Rehabilitation of degraded rangelands in Jordan: The effects of mechanized micro water harvesting on hill-slope scale soil water and vegetation dynamics

Authors: STROHMEIER, STEFAN - International Centre For Agricultural Research In The Dry Areas (ICARDA); FUKAI, S - Tottori University; HADDAD, MIRA - International Centre For Agricultural Research In The Dry Areas (ICARDA); AINSOUR, M - Watershed And Development Initiative(WADI); MUDABBER, M - National Agriculture Research Center(NARC); AKIMOTO, K - Tottori University; YAMAMOTO, S - Tottori University; Evett, Steven - Steve; OWEIS, T.Y. - International Centre For Agricultural Research In The Dry Areas (ICARDA)

Submitted to: Journal of Arid Environments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/22/2020
Publication Date: 10/18/2020
Publication URL: https://handle.nal.usda.gov/10113/7149047
Citation: Strohmeier, S.M., Fukai, S., Haddad, M., Ainsour, M., Mudabber, M., Akimoto, K., Yamamoto, S., Evett, S.R., Oweis, T. 2020. Rehabilitation of degraded rangelands in Jordan: The effects of mechanized micro water harvesting on hill-slope scale soil water and vegetation dynamics. Journal of Arid Environments. 185. Article 104338. https://doi.org/10.1016/j.jaridenv.2020.104338.
DOI: https://doi.org/10.1016/j.jaridenv.2020.104338

Interpretive Summary: The health and productive sustainability of dry grazing lands is important for meat and milk animal production globally and is particularly important in the semi-arid and arid regions of the US such as the western Great Plains and Intermountain West. Methods for increasing sustainable production include various methods of water harvesting, all of which collect runoff water on open range into some sort of basins, large or small, where vegetative growth is thereby enhanced. In the US, the Vallerani system of water harvesting has not been much used but is of interest because large areas of grazing land may be treated by machine at reasonably low cost. Therefore, a USDA ARS scientist collaborated with researchers from the US Forest Service and the International Centre for Agricultural Research in the Dry Areas (ICARDA) to test the Vallerani system in an arid rangeland of Jordan that is similar to arid rangelands of the western US. Initial results were promising with increased soil water storage that persisted for long periods after sporadic rainfalls and increased growth of shrubs suitable for grazing animals. Although multiple years are needed to confirm the initial results, the Vallerani system may well be a worthwhile addition to water harvesting methods already employed by the Bureau of Land Management, U.S. Forest Service and NRCS.

Technical Abstract: Overexploitation and climate change trigger the degradation of Jordan’s arid rangelands. Uncovered and crusted soils increase runoff and erosion and hinder the emergence of the native vegetation. Micro water harvesting combined with shrub-seedling plantation have been widely applied to reverse these trends. However, soil water and vegetation development have been barely assessed, which constrains further out-scaling to complex environments. In Jordan, an experiment was set up to study the linkages between local rainfall characteristics, soil moisture dynamics and the development of out-planted shrub-seedlings. Soil moisture was recorded at approximately weekly time-interval during the rainy and dry season 2017/2018 using a manually operated soil water sensor. Transect monitoring was pursued up and down the slope across four micro water harvesting pits and the interspaces. Data confirmed a significant soil moisture increase inside the pits - bridging intra-seasonal dry spells and potentially fostering soil water deep-percolation into the karstic bedrock underneath. The study concludes that the out-planted shrubs’ stem diameter and height predominantly increased during post rainy season, when the interspaces dried up while the pits continued providing moisture. The results are promising and feed into an integrated research towards halting land degradation for sustainable agro-pastoral development.