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Nesime Cebel 1 , Michael Mullen 2 , Michael Kircner 2 1 Toprak ve Gübre Araştırma Enstitüsü 2 University of Tennessee, Department of Plant and Soil Sciences, Knoxville, TN, USA ABSTRACT Minimum tillage is a general term that may be applied to any of the numerous practices that require fewer trips across the field than are required by conventional methods of preparing a seedbed. A plowed surface left rough and containing appreciable plant residue allows water to infiltrate more rapidly, has greater surface and plow-layer storage, and is less easily eroded than a pulverized soil surface. In this study conventional tillage and no tillage system was compared by some chemical, biochemical and microbiological properties of soils. Soil samples were collected from erosion plots next to each other that cultivated with two systems for long years at the Milan No-till Research Station in Milan, Tennessee. In these samples pH, C%, S%, N%, NH4+-N, NO3--N and Mehlich-exractable Ca, Cu, Fe, K, Mg, Mn, Na, P, Zn and enzyme activities of dehydrogenases, acid and alkaline phosphatases, arylsulfatase, b-glucosidase and microbial biomass were determined. According to results No-till practices provides better soil features than Conventional tillage. INTRODUCTION Conservation tillage was recently defined as a system in which either crop residues are retained on or near the soil surface, a rough soil surface is maintained, or both to control soil erosion and to achieve good soil-water relations (Allmaras, R. R. et al. 1985; Mannering and Fenster 1983). Numerous research workers (Meyer, Wischeimer, and Daniel, 1971; and Van Doren and Stauffer, 1944) have found that crop residues and other forms of surface mulches are very effective in reducing soil erosion and the velocity of runoff. Nutrient cycling in soils involves biochemical, chemical, and physiochemical reactions, with the biochemical processes being mediated by microorganisms, plant roots, and soil animals. It is well known that all biochemical reactions are catalyzed by enzymes, which are proteins with catalytic properties owing to their power of specific activation. Soil enzyme activities are often measured as a potential indicator of microbial activity. Doran (1980) evaluated seven soils from five states that had been in no-till or conventional tillage systems. He concluded that no-tillage results in higher total organic C and total kjeldahl N than does conventional tillage. Beare and coworkers (1994) found that the formation of macroaggregates in no-till soils protected a significant amount of the increased C from decomposition. The purpose of this study was to evaluate some chemical, biochemical and microbiological properties of erosion plots soils in long-term, no-till and conventional tillage systems. MATERIALS and METHODS Five soil samples of each plot were collected from erosion plots at the Milan No-till Research Station in Milan, Tennessee. The depth was 0-5 cm. The moist soils were sieved to less than 2 mm and then stored at 4°C until analyzed. Enzyme activities: Phosphomonoesterases (Acid and Alkaline Phosphatases), The assay of phosphomonoesterase activities are based on colorimetric estimation of the r-nitrophenol released by phosphatase activity when soil is incubated with buffered (pH 6.5 for acid phosphatase activity and pH 11 for alkaline phosphatase activity) sodium r-nitrophenyl phosphate solution and toluene (Tabatabai and Bremner, 1969; Eivazi and Tabatabai, 1977). Arylsulfatase, The method is based on colorimetric determination of r-nitrophenol released by arylsulfatase activity when soil is incubated with buffered (pH 5.8) potassium r-nitrophenyl sulfate solution and toluene (Tabatabai and Bremner, 1970). Dehydrogenases, The method based on extraction with methanol and colorimetric determination of the TPF produced from the reduction of TTC in soils (Casida et al., 1964). ß-Glucosidase, The method is based on colorimetric determination of r-nitrophenol released by b-glucosidase activity when soil is incubated with buffered (pH 6.0) PNG solution and toluene (Eivazi and Tabatabai, 1988). pH, was determined by a glass electrode (soil/water ratio, 1:5). Microbial biomass, was determined using a chloroform-fumigation extraction procedure that was a modification (Vance et al., 1987;Sparling and West, 1988) of the fumigation-incubation technique developed by Jenkinson and Powlson (1976). Soils were analyzed for total carbon, nitrogen and sulfur with a LECO CNS-2000 C, N and S analyzer (Matejovic, 1995). The inorganic N was analyzed using the microplate method by Sims et.al. (1995). Other nutrients (Ca, Cu, Fe, K, Mg, Mn, Na, P, Zn) were analyzed by extraction with Mehlich and determined on the Inductively Coupled Plasma Spectrophotometer (ICP). All data were analyzed using ANOVA and means were separated using the Least Significant Difference method at p=0.05. RESULTS and DISCUSSION Soil enzymes are largely a function of microbial activities, and treatments that enhance microbial numbers or biomass in soils are likely to enhance measurable enzyme activities (Tabatabai, 1996). Arylsulfatase catalyzes the hydrolysis of organic sulfate esters, an important source of organic S in soils. Glycosidases catalyze the hydrolysis of glycosides resulting in the release of monomeric sugar molecules. These enzymes are thought to be important to microbial energ production in soil. The enzyme b-Glucosidase catalyzes the final step in the breakdown of cellulose to glucose, and would be important in soils with accumulation of plant materials, such as a no-till soil. Long-term no-tillage results in many changes in soil properties. Among the most important of these changes are increases in total soil carbon. Increased soil C enhances many other soil properties and will often impact soil biological and biochemical properties. Table 1 gives data for some soil enzyme activities and Table 2 for total C, N, S, pH, Inorganic N, and Microbial Biomass C in the 0-5 cm layer of soil. Except Alkaline phosphatase, Acid phosphatase, Arylsulfatase, b-Glucosidase and Dehydrogenase activities were higher in N.T. than does C.T. (Table 1). Total C, N, and S; MBC; NO3-N were higher in N.T while pH is lower and NH4-N is the same (Table 2). No-tillage, and other practices that increase the amount of crop residue on the soil surface , has been shown to increase total C in soil surface (e.g., Doran, 1980; Ismail et al., 1994). Other workers have observed an increase in total N with no-tillage and increased levels of residue cover (Havlin, 1990; Ismail et al., 1994).  Mehlich extractable Ca, Cu, K, Na, and P were not significantly different between N.T. and C.T. Fe, Mn and Zn were higher in N.T. while Mg was higher in C.T. (Table 3). This is expected results that obtained at low soil pH.   REFERENCES ALLMARAS, R. R., UNGER, P: W. , and WILKINS, D. E. (1985). Conservation tillage systems and soil productivity. In R. F. Follet and B. A. Stewart (editors) Soil Erosion and Crop Productivity. American Society of Agronomy, Madison, Wisconsin. pp. 357-413. BEARE, M. H., CABRERA, M. L., HENDRIX, P. F., and COLEMAN, D. C. (1994). Aggregate-protected and unprotected organic matter pools in conventional- and no-tillage soils. Soil Sci. Soc. Am. J. 58:787-795. CASIDA, L. E., KLEIN, D. A. ve SANTORO, T. (1964). Soil dehydrogenase activity. Soil Sci. 98:371-376. DORAN, J. W. 1980. Soil microbial and biochemical changes associated with reduced tillage. Soil Sci. Soc. Am. J. 44:765-771. EIVAZI, F. ve TABATABAI, M. A. (1977). Phosphatases in soils. Soil Biol. Biochem. 9: 167-172. Soil Enzymes. In: Methods of Soil Analysis. Part 2. Microbiological and Biochemical Properties. p 775-833. 1994. R. W. Weaver et al., editors. S.H.Mickelson, managing editor. EIVAZI, F. ve TABATABAI, M. A. (1988). Glucosidases and galactosidases in soils. Soil Biol. Biochem. 20:601-606. Soil Enzymes. In: Methods of Soil Analysis. Part 2. Microbiological and Biochemical Properties. p 775-833. 1994. R. W. Weaver et al., editors. S.H.Mickelson, managing editor. HAVLIN, J. L., KISSEL, D. E., MADDUX, L. D., CLAASSEN, M. M., and LONG, J. H. (1990). Crop rotation and tillage effects on soil organic carbon and nitrogen. Soil Sci. Am. J. 54:448-452. ISMAIL, I., BLEVINS, R. L., and FRYE, W.W. (1994). Long-term no-tillage effects on soil properties and continuous corn yields. Soil Sci. Am. J. 58:193-198. JENKINSON, D. S., and POWLSON, D. S. (1976). The effects of biocidal treatments on soil. V: A method for measuring soil biomass. Soil Biol. Biochem. 8:209-213. MANNERING, J. V. and FENSTER, C. R. (1983). What is conservation tillage? Journal of Soil and Water Conservation 38: 141-143. MATEJOVIC, I. (1995). Total nitrogen in plant material determined by means of dry combustion: a possible alternative to determination by Kjeldahl digestion. Commun. Soil Sci. Plant Anal. 26:2217-2229. MEYER, L. D., WISCHMEIER, W. H., AND DANIEL, W. H. (1971). Erosion, runoff, and revegetation of denuded construction sites. Trans. of the ASAE 14 (1): 138-141. SIMS, G. K., ELLSWORTH, T. R. and MULVANEY, R. L. (1995). Microscale determination of inorganic nitrogen in water and soil extracts. Commun. Soil Sci. Plant Anal. 26 (1&2):303-316. SPARLING, G. P., and WEST, A. W. (1988). Modifications to the fumigation-extraction technique to permit simultaneous extraction and estimation of soil microbial C and N. Commun. Soil Sci. Plant Anal. 19:327-344. TABATABAI, M. A. and BREMNER, J. M. (1969). Use of r-nitrophenyl phosphate for assay of soil phosphatase activity. Soil Biol. Biochem. 1:301-307. Soil Enzymes. In: Methods of Soil Analysis. Part 2. Microbiological and Biochemical Properties. p 775-833. 1994. R. W. Weaver et al., editors. S.H.Mickelson, managing editor. TABATABAI, M. A. and BREMNER, J. M. (1970). Arylsulfatase activity of soils. Soil Sci.Soc. Am. Proc. 34:225-229. Soil Enzymes. In: Methods of Soil Analysis. Part 2. Microbiological and Biochemical Properties. p 775-833. 1994. R. W. Weaver et al., editors. S.H.Mickelson, managing editor. TABATABAI, M. A. (1996). Soil Enzymes. p. 775-833. In D. L. Sparks (ed.) Methods of Soil Analysis, Part 3. Chemical Methods. SSSA Book Series no.5. Soil Science Society of America and American Society of Agronomy, Madison, WI. VAN DOREN, C. A., and STAUFFER, R. S. (1944). Effect of crop and surface mulches on runoff, soil losses, and soil aggregation. Soil Sci. Soc. Amer. Proc. 8: 980101. VANCE, E. D., BROOKES, P. C., and JENKINSON, D. S. (1987). An extraction method measuring soil microbial biomass C. Soil Biol. Biochem. 19:703-707. |