Diurnal Soil Water Regime in the Tilled Plow Layer of a Warm Humid Climate

Abstract

AbstractThe soil water content in 10 depth intervals in the surface 15 cm of soil was determined hourly for 9 days in June at 83° 25′W, 33° 52′N. Over the same period at 15‐min intervals soil temperatures were measured at eight depths, windspeed and air temperatures at six elevations, atmospheric water vapor pressures at three elevations, incident solar and net radiation at one meter. From the microclimate data, flux of water vapor at the soil surface was calculated, which was then used to compute soil water flux at several depths by using soil water content data. The diurnal soil water content and soil water flux patterns are compared for a dry period before a rainfall event and afterward. Dramatic diurnal variation of the soil water content at depths < 2 cm was observed. This variation during periods of no rain is related to daily radiation inputs at the soil surface, which generated the observed temperature and soil water gradients responsible for soil water redistribution. Occurrence of rainfall and infiltration events during the measurement period show additional dynamics of the field system. Description of the diurnal soil water dynamics in the plowlayer provide a basis for examining soil processes dependent upon soil water regime.