(1) Microclimatic maesurements and flux determinations were made on natural Agropyron-Koeleria grassland during two growing seasons. (2) The calculated evaluation fluxes were analyzed in terms of the potential evaporation, soil moisture content, and plant water potential. The analysis fitted Monteith's canopy-resistance concept. (3) The fraction of net radiation involved in evaporation was closely correlated with green leaf area index during the last half of the growing season, and with soil-water content (0-30 cm) during the latter half of the growing season. (4) Seasonal water-use estimates, by micrometeorological and soil moisture balance approaches, agreed to within 10%. ©1978 British Ecological Society. Abstract reproduced by permission.