Abstract

ZERIZGHY, Mussie G; VAN RENSBURG, Leon D  and  ANDERSON, Jan J. Comparison of neutron scattering and DFM capacitance instruments in measuring soil water evaporation. Water SA [online]. 2013, vol.39, n.2, pp.183-190. ISSN 1816-7950.

Soil water evaporation is an important parameter that needs to be accurately measured for the design of water-efficient agricultural systems. With this study, the abilities of the DFM capacitance probes and a neutron water meter (NWM) to measure evaporation from the soil surface were compared. Measured evaporation was compared to the control values measured with mini-lysimeters. Calibration of DFM capacitance probes and the NWM was done in the laboratory using the topsoil of a Bainsvlei soil form. Field measurements of soil water content were done on the same Bainsvlei soil. Calibration results indicated a good correspondence (r² = 0.99) between the measured values and known volumetric soil water contents. There was no significant difference (p = 95%) between the DFM evaporation measurements and the control, whereas the NWM and control differed significantly. It was concluded that the DFM capacitance probe is a better tool than the NWM in measuring evaporation from the topsoil surface.

Keywords : neutron water meter; capacitance probes; evaporation; soil wetness.

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