why is moisture retained longer in the soil if it is harrowed ?

Q: why is moisture retained longer in the soil if it is harrowed ?

Sol: When the soil is not harrowed , there are large capillaries in it . Water in the soil rises up the capillary holes to the surface from where it evaporates continuously . Thus the soil continuously loses water . When harrowed , all these capillaries are destroyed and so capillary suction stops altogether . Thus water is retained longer in the soil .