This review presents data from the past five years on the use of polymeric superabsorbent hydrogels in agriculture as water and nutrient storage and retention materials, as well as additives that improve soil properties. The use of synthetic and natural polymeric hydrogels for these purposes is considered. Although natural polymers, such as various polysaccharides, have undoubted advantages related to their biocompatibility, biodegradability, and low cost, they are inferior to synthetic polymers in terms of water absorption and water retention properties. In this regard, the most promising are semi-synthetic polymeric superabsorbents based on natural polymers modified with additives or grafted chains of synthetic polymers, which can combine the advantages of natural and synthetic polymeric hydrogels without their disadvantages. Such semi-synthetic polymers are of great interest for agricultural applications, especially in dry regions, also because they can be used to create systems for the slow release of nutrients into the soil, which are necessary to increase crop yields using environmentally friendly technologies.

This paper presents experimental data on a physico-chemical and biological study of C₆₀-l-hydroxyproline derivative water solutions.

The influence of crop residues with different C: N ratios on the N₂O emission from differently managed loamy sand soddy-podzolic soils was studied in a 50-day laboratory experiment. The application of crop residues into the soil increased the N₂O emission from the soil. The N₂O emission was lower from the poorly managed soil as compared to the soil with the high degree of cultivation. The crop residues form the following decreasing sequence in terms of their effect on the cumulative N₂O flow: cabbage > red clover > perennial grasses > straw of spring wheat. The composting of crop residues with a wide C: N ratio for 50 days did not exceed the critical value of the emission factor (1.25%), whereas, in the composting of crop residues with a narrow C: N ratio, the critical value of the emission factor was 1.3–2.0 times higher.

The present paper reports data on the biological activity of nanocompositions based on a C₆₀-L-threonine (C₆₀-Thr) derivative. These nanocompositions promote the nonspecific resistance of plants to the action of stress factors (ultraviolet radiation, pesticides, and phytopathogens). Additionally, we determined the perspectives of the C₆₀-Thr adduct application in the cultivation of plants due to the decrease of the pesticide load on the environment. The biological study of C₆₀-Thr revealed the plant growth-stimulating ability due to its influence on the photosynthetic apparatus activity and antioxidant properties.