Mixing superabsorbents, such as cross‐linked polyacrylamides (PAM), with sandy soils may decrease water percolation rates and increase water availability to crops. Four polymers were evaluated for their effects on water retention and hydraulic conductivity (HC) in the presence of either tap or distilled water and within sand mixtures. Water retained by the absorbents alone (at low suction) ranged between 200 and 500 kg kg−1 of polymer; water retained by the polymers when mixed with sand ranged between 40 and 140 kg kg−1 Water retained per kilogram of polymer increased with an increase in polymer concentration in the sand while undergoing desorption, but absorbed water decreased with polymer concentration during sorption, indicating an effect of hysteresis and absorption kinetics in the water absorption process. Applying a hydraulic head of tap water initially caused a decrease in the HC, explained by the decrease in the volume of the soil–absorbents mixtures, followed by a steady increase in HC ascribed to drainage of water from the swollen polymer granules that led to an increase in the size of pores available for water flow. Leaching the soil–absorbent mixtures with distilled water, simulating rainwater, increased the volume of the mixtures (due to polymer swelling) and decreased their HC due to pore blockage by the swollen polymer grains. Better understanding of the interaction among absorbents, soil, and water quality may produce an efficient and economic technology for improving the water management of sandy soils.

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Past attempts to use aggregate stability to predict soil susceptibility to seal formation indices (final infiltration rate and runoff) have yielded inconsistent results. We hypothesized that determining aggregate stability in a method in which a controlled wetting process was used to break aggregates will correlate well with seal formation indices, as the latter strongly depend on rate of aggregate wetting. We studied aggregate stability from soils varying in clay content, and exchangeable Na percentage (ESP), using the high‐energy‐moisture‐characteristics (HEMC) method. Aggregate stability indices were correlated with previously published seal formation data for the same soils. Aggregates were placed in a funnel equipped with a fritted disk, and wetted either fast (100 mm h−1) or slow (2 mm h−1), using a peristaltic pump. Thereafter, the aggregates were subjected to a stepwise increase in matric potential up to 5.0 J kg−1, to obtain a moisture retention curve, which served as the base for calculations of stability parameters. Aggregate stability correlated with clay content, but not with soil organic matter. Aggregate stability and sodicity correlated only in clay soils. Generally, poor correlation (R < 0.5) was obtained between aggregate stability and seal formation and runoff data, irrespective of soil ESP, when infiltration and runoff measurements were carried out on fast‐wetted soils. Conversely, aggregate stability significantly correlated (R > 0.70) with seal formation and runoff data from slow wetted soils for samples having ESP of <6.6. Our results suggest that aggregate stability determined with the HEMC method could serve as a predictor for soil susceptibility for seal formation only under the aforementioned specific conditions.

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