Superabsorbent nanocomposite hydrogels based on polyacrylamide (PAAm), cashew tree gum (CG), and laponite (LAP) were synthesized in different concentrations to investigate swelling, thermal, morphological and rheological properties. Vibrational modes confirmed the formation of hydrogels, while X-ray diffraction patterns reveal the semi-crystalline structure of the hydrogels. Thermal analysis showed that higher LAP content and CGLAP interactions improved the thermal stability of the hydrogels. Morphology analysis presented porous structures in CG-based hydrogels, contrasting with irregular plate-like structures in those without CG. The swelling capacity had better results in hydrogels with CG that were subjected to alkaline hydrolysis, mainly in a buffer solution with a pH > 4, due to the ionization of the hydrophilic groups. Hydrogels containing LAP maintained swelling degree stability at pH 10 and 12. In rheological tests, the addition of LAP increased the viscosity of the hydrogels, significantly improving the mechanical resistance of the hydrogels. Rheological parameters, such as the storage modulus (G ') and loss modulus (G ''), indicated that the materials exhibited predominantly solid behavior, particularly in CG-LAP-rich hydrogels. Low mortality of Artemia salina nauplii in toxicity tests confirmed material safety. The results indicate that CG-LAP hydrogels are promising for agricultural applications, offering optimized swelling properties, thermal stability, and mechanical strength.

The impact of climate change has become increasingly severe in forests, where droughts and strong winds on the one hand and extreme rainfall events on the other hand can damage forest ecosystems. To mitigate the effects of drought and enhance soil water retention capacity, three types of soil conditioners (SCs), labeled SC_R, SC_CG, and SC_ZZC, were developed as part of the European project ONEforest. All the conditioners are based on Xanthan gum and have different types and amounts of fillers with diverse cellulose fiber lengths. These can offer the potential to optimize the SC characteristics, e.g., water absorption, water retention, and mechanical stability. This paper focuses on the influence of fillers in the SCs on the geotechnical properties of forest soils from Ljubelj in the Alpine part of Slovenia (S1), Catalonia, northeastern Spain (S2), and Heldburg, Germany (S3). The results show an increase of 53% to 100% in the water absorption of treated soil. A less favorable impact of the SCs was found on the drained shear strength and the compressibility. The drained shear strength of untreated forest soils in a saturated state was S1 c ' = 4.4 kPa, phi ' = 33.5 degrees; S2 c ' = 1.4 kPa, phi ' = 30.0 degrees; and S3 c ' = 12 kPa, phi ' = 28.0 degrees. The addition of SCs results in a reduction in the drained shear strength of saturated mixtures. The reduction depends on the dosage of added SC-whether it is a low (L) or a high (H) dosage. For instance, when the soil S1 was treated with a low dosage of the soil conditioner SC_R, it demonstrated a cohesion (c ') of 11 kPa and a friction angle (phi ') of 27.0 degrees. However, increasing the dosage of the SC_R led to a decrease in both the cohesion and the friction angle for the same soil (c ' = 7.7 kPa, phi ' = 25.0 degrees). Additionally, the type of soil conditioner also impacts the drained shear strength. Among the mixtures with a high dosage of the SC_R, SC_CG, or SC_ZZC, those containing the SC_CG with the longest fibers stand out, demonstrating the highest friction angle. Therefore, longer fibers can be a promising component of the SCs to reduce the negative influence of XG on the mechanical properties of treated soils.

Globally, soil acidification is a serious environmental issue that reduces commercial agricultural production. Rice is subjected to nutritional stress due to acidic soil, which is a major impediment to rice production. Since acid soil threatens rice plants with soil compaction, nutrient loss, and plant stress-induced oxidative cell damage that results in affecting the photosynthetic system, restricting the availability of water, and reducing overall plant growth and productivity. Since contemporary soil acidification management strategies provide mediocre results, the use of Sargassum wightii seaweed-based biostimulants (BS) and soil amendments is sought as an environmentally friendly alternative strategy, and therefore its potential isevaluated in this study. BS was able to mediate soil quality by improving soil pH and structure along with facilitating nitrogen phytoavailability. BS also increased the activity of the antioxidant enzyme system, superoxide dismutase ((48%), peroxidase (76.6%), and ascorbate peroxidase (63.5%), aggregating the monaldehyde-mediating accumulation of osmoprotective proline in roots, that was evident from rapid initiation of root hair growth in treated seedlings. BS was also able to physiologically modulate photosynthetic activities and chlorophyll production (24.31%) in leaves, maintaining the efficiency of plant water use by regulating the stomatal conductance (0.91 mol/m/s) and the transpiration rate (13.2 mM/m/s). The BS compounds were also successful in facilitating nitrogen uptake resulting in improved plant growth (59%), tiller-panicle number, and yield (52.57%), demonstrating a resourceful nitrogen use efficiency (71.96%) previously affected by stress induced by acid soil. Therefore, the study affirms the competent potential of S. wightii-based soil amendment to be applied not only to improve soil quality, but also to increase plant production and yield.