Adsorption of Poultry Litter Extracts by Soil and Clay Kim H. Tan,* Vaman G. Mudgal, and Ralph A. Leonard Department of Agronomy, University of Georgia, and U S D A , Watkinsville, Ga.
Adsorption of the water-soluble fraction of poultry litter was investigated at constant temperatures using Cecil, Tifton, and Hayesville soils and kaolinite and bentonite as adsorbents. Organic matter extracts were characterized by infrared spectroscopy. The results indicated that broiler litter was adsorbed in almost similar amounts as layer litter extract by either soils or clays. However, degree of adsorption varied with types of clays as well as with soil series. The slope of the adsorption isotherms was steeper for bentonite than for kaolinite. For soils, the slope of the isotherms decreased in the following order: Hayesville > Tifton > Cecil. The adsorption isotherms were linear within the concentrations ,examined; the slopes decreased with increasing temperature from 25, 35 to 50°C. Protonated poultry litter extract was adsorbed in larger amounts than Naf -saturated extract, indicating that ionic bonding might be involved, or that ionization of carboxyl groups was reduced.
The application of organic matter as a soil amendment currently receives considerable research attention due to the ever-expanding production of organic waste and the resultant sanitary disposal problem. Poultry litter is of special concern in the southeastern part of the United States. Eleven million tons are produced each year in the Southeast ( I ) and, if not properly disposed, may constitute a pollution hazard. Investigations have shown that the manure and litter from broiler and layer houses could be a valuable source of plant nutrients (2, 3 ) . Significant yield responses resulting from the use of poultry litter have been reported for corn, millet, potatoes, cotton, oats, vegetables, and forage crops (3-5). However, heavy applications of poultry litter to the same field each year could also prove wasteful, with respect to some plant nutrients, in addition to creating hazards of grass tetany and fat necrosis in cattle and environmental pollution. The problems of pollution and plant nutrient losses resulting from the use of poultry litter depend to some extent on the rate of litter decomposition and mobility of soluble components in the soil. Since little is known regarding adsorption and leaching of poultry litter components in soils, this study was initiated to investigate adsorption of different types of poultry litter by soils. Materials and M e t h o d s
Poultry Litter. Litter selected for this investigation was from broiler and layer poultry. Poultry litter (broiler and layer) consisted of accumulated droppings, pine wood shavings, feathers, and wasted feed. Each poultry litter (fresh) was freeze-dried, ground, and separately extracted with distilled water according to the following procedures. A sample of 100 grams of poultry litter was added to 1000 ml of boiling water, cooled overnight, and centrifuged to remove suspended particulate matter. This method dissolved 16% of the broiler litter and 13% of the layer litter ( I ) . The soluble extracts were then freezedried and stored for later use and analysis. Part of the ex132
Environmental Science & Technology
tracts were saturated either with H + or Na- by shaking with H + - or Na+-saturated Dowex 50W-X8 cation exchanger (20-50 mesh). The H + - and Na+-saturated organic matter extracts were recovered by centrifugation a t 15,000 rpm, freeze-dried and stored for use in the adsorption experiments. The organic material was not adsorbed by Dowex 50W-X8 and was anionic in nature. Therefore, it was acting as a cation exchanger. Total elemental analysis of the original litter and its extracts was performed by direct-reading emission spectrographic techniques. One gram of freeze-dried sample was ashed a t 450°C in a muffle furnace and the ash was taken up in a buffer solution for burning in a carbon arc to determine macro- and microelement content. For further details, reference is made to Jones and Warver (6). Nitrogen was analyzed separately by the semimicro Kjeldahl method ( 7 ) . Soils. Soils used for the experiments were (a) Cecil surface soil (0-15 cm) and Cecil subsoil (15-46 cm), ( b ) Tifton A2 (5-25 cm) and B l t (25-46 cm), and (c) Hayesville B21t (51-71 cm) samples. According to the U S . Soil Taxonomy, these soils are classified as Typic Hapludults, Plinthic Paleudults. and Typic Hapludults, respectively (8). These soils were selected to represent large areas of (a) the Piedmont, ( b ) the Coastal Plain, and (c) the Mountain region of the Southeast. The samples were airdried and sieved to pass a 2-mm sieve before use. In addition, pure kaolinite and bentonite (purchased from Ward’s Natural Science Establishment, Inc.) were used for the adsorption experiments. Adsorption Analysis. To 10 grams (oven-dry basis) of soils (or 1 gram of kaolinite or bentonite, Tifton > Cecil. The isotherms in Figure 3 for adsorption of broiler litter on Cecil topsoil at 25", 35", and 50°C show that adsorption decreased with increasing temperature. No measurements were made as to the exo- or endothermic nature of the adsorption process, since analyses were done at constant temperatures.
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Figure 1. Adsorption of water extracts of poultry litter at 35°C by clays (significant at the 1% level of probability) ( 1 ) Broiler litter by bentonite, ( 2 ) layer litter by bentonite, (3) layer litter by Kaolinite, and ( 4 ) broiler litter by kaolinite
The isotherms in Figure 4, contrasted adsorption of Na+ - and "-saturated extracts by Cecil topsoil and Cecil subsoil. In each soil horizon, adsorption was greatest for the H + -saturated extract. Protonated organic compounds are generally considered more reactive with clay surfaces than nonprotonated compounds ( I , 13, 1 5 ) . Protonation of weak base functional groups such as -HN2+ might produce positive electrical charges that would bind tightly to the negative clay surface, a process which might be active in present experiments. Another possibility was that neutralization of carboxylic acid groups would also increase adsorption by reducing the negatively charged groups on the molecule which would be repelled by the negative clay surface. The effect of Na- or H+ treatment on adsorption was greater in the subsoil system than in the topsoil. Again, this difference might be a reflection of the presence of higher native organic matter in the topsoil. Infrared Analysis. Poultry litter extracts undoubtedly contained a range of compomds. Infrared spectra (Figure 5) of the freeze-dried extract were characterized by weak Volume 9, Number 2 , February 1975 133
bands at 2920 cm-1 and strong bands at 1620 and 1400 cm-1 for aliphatic C-H and carboxyl stretching vibrations, respectively. Strong, unassignable bands were also present in the 1130-1050 cm-1 region. These band characteristics and general spectral features corresponded closely to those reported earlier for polysaccharides (16, 17). Although the extracts contained nitrogenous compounds (Table I) and other substances, apparently the dominant compound was polysaccharidelike material originating
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probably as a microbial decomposition product of the wood shavings, feed residues, or both. Infrared spectra (Figure 5 ) of material remaining in solution after contact with soil were similar to those of the original material. However, for both broiler litter and layer litter extracts, the carboxyl vibration at 1400 cm-1 was reduced by contact with soil. This observation suggested that compounds with more reactive carboxyl groups are preferentially adsorbing.
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Adsorption of H + - and Na+-saturated broiler extracts by Cecil soil (significantat the 1% level probability) Figure 4.
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Adsorption of water extracts of broiler litter at 35°C by soils (significantat the 1 % level of probability) Figure 2.
( 1 ) Tifton A2, ( 2 ) Hayesville B211, (3)Tifton B l t , and ( 4 ) Cecil subsoil
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Adsorption of water extracts of broiler litter by Cecil topsoil at (1) 25°C (2) 35"C, and (3) 50°C Figure 3.
134
Environmental Science 8, Technology
(1) Layer litter extract after adsorption, (2) layer litter extract before adsorption, (3) broiler litter extract after adsorption, and ( 4 ) broiler litter extract before adsorption.
Literature Cited
(1) Tan, K. H., Leonard, R. A., Bertrand, A. R., Wilkinson, S. R., Soil Sei. Soc. Amer. Proc., 35,265-9 (1971). (2) Lassiter, J. W., Mason, J. V., Perkins, H. F., Brown, A. R., Beaty, E. R., Univ. Ga. College Agr., Ga. Agr. Expt. Sta., Res. Bull., 25,23 pp, 1967.
(3) Perkins, H. F., Parker, M. B., Walker, M. L., ibid., Bull. N.S., 123,24pp, 1964. (4) Papanos, S., Brown, B. A., Storrs Agr. Expt. Sta., Univ. Connecticut, INF Series 13, 1-5, 1950. (5) Parker, M. B., Univ. Ga., College Agr., Ga. Agr. Expt. Sta., Bull. N.S., 159,5-15, 1966. (6) Jones, J. B., Jr., Warver, M. H., “Analysis of Plant Ash Solution by Spark Emission Spectroscopy,” in E. L. Grove and A. J. Perkins, Eds., “Development in Applied Spectroscopy,” Vol. 7A, pp 152-60, Plenum Press, New York, N.Y., 1969. (7) Bremner, J. M., “Total Nitrogen,” in C. A. Black (Editor-inChief), “Methods of Soil Analysis,” Part 2, A.S.A. Monograph 9, 1149-78, 1965. (8) Soil Survey Staff, “Soil Series of the United States, Puerto Rico, and the Virgin Islands, Their Taxonomic Classification,” 361 pp, Soil Conservation Service, USDA, 1973. (9) Tan, K . H., McCreery, R. A., Soil Sei. Plant Anal., 1, 75-84 (1970).
(10) Tan, K . H., King, L. D., Morris, H. D., Soil Sei. Soc. Amer.
Proc., 35,718-51 (1971). (11) Weber, J. B.,Amer. Mineralog., 51,1657 (1966). (12) Greenland, D. J., Oades, J . M., Trans., 9th Intern. Congr. Soil Sci. I, pp 657-78, 1968. (13) Bailey, G. W., White, J. L., Rothberg, T., Soil Sci. SOC. Amer. Proc., 32,222-34 (1968). (14) Inoue, T., Wada, K., Trans., 9th Intern. Congr. Soil Sci. 111, pp 289-98, 1968.
(15) Mortland, M. M..Adv. Aeronomv. 22.75-117 (19701. (16) Mortenson, J. L., Anderson, D.” M.,’ White, J . L.; “Infrared Spectroscopy,” in C. A. Black (Editor-in-Chief), “Methods of Soil Analysis,”Part 1,A.S.A. Monograph 9,743-70, 1965. (17) Tan, K. H., Clark, F. E., Geoderma, 2,245-55 (1969).
Received for review April 19, 1974. Accepted Oct 15, 1974. Contribution from the University of Georgia, Agricultural Experim‘ent Station, College Station, Athens, Ga., and Soil, Water and Air Sciences, Southern Regional Agricultural Research Service, U.S. Department of Agriculture. Mention of commercial products is for identification only and does not constitute endorsement by any agency of the U.S. Government.
Rates of Degradation of Malathion by Bacteria Isolated from Aquatic System Doris F. Paris,* David L. Lewis, and N. Lee Wolfe
Freshwater Ecosystems Branch, Southeast Environmental Research Laboratory, National Environmental Research Center-Corvallis, U . S . Environmental Protection Agency, Athens, Ga. 30601
A heterogeneous bacterial population that grew in culture solution with 0,O-dimethyl S-(1,2 dicarbethoxy)ethylphosphorodithioate (malathion) as the only extraneous source of carbon has been isolated. Gas-liquid chromatographic analysis of methylated samples from the cultures showed that the major metabolite was @-malathion monoacid. Only 1% of the malathion was transformed to malathion dicarboxylic acid, 0,O-dimethyl phosphorodithioic acid, and diethyl maleate. At low concentrations of malathion (less than the value of K,) and low concentrations of bacteria, the rate of bacterial degradation can be described mathematically by a second order rate expression. System analysts may find this kinetic expression useful in the construction of models.
0,O-dimethyl S -( 1,2 dicarbethoxy)ethylphosphorodithioate (malathion) is a widely used organophosphorus pesticide. Its increased application is evidenced by a steady rise in production, approaching 35 million lb in 1971 ( 1 ) . This nonsystemic insecticide and acaricide has received wide usage primarily because of its low mammalian toxicity and its biological selectivity. I t is used in agriculture for insect control and in mosquito control by direct application to water areas. Malathion can therefore enter the aquatic environment either directly or through agricultural runoff. Because of its wide usage, extensive research has been stimulated concerning the biological degradation of malathion. Most studies to date have revolved around its degradation in soils. Matsumura and Boush ( 2 ) reported rapid degradation of malathion in cultures of the soil fun-
gus, Trichoderma viride, and a bacterium, P s e u d o m o n a s sp., isolated from soil, The products of metabolic degradation were mainly carboxylic acid derivatives of malathion, indicating carboxylesterases are probably involved in microbial metabolism. High demethylation activity was also evident in some Trichoderma uiride varieties indicating another degradation pathway. Walker and Stojanovic ( 3 ) found that malathion is readily degraded by an Arthrobacter sp. The four metabolites produced were identified as malathion half-ester, malathion dicarboxylic acid, potassium dimethyl phosphorothioate, and potassium dimethyl phosphorodithioate. The studies of Mostafa et al. ( 4 ) also indicate that malathion is readily degraded. These researchers report that the fungi, Penicillium rota t u m and Aspergillus niger, metabolized 76 and 59% of the malathion in the medium within 10 days. Both fungi degraded the insecticide through carboxylesteratic hydrolysis as well as by a demethylation process. Data concerning the fate of malathion and its degradation products in natural waters are not available. Most information concerning its breakdown by aquatic microorganisms pertains to its toxicity to such organisms. Algal growth was reported to be inhibited by malathion ( 5 ) ; Sanders and Cope (6) found that malathion was toxic to two species of daphnids; and Macek and McAllister (7), in their insecticide susceptibility studies of fish (catfish, bullhead, goldfish, minnow, carp, sunfish, bluegill, bass, rainbow salmon, brown salmon, coho salmon, and perch), reported considerable species differences, the lowest tolerance being coho salmon (96-hrTL50 = 0.101 ppm). An evaluation of the environmental impact of malathion on the aquatic environment requires an understanding of the breakdown processes, biological and otherwise, of the insecticide. An integral part of this underVolume 9, Number 2,February 1975 135
