Mapping of arid-cultural systems for biomass production with low energetic input in marginal areas

In the last years, geographical Information System (GIS) has been used to identify the agro-climate suitability of different crops. Cynara cardunculus L. var. altilis, is a biomass plant suitable for cultivation with low energy input in Mediterranean environment. In this work we studied the spatial correlation between biomass and productivity distribution and spatial feature of natural resources. Three years of experimental works (2011-2014) had been carried out in Porto Torres (SS), 40°48'59.45"N; 8°20'49.94"E, Sardinia, using common agricultural practices and machinery. The evaluation of the field ground cover was performed by an aerial flight with 0.5 m spatial resolution (July 2014). The results were ortho-rectified from digital true color aerial photographs. All the data were geo-referenced using a metric Universal Transverse Mercator (UTM) coordinate system, Zone 32, E.D. 50. In order to assess the environmental suitability for cultivation under conditions of low energetic input and to ensure the field homogeneity and production, were considered different parameters, integrating spatial-structural characters with cultural practice. In the experimental field of 25 ha were identified, through sampling parcels of 9 m2, the correlations between variations of cover land, highlighted by the orthophotography analysis, and the variations field yields. It was possible to define four classes of ground cover that corresponding to different seeding density and crop yield, distributed as follows: 24% class 0 (without cardoon); 13% class 1 (<30%); 30% class 2 (30-50%); 34% class 3 (>50%). Was defined a real yield map and a potential yield map that displays the expected yield for the future of the crop in this area. The data collected will allow a specific crop management for planning fertilization between the different areas, considering the local variability of the physical, chemical and biological field.