Irrigation agrosystems in eastern Spain: Roman or Islamic origins?

The long-standing controversy concerning Islamic diffusion of cultivars and irrigation technology to Spain is approached by comparing Roman and Islamic agrosystems at the general, regional, and local levels. We describe the Roman intensification of the older Mediterranean agrosystem and then examine the subsequent agricultural and demographic decline between A.D. 250 and 800. The operation, organization, and evolution of large, intermediate, and small-scale irrigation are analyzed in seven case studies from the Valencia region of eastern Spain. The largest systems were refurbished in Islamic times, but during a period when Berber and Arab settlement was thin and acculturation of the indigenous population incomplete. As a result the Roman agrosystem and irrigation networks remained largely unchanged, despite the presence of new technologic features and cultivars. Later transfer of irrigation agriculture to the adjacent mountain valleys followed the Roman model, but with more Islamic elements apparent. Muslim agriculture in the area remained characteristically Mediterranean after the Christian Reconquest (A.D. 1238), and it survived largely intact into the present century, even after the Muslim expulsion in 1609. By focusing on the cultivars and the technology, as well as on the agrosystems as a whole, we are able to compare Roman and Islamic intensification objectively. They differed in degree rather than kind, with far more continuity than change. Finally, we examine the processes of Islamic diffusion and indigenous adaptation.