In all kinds of watering, whether on the surface or from below, the surface must be stirred soon after the wetting to prevent baking and to conserve the moisture. If this is neglected with surface-watering the outcome will prove doubtful as to benefit.
Thorough culture and the exclusion of weeds tends to hold the moisture in the soil. All systematic gardeners cultivate soon after rains, but the need of it after surface
irrigation is much greater, as artificial watering seems to harden the surface soil and the process is local, with dry-air around it, favoring rapid evaporation from impacted soils.
With sub-irrigation the need of culture or stirring the surface soil is quite as essential, as. it favors the ascent of moisture from below and the admission of air from above, both in outdoor and indoor work.