Impact of stone bunds on temporal and spatial variability of soil physical properties: A field study from northern Ethiopia

Abstract

In the Ethiopian Highlands, stone bunds (SBs) are a common practice for soil and water conservation, influencing runoff and erosion processes from sloped agricultural areas. The objective of this study was to investigate how SBs affect spatiotemporal relationships of these processes to better understand their impacts on soil water development at the smallholder farmer's field level. Study area was the Gumara‐Maksegnit Watershed in northern Ethiopia, where two representative transects were investigated: One transect crossed a 71 m‐long field intersected by 2 SBs traced along the contour. The second transect crossed a similar hillslope without conservation structures at a length of 55 m representing baseline (untreated) conditions (no stone bund). During the rainy season of 2012, bulk density and volumetric water content were monitored, and tension disc infiltrometer experiments were performed to determine the saturated hydraulic conductivity and to derive soil water retention characteristics. Our observations show that SB decreased significantly soil bulk density in center and lower zones of SB transect compared with no stone bund. No temporal change was observed. Results targeting the surface soil moisture indicate that infiltration was higher with SB and happened earlier in the rainy season in the zones around the SBs. Saturated hydraulic conductivity was positively affected by SB and increased significantly. Improved soil hydrology by SB fields may increase crop yields by higher soil water contents but also by extending the growing season after the rainy season. Therefore, SBs are a successful measure to establish climate‐resilient agriculture in the Ethiopian Highlands.

Influence of Stone Bunds on Vegetation and Soil in an Area Reforested with Pinus engelmannii Carr. in the Forests of Durango, Mexico

“…Since the literature establishes that stone SB have an influence on vegetation and soil [4,12,21,22], three main aspects were evaluated to measure this influence: (a) survival and growth of P. engelmannii Carr. ; (b) aerial cover and production of aerial herbaceous plants; and (c) physicochemical characteristics of the soil.…”

“…On the other hand, SB compared to Level Soil Bunds and non-terraced cropland did not show significant differences on organic carbon, N, P, K and others [22]. An increment of soil depth may improve the crop yield due to longer periods of humidity in the soil-even after the rainy season [4]. Nevertheless, there is a lack of information concerning the influence of SB on the growth of trees and vegetation.…”

“…When erosion occurs, the soil undergoes a gradual decrease in productivity due to the loss of nutrients through the transportation of fine particles and organic matter [2]. This process modifies the physical structure of the soil, whereby the surface is sealed and crusts are formed, which results in a lessening of water infiltration and, consequently, drainage becomes faster [3,4]. However, there are other factors that influence infiltration, such as the intensity and duration of rain, soil texture and the moisture content of the soil [5].…”

“…The distance between SB depends on the steepness of the terrain, but they normally range from 10 to 25 m (recommended slope is 5% to 60%). SB are used to reduce surface runoff, increase infiltration and trap soil [4,12]. Moreover, they can be improved by establishing vegetation (i.e., herbaceous, shrubs and trees) [15].…”

“…SB have been evaluated on forest plantations in diverse ecosystems [16,17]; as well as in transition zones [18]. Klik et al [4] reported that SB increased infiltration rates and hydraulic conductivity in the Ethiopian highlands. In another study, Radulovich [19] observed that after three years, SB increased soil retention once vegetation was established.…”