Co-fertilization of Sulfur and Struvite-Phosphorus in a Slow-Release Fertilizer Improves Soybean Cultivation

Microbial communities in the rhizosphere of tropical soils cultivated with maize as a function of nitrogen and phosphorus fertilizers

Phosphorus (P) has a strong affinity with soil colloids in humid tropical conditions, reducing its availability to plants. The use of alternative sources of P can provide nutrients to plants and reduce countries' dependence on imports of phosphate fertilizers. Some nitrogen (N) sources can acidify the soil and affect the efficiency of P fertilizers. In this study, evaluated the changes in the microbial community of the rhizosphere of maize (Zea mays) affected by N and P fertilizers in soils with contrasting textures. The N sources used were calcium nitrate (CN) and ammonium sulphate (AS), and the P sources: triple superphosphate (TSP), organomineral (OR) and struvite (ST), and two control treatments without the addition of N and P fertilizers, with (Control) and without plant (Control NP). The rhizosphere samples were subjected to genetic sequencing of the 16S rRNA region, and the structures, diversity, richness and differential abundance of the microbial communities were assessed. Distinct microbial compositions were identified between medium-textured (MT) and clayey (CT) soils, influenced by soil texture, organic matter and fertilizers. Nitrogen fertilizers had the greatest impact on the structure of microbial communities in MT soil. Differential abundance analysis revealed specific variations in microbial taxa in response to nutrient sources, with an impact on nutrient cycling and acquisition. The ST + CN treatment in MT soil was enriched with pollutant bioremediating genera such as Sphingbium, Flavitalea, Devosia and Rubellimicrobium. The study highlights the intricate interaction between soil type, fertilizer sources and microbial community dynamics, with an impact on overall productivity.

Advancing agricultural efficiency and sustainability: Bio-inspired superabsorbent hydrogels for slow and controlled release fertilizers

Bio-inspired superabsorbent hydrogels (BiSAHs) represent a versatile polymeric material class that has garnered significant interest due to their multifunctional attributes and extensive range of applications. A thorough examination of the literature and patents on BiSAHs highlights their critical role across diverse sectors. This review provides an in-depth analysis of BiSAHs, focusing on their classification, synthesis methodologies, and potential applications in agriculture. It critically examines biopolymer-based SAHs as soil conditioners and slow and controlled, focusing on their classification, synthesis methodologies, and potential applications in agriculture. It critically examines biopolymer-based SAHs as soil conditioners and slow and controlled-release fertilizers, elucidating the mechanisms governing water retention, swelling capacity, and nutrient release kinetics. The review further presents detailed case studies illustrating the enhancement of crop growth and productivity facilitated by BiSAHs and their effectiveness as agrochemical carriers. Moreover, it explores the role of SAHs in crop protection, particularly in mitigating adverse abiotic stresses such as heavy metal toxicity, salinity, and drought. The ecological, economic, and societal impacts of BiSAH-based controlled-release fertilizers are evaluated, providing a balanced perspective on their sustainability. Ultimately, the review offers insights into future directions and emerging advancements in the development and application of BiSAHs in agricultural settings.

Struvite-based composites for slow-release fertilization: a case study in sand

Struvite (St) recovered from wastewaters is a sustainable option for phosphorus (P) recovery and fertilization, whose solubility is low in water and high in environments characterized by a low pH, such as acidic soils. To broaden the use of struvite in the field, its application as granules is recommended, and thus the way of application should be optimized to control the solubility. In this study struvite slow-release fertilizers were designed by dispersing St particles (25, 50, and 75 wt%) in a biodegradable and hydrophilic matrix of thermoplastic starch (TPS). It was shown that, in citric acid solution (pH = 2), TPS promoted a steadier P-release from St compared to the pure St pattern. In a pH neutral sand, P-diffusion from St-TPS fertilizers was slower than from the positive control of triple superphosphate (TSP). Nevertheless, St-TPS featured comparable maize growth (i.e. plant height, leaf area, and biomass) and similar available P as TSP in sand after 42 days of cultivation. These results indicated that St-TPS slow P release could provide enough P for maize in sand, achieving a desirable agronomic efficiency while also reducing P runoff losses in highly permeable soils.