Pre-farming environment and OSL chronology in the Negev Highlands, Israel

• Published in: Journal of arid environments 2012-11, Vol.86, p.12-27
• Main Authors: Avni, Y., Porat, N., Avni, G.
• Format: Article
• Language: English
• Subjects: bedrock; biomass; byproducts; climate change; Desert agriculture; desertification; deserts; Erosion; flood irrigation; Israel; Loess sediments; luminescence; Negev Highlands; OSL dating; runoff; sediment deposition; sediments; soil; soil conservation; soil erosion; terraces; valleys
• ISSN: 0140-1963; 1095-922X
• DOI: 10.1016/j.jaridenv.2012.01.002

The ancient agriculture in the southern Levant is very much dependant on the interaction between the geological and geomorphological characteristics of the desert environment and the arid climatic conditions. Field observations and luminescence dating in the Negev Highlands, southern Israel, indicate that deposition of fluvio-loess sediments occurred mainly during the late Pleistocene glacial period. These sediments, which were transformed into loessy soil, support a high natural biomass and have an agricultural potential. Major soil erosion started after 27 ka, exposing bedrock, increasing runoff and erosion. These feedback processes were intensified during the Holocene. Since the mid Holocene, the co-existence of soil and runoff created a unique setup which enabled the establishment of desert agriculture in the southern Levant, based on runoff-harvesting techniques. Extensive construction of stone terrace walls on top of diachronous middle–late Holocene alluvial units in the less degraded valleys led to the deposition of the anthropogenic unit, consisting of fine grained re-deposited loess as a by-product of the flood irrigation. This process contributed to soil conservation and counteracted the continuous natural soil erosion and desertification. The ability to practice desert agriculture is still preserved in the southern Levant, and historic climate changes are not required to explain the rise and fall of the great farming cultures. ► Sediments underlying agricultural terraces in the arid Negev were dated by OSL. ► The farming installations were established on early Holocene degraded landscape. ► Accelerated natural desertification continued throughout the Holocene. ► Co-existence of soil and runoff enabled runoff-harvesting agriculture. ► Climate changes were not crucial in the rise and fall of the desert farming.