RAHMAN S.M., ALI M.I,

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1 Scientific registration n o : 754 Symposium n o : 21 Presentation : poster Use of irradiated sewage sludge to increase soil fertility, crop yields and its impact on the environment. Utilisation de N 15 pour l'étude de l'effet d'une boue de station d'épuration sur la fertilité du sol, le rendement des cultures et sur l'environnement AHMED Sultana, RAHMAN S.M., ALI M.I, and HOSSAIN M.B. Bangladesh Institute of Nuclear Agriculture P.O. Box # 4, Mymensingh-2200, Bangladesh Introduction With increase in human population and rapid urbanization along with industrialization there is a progressive increase in disposal problem of sewage sludge. Sewage sludge can be considered both as a fertilizer and environmental pollutant. It improves fertility status and acts as a soil conditioner. But it also contains potentially toxic heavy metals which may affect the plant vis-a-vis human and animal through food-chain (McGrath et al, 1994). Proper management of sewage sludge in agricultural land is likely to reduce the pollution potential by recycling the hazardous gases through plant assimilation which is considered ecologically viable means of its disposal. (Wollenweber and Raven, 1993). Researches on irradiation of sewage sludge indicated its feasibility both economical and hygienical but work in this area is limited. Thus to assess the effect of sewage sludge (non-irradiated and irradiated) as a source of N on crop yields, heavy metal concentration in crops and improvements in soil fertility status the present study was initiated by the Joint FAO / IAEA Division under its Contract Research Programme. Materials and methods The moist sewage sludge (semi-solid) was collected from the Sewerage Treatment Plant, situated 15 km away from the capital city of Dhaka. The collected sewage sludge was air dried for a month, ground and processed. Calculated amount of the sewage sludge was irradiated at a dose rate of 5 kgy (500 krad) in a Co-60 Gamma-ray Irradiator. The physico-chemical and microbiological analyses of non-irradiated and irradiated sewage sludge were done. A field experiment was conducted at the experimental field of Bangladesh Institute of Nuclear Agriculture, Mymensingh. The experimental soil was dark grey floodplain (Haplaquept) with sandy loam texture. The experiment comprised of 10 treatment such as T kg N/ha from Urea, T 2-20 kg N/ha from Urea, T 3-50 kg N equivalent (eqv.)/ha T kg N eqv./ha, T kg N eqv./ha, T kg N eqv./ha from non irradiated sewage 1

2 sludge, T 7-50 kg N eqv. / ha, T kg N eqv. /ha, T kg N eqv./ha, T kg N eqv./ha from irradiated sludge were used. N-15 labelled urea was applied at the rate of 20 kg N/ ha (10% a.e) in treatments Unit plot size was 4m x 3m out of which 1m x 1m was separated by G.I sheets as isotope subplot. The experimental design was RCB with 4 replications. Results The data on the physico-chemical characteristics of both non-irradiated and irradiated sewage sludge including the experimental soil is presented in Table 1. The ph of sewage sludge was acidic. The organic matter content was considerably high. There was not much difference in total N content of non-irradiated and irradiated sewage sludge. Available P was high. Among content of heavy metals, Zn and Cu content were fairly high while Pb content was relatively low and lowest was Cd. McGrath, et al (1995) reported that sewage sludge containing domestic waste may have significant amount of Zn and Cu. The heavy metal contents were not much affected by irradiation. The ph of the experimental soil was. Total N and available P content were.09% and 9.3 ppm, respectively. The heavy metal status of the soil were reasonably high. Total bacterial counts were fairly high in the experimental soil and also in the nonirradiated sludge. The pathogenic bacteria and parasites were nil in the irradiated sludge. Highest grain yield was produced by application of 100 kg N/ha from urea fertilizer followed by fertilization with 200 kg N equivalent of irradiated sewage sludge. Increased grain yield in wheat by 1% was recorded from application of irradiated sewage sludge on an average over non-irradiated sludge treatments (Fig. 1). Increased crop yield by application of irradiated sewage sludge was reported due to inactivation of growth inhibitors in sludge by irradiation (Panday et al., 1988). Heavy metal concentrations in wheat grain as affected by different treatment did not follow any specific order and showed variable results (Table 2). Fe concentration was recorded to be highest followed by Zn while lowest concentration was noted in Cd. Table 3 shows the total N, fertilizer N and other N - 15 derived data. The irradiated sewage sludge contributed more N towards total N yield which was attributed to higher drymatter production. Percent Ndff ranged between 12.6 and 22.0 but the fertilizer N yield was quite low. The recovery of fert. N (applied N-15) by wheat ranged from 7.0 to 32.4% in different treatments. The highest being recorded from application of 200 kg N equivalent/ha of irradiated sewage sludge. The isotope aided experiment using N-15 indicated that availability of N to plant was more from irradiated sewage. However, application of irradiated sewage sludge along with chemical nitrogenous fertilizer is expected to contribute much towards nitrogen pool and significantly higher yield. Post harvest soil There were marginal differences in post harvest soil properties (Table 4). Heavy metal concentrations in soil were not much variable as compared to initial soil except Cd which showed increasing trend with increased rates of applied sewage sludge. It was reported that the metals are generally, strongly bound in the top soil (Williams et.al., 1987). Acknowledgment

3 Authors are grateful to the Joint of FAO/IAEA Division, Vienna, Austria for financial support provided to this co-ordinated Research Project. Bibliography McGrath S.P. Chang A.C. Page A.L. and Witter E Environ, Rev. 2: Pandya G.A., Prakash L., Devasia P Environ. Pollution 51 (1) : McGrath S.P., Chaudri A.M. and Giller, K.E J Industrial Microbiology 14 : Williams D.E., Vlamis J., Pukite A.H. and Corey J.E Soil Science 143: Wollenweber B., and Raven J.A Bot Acta 106 : Keywords : sewage sludge, irradiation, isotope, heavy metals, environment, pollution, Bangladesh. Mots clés : boue d'épuration, isotope radioactif, métaux lourds, environnement, pollution, Bangladesh Table 1. Physico-chemical and microbiological properties of initial soil, non-irradiated and irradiated sewage sludge. Parameters Initial Non-irradiated Irradiated soil sewage sludge sewage sludge ph (1:2.5 Soil:H 2 O) C.E.C (meq. %) Organic Carbon (%) Total N (%) Bray-II extractable P (mg kg -1 ) Exchangeable K (meq%) Heavy metals Aqua regia soluble (mg kg -1 ) Zn Cu Cd Pb Microbiological analysis Total bacterial Counts (22 o C) 3.0 x x x 10 3 " " " (36 o C) 1.9 x x x 10 3 Total Coliform 1.5 x x 10 4 nil Faecal Coliform 0.5 x x 10 2 nil E. Coli 1.0 x x 10 3 nil Other parasites nil 150 nil (TrichurisTrichuira)

4 Grain Straw Yield (kg/ha) T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 Treatment Fig.1.Effect of N urea, non-irradiated and irradiated sewage sludge on grain and straw yield of wheat. Table 2. N, P and heavy metal concentrations in wheat grain. Treatments N P Zn Cu Mn Fe Cd Pb % mg kg T 1 T 2 T 3 T 4 T 5 T 6 T 7 T 8 T 9 T CD(P=0.05) NS =Non Detectable

5 Table 3. Total and fertilizer N, Ndff, Ndfs and N-recovery by wheat as influenced by urea N, non-irradiated and irradiated sewage sludge application. Total DM Total Total N Fert. N Ndff Ndfs * N Treatments yield N yield yield & Recovery kg ha -1 % kg ha -1 kg ha -1 % Ndss * % % T T T T T T T T T T CD (P=0.05) NS NS 4.09 * Ndfs- Nitrogen derived from soil * Ndss- Nitrogen derived from sewage sludge

6 Table 4. Some physico-chemical properties of the post harvest soil as affected by different treatments. Treatments Soil depths cm ph soils: CaCl 2 (1:2.5) CEC meq% Organic C% Total N % Avail P mg kg -1 Aqua regia soluble mg kg -1 Zn Cu Cd Pb T T T T T T T T T T

TR02-5. Technical Re.port. Application of Anaerobically Digested Biosolids to Dryland Winter Wheat

TR02-5. Technical Re.port. Application of Anaerobically Digested Biosolids to Dryland Winter Wheat Technical Re.port TR02-5 Agricultural - Department of Cooperative April 2002. Experiment Soil and Crop Extension Station Sciences i Application of Anaerobically Digested Biosolids to Dryland Winter Wheat