Pattern, structure, archaeology, chronology and functionality of the Early Islamic Plot-and-Berm agroecosystem by ancient Caesarea, Israel

“Plot-and-Berm” (P&B) agroecosystems consist of relatively unrecognized but sophisticated in-situ agricultural utilization of a high water table within loose, aeolian sand sheets situated in agricultural hinterlands in arid to Mediterranean climates in the Middle East, north Africa and Iberia, the latter historically dating between the Middle Ages to Early Modern times. The agroecosystem is comprised of a checkerboard array of agricultural plots sunken between 3-8 m high berms. The earliest recognized P&B agroecosystems are Early Islamic to early Crusader (9th-early 12th centuries a.d.) within several coastal sand bodies of Israel, that were abandoned by unclear reasons. We focus on the agroecosystem at the southern outskirts of ancient Caesarea that include limekilns, walls, and small structures with small amounts of in-situ artifacts. Our methods include geospatial mapping, relative and absolute luminescence chrono-stratigraphy, and analysis of pedological, geochemical, archaeological, archaeobotanical, and artifactual finds from surveys and three excavations coupled with a review of medieval Arabic agricultural manuals (kutub al-filāḥa) as well as other relevant literary sources.

The plot level enables easy and year-round access to the groundwater for crop roots and for digging shallow and open pit-like wells for manual irrigation. The current water table at the Caesarea was found to be uniformly 1 m beneath the anthrosol in several plots. The confined plots are hypothesized to also provide enhanced climatic conditions for agriculture: increased solar insolation while being protected from winds. Imported fine-grained refuse from nearby town dumps enrichen the inert plot sand forming distinct 30-50 cm thick, dark grey, sand-loam anthrosols that served agriculture. The plot anthrosols are not uniform in their geochemistry, texture and compaction. Initial OSL ages of the anthrosol suggest a ~200 year span of agriculture practice.

The berms are coated with a similar but less dense mix of sand with refuse, forming a dark anthrosediment. Atop the anthrosediment is a thin coat of 2-15 cm wide ceramic and artifacts that protect the berms from aeolian and slopewash erosion and therefor berm slopes were probably not utilized for crops. Berms are found to be fully made of sand mixed with refuse, with hints of Roman activity at the level of their basal sand.

Despite the current absence of historical documentation regarding the Early Islamic agroecosystems, and based on gross calculations of the immense efforts to construct the berms and import refuse, we suggest that these enterprises required administrative support. The presence of several agroecosystems along the coast of Israel, two of which date by OSL and artifacts to the same timespan, strengthen our understanding that a regional governance was behind the development of these agroecosystems. These agroecosystems are proposed to have been developed in response to religio-administrative calls for a type of mawāt (Arabic: “dead”) land reclamation. This effort was probably combined with an economic agricultural incentive and demand for a certain productive, rewarding and possibly unique crop whose type remains a pressing mystery.