ABSTRACT: Nitrate concentrations in groundwater as an indicator of the environmental impact of all farm activities, particularly those in the farmstead and its vicinity, were studied using the results of several years' groundwater monitoring in the demonstration farms situated in different sites in Poland. All farmstead operations, mainly those connected with animal production, were shown to be an important source of nitrate and ammonium ions in ground and neighbouring surface waters. For that reason the nitrate, and even more, the dynamic system of ions — ammonium and nitrate in groundwater — is proposed as an indicator of the impact of the farmstead on the environment.