This review aims to be a reference article on designing and manufacturing different SAP materials for use in agriculture. The structure used for the content described reveals significant progress in the agricultural sector in recent years. SAP materials to enhance sandy soil compactness, topology, and mechanical properties (swelling, water harvesting, and nutrient release). SAPs in agriculture also promote a 60-80% swelling rate, slow release of nutrients for plants to last longer, and maximum water retention. This systematic review examined methods for designing, manufacturing, and processing SAPs for their properties and impact on agriculture in arid areas and plant growth. SAP materials are designed and manufactured in three morphologies. The first is the preparation of technical processes for manufacturing SAP (hydrogel) powder. Second, SAPs are prepared by mixing the monomer solution and crosslinking agent and converting the SAP solution into fibers using an electrospinning machine and wet spinning technique. Finally, the sheet was produced using a spun lace (hydroentangling) machine that converts SAP fibers into sheets. Similarly, the production processes used a spun-bond machine that converts SAP powder into sheets and a sheet modeling machine that converts SAP fibers into SAP sheets. Furthermore, many SAP materials used for agriculture in arid areas, functional monomers, initiators, and cross-liner agents can be manufactured as powders, fibers, and sheets and have high success rates. This is demonstrated by the excellent maximum absorbent capacity, and maximum water retention of the sheets, followed by those of the fibers and powders. This is supported by the quantitative standards for SAP morphology manufacturing process cost, water absorption, and water retention time. Characteristics of SAPs for use in agriculture.Design and manufacture of SAPs suitable for agriculture.Evaluation of SAP performance for use in agriculture.The appropriate SAP morphology should be chosen to ensure the maximum planting performance.

Freeze -thaw (FT) cycles are regarded as a damage effect to the dynamic resilient modulus (MR) of subgrade soil in seasonal frozen regions and improving the resistance on freeze -thaw cycles must be concerned urgently. For this purpose, the bentonite superabsorbent polymer (BT -SAP) was developed as an available admixture to relieve the attenuation of MR of subgrade soil under FT cycles. In order to evaluate the improvement of resistance on FT cycles, a series of dynamic triaxial tests were conducted after various FT cycles. The main influences on MR were investigated including the numbers of freeze -thaw cycles, BT -SAP contents, deviator stress and confining stress. The experimental results indicate that the BT -SAP can delay the attenuation trend of MR that means the resistance on freeze -thaw cycles have been promoted. The ensuing discoveries are that with the increment of BT -SAP content, the sensitivity of the subgrade soil to FT cycles is gradually reduced. Nevertheless, results reveal that a proper content of BT -SAP is recommended as 0.5%, where if the BT -SAP content exceeds 0.5%, the improvement effect of resistance on FT cycles decreases. Moreover, the improved effect caused by BT -SAP can produce a coupling enhancement combining with confining stress, and it also can offset the softening effect due to the deviator stress. For better application and practicability, the high -accuracy empirical model for predicting MR is established and validated. Finally, based on the soil freezing temperature, unfrozen moisture content and moisture distribution characteristics, the mechanism of BT -SAP reducing the freeze -thaw cycle sensitivity is analyzed. The conclusions mentioned above show that employing BT -SAP material is acceptable and significant to improve resistance on freeze -thaw of subgrade soil.