Summary
Urea hydrolysis was measured in two separate sets of experiments. (1) Nine soil (0–15 cm) samples were treated with 200 μg of urea-N g−1 dry soil and incubated (at 37°C) at 50 per cent of the water holding capacity. Samples were periodically analysed for the remaining urea-N. The urease activity (time in hoursrequired to hydrolyse half the applied urea-N) was determined to be 5.8 to 15.2 hours in the various soils, which appeared to associate principally with the organic carbon content of the soils (r=−0.80**). (2) Three soils were treated with 25 to 2000 μg urea-N g−1 dry soil amounting to 0.9 to 72.0 mM urea in 1∶1 soil: solution. The system was buffered at pH 7.2 and agitated for 5h when the remaining urea-N was determined. The values of Km and Vmax were computed by two methods (i) from the integrated form of the Michaelis-Menten equation based on the results of the first study, and (ii) from the Michaelis-Menton equation based on urea hydrolysis in the second study. The integrated method appeared to be more suitable for enzyme kinetic studies in soil systems where the Km and Vmax values bore close relationship (r=−0.88**).
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References
Anderson, J. R., Urease activity, ammonia volatilization and related microbiological aspects in some South African Soils. Proc. 36th Congr. S. Afr. Sugar Tech. Ass. 97–105 (1962).
Bremmer, J. M. and Douglas, L. A., Effect of some urease inhibitors on urea hydrolysis in soils. Soil Sci. Soc. Am. Proc.37, 225–226 (1973).
Burns, R. G., Pukite, A. M. and McLaren, A. D., Concerning the location and persistence of soil Urease. Soil Sci. Soc. Am. Proc.36, 308–311 (1972).
Burns, R. G., El-Sayed, M. H. and McLaren, A. D., Extraction of an urease active organo-complex from soil. Soil Biol. Biochem.4, 107–108 (1972).
Chapman, H. D. and Lebig Jr., C. F., Field and laboratory studies on nitrite accumulation in soil. Soil Sci. Soc. Am. Proc.16, 272–276 (1952).
Conard, J. P., Catalytic activity causing the hydrolysis of urea in soils as influenced by several agronomic factors. Soil Sci. Soc. Am. Proc.5, 238–241 (1940).
Delaune, R. D. and Patrick, Wm. H., Urea conversion to ammonia in waterlogged soils. Soil Sci. Soc. Am. Proc.34, 603–607 (1970).
Douglas, L. A. and Bremner, J. M., Extraction and colorimetric determination of urea in soils. Soil Sci. Soc. Am. Proc.34, 859–862 (1970).
Douglas, L. A. and Bremner, J. M., A rapid method of evaluating different compounds as inhibitors of urease activity in soils. Soil Biol. Biochem.3, 309–315 (1971).
Durand, G., Modifications de L'active de L'urease en presence de bentonite. C.R.H. Acad. Sci. Paris series D.259, 3397–4000cf Soils Fert.28, 155 (1964).
Gasser, J. K. R., Urea as fertilizer. Soils Fert.27, 175–180 (1964).
Gould, W. D., Cook, F. D. and Webster, C. R., Factors affecting urea hydrolysis in several Alberta soils. Plant and Soil38, 393–401 (1973).
Laidler, K. J. and Bunting, P. S.,In the chemical Kinetics of Enzyme Action 2nd Edn. pp. 163–196. Oxford Clarendon Pr. (1973).
McGarity, J. W. and Myers, M. C., A survey of urease activity in soils of Northern New South Wales. Plant and Soil27, 217–238 (1967).
McLaren, A. D. and Packer, L., Some aspects of enzyme reactions in hetrogenous system. Adv. Enzymol.33, 245–308 (1970).
Myers, M. C. and McGarity, J. W., The urease activity in profiles of five great soil groups from Northern New South Wales. Plant and Soil28, 25–37 (1968).
Paulson, K. N. and Kurtz, L. T., Locus of urease activity in soil. Soil Sci. Soc. Am. Proc.33, 897–901 (1969).
Paulson, K. N. and Kurtz, L. T., Michaelis constant of soil urease. Soil Sci. Soc. Am. Proc.34, 70–72 (1970).
Roberge, M. R. and Knowless, R., Ureolysis immobilization and nitrification in black spruce humus. Soil Sci. Soc. Am. Proc.30, 201–204 (1966).
Simpson, D. M. H. and Melsted, S. W., Urea hydrolysis and transformation in some illinois soils. Soil Sci. Soc. Am. Proc.27, 48–50 (1963).
Singh, B. and Sekhon, G. S., Some measures of reducing leaching loss of nitrates beyond potential rooting zone. 1. Proper coordination of nitrogen splitting with water management. Plant and Soil44, 193–200 (1976).
Skujins, J. J., Enzymes in soils.In Soil Biochemistry-1, ed. A. D. McLaren and G. H. Peterson, 371–414 Marcel Dekker, New York. (1967).
Tabatabai, M. A., Michaelis constants of urease in soils and soil fractions. Soil Sci. Soc. Amer. Proc.37, 707–710 (1973).
Viraj, Beri, Ph.D. Dissertation, Transformation and Movement of Urea in Punjab Soils. Punjab Agric. Univ. Ludhiana (1974).
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Beri, V., Goswami, K.P. & Brar, S.S. Urease activity and its Michaelis constant for soil systems. Plant Soil 49, 105–115 (1978). https://doi.org/10.1007/BF02149912
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DOI: https://doi.org/10.1007/BF02149912