EFFECTS OF NATURAL AND ARTIFICIAL AGGREGATING AGENTS ON SOIL STRUCTURAL FORMATION AND PROPERTIES - A REVIEW PAPER

The structural characteristics of soils are the leading soil quality factors which exert a significant influence on sustainable agricultural land uses and yields. This review paper collates and summarizes all necessary information relating to the processes of soil structural formation, artificial and natural aggregating agents as well as their effects on soil structural formation and its dynamic property improvement. Soil aggregation is a core process involving in soil structural development, and artificial and natural aggregating agents synergistically interact to determine soil aggregation. The rearrangement followed by flocculating and cementing of soil particles result in forming aggregates of different manners and sizes. Aggregating agents, which encompass organic matter (OM), biotic factors including plant roots and soil microorganisms, clay minerals, sesquioxides, lime and dolomite materials, considerably contribute to soil aggregates formation dubbed 'soil aggregation' through the drawing of soil primary particles together into aggregates of different manners and sizes. These aggregating agents significantly involve in soil aggregation and aggregates stability through the improving of soil porosity, hydraulic properties, water retention and other soil physical properties associated with aggregates. Organic carbon, microbial biomass carbon, mucilage (like polygalacturonic acid), glomalin, cations like (Si4+, Fe3+, Al+3 and Ca2+), all of which emanate from aggregating agents significantly help bind soil particles together into macro aggregates during aggregation.