engleski

Water Balance Estimation in Ameliorated Soil Containing Rock Fragments: Connecting X Ray Imaging andNumerical Modeling

Coastal karst areas are often characterized by a scarce amount of soil, thus amelioration practices such as crushing and turning of the rocks are frequently applied to form a growing media for crops. Clearly, this plant growth media has a large percentage of rock fragments (>90%) and defining the appropriate water (irrigation) and nutrient management is of major importance. Commonly used sensor technologies for water balance estimation cannot perform satisfactory in such conditions because of, amongst other, the lack of sensor contact with soil matrix, thus it is necessary to explore other approaches for adequate description of water flow. In short, the objective of this work was to combine numerical modeling with X ray imaging to estimate water flow in ameliorated soil containing a large percentage of rock fragments of various shapes and sizes. Small soil columns were taken at the field site located in Croatian coastal area (vineyard) and examined with 3-D X-ray tomography. Image analysis was performed to separate rock fragments from the soil matrix. The soil hydraulic properties of the soil matrix were estimated using a sieved soil (excluding rock fragments). Next step was introducing this complex structure into HYDRUS 3D and running short numerical experiments which included different irrigation rates and single and dual porosity model application. Simulations revealed water flow behavior (i.e., local water content and pressure head variations) with a respect to rock spatial distribution, improbable to be measured with sensors. These numerical reproductions including a complex distribution of rock fragments in the soil should help optimize irrigation management (scheduling and water volume), increase crop production and reduce certain environmental issues (e.g. nutrient leaching) in such soils.

stony soil, soil X-ray CT, HYDRUS 2D/3D, irrigation water management

nije evidentirano