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A laboratory experiment was performed in the College of Agriculture's laboratories, University of Anbar is to study the effect of sawdust's extract and cycles of wetting and drying. Irritated soil samples were collected from the fields of the College mentioned and their aggregates were distributed in an order which is above than 9.5, 4, 2, 1, 0.5, 0.25, and below than 0.25 mm. The diameter and the height of the cylinders were 100 mm consecutively, they were filled by soil which weighs 800 g with the same size distribution of the original soil samples. Approximately, 5% of the organic matter exists in the soil was injected in Sawdust's extract depending on the dry weight without any addition The addition of (Non-ESD), Nano-Powdered Extract Drye r(np ESD), and sawdust's extract as a solution without treatment (SESD), Then the containers were applied to five cycles of wetting and drying (DW) and incubated at a temperature of 22°C. The size distribution of the soil after incubation was estimated in the same order as the size distribution of the original sample, and the hydraulic conductivity to the size-distributed soil aggregates was estimated as well.
According to the results obtained, the np ESD addition was the best to increase the soil aggregations above than 9.5 mm and the ratios were higher in comparison with the rest of the ranges size, while SESD was the best to form clusters less than 9.5 mm, and that the np ESD addition increased the hydraulic conductivity of the aggregates larger than 9.5 mm, The DW cycles highly affected the weight ratios of the soil aggregations greater than 9.5 mm and those with a size range of 9.5-4 mm fluctuating.