Owing to its significant capacity to conserve water in soils, polyacrylamide (PAM) hydrogels have been applied extensively in croplands to combat droughts. However, the influences of different mechanical and chemical factors of sand on its swelling capacity is still unclear. The objective of this study is to reveal the relationships between swelling profile of PAM in sand and sand mechanical and chemical properties, using an originally designed laboratory-scaled column apparatus. Different water management strategies and sand properties, including water infiltration rates (0.6, 1.4, 1.9, and 2.5 m day^–1), application depth (5.5, 11.0, and 16.5 cm), solution pH (5.0, 6.9 and 9.0), and ionic strengths (0.001, 0.01, and 0.1 M) were investigated in the present study. Chemical properties of sand medium (i.e. ionic strengths and pH conditions) reduced up to 70% of water holding capacity. Vertical stress limited water holding capacity to 50–60% of the maximum value, demonstrating that its effect has been underestimated in the past. Infiltration rate influenced the swelling profile but not the maximum water holding capacity. Results were fitted with the Korsmeyer-Peppas model, Gallagher-Corrigan model and First-Order model to derive parameters that highlight the impacts of the sand properties. Through model simulation, swelling behaviour was well explained with rapid swelling followed by further release in swelling. The discoveries in this study demonstrate the important roles of mechanical and chemical factors during the water absorption process of agricultural hydrogels.

聚丙烯酰胺（PAM）水凝胶由于其具有在土壤中保水的显着能力，已在农田中广泛用于抗旱。然而，沙的不同机械和化学因素对其溶胀能力的影响仍不清楚。这项研究的目的是揭示使用原始设计的实验室规模的色谱柱设备，分析PAM在沙子中的溶胀曲线与沙子的机械和化学性质之间的关系。不同的水管理策略和砂质，包括水渗透率（0.6、1.4、1.9和2.5 m天^–1），施加深度（5.5、11.0和16.5 cm），溶液pH（5.0、6.9和9.0）和离子强度（0.001、0.01和0.1 M）进行了研究。砂土的化学性质（即离子强度和pH条件）降低了持水量的70％。垂直应力将持水能力限制在最大值的50％至60％之间，这表明过去其作用被低估了。渗透率影响溶胀曲线，但不影响最大持水量。将结果与Korsmeyer-Peppas模型，Gallagher-Corrigan模型和First-order模型拟合，以得出突出砂性影响的参数。通过模型仿真，可以很好地解释溶胀行为，先进行快速溶胀，然后进一步释放溶胀。