Soil Chemical Analysis Lab Report

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Analysis of soil chemical and biological properties

Soil chemical analysis and enzymes like urease, protease and nitrite reductase were carried out in the soil analysis laboratory, Guangxi University, Nanning, Guangxi Province, China. Soil pH analysis (soil:water = 1:1) performed by pH meter and Soil organic carbon was determined by dichromate oxidation (Walkley and Black, 1934). Total N in soil was determined by Semimicro-Kjeldahl method (Bremmer and Mulvaney, 1982). Nitrate nitrogen (NO3−-N) and exchangeable ammonium nitrogen (NH4 +-N) in soil was determined using FeSO4/Zn reduction method described by Carter (Carter, 1993). Total P in soil was determined using Sodium carbonate fusion described by Carter (Carter, 1993). Available phosphorus (P) in soil was determined by extracting samples with 0.5 M NaHCO3, and
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Total K in soil was determined using Flame photometry method (Bao, 2000). Available K in soil was determined using 1 N ammonium acetate extraction-flame photometry method (Bao, 2000). Urease activity was determined using phenol-sodium hypochlorite colorimetry and expressed as mg NH3-N Kg-1 d-1 (Guan et al. 1986). Nitrite reductase activity was determined using the Gerry reagent method and expressed as mg NO2-N g-1 d-1 (Li et al. 2008). Protease activity was determined and expressed as mg Kg-1 d-1 (Ruan et al. 2009). Other soil enzymes like dehydrogenase (DHA) and nitrogenase were assessed by following methods. Soil dehydrogenase activity was assessed by the method of Singh and Singh, 2005. Nitrogen fixation activity was measured using the acetylene reduction assay (ARA) (Hardy et al. 1968). All soil samples were incubated individually with 10% acetylene for 3 h. The assay included control using

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