Measurement and estimation of capillary upflow from water tables under maize on irrigated soils

An experiment with maize on two soils in lysimeters L1 and L2 (Hanwood clay loam and Mundiwa clay loam respectively) was conducted to measure daily capillary upflow and to establish a relationship between capillary upflow and significant soil, watertable, crop and environmental factors. Total evapotranspiration from L1 and L2 during the season was 748 and 631 mm respectively. Capillary upflow contribution to evapotranspiration in L1 and L2 was 215 (29%) and 101 (16%) mm respectively. Daily capillary upflow ranged from 0 to 5 mm day-1 in the Hanwood clay loam and 0 to 2 mm day-1 in the Mundiwa clay loam during the experiment. Measured daily capillary upflow was significantly (P < 0.001) different between the two soils studied. A stepwise multiple regression, by using the combined data from L1 and L2, showed that the depth to the watertable, water content of the soil layers at 0.1 and 0.4 m and root length density Lv at 0.65 m significantly influenced capillary upflow (n = 68, R2 = 0.79, P < 0.05) in both soils.