Arid and semi-arid landscapes often show a patchwork of bare and vegetated spaces. Their heterogeneous patterns can be of natural origin, but may also indicate soil degradation. This study investigates the use of unmanned aerial vehicle (UAV) imagery to identify the degradation status of soils, based on the hypothesis that vegetation cover can be used as a proxy for estimating the soils’ health status. To assess the quality of the UAV-derived products, we compare a conventional field-derived map (FM) with two modelled maps based on (i) vegetation cover (RGB map), and (ii) vegetation cover, topographic information, and a flow accumulation analysis (RGB+DEM map). All methods were able to identify areas of soil degradation but differed in the extent of classified soil degradation, with the RGB map classifying the least amount as degraded. The RGB+DEM map classified 12% more as degraded than the FM, due to the wider perspective of the UAV compared to conventional field mapping. Overall, conventional UAVs provide a valuable tool for soil mapping in heterogeneous landscapes where manual field sampling is very time consuming. Additionally, the UAVs’ planform view from a bird’s-eye perspective can overcome the limited view from the surveyors’ (ground-based) vantage point.

Sandy soils with fragipans are usually considered poorly suited for agriculture. However, these soils are cultivated in north-central Namibia as they can secure a minimum harvest during droughts. To understand the hydrological influence of fragipans in these soils, Ehenge, and what makes them valuable, their soil moisture content was measured over a time span of four months. These data were then compared to a deep soil without fragipan, Omutunda, which is more productive during normal years, but less productive during droughts. The results illustrate that the combination of sandy topsoil and shallow fragipan has beneficial effects on plant available water during dry periods, because of three reasons: (i) The high infiltration rate in the sandy topsoil, (ii) the prevention of deep drainage of water by the fragipan, and (iii) the limited evaporation losses through the capillary rise in the sand. The results also confirm the disadvantages of Ehenge during wet periods. Description of Dataset The dataset comprises a .pdf-file with a detailed data description, seven .csv-files (relevant datasets), and two txt-files with the R-code to produce the relevant Figures 4 and 5 from the paper “The Potential of Fragipans in Sustaining Pearl Millet during Drought Periods in North-Central Namibia” by Prudat et al. 2021. File description Rainfall.csv: daily rainfall in mm at two locations (Omutunda & Ehenge) NDOB13_ehenge.csv/ NDOB13_omutunda.csv: soil temperature and soil moisture per minute NDOB13_ehenge_daily.csv/ NDOB13_omutunda_daily.csv: soil temperature and volumetric soil moisture content (θ_TDR) aggregated per day using the arithmetic mean NDOB13_ehenge_RASW_daily.csv/ NDOB13_omutunda_RASW_daily.csv: The relative available soil water (RASW) was calculated based on the measured plant available water, Scripts (1) RASW_rainfall_daily: Script to calculate and plot the relative available soil water (RASW) at the two stations and the rainfall (2) Max_soil_surface_temperature: Script to calculate and plot the maximum soil surface temperature at the two stations References Cobos, D., Campbell, C., 2007. Correcting temperature sensitivity of ECH2O soil moisture sensors. Decagon Devices Pullman WA. Hillel, D., 1998. Environmental soil physics: Fundamentals, applications, and environmental considerations. Academic press.

Introduction: Intensive agriculture causes substantial negative impacts on agroecosystems. One approach to reduce impacts while maintaining productivity is the inoculation with beneficial microbes. Inoculants can positively affect crop growth for instance through enhancing nutrient uptake or pathogen protection. However, the efficacy of inoculants is inconsistent across different agricultural soils. In this study, we investigated to which degree the varying growth responses to an inoculant can be modelled from soil parameters.Materials and Methods: As inoculant, we worked with the commercially available fungus Cladosporium tenuissimum and tested its effectivity on wheat plants. Variation between soils was specifically tested, while keeping other factors constant in pot experiments under controlled conditions. We assessed 25 field soils for their influence on wheat biomass response to inoculation (BRI). For each soil, we measured physicochemical parameters and characterised the soil fungal community composition. We then performed variable selection and exhaustive model screenings to find the best model explaining variations in BRI.Results: A combined model incorporating physicochemical and fungal soil parameters outperformed models using only one of the two types of data. The best model was based on six predictors and explained 80% of the observed variability in BRI. Predictive parameters included water holding capacity and organic carbon levels as well as soil fungi of the taxa Alternaria, Cladosporium (another species than the inoculant), Acrostalagmus and Fusicolla. Organic carbon and Alternaria negatively affected the effectivity of the inoculant while the other parameters were positive predictors for inoculation success.Conclusion: We showed that six soil parameters were sufficient to explain most of the variation of wheat responses to inoculation with C. tenuissimum. This result serves as proof‐of‐concept that the effectivity of inoculants can be modelled from soil parameters. It is now necessary to take this approach to practice and evaluate predictions for inoculant efficacy under field conditions.