Use of neutron probe and tensiometry techniques in determining water characteristics of the two soil types

Abstract

Characterisation of soil water, in particular water flow dynamics is fundamental in assessing the environmental implications to soil management. Soil water characterisation was assessed by measuring soil water content and soil water potential in a draining profile of sandy and loamy soils. Mercury manometers and Neutron probe meter were connected to a 1.2 m high metal-reinforced container filled with soil samples, to simultaneously measure soil water potential and volumetric water content, respectively. Soil water contents (SWC) were found to decrease monotonically with time, with a rapid decrease in the first 50 hrs of free drainage in both soils. Sandy soil was more prone to huge losses of water than loamy soil attributed to numerous large drainable pores in sandy soil. An appreciable difference of SWC in the upper layer (SWC= 0.22 cm3/cm3) and the bottom layer (SWC= 0.35 cm3/cm3), in the case of loamy soil was attributable to its poor drainage properties.

Key words: Soil water content; water potential; soil water characteristic; mercury manometer; neutron probe