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Title: ENZYME ACTIVITIES IN SOIL INFLUENCED BY LEVELS OF APPLIED SULFUR AND PHOSPHOROUS

Author
item Baligar, Virupax
item WRIGHT, R - NPS STAFF
item HERN, J - REIC LAB, BECKLEY, WV

Submitted to: Communication in Plant and Soil Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/9/2005
Publication Date: 7/20/2005
Citation: Baligar, V.C., Wright, R.J., Hern, J.L. Enzyme activities in soil influenced by levels of applied sulfur and phosphorous. Communications in Soil Science and Plant Analysis. 36(1-9): 1727-1735.

Interpretive Summary: Management practices and type of plant cover greatly influence soil biochemical properties such as enzyme activities. In soil, enzymes mediate transformation of organically bound nutrients into plant available inorganic forms. Soils of the Appalachian region are acidic and infertile. Addition of sulfur (S) and phosphorous (P) fertilizer are needed to improve their productivity. A field experiment was carried out on acidic Gilpin soil in West Virginia to assess the influence of various levels of P and S on enzyme activities. After three years of P and S applications, acid phosphatase, arylsulfatase , and urease activities were determined. Increasing levels of P and S reduced levels of enzyme activities. Activities of all three enzymes were significantly correlated with soil moisture content, total C and N, S, and organic sulfur. Farmers of the Appalachian region could achieve higher crop yields by applying proper levels of P and S fertilizers. Soil management practices that improve soil organic matter content could lead to higher levels of enzymes activities; that in turn improves the productivity of infertile acidic soils. Findings of this research are helpful in designing management systems that could improve the production potentials of tropical acid soils under the plantation crops.

Technical Abstract: Soil biochemical properties are influenced by management practices and the type of plant cover. Such changes affect the levels of enzyme activities in soil. In turn, enzymes influence the nutrient supply in soil, growth and mineral composition of the plants. Acidic infertile upland soils are relatively colder in crop growing season than low land soils, and require application of S and P to improve crop production. Field experiment was carried out on Gilpin silt loam (Typic Hapludult at elevation of 908 m) soil with initial application of four levels of S (0,16.8, 33.6, 67.2 kg S ha-1) and three levels of P (22.4, 89.6, 358.4 kg P ha-1). Acid phosphatase (AP), arylsulfatase (AS) and urease (UR) activities were determined three years after the initial fertilizer application. Increasing levels of soil applied S decreased enzyme activities, however highest level of applied S (67.2 kg S ha-1) in fact stimulated higher enzyme activities. Increasing levels of soil applied P reduced AP activities significantly, and resulted in reducing trends in AS and UR activities. Overall, the enzyme activities were reduced significantly with increasing soil depth. Activities of all three enzymes were significantly correlated with soil moisture content, total C and N, S, and organic sulfur.