Collapse and failure of ancient agricultural stone terraces: On-site geomorphic processes, pedogenic mechanisms, and soil quality

Ilan Stavi, Yulia Gusarov, Rares Halbac-Cotoara-Zamfir

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Water is the major limiting factor for primary productivity in drylands. In ancient times, stone terraces aimed at runoff harvesting and soil erosion control were established, allowing agricultural crop production. Land abandonment and cease of maintenance have led to the collapse and failure of terraces in the hinterlands of the Roman/Byzantine city of Avdat in the arid Negev Desert, Israel. The objective of this study was to assess the geomorphic processes and pedogenic mechanisms related to terrace collapse, and their on-site impact on soil quality. We studied key properties of the top 10 cm of soil in intact-terrace plots and partially-collapsed terrace plots, as well as in ‘natural’ lands. Unexpectedly, the soil texture was finer in the partially collapsed-terrace plots (clay loam) than that in the intact-terrace plots (loam). This was attributed to transportation of mineral material by rolling, which sorts out the large primary particles. This process, which characterizes rill erosion of high erosive power, is probably the predominant surface process in this study. The soil penetration resistance was significantly greater in the partially-collapsed terrace plots, and was attributed to the continuous removal of recently deposited loose sediments and exposure of the underlying, compacted older sediments. Soil stoniness, which was 16-fold greater in the partially-collapsed terrace plots, was also attributed to soil erosion. Unexpectedly, the total organic carbon was similar in both terrace states. Yet, labile organic carbon was 41% lower in soil of the partially-collapsed terrace plots, suggesting greater susceptibility of this fraction to erosional processes. The low electrical conductivity in the soil of the intact-terrace plots, was attributed to the better leaching of salts. The soil's calculated available water capacity was 42% greater in the intact-terrace plots. The study suggests that these processes and mechanisms strengthen each other through a chain of feedbacks, resulting in accelerated degradation of the collapsed-terrace lands.

Original languageEnglish
Pages (from-to)144-152
Number of pages9
JournalGeoderma
Volume344
DOIs
StatePublished - 15 Jun 2019
Externally publishedYes

Keywords

  • Geoarchaeology
  • Hydrological connectivity
  • Patch- vs. meso-scale geodiversity
  • Soil salinity
  • Vegetation cover

ASJC Scopus subject areas

  • Soil Science

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