The collected fractions were oven dried at 40 8C and weighed to compute the mean weight diameter (MWD), and percent WSA calculated by the methods of Kemper and Rosenau (1986).The aggregates retained on each sieve size fractions were then mixed together to get proportionate sample of macroaggregates for total C (TC) and total N (TN) analyses. Subsamples from each aggregate fraction were grouped and mixed together to represent two aggregate-size fractions (Tisdal and Oades, 1982): macroaggregates (>0.25 mm), and microaggregates (<0.25 mm), ground using a mortar and
pestle, sieved through 0.125 mm sieve and stored at room temperature and then shaken overnight (16 h) in glass vials on
end to end floor shaker pending total C and total N analyses using CN analyzer for surface (0–15 cm) soil only.
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