It has the largest water holding capacity which helps to absorb water during the rain and helps in reducing soil erosion (Genna Dunjo Denti,2004, p.125).
Soil aggregates are group of soil particles that are bonded together strongly to each other than to the adjacent particles with the help of organic matter. The space between the aggregates provides pore space for retention and exchange of air and water. Desirable aggregates are stable against rainfall. When less organic matter is used to bind these aggregates, due to rainfall these aggregates break down and leads to soil crust formation, this crust in turn increases the infiltration and air permeability, this in turn disturbs the surface soil and sub-soil structure. Thus inclusion of organic matter aids in the formation of stable aggregates and strengthen them. They also increase the porosity of the soil for air and water movement. Thus aggregating helps in reducing soil erosion.
As the strength aggregates depends on the organic matter, since the organic matter acts as a binder to the aggregates. Hence weakening of this bond due to frequent tillage ultimately breaks down the aggregate structure of surface soil (Rachman, Anderson, Gantzer and Thompson, 2004, p. 31).
Splash erosion is the removal of sand by impact of raindrops on the soil surface, this is also known as soil splash detachment (Jean Poesen, Gerard Govers(2001), p.1,2). If the soil is loose and friable, it has the maximum water holding capacity. This water holding capacity of soil stops soil erosion due soil splash detachment.
If the soil is too loose it is very much prone to both the wind and water erosion. Wind erosion includes moving of the soil particles due to wind velocity and when these moved soil particles collide with the other particles and break them .If this continues then the soil is eroded by the wind. Wind also makes some soil particles to remain suspend in air and stay there till the wind continues leading to erosion. Water erosion mainly removes the soil particles by force of water and loss of various soil particles into ground water through infiltration. This leads to rapid dry out of soil due to lack of moisture holding capacity and leachate of minerals and other desirable elements.
If the soil is dense, more overland flow may increase the erosion rate (Dr.Cooper, 2005, chapter-2).
Soil color is one of the physical indicators of soil condition. Soil color is most easily determined characteristic and helps in determining the other characteristics of soil like water-able depth and chemical constituents.
Surface-soil is the top most layer of the soil and is in interference with the atmosphere. This soil comprises of the organic matter such as manure and dead plants