Measurement of sustainability of model arable farming systems

Nine model arable farming systems, long-term stationary field trials (Norfolk crop rotation, spring barley continuous cropping, winter wheat continuous cropping, both in four variants of organic manuring), were analysed for their sustainability using the following parameters: total factor productivity trend of the TFP index, production stability and changes of selected soil properties - humus content and soil pH. A method for energy balance was used to calculate total factor productivity. Summarised data were analysed graphically, Among the examined long-term trials there was none that would have met all selected criteria of sustainability. Four systems failed in one of the studied parameters only as follows: Norfolk crop rotation - a decreasing trend of the TFP index was determined; spring barley continuous cropping, variant B (straw incorporation + green manure) - a considerable decrease in soil pH was assessed; winter wheat continuous cropping, variant C (green manure) and D (a check without organic manuring) - the systems show an unstable level of production. In variant D of spring barley continuous cropping, degradation of resource base (due to deficient nutrient balance and an inappropriate farming practice) affected productivity of the system in the delay of about 15 years. Development of productivity in all systems was affected by replacement of grown varieties.