Relevance of subsoil irrigation usage for growing feed crops on alluvial meadow soils is shown. Distribution of pjezometric pressure, along the water emitter line during the irrigating period, is analyzed. Formation of moisture patterns in the soil regarding the quantities of irrigating water and emitters design are considered. In order to define the characteristics of moisture patterns in the soil, depending on the quantities of irrigating water, the ratios of vertical water spreading K_v and forms K_f are calculated. Expediency of usage low irrigating rates is substantiated. As a result of research, mathematical relations were derived in order to define water outlays in the emitters made of pottery tubes with diameter 50 mm under water pressure at the line 0.1…0.7 m. It is determined that usage of subsoil irrigation allows increase of commercial crop harvest, significantly save water resources, labour and energy comparing to sprinkling.