This book is about how to fractionate soil aggregates into different sizes having different levels of bonding energy. What the chemical characteristics of the fractionated aggregates compared to the bulk soils are. Furthermore, how each aggregate fraction behaves in physically protecting soil organic matter (SOM)as well as in releasing CO2 as affected by tillage under different micro-climate. What other factors affecting SOM decomposition either under field or under controlled laboratory and glasshouse condition. Those are interesting to study the aggregate building process in soils. And it can be applied for soil tillage operation. At this occasion, I would like to say thanks to Lambert Academic Publishing (LAP) which invited me to publish my writing without any cost at all. By this, many people over the world will know what I did.