Pore size distribution of soil treated with different plowing depths and its relationship to the efficiency of water use for corn

The soil pore size distribution is one of the propertiesthat directly affect water infiltration, hydraulic conductivity, and water holding capacity. Soil tillage often results in an unstable soil structure with an increase in the percentage of drainage pores between soil aggregates, which change with time due to the wetting and drying cycle, soil solution components, agricultural processes, and biological activity, as well as the change of water conductivity with time.In order to test the effect of the plowing depth on the soil pore size distribution, an experiment was carried out in a silty clay loam in the Nile sub-district of Babylon Governorate, south of Baghdad, Iraq, with four plowing depths. The first treatment was No-tillage (T0), and Minimum tillage usingspike pin harrows, at a depth of 0.10 m (T1). The chisel plowwas used for plowing with two depths of 0.20 m and 0.30 m, which represented treatments (T2),and (T3), respectively. Irrigation was carried out by applying three irrigation systems which are surface drip irrigation I1, subsurface drip irrigation I2 and basin irrigation I3.Soil water retention curve (θ(h)) was estimated for field soil.