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The ATP-BF-P(HEC-AA-AMPS) composite highly absorbent polymer was copolymerized with acrylic acid (AA) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) using an aqueous solution method with attapulgite (ATP) and attapulgite (ATP) as a matrix. The prepared ATP-BF-P(HEC-AA-AMPS) was characterized in terms of microstructure and tested for its water absorption capacity, water retention properties, and pH dynamic sensing ability. The results showed that the synthesized ATP-BF-P(HEC-AA-AMPS) had a rough and porous surface and a high water absorption capacity and rate, almost reaching the maximum water absorption around 20 min, and demonstrated excellent water retention performance at low and medium temperatures. ATP-BF-P(HEC-AA-AMPS) has a sensitive dynamic sensing ability in different pH solutions, with a high swelling capacity between pH 6.0 and 10.0. When the pH value exceeded 10.0, the swelling rate decreased rapidly. Additionally, the thermal stability and mechanical strength of the highly absorbent polymers were significantly improved after blending with ATP and BF.

A field-based pot experiment with maize plants was conducted to examine the effect of combined fulvic acid (FA) and super-absorbent polymer (SAP) on leaf gas exchange, water use efficiency, and grain yield under soil water deficit. SAP (45 kg hm −2 ) was applied to the topsoil at sowing. Plants were well-watered (80% field capacity), but subjected to water deficit (50% field capacity) from tassel stage to grain-fill. FA solution (2 g L −1 ) was sprayed onto plant leaves at 2 and 9 days after imposing water deficit. Under water deficit, SAP and FA application did not affect evapotranspiration, but increased leaf abscisic acid and decreased leaf transpiration rate with a little change in photosynthesis, thus improving instantaneous water use efficiency. Applying SAP and FA under water deficit also increased grain yield by 19% and grain water use efficiency by 24%, largely attributed to an increase in kernel number. In contrast, under well-watered condition the two chemicals increased stomatal conductance, leaf transpiration, photosynthesis and chlorophyll content, but did not change kernel number and were relatively less effective in respect to water use efficiency compared to water-stressed condition. This study showed that application of foliar FA and soil SAP had little effect on evapotranspiration but maintained high photosynthesis and kernel number, and improved water use efficiency under soil water deficit.

Increased global CO 2 emissions may result in erratic weather conditions, especially uncertain, pertaining to rainfall uncertainties and temperature anomalies, and could reduce India’s overall rice production by 3–10% under medium- to high-emission scenarios. The water crises nowadays have been prioritized as one of the top five global risks. Further, the uncertainties in rice production due to climate change will be more than just rice yield reductions. Several adoption strategies such as direct seeding, selecting water stress-tolerant varieties, enhancing soil water-holding capacity and improving crop management practices, are suggested to address the risks of rice production. Keeping in view the above fact, a field experiment was initiated during kharif season of 2015 and 2016 at Agricultural Research Farm (BHU), Varanasi, Uttar Pradesh (India), to assess the effect of super-absorbent polymer (hydrogel) and Trichoderma in rice varieties with six hydrogel-based Trichoderma -formulated treatments. The results indicated that Trichoderma was found effective in improving crop growth, yield, nutrient uptake and water use efficiency with the application of hydrogel. It was also found that soil amendment with hydrogel at 2 g m −2 and sowing of Trichoderma -treated seed at 10 g kg −1 seed significantly improved the crop growth parameters (viz . shoot dry weight by 6.45%), yield parameters (viz . number of productive tillers by 12.32%, number of grains per panicle by 8.26%), nutrients uptake and water use efficiency (by 24.15%) over control. The present study reveals that the use of hydrogel with Trichoderma fungus is found effective in enhancing the growth and yield parameters of rice in Indo-Gangetic Plains (IGPs).

Drought is one of the major environmental stress factors limiting sugarcane production. Under rainfed conditions, sugarcane crops are highly at risk of drought, especially after planting. The use of superabsorbent polymers capable of absorbing huge amounts of water is of great prospect; however, information on its use in sugarcane production under drought is relatively scarce. Greenhouse experiments were thus carried out to examine the effects of polymer application at planting on sugarcane germination and early growth as well as water content in sandy soils. When mixed with sandy soils in different ratios (0, 0.1, 0.3, and 0.5% in Experiment 1; 0, 0.05, 0.1, 0.15, and 0.2% in Experiment 2), the polymers significantly improved soil water-holding capacity as the ratios increased, though the treatments did not affect the water release rate. The best germination rates were obtained with the applications of 0.1% and 0.15% polymer in Experiments 1 and 2, respectively, which further yielded the highest biomass production. Despite higher water contents, the applications of 0.3% and 0.5% polymer remarkably lowered the germination rates in Experiment 1. One of the possible reasons for its negative impact is that the water contents greatly exceeded the optimum level for sugarcane germination in the sandy soil. From this study, it is suggested that the application of 0.15% polymer is likely to be most suitable. Meanwhile, the available water in the soil at the time of polymer application must be considered as high moisture contents rather resulted in impairing sugarcane germination and growth.

The water-retaining and yield-increasing capacity of super-absorbent polymer (SAP) are essential for soil remediation in arid and semi-arid areas. Water availability is an increasing challenge to plant development and crop yield. During the growing seasons in 2021 and 2022, the present study was conducted to evaluate the effect of the addition of different amounts of SAP on the development and yield of green beans (Phaseolus vulgaris L. cv Bronco) under varying water deficit stresses, compared with the control treatment without SAP and water deficit stress. The results demonstrated that a 50% reduction in water requirement (WR) resulted in significant decreases in leaf fresh weight, specific leaf area, leaf total chlorophyll content, pod number, leaf free water content, pod fresh weight per plant, and yield. Decreases were also found in pod total chlorophyll content, carotenoids, dry matter and total protein, leaf proline content, and crude fiber content. Additionally, leaf water saturation deficit was significantly increased under the stress compared with the full irrigation at 100% WR. However, irrigation at 75% WR increased pod contents of ascorbic acid, total sugars, and leaf bound water. The current study also indicated that addition of SAP significantly enhanced the above-mentioned growth characteristics under irrigation at 50% and 75% WR. Treatment with SAP at 3 g/plant was the most effective in mitigating the adverse effects of water deficiency, especially at the irrigation rate of 75% WR. Pearson’s correlation analysis showed significantly positive correlations between the growth parameters, as well as pod yield, under water stress and SAP. This study provides a promising strategy for green bean cultivation by adding SAP to soil to alleviate water shortage stress.

With an increasing population, world agriculture is facing many challenges, such as climate change, urbanization, the use of natural resources in a sustainable manner, runoff losses, and the accumulation of pesticides and fertilizers. The global water shortage is a crisis for agriculture, because drought is one of the natural disasters that affect the farmers as well as their country’s social, economic, and environmental status. The application of soil amendments is a strategy to mitigate the adverse impact of drought stress. The development of agronomic strategies enabling the reduction in drought stress in cultivated crops is, therefore, a crucial priority. Superabsorbent polymers (SAPs) can be used as an amendment for soil health improvement, ultimately improving water holding capacity and plant available water. These are eco-friendly and non-toxic materials, which have incredible water absorption ability and water holding capacity in the soil because of their unique biochemical and structural properties. Polymers can retain water more than their weight in water and achieve approximately 95% water release. SAP improve the soil like porosity (0.26–6.91%), water holding capacity (5.68–17.90%), and reduce nitrogen leaching losses from soil by up to 45%. This review focuses on the economic assessment of the adoption of superabsorbent polymers and brings out the discrepancies associated with the influence of SAPs application in the context of different textured soil, presence of drought, and their adoption by farmers.

The ability of superabsorbent polymers (SAPs) to absorb and retain a large amount of aqueous solution enables their applications in agriculture, medicine and water treatment. As a result, there were numerous studies reporting the present status and application prospects of raw materials and the mechanism of cross-linking agents. Conversely, there was a lack of research on the factors affecting SAP performance and the summaries of methods to improve performance. In this paper, a comprehensive and systematic review based on the structure and water absorption mechanism of SAPs was performed. The methods of improving the performance and main factors of the synthesis of SAPs, such as monomer, cross-linking agent, initiator, ion concentration, hydrophilic group, neutralization degree and particle size, were discussed. The improvement methods of salinity tolerance, reusability, water absorption and rate of SAP were explored. In addition, some applications and future research in SAPs are also discussed in this review.

Super-absorbent polymers (SAPs) refer to a three-dimensional network polymer, water-swellable, water-insoluble, organic or inorganic material that can absorb thousands of times its own weight of distilled water. It is widely used in various fields, such as: agricultural, biomedical, daily physiological products, separation technology and wastewater treatment. In the review, the development history of superabsorbent polymers since 1961 is described, and the polymerization methods of superabsorbent polymers and the wide-ranging use of this type of polymers in life are described in detail. The article introduces four basic polymerization methods, bulk polymerization, solution polymerization, suspension polymerization and radiation polymerization from the preparation methods and types. Not only the detailed methods of polymerization but also their respective advantages and disadvantages are introduced. In recent years, new progress has been made in polymerization methods, for example, in-situ polymerization to obtain an onion-like multilayer tube cellulose hydrogel. The hydrogel has super-absorbent properties, and the water swelling mechanism is briefly introduced. Finally, the latest advances in super-absorbent polymers are pointed out.

Soil hydraulic properties are important for the movement and distribution of water in agricultural soils. The ability of plants to easily extract water from soil can be limited by the texture and structure of the soil, and types of soil amendments applied to the soil. Superabsorbent polymers (hydrogels) have been researched as potential soil amendments that could help improve soil hydraulic properties and make water more available to crops, especially in their critical growing stages. However, a lack of a comprehensive literature review on the impacts of hydrogels on soil hydraulic properties makes it difficult to recommend specific types of hydrogels that positively impact soil hydraulic properties. In addition, findings from previous research suggest contrasting effects of hydrogels on soil hydraulic properties. This review surveys the published literature from 2000 to 2020 and: (i) synthesizes the impacts of bio-based and synthetic hydrogels on soil hydraulic properties (i.e., water retention, soil hydraulic conductivity, soil water infiltration, and evaporation); (ii) critically discusses the link between the source of the bio-based and synthetic hydrogels and their impacts as soil amendments; and (iii) identifies potential research directions. Both synthetic and bio-based hydrogels increased water retention in soil compared to unamended soil with decreasing soil water pressure head. The application of bio-based and synthetic hydrogels both decreased saturated hydraulic conductivity, reduced infiltration, and decreased soil evaporation. Hybrid hydrogels (i.e., a blend of bio-based and synthetic backbone materials) may be needed to prolong the benefit of repeated water absorption in soil for the duration of the crop growing season.

Water management is rapidly becoming one of the most pressing issues facing all countries in semi-arid and arid parts of the world. Global water consumption is predicted to increase by 50% in 2030, resulting in an acute water shortage. Presently, the agricultural sector consumes more than 70% of freshwater in most regions of the world, putting more pressure on water scarcity. Hydrogels are superabsorbent polymers that can hold plant nutrients and water when the soil around plant roots starts to dry out. Research evidence has revealed that water stored by hydrogel slowly returns to the soil, thereby increasing the volumetric water content of the soil. Hydrogel increases water use efficiency and irrigation intervals, decreases irrigation costs, and provides plants with the required nutrients and moisture. Numerous properties of hydrogels, including moderate water retention and high swelling, make them ideal as a safe delivery mechanism in agriculture for soil conditioners and agents for the controlled release of fertilizers. Numerous research publications on hydrogel polymer synthesis and its characteristics have been published. However, the current review emphasizes the critical role of superabsorbent hydrogels in an integrated approach for the balanced protection of seeds, plants, and soil to conserve the ecosystem.