The article is devoted to the substantiation of the parameters of the method of accumulation and retention of rain and irrigation water in agricultural fields, reducing its losses due to evaporation and convective removal. To preserve water in arable land, it is proposed to arrange parallel rows of grooves of a certain depth and width, which are filled with fine material, mainly mining waste — burnt-out waste heaps. The design of a device for implementing the method is proposed taking a seeder as a basis. The most probable parameters of the method, groove width and depth and the distance between the groove rows, are substantiated in practice. For the first time, the dependence of the water accumulated in arable land on the parameters of the proposed method was theoretically obtained in the form of a polynomial regression equation. Statistical analysis has confirmed the sufficient reliability and significance of the results. The obtained research results can be used to substantiate the rational parameters of the technology of water retention in agricultural fields.