Browsing by Subject "soil water depletion"

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    Water Flow in Soil in Presence of Soybean Root Sinks
    (Water Resources Research Center, University of Minnesota, 1973-06) Mohan Arya, Lalit
    Water depletion patterns in the 10 to 70 cm soil depth in the root zones of two soybean varieties, 79.648 and Chippewa - 64, and in a bare soil were established on Waukegan loam. Soil hydraulic properties of the soil profile, suction-water content and hydraulic conductivity-suction relationships were determined in the laboratory and supported by field measurements. Following irrigation, proportional contribution of various soil layers to the total water loss showed a downward shift with the growth stage of soybeans. In general, 10-cm layers in the upper horizons contributed a major portion to the total water losses. The contribution of the 10 to 20-cm layer remained above 20 percent while that of the 50 to 60-cm layer accounted for less than 10 percent of the total water loss from the 10 to 70-cm profile. During the early stages of growth the evapotranspiration rate was .64 cm/day which agrees with the pan evaporation rate of .66 cm/day. Soil outside the 10 to 70-cm zone contributed about .2 cm/day towards evapotranspiration. About 55 percent of the soil volume showed root densities of 1.0 to 2.0 cm/cm(3). Generally, root density tended to be higher near the plant rows and between the 25 and 45-cm depths below the surface.