BIOCHEMICAL ENZYMATIC STUDIES ON STATUS AND DISTRIBUTION OF SOIL ORGANIC-S FRACTIONS UNDER DIFFERENT DRAINAGE CONDITIONS | ||||
| Journal of Soil Sciences and Agricultural Engineering | ||||
| Article 6, Volume 33, Issue 8, August 2008, Page 6241-6264 PDF (722.55 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/jssae.2008.200227 | ||||
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| Author | ||||
| M.A.M. El-Kammah | ||||
| Soil Science Dept., Fac. of Agric., Kafrelsheikh Univ., Kafr El-Sheikh, Egypt. | ||||
| Abstract | ||||
| This investigation was conducted under field conditions at three locations representing the semi-arid conditions of Kafr El-Sheikh Governorate. The selected soils were irrigated for a long time with different sources of wastewaters in non-rational rates under different drainage conditions. A novel conceptual diagram was established to integrate main fractions of labile and stable organic-S and the ways by which their values are determined and calculated. The obtained results, could be summarized as follows: Grand mean value of arylsulfatase activity was 173.3 µg –r nitrophenol produced. g-1 soil. hour-1. Whereas, dehydrogenases activity was 9.4 mg TPF produced. g-1 soil. hour-1. Grand mean values of total-S and organic-S were 300 and 188.9 mg S. kg-1 soil. Organic-S was the main S-constituent in studied soils accounted for 62.23% of total-S, but its value was lower than reported from other regions. Grand mean value of ester sulfate-S was 56.4 mg S. kg-1 soil, accounted for 17.9% of total-S and 28.7% of organic-S. Sulfate esters constitute a major source of S for inorganic-S through biochemical enzymatic processes. This fraction was much more lower than reported from other regions. Grand mean value of organic-bonded S was 132.5 mg S kg-1 soil, represented 44.4% of total-S and 71.3% of organic-S, which was lower than reported from other regions. This fraction constitutes a greater proportion of total-S than ester sulfate-S. Grand mean value of amino acids-S and organic unidentified-S were 49.4 and 83.1 mg S. kg-1 soil. Amino acids-S value accounted for 16.7% of total-S, 27.7% organic-S and 39.3% of organic-bonded S. Amino acids-S content was greater than reported from other regions. Generally, soil enzymatic-S activities and either total-S or all organic-S compounds had their superiority values in traditional drained soils in winter seasons. Whereas it reached their minimum values in badly drained soils in summer seasons. These findings in year 1999/2000 were markedly pronounced than those obtained in year 2000/2001. Monthly maximum activities of the studied enzymes were happened in winter months (Feb.), while their minimum activities were in summer month (July). These activities were negative correlated with max. air temp. and soil temp. (20 cm depth) which prevailing in studied area. Arylsulfatase and dehydrogenase activities had a significant positive correlations with total-S and all different organic-S fractions; furthermore with water table depth, soil pH values organic-C and –N contents. These activities were negative highly significant correlated with C/S ratio; ionic strength and bulk density. | ||||
| Keywords | ||||
| Arylsulfatase; dehydrogenase; total-S; organic-S; ester sulfate-S; amino-acids-S; sulfur fractionation; modified Johnson-Nishita apparatusu | ||||
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