Quantitative analysis of selected land-use systems with sunflower.

Land-use systems with sunflower were quantified using a dynamic crop-growth simulation model for calculating the biophysical production potential and water-limited production potential.Crop data were collected in 1993 and 1994 in field experiments with three varieties of sunflower and three water regimes at Coria del Rio, Andalusia, Spain. Soil and weather conditions were monitored.The output of the calculations are potential yield and production; they reflect the effects of soil and weather conditions during the growing season for Land Utilization Types with defined crop characteristics and management activities.The evaluation of crop performance with weather data of many years reveals the long-term success of specific land use systems and the risk of crop failure in rainfed agriculture.Land suitability is established by matching land use requirements with the compounded land qualities and land characteristics. Sustainability is achieved by adapting the use of inputs or by changing the land use requirements (changing the crop/variety) to fit the actual land characteristics and land qualities.Quantified land-use system evaluation is a point analysis. The basic spatial unit is defined by the scale of the evaluation exercise, i.e. by the resolution of data on the environmental conditions, the soil properties, the crop characteristics and the management applied. A set of point analyses, with their variabilities, over a number of years may be processed by a geographic information system to yield a regional suitability map for a specific land use.