10 cm to a depth measured with a flame photometer (Klute, 1986). of 100 cm. The representative data obtained from the Correlations between the selected parameters, level of soils at selected depths and the weight of the topsoils significance and standard deviation were determined

(1 m extending over an area of 5,000 ha: (topsoil using statistical packages in Office 2003 Program. sampling areas) were considered for the determina- Results and Discussion tions of nutrients. The bulk samples obtained from each section were stored in the field under moist Sites and soil conditions conditions by putting the soil samples into polyethylene The total land area of Bangladesh has been bags in an airtight box immediately prior to laboratory divided into 30 agro-ecological zones (AEZ), which analysis. The sub-samples were air-dried and gently provides extended national, district and thana digitized crushed to pass through 1 and 2 mm mesh sieves, as databases related to soil/land types, climatic condi- required. After treatment with 300 g kg-1 H2O2,particle tions, hydrology, crops, land use and crop suitability as size distribution was determined by the pipette method well as computerized procedures for land productivity (Day, 1965). Textural classes were determined using a assessment and mapping, demographic and socio- triangular co-ordinate diagram. The pH of the soil economic information. Detailed information about the samples was determined in the laboratory (dry soil individual AEZs can be obtained from www.fao.org. and distilled water ratio of 1:2.5) and measured by The present study sites in the five agro-ecological using a Corning glass electrode pH meter (Jackson, zones exhibited average rainfall values ranging from

1973) . Electrical conductivity (EC) of the soils was 1500 to more than 5000 mm and temperatures ranging determined at a ratio of soil:water=1:5 according to from less than 15•Ž to more than 40•Ž, and differed in the method of Richards (1954). Organic carbon content the soil types, soil fertility and land use conditions of the soil samples was determined volumetrically by (Table 1). Among the sites, drier conditions prevailed the wet oxidation method with a 1N K2Cr2O7 solution at Keraniganj in Dhaka while moister conditions and concentrated H2SO4 mixture, followed by rapid prevailed at Ramu in Cox's Bazar. Eight general soil titration with a 1N FeSO4 solution, as recommended by types (Hussain,1992: based on FAO/UNESCO Legend)

Nelson and Sommers (1982). Organic matter content predominated in the selected five AEZs (BARC, 1997). of the soil samples was estimated by multiplying the The fertility of the soils in the different AEZs ranged percentage of organic carbon using the conventional from medium to low based on the soil fertility

Van Bemmelen's factor of 1.724. Available nitrogen was classification (BARC, 1997). The soils at Devidar in extracted with a 2M KCl solution and the amount was Comilla were relatively more fertile, followed by the determined according to the Micro-Kjeldahl distillation soils at Srimangal in Moulvibazar and the soils with the method (Jackson, 1973). Available P in soil was extracted lowest fertility were identified at Keraniganj in Dhaka with a 0.5 M NaHC03, as recommended by Olsen et al. (Table 1). (1954) and the amount was determined with a spectrophotometer after the development of a blue Distribution of soil properties color using ascorbic acid and potassium antimony The pH values in the burnt and unburnt soil tartrate as reagents. Available S was extracted with a profiles ranged from 6.8 to 7.5 (burnt) and 4.3 to 5.8

500 mg P kg-1 solution of Ca (H2PO4) and the amount (unburnt) for Cox's Bazar, 4.9 to 8.1 and 6.3 to 6.5 for was determined with a spectrophotometer after the Comilla, 3.8 to 6.2 and 4.1 to 4.6 for Moulvibazar, 4.9 to development of turbidity with BaC12using Tween-80 as 6.2 and 5.1 to 6.6 for Dhaka and 5.1 to 6.5 and 4.2 to 6.5 the suspending agent of sulfate precipitation (Klute, for Mymensingh (Table 2). The pH values in the

1986). Total N content in soil was determined by the profiles of the unburnt soils increased with increasing Micro Kjeldahl method following H2SO4acid digestion depth, except for the soil profile in Cox's Bazar, where and alkali distillation (Jackson, 1973) . Total P, K and S the pH values of the sub-soils decreased at depths from contents were determined by digestion with a mixture 60 cm (Table 2). The pH values of the burnt soils also of concentrated HCl/HNO3 (1:3), as described by increased toward the deeper layers of soils, except for 186 Jpn. J. Trop. Agr. 50 (4) 2006

Table 2 Some selected properties of burnt and unburnt soils sampled from soil profiles (lm depth) in the eastern region of Bangladesh

*Texture: C =Clay , L=Loam, SiC=Silty Clay, SiL=Silt Loam, SCL=Sandy Clay Loam, SiCL=Silty Clay Loam, SL=Sandy Loam. Khan et al.: Degradation of agricultural soils associated with brick burning 187

the soil profile in Moulvibazar, where the trend of pH the available K content (Table 2). The soils of Mymensingh distribution was opposite (Table 2). The profile of the ranked 4th for the K content. The average loss of these unburnt soil up to 1 m depth in Moulvibazar was components due to burning of the agricultural topsoils strongly acidic with an average pH value of 4.3, amounted to 66% (IOAC) for soil organic matter, 67 to followed by pH 5.0 in Cox's Bazar and 5.8 in 90 % and 27 to 73% for available and total N, P, K and S,

Mymensingh (Table 3). Soil burning was found to respectively (Table 3). Khan et al. (2004) reported in increase the average pH values of soils, except for the their other studies that the losses of the total N, P, K soils at the Dhaka site and the increment was striking and S in the surface (15 cm depth) soils amounted to for the soils of Cox's Bazar, which might be due to the 66, 59, 91 and 58%, respectively. It is well known that high EC value of the soils (Table 3). In the present soil organic matter is a reservoir for plant nutrients, study, the increment in pH was 8% (IOAC=increase enhances the water-holding capacity, protects the soil over average content of unburnt soil), while in other structure against compaction and erosion, and thus studies (Khan et al., 2004), in the surface soils (15 cm determines soil productivity. All agriculture to some depth) in the separate AEZs of the Northwestern region extent depends on the content of soil organic matter as

( division) of Bangladesh, the IOAC was 15%. well as those the above soil nutrients. Maintenance of The EC values of all the soil profiles, except for organic matter is critical for preventing land degradation the Cox's Bazar profile increased due to burning of the (Martius et al., 2001). The distribution of organic soils (Table 2) and the average increment was 520% matter, total N, P, S and available N, S in the unburnt (IOAC: Table 3). However, the IOAC was only 3% in soil profiles showed significant (p•…0.05) negative the studies reported by Khan et al. (2004) for the relationships with the corresponding depths of soils surface soils of the Rajshahi division. Sand content of (data not shown), though that of total-K in the unburnt all the soils increased by 245% (IOAC), while the silt soils showed a significant positive relationship. The and clay contents decreased by 42 and 36%, respectively trend of the relationships of these components was (Table 3), which may lead to the reduction of the very similar to that in the burnt soils but not strength and quality of bricks. significant. Soil organic matter content showed a

significant positive relationship with the contents of the

Losses of nutrients nutrients in the unburnt soils, while these relationships

The contents of organic matter, available and total were not significant for the burnt soils, except for the

N, P and K were higher in the unburnt soils of Cox's total S content. The available N content displayed a

Bazar, followed by the soils of Mymensingh, except for significant positive relationship with the nutrient

Table 3 Average values of selected soil properties in different soil profiles up to 100 cm depth in the eastern region of Bangladesh

IOAC = Increase over average content of unburnt soil. 188 Jpn. J. Trop. Agr. 50 (4) 2006

contents in both the burnt and unburnt soils but no to the Alexander von Humboldt Foundation in Germany significant relationship was observed for P. The trends for their instrumental support. They are also grateful of the relationships among the components studied in to the project staffs and technicians of the Department both the burnt and unburnt soils were very similar of Soil, Water and Environment, University of Dhaka, with a few exceptions. These relationships revealed Bangladesh for their generous support to complete that the burning of topsoils seriously degraded the soil this research work. fertility, productivity and sustainability level of the References environments. This large loss of nutrients associated BARC (Bangladesh Agriculture Research Council). 1997. Fertilizer with the burning of topsoils, (almost three-quarters: Recommendation Guide. Publ. BARC, Farm gate, Tejgaon, Table 3) reduced crop production and also led to Dhaka, Bangladesh. pollution of the environment and atmosphere. The Blum, W. E. H. 2002. Bulletin of the international union of soil science, No. 101. losses by burning of 66% of organic matter, 44% of Day, P. R. 1965. Particle fractionation and particle size analysis. total N and 70% of total S throughout the 1 m deep Methods of Soil Analysis. Part 2 (Black, C. A. ed.), Agron. profile (Table 3) over an area of 5000 ha, led to a large Series 9, Am. Soc. Agron., Publ. Madison, (WI) p.545-566. Dowdeswell, E. 1998. Extent and impacts of soil degradation on a depletion of nutrients from the soils and also adversely world-wide scale. Advances in Geoecology 31 (Blume, et al. affected the environment, along with contribution to eds.). Catena V. GmbH. p.xi-xv. changes in the global climate. Khan et al. (2004) stated Eswaran, H. 1999. Recommendation in the proceedings of the 2 ndinternational conference on land degradation. January 25-29, that the losses of total N and S from the 0 to 15 cm Khon Kaen, Thailand. p.9. layers of the surface soils amounted to 66 and 58%, Eswaran, H., S. M. Virmani, and L. D. Spivey Jr 1993. Sustainable respectively, which revealed that soil type/position, agriculture in developing countries: constraints, challenges, and choices. Technologies for sustainable agriculture in the climatic conditions in the different AEZs exerted a tropics, (Ragland, J. and R. Lal eds.). ASA Sp. Publ. 56, considerable influence on the extent of nutrient loss. Madison, (WI) p.7-24 The present assessment should result in increasing Hussain, M. S. 1992. Soil classification with special reference to the soils of Bangladesh. Publ. Univ. of Dhaka, Dhaka, Bangladesh. the awareness about the status of soil degradation and IUSS (International Union of Soil Science). 2002. Soil and the environmental consequences induced by brick burning. environment, IUSS Commission VIII, World congress of soil

Losses of organic matter, N, P, K and S of the topsoil science, 14-21 August, Thailand. p.66. Jackson, M. L. 1973. Soil Chemical Analysis. Prentice Hall of amounted to about three-quarters through brick India Pvt. Ltd., (New Delhi) p.41-330. burning. The striking loss of soil organic matter and Khan, H. R., M. K. Rahman, A. J. M. A. Rouf, and G. S. Sattar essential plant nutrients led to a decrease in crop 2004. Land evaluation and effects of brick burning on soil degradation at all in Rajshahi division. Dhaka Univ. production and associated habitats and also adversely J. Biol Sci.13: 49-60. affected the environment. Dust, high temperatures Klute, A. (ed.) 1986. Methods of Soil Analysis. Agron. Series 9. Am. Soc. Agron. Publ., Madison, WI. (400 to 1000•Ž) and unhygienic conditions of living of Martius, C., H. Tiessen, and van P. L. G. Vlek (eds.) 2001. workers create hazards to the survival of the local Managing organic matter in tropical soils: scope and habitats. The present investigations suggested that the limitations. Nutrient Cycling in Agroecosystems, 61, 1-2. brick producers should strictly follow the rules NRDC (National Research Development Corporation-a government of India enterprise) 2001. Technology offer: Semi-mechanized restricting the use of agricultural topsoils for brick brick manufacturing plant. Website: www.nrdcindia.com p.l-3. production. They can also adopt suitable international Nelson, D. W., and L. E. Sommers 1982. Total carbon, organic technology to produce bricks or blocks with a good carbon and organic matter. Methods of Soil Analysis. Part 2 (Page, L. A. ed..), Agron. Series 9, Am. Soc. Agron., Publ. quality, as practiced in the developed countries, through Madison, (WI) p.539-579. the use of alluvial clay and cement or black cotton and Olsen, S. R., C. V. Cale, F. S. Watanabe, and L. A. Dean 1954. Estimation of available phosphorus in soils by extraction lateritic clay (NRDC, 2001). Soil degradation and with sodium bicarbonate. USDA Circ. 939, Washington. environmental pollution are not inevitable and can be Rahman, M. K, and H. R. Khan 2001. Impacts of brick kiln on controlled if major abuses are avoided and improved topsoil degradation and environmental pollution. Project report methods of environmental management are developed. submitted to the Ministry of Science and Information & Communication Technology, Bangladesh Secretariat (Dhaka)

Acknowledgements p.210. Richards, L. A. (ed.) 1954. Diagnosis and improvement of saline

The research was funded by the Ministry of and alkali soils. Agriculture Handbook No. 60, USDA. US Govt. Print. Office (Washington) p.84-156. Science and Information & Communication Technology, Schlichting, E., and H. -P Blume 1966. Bodenkundliches Praktikum. Government of Bangladesh. The authors are grateful Verlag P Parey Hamburg. Khan et al.: Degradation of agricultural soils associated with brick burning 189

バ ングラデ シュ東部 における土壌断面 からみた レンガ焼成 による 農地土壌 の劣化 評価

Md. Harunor Rashid KHAN1*• Md. Khalilur RAHMAN2 A.J.M. Abdur ROUF3 •E 沖 陽子1・ 足 立 忠 司1

1岡 山大学大学院環境学研究科 2 Department of Soil, Water and Environment, Faculty of Biological Sciences, University of Dhaka, Dhaka 1000, Bangladesh 3 Ministry of Science and Information & Communication Technology , Bangladesh Secretariat, Dhaka 1000, Bangladesh

要 約 レ ン ガ焼 成(400～1000℃)に よ る 農 地 土 壌 の 劣 化 を レ ン ガ 窯 近 傍 の土 壌 と農 地土 壌 と を比 較 す る こ と に よ り検 討 し た.供 試 し た 土 壌 は バ ン グ ラ デ シ ュ東 部 に 位 置 す るCox's Bazar地 方, Comilla地 方, Moulvibazar地 方, Dhaka地 方 お よ びMymensingh地 方 か ら得 た も の で あ る.農 地 土 壌 のpHは, Cox's Bazar地 方 の 下 層 土 を除 き(こ の 場 合 は逆 の 現 象 を示 し た),土 層 の 深 さ と共 に 増 加 す る が,レ ン ガ 窯 近 傍 の 土 壌 に お い て は,5%水 準 で 有 意 にpHは 平 均8%,ECは520%に 増 大 し た.土 層 の砂 質 含 量 は245%ま で 増 加 し,シ ル トと粘 土 含 量 は39%お よ び36%減 少 し た.対 照 と して 実 施 し た農 地 土 壌 へ の 火 入 れ は 有 機 物 含 量 を66%減 少 させ, N, P, Kお よびS含 量 も有 効 態 と して67%か ら90% ,総 量 と して27%か ら73%減 少 した.こ の 総 量 の3/4程 度 の 農 地 土 壌 の 劣 化 現 象 は 肥 沃 度 を低 下 させ る の み な らず,レ ン ガ窯 近 傍 の5000haの 面 積 で1m 以 浅 の プ ロ フ ァ イ ル か ら有 機 物 総 量 の66%,全 窒 素 量 の44%お よ び 全 硫 黄 量 の70%の 焼 失 が 算 出 され た の で,二 酸 化 炭 素, 窒 素 酸 化 物 お よび 硫 黄 酸 化 物 の 放 出 に よ る環 境 公 害 や 気 候 変 動 へ の 影 響 が 懸 念 さ れ る. キ ー ワ ー ド:土 壌 肥 沃 性 の 劣 化,農 地 土 壌 の 火 入 れ,プ ロ フ ァ イル 調 査

* Corresponding author

〒700-8530岡 山 市 津 島 中3-1-1 [email protected].