Study Effect of Carbon: Nitrogen Ratio on the Minerals Weathering by Using Scanning Electron Microscope

ABSTRACT:

This study conducted to investigate the effect of soil C:N ratio under different tree types characterized by similarity in all soil forming factors (climate, parent material, topography, organisms ,time) located north of Iraq , difference between them was just in the composition rate of organic matter produce by different tree types which due to variation in c:n ratio, some clay fraction of studied pedons in surface and subsurface horizon has been tested under scanning electron microscope and x-ray diffraction, the result of SEM emages showed that the green grain forest was the higher effected soil through weathering signs which was very clear , clay samples showed breakness of mineral layers and edges also the minerals appear in different size and shapes and that correlated with decrement in C:N ratio in tree types, the results showed there is series of changes in mineral morphological features , then mineral particles surfaces in green grain and pine forest appear irregular and complicated especially in pine forest samples as well as the minerals in green grain forest appear spongy like shape which due to swelling and expansion sequence for mineral interlayer. images for wild pears and oak forests showed the mineral surfaces was in the exfoliation state where the exfoliation tracks appear very clear whereas some of them exposed to edge weathering indicated by appearance of edges in pale color which can recognize from surface zone which caused by bleaching process resulting from interlayer cation removal by the weathering process which probably be potassium or iron absence of complication state and restricted in exfoliation process associated with edge weathering of exfoliated surfaces explain weathering intensity reduction as compared with green grain and pine forest and less weathering intensity found in almond tree type which was more C:N ratio value. If we focused on the C:N ration results we can recognize the variation in this value between plant species and less value found in green grain and pine forests and greater value found in almond.