The purpose of study is to obtain calculated experimental dependencies and to develop methodology for determining the inner contour soil moisture distribution parameters by drip irrigation. The approved techniques as well as the materials and data given in well-known publications were used during research and generalization. When obtaining the dependencies for determining the inner contour moisture distribution parameters the drip humidification contours got by authors under various drip irrigation conditions were analyzed. As a result of the correlation-regression analysis of the actual and approximated local drip humidification contours recorded by authors, experimental dependences describing the linear sizes of moisture lines (isopleth) in relative coordinates that reflect the intrinsic distribution of soil moisture were obtained. The factors influencing the inner contour moisture distribution taken into account in this technique are the following – the irrigation norm, as the depth and diameter of the contouring isopleth depend on its value; the content of clay particles in soil; the lowest moisture capacity of soil; the contouring isopleth moisture. To confirm the obtained dependences for determining the inner contour soil moisture distribution the calculation and comparison with data on local drip humidification contour parameters recorded by other authors were carried out. The results of comparison of the values of the depth and the diameter of the inner contour isopleths calculated by the proposed experimental dependences with data obtained under different drip irrigation conditions showed the allowable deviations which do not exceed 12 % in contour on average that indicates the acceptability of the proposed experimental dependences and the methodology for practical calculations.
Key words: drip irrigation, moisture contour, inner contour space, pre-irrigation moisture, isopleth, soil moisture.
