The aim of the study was to establish the functional relationships and dependencies describing these relationships between the values of the near-surface and maximum diameters of soil drip moistening contour. When assessing the quality and determining the drip irrigation contour parameters, the maximum contour diameters characterizing their main plan dimensions are determined. To determine these diameters under field conditions, labor-consuming measurements of soil moisture in a sub-drip space with a considerable amount of soil samples selection and handling are carried out. In the process of research, a working hypothesis that the amount of experimental and cameral work can be significantly reduced at the opportunity to determine the maximum contour diameter in terms of diameter determined in the near-surface (5 cm) layer of moistened soil was put forward. The expected result on the proposed working hypothesis can be achieved in the presence of functional relationships and describing these relationships dependencies between the values of the contour near-surface and maximum diameters. As a result of the study, the experimental dependencies reflecing the relationships between the value of the maximum diameter of the soil drip moistening contour and its near-surface value were found. The obtained dependences are estimated based on their accuracy and tested on the materials of own investigations and data of contour measurements, given in the works of experts in the field of drip irrigation. The average deviations of the experimental values from the calculated ones do not exceed 8.1 %. This circumstance makes it possible to draw a conclusion about the coincidence of the calculated results by the proposed experimental dependences with the data on moisture contour processing obtained by a number of researchers under different soil conditions for drip irrigation.
Key words: drip irrigation, moisture contour, soil parameters, near-surface contour diameter, maximum contour diameter.
