Activated ZnCl2 biochar and humic acid as additives in monoammonium phosphate fertilizer: Physicochemical characterization and agronomic effectiveness.

Activated zinc biochar (ZnBC) and humic acid (HA) were used as coating agents in a soluble monoammonium phosphate (MAP) to modify phosphorus (P) use efficiency by altering adsorption/desorption kinetics between the granule region and the soil. The coated treatments MAPZnBC and MAPHA were compared with MAP through P diffusivity, kinetics, and agronomic evaluation. Eucalyptus sawdust was used as biomass for biochar synthesis, and a pre-pyrolysis treatment with zinc chloride (ZnCl) was applied.

Biochar as composite of phosphate fertilizer: Characterization and agronomic effectiveness.

Organomineral phosphate fertilizers (OMP) may reduce phosphate release rate and its direct contact to the soil solid phase, increasing the effectiveness of phosphorus (P) fertilization. This study aimed to evaluate the effect of granulating biochar (BC) with triple superphosphate (TSP) in two forms (blend or coated) and three proportions (5, 15 and 25%, w/w) on the P release kinetics and plant growth. A successive plant trial using two soils of contrasting P buffering capacities and five P doses (0, 20, 40, 80 and 120 mg kg) was set to investigate the agronomic effectiveness of OMP that presented the slowest P release kinetic.

Agronomic efficiency of phosphate fertilizers produced by the re-use of a metallurgical acid residue.

The production of fertilizers with industrial wastes reduces the environmental impacts of waste disposal and improves environmental sustainability by generating added-value products. Our objective with this study was to evaluate the agronomic performance and potential soil/plant contamination with heavy metals of alternative phosphate (P) fertilizers, obtained from the acidulation of phosphate rocks (PR) by a metallurgical acidic waste. Seven P fertilizers were evaluated: three PR (Araxá, Patos, and Bayóvar), their respective acidulated products (PAPR), and triple superphosphate fertilizer (TSP).