Soil Porosity

Soil Porosity space left free in particles, between particles or between structural units of a soil. Pore space can be divided as (i) intermineral space, tubular pores of feldspars undergoing weathering; (ii) inter-particle space, created by the fabric of the particles or textural porosity; (iii) fissural space, generally climatic origin, can be narrow, within the finest or coarse aggregates; (iv) tubular space, either inside or outside the aggregates, generally of biological origin; and (v) fabric space in aggregates, other than the fissural space. These pore spaces vary in size, shape, arrangement and morphology. Pore spaces in soil contain water in micropores (> 0.08 mm diameter) under field capacity condition of water content. Under dry condition almost all the pores are filled with air and the reverse is true under the water content of maximum water holding capacity. Small holes formed by the decay of plant roots and burrowing animals provide channels, allow air and water to pass through the soil mass. The plant roots and soil animals mix soil material and thus disturb the natural pore spaces. The pressure created by plant roots passing through soil material disturbs alluvial stratification and rock layers. [Sirajul Hoque]