Development and analysis of the Soil Water Infiltration Global database

In this paper, we present and analyze a novel global database of soil infiltration measurements, the Soil Water Infiltration Global (SWIG) database. In total, 5023 infiltration curves were collected across all continents in the SWIG database. These data were either provided and quality checked by the scientists who performed the experiments or they were digitized from published articles. Data from 54 different countries were included in the database with major contributions from Iran, China, and the USA. In addition to its extensive geographical coverage, the collected infiltration curves cover research from 1976 to late 2017. Basic information on measurement location and method, soil properties, and land use was gathered along with the infiltration data, making the database valuable for the development of pedotransfer functions (PTFs) for estimating soil hydraulic properties, for the evaluation of infiltration measurement methods, and for developing and validating infiltration models. Soil textural information (clay, silt, and sand content) is available for 3842 out of 5023 infiltration measurements ( ∼ 76%) covering nearly all soil USDA textural classes except for the sandy clay and silt classes. Information on land use is available for 76% of the experimental sites with agricultural land use as the dominant type ( ∼ 40%). We are convinced that the SWIG database will allow for a better parameterization of the infiltration process in land surface models and for testing infiltration models. All collected data and related soil characteristics are provided online in *.xlsx and *.csv formats for reference, and we add a disclaimer that the database is for public domain use only and can be copied freely by referencing it. Supplementary data are available at https://doi.org/10.1594/PANGAEA.885492 (Rahmati et al., 2018). Data quality assessment is strongly advised prior to any use of this database. Finally, we would like to encourage scientists to extend and update the SWIG database by uploading new data to it

Soil sealing indicator for agricultural soils in Venezuela

Soil sealing is a degradation problem that involves different factors, processes and mechanics. Different methods and methodologies to assess those factors and processes can reflect different results and levels of soil structure degradation within the same soil, under different climate and management conditions. Standardized methods were evaluated for assessing soil sealing in five Venezuelan soils, with different texture and organic carbon content. The objective is to select indicators for predicting soil sealing. The results showed that the amount of water stable aggregates (WSA), the medium weight diameter (MWD) of the aggregates, the particles with diameter < 0.25mm (P250), the absolute sealing index (ASI), the consistency index (C5-10) and the soil losses from simulation rainfall were able to evaluate the stability of the soil surface structure. However when all the methods were compared based on the classification criteria of each method, the MWD and C5-10 had a discrepant class of soil sealing degradation when compared with other methods. The WSA, P250, ASI methods and soil characteristics as SOM chemical fractions and particles between 2 and 100 μm diameters, had high correlations among each other but all had good relationship with soil losses under simulated rainfall. From this study it can be concluded that a simple laboratory method is enable to evaluate soil surface sealing susceptibility but the method needs to be validated under field conditions as well

Impact of potential bio-subsoilers on pore network of a severely compacted subsoil

Subsoil compaction is a major threat to soil quality. The use of bio-subsoilers has been proposed as a mitigation practice. There is, however, a paucity of knowledge on the effects of potential bio-subsoiling crops in alleviating severely compacted subsoil. X-ray Computed Tomography (CT) was used to assess the changes caused by different crops in the pore network of a severely compacted subsoil. The potential bio-subsoilers, chicory, lucerne, radish and tall fescue, with spring barley as reference, were grown for one year in undisturbed soil columns (empty set = 0.20 m, h = 0.50 m) with soil originating from a heavily compacted soil after mechanical impact. Soil columns were X-ray CT-scanned before and after the experiment. CT-pore soil characteristics were quantified by image analysis. Crop treatments affected the soil porosity differently on the studied soil. Radish and tall fescue did not show a significant impact on CT-derived pore characteristics at any depth. In the compacted layer, the macropore density, the branches number, and the number of pores (for volume sizes of < 100 mm(3) and diameter <= 1.5 mm) were larger for chicory and lucerne compared to barley (P < 0.05). Chicory and Lucerne appear to contribute to the development of a large number of complex-shaped pores. Differences in the CT-derived pore network indicate that chicory and lucerne are likely to perform better than the other crops when used as bio-subsoilers by creating a larger, more connected and complex pore network. Longer-term growth is needed to obtain a marked loosening effect in the compacted layer