Agronomic performance, carbon storage and nitrogen utilisation of long-term organic and conventional stockless arable systems in Mediterranean area.

The Montepaldi Long Term Experiment (MOLTE) trial in central Italy has been comparing three agroecosystems with different management: two organic (Old Organic since 1992 and Young Organic since 2001) and one conventional. After sixteen years of comparison, the agronomic performance and environmental sustainability of the three agro-ecosystems were assessed. Crops grain yield, total C inputs and N budget at field level were evaluated. N use efficiency (NUE) at micro-agroecosystem level was determined. Soil samples were collected from the three agroecosystems in order to quantify soil C and N pools. Results showed comparable grain yields in the three agro-ecosystems. The conventional system showed a larger N surplus and a lower crop N use efficiency in comparison with the organic ones. Moreover, the organic systems presented a lower potential risk of N losses with respect to the conventional one. The Young Organic agro-ecosystem was the most effective in terms of long term soil C (13% higher than conventional) and the oldest organic agro-ecosystem was the most effective in terms of soil N storage (9% higher than conventional). The results obtained demonstrated that the application of the organic farming method could increase the environmental sustainability in stockless arable systems under Mediterranean type of climate.