The productivity of phytocenoses on the meadow-chestnut soils is theoretically calculated under hydrothermal conditions and practically implanted moisture integral. It is found that high productivity (0.5 t/ha of air-dry weight) of ephemeral synusiae is achieved through the combination of the following environmental factors in April-May; precipitation 80-85 mm, the average temperature is 15-16°C, relative humidity 70-73%, volatility 130-140 mm, coefficient of moisture 0.30, integral hydration period 29.8. In this case, the degree of salinity in soil layer 0-23 cm classified as weak, salinity type is sulfate-chloride. In normal climatic conditions of the year (2013), when precipitation during the vegetation period is distributed relatively evenly, productivity of ephemers and ephemeroids is 2.0 c/ha (centner/hectare) of grasses and thistles – 18.2 c/ha, the coefficient the use of  FAR during the vegetation period of 0.30, the share of the ephemeral synusiae in it – 0.16%.