Plant available soil moisture and its spatial variability is among the most important limiting factors for crop and livestock productivity in semi-arid Ethiopia. The objectives of this study were therefore: 1) to measure the effects of land use and slope gradient on spatial variability of topsoil moisture content. 2) to analyze the variability of topsoil moisture content and crop responses under different soil and water conservation (SWC) structures and 3) to analyze whether topsoil moisture content, grain and biomass yields vary in relation to SWC structures. In total, 21 large runoff plots (600–1000 m²) were installed and treated with stone bunds, trenches, stone bunds with trenches and a control plot at each site. Plot sites were located on gentle (5%), medium (12%) and steep (16%) slopes of cropland and rangeland. Topsoil (0–15 cm) moisture content for plots were monitored daily using soil moisture probes (Theta-Probes) and weekly using manual sampling over two growing seasons. Crop performance was monitored during two growing seasons and grain and biomass yield were measured at harvest. Results show that average gravimetric moisture content of the topsoil during growing seasons is remarkably higher for cropland (33–25 g/100 g) compared to rangelands (24–20 g/100 g). This is due to tillage-induced runoff retention and infiltration. Soil moisture content decreases with increasing slope gradients, owing to increased drainage. Considering the effects of SWC structures, average topsoil moisture contents at accumulation and erosion zones are generally higher as compared to middle zone between two successive SWC structures. Average seasonal volumetric soil moisture content of 38.2 (cm³/100 cm³) in 2011 and 39.4 (cm³/100 cm³) in 2012 for accumulation zone of plots with stone bunds with trenchers are significantly higher than at other sampling locations. Crop growth performance, grain and biomass yield varied among plots and depended on slope gradients and SWC structures. Grain yields of wheat in 2011 and barley in 2012 were significantly higher for plots with SWC structures as compared to control plots and are highly correlated to topsoil moisture content (r = 0.64; p < 0.04 in 2011 and r = 0.59, p < 0.01 in 2012). Even when taking into account the cropland area occupied by SWC structures, grain yield increased by (4.2%−33%) for plots with SWC structures as compared to control plots. Overall, our results show that implemented measures may not only reduce runoff and soil loss, but also increase crop productivity by enhancing soil moisture and thus can significantly contribute to sustainability of agro-ecosystems in semi-arid environments.

植物有效土壤湿度及其空间变异性是半干旱埃塞俄比亚作物和牲畜生产力最重要的限制因素之一。因此，本研究的目标是：1）测量土地利用和坡度对表土含水量空间变异的影响。2) 分析不同水土保持 (SWC) 结构下表土含水量和作物响应的变化；3) 分析表土含水量、谷物和生物量产量是否随 SWC 结构而变化。总共设置了 21 个大型径流地块（600-1000 m ² ），并用石堤、沟渠、带沟渠的石堤以及每个地点的控制地块进行了处理。样地位于农田和牧场的缓坡（5%）、中坡（12%）和陡坡（16%）上。每天使用土壤湿度探针（Theta-Probes）监测地块表土（0-15 厘米）的水分含量，并在两个生长季节每周使用手动采样监测。在两个生长季节监测作物表现，并在收获时测量谷物和生物量产量。结果表明，生长季节农田表土的平均重量含水量（33-25 克/100 克）明显高于牧场（24-20 克/100 克）。这是由于耕作引起的径流滞留和渗透。由于排水增加，土壤含水量随着坡度的增加而降低。考虑到SWC结构的影响，积累区和侵蚀区的平均表土含水量通常高于两个连续SWC结构之间的中间区域。带挖沟机的石堤堆积区2011年和2012年土壤季节平均体积含水量分别为38.2（cm ³ /100 cm ³）和39.4（cm ³ /100 cm ³），显着高于其他采样点。作物生长性能、谷物和生物量产量因地块而异，并取决于坡度梯度和 SWC 结构。与对照地块相比，具有 SWC 结构的地块 2011 年小麦和 2012 年大麦的粮食产量显着更高，并且与表土含水量高度相关（2011 年 r = 0.64；p < 0.04；2011 年 r = 0.59，p < 0.01）。 2012）。即使考虑到 SWC 结构占用的农田面积，与对照地块相比，具有 SWC 结构的地块的粮食产量也增加了 (4.2%−33%)。总体而言，我们的结果表明，采取的措施不仅可以减少径流和土壤流失，还可以通过提高土壤湿度来提高作物生产力，从而显着促进半干旱环境中农业生态系统的可持续性。