TiO2-WO3 activated weathered lignite coating phosphate fertilizer to improve longitudinal migration efficiency

Phosphorus (P) is an essential nutrient widely used in crops. Phosphate fertilizers are easily adsorbed on the soil surface, resulting in poor migration to the roots of crops, and a large amount of nutrients cannot be absorbed and utilized, resulting in waste of resources and low bioavailability. To solve the problem of insufficient mobility of phosphate fertilizer, this work uses TiO₂-WO₃ to catalyze the oxidation and pyrolysis of lignite to synthesize small molecular humic acid, and uses small molecular humic acid to coat commercial phosphate fertilizer (MAP) to obtain a new type of phosphate fertilizer (AMAP) with good fluidity. Water contact angle was determined from initially hydrophobic (132°) to hydrophilic (76°). Humic spectroscopic ratio (E₄/E₆), H/C and molecular weight distributions confirmed the effectiveness of the TiO₂-WO₃ catalyst and the successful modification of weathered lignite. The migration characteristics of phosphorus in the soil were studied by leaching migration experiments. The results showed that the effective phosphorus content of the new coated phosphate fertilizer (AMAP) in the soil exceeded that of the commercial phosphate fertilizer (MAP) at different vertical migration distances. After 21 d of incubation at the same fertilizer level, new coated phosphate fertilizer (AMAP) of phosphate fertilizer added with different products showed elevated levels of P. Migration data indicated that the migration distance of effective phosphorus approximated the long root distance of early corn, which benefitted crop growth. The pot experiment confirmed improved corn growth and improvement in the utilization rate of phosphorus fertilizer. All in all, activated lignite (AHA) can reduce or inhibit the fixation of phosphorus nutrients in the soil, and has obvious application value for improving the efficiency of phosphate fertilizers.