Impact of different climate change scenarios on rainfed cropping systems in Central Italy

Abstract The rainfed cropping system based on the durum wheat-sunflower rotation is very common in Central Italy, to the point of being the almost exclusive systemi n somea reas.T he predominanceo fthe system,a nd the suboptimale nvironmentalc onditions in which such system is implemented make it at risk in scenarios of possible worsening ofweather pattems as estimated by weather change scanarios. The objectives ofthis paper were: l) to estimate the impact of climate change on the agronomic performance and long term soil fertility; 2) to explore adaptation sfategies and to identift research needs. Three yéars of field data on current cropping systemp racticesw ere collected at two microcatchmentso f the Marche (Central It- ;ly) to calibratet he cropping systemss imulation model Cropsyst. Cropsi eld and soil organic matter_dynamicsw ere analyzed in relation to incrèaseda ir temperaturea nd CO2c oncentration,a s forecastedb y different future climate scenarios. io ^se.. the impact of climatic change on mean crop yields and variability, two fifty-years equilibrium climate dataseÎs were generatedf rom a local 2O-yearsd aily temperaturea nd rainfall dataseta ssumingf or each scenarioc onstantc limate at differànta tmospheriCc O2c oncentration":b aseline"[ COr1= 359 ppm; 2040e quilibrium[ COrl : 450 ppm-T o assestsh e long term impait of climatic change on soil organic matter content, three 100-yearc transient climatic scenarios were gen- "ruÉd ftorn a 20-years daily temperature and rainfall dataset of a neighbouring station: transienf "baselrne" scenarios with current [CO2] = jSO ppm; transienî "A2'and "B2" scenarios,c haracterisedb y an yeady increaseo f [CO2] starting ffom current conditions to final values of 840 and 620 ppm respectively' Under 2040 equilibrium scenario, sunflower showed a slight increase of mean grain yield +12%, while durum wheat grain yield was not ìignificantly different from "baseline". Under "baseline" tronsient scenariosa nd starting from a current soil órganic matter conte nt of 0.9Vo,C ropsyst simulateda progressived ecreaseo f soil organic matter down to 0.6% after I 00 yJars. Under "B2" and "A2" scenarios,in creaseds oil ternperatures imulatedb y CropSystr esulted in a sharperd ecreaseo f ihe soil organic matter, leading respectively0 .5o/oa nd0 .4%oa fter 100y ears. Resultss uggestî hat while. climate changei mpacts on current rainfed cropping systems of central Italy may not be visible in the short term on crop yields, long term sus- Linubitity is expected to aàitinè noticeably, even under "baseline" climatic scenarios. In terms of bio-physical research, further eiforts súould be addressedo n the relationshipsb etweena gronomicp racticesa nd seasonadl ynamicso f soil organic matter mineralization due to soil temperature.