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Soil salinization from shallow ground waters is problematic in numerous regions of the world. These ground waters can degrade soil physical properties and require special land management to maintain soil salinity levels ideal for crop and rangeland production. The objectives of this study were to evaluate how saline and sodic solutions changed soil hydrologic properties and how hydrologic parameters change with solution composition. Four soils ranging in texture from sandy loam to silty clay, were saturated with solutions ranging in electrical conductivities (EC) of 0.5 to 8 dS m−1 and sodium adsorption ratios (SAR) of 0 to 20. The hydraulic conductivity and water retention were measured using pressure plates, HYPROP evaporation method, and a dewpoint potentiometer. Data was fit with the van Genuchten and dual porosity models and the model parameters were evaluated. There was an increase in water retention and decrease in hydraulic conductivity when soils were near saturation as solution SAR increased and EC decreased at potentials near saturation. Water retention method combinations agreed well for low salinity treatments, but fitting parameters did not agree well for the higher salinity treatments. The coarser textured soil had a stronger disagreement in fitting parameters for the different water retention method combinations and greater salt build up near soil surface. Capillary rise of salt bearing waters of low EC and high SAR increases soil water retention and decreases hydraulic conductivity near saturation which will slow rates of downward water movement and salt leaching.

Crop residues are often removed for livestock and biofuel production, but how such removal impacts soil physical properties has not been widely discussed. The objectives of this paper were to discuss: (a) the impacts of crop residue removal on soil physical properties, (b) factors affecting residue removal effects on soils, (c) threshold level of residue removal, (d) strategies to offset the removal negative effects, and (e) research needs. We compiled 66 studies on crop residue removal and soil physical properties published prior to 17 Aug. 2021. Residue removal may not affect bulk density and water infiltration rate but increases penetration resistance by 55% and soil temperature by 1.8 ˚C in spring. However, it reduces wet aggregate stability by 31%, dry aggregate stability by 44%, and water retention at -33 kPa by 24% in most studies, indicating residue removal can increase erosion risks and reduce soil water storage. Residue removal rate is the leading factor that explains changes in soil physical properties. Residue removal at rates above 50%, in general, adversely affected soil physical properties, which correlates to retaining about 4 Mg ha -1 of residue. Cover crops and manure application may partially offset adverse effects of residue removal on soil physical properties, but studies are too few to make a strong conclusion. Consistency of soil sampling depths, accurate reporting of residue removal rates, and additional data from long-term experiments are needed. Overall, high rates of residue removal can increase erosion potential and reduce soil water but have mixed impacts on other physical properties.

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