Phosphorus transport modeling in soils treated with nano-phosphorus fertilizers

Nanofertilizers play a promising role in crop production by reducing the application amount and increasing the application efficiency. Understanding the transport of plant nutrients in the soil is crucial for effectively managing nanofertilizer applications and minimizing their impact on the environment. This study investigated phosphorus transport in agricultural soil using 15-day and 30-day soil column experiment data from 2017 and 2018. Two soil column experiments were conducted using nano-rock phosphate, nano-hydroxyapatite fertilizers, and a commercial fertilizer (single super phosphate). The Hydrus 1D model was used to understand the transport mechanism of nano and bulk phosphorus fertilizers. Water and dissolved phosphorus fluxes were simulated using leachate data, and key phosphorus transport parameters, including longitudinal dispersivity and the diffusion coefficient, were determined. The Hydrus-1D model accurately captured leachate dynamics (R² = 0.82–0.99 and MAE = 0.38–0.56 cm/days). Phosphorus transport performed well for bulk fertilizer treatments (R² = 0.86–0.90, MAE = 0.08–0.19 ppm, and RMSE = 0.14–0.36 ppm). However, mixed results were obtained while validating nano fertilizer treatments (R² = 0.31–0.98, MAE = 0.046–0.41 ppm, and RMSE = 0.084–0.35 ppm). For nanofertilizers, the longitudinal dispersivity and distribution coefficient were reduced by 80.71 % and 19.20 %, respectively, compared to commercial fertilizers. The lower longitudinal dispersivity indicates that nano fertilizers release nutrients more slowly than bulk fertilizers. Similarly, a smaller distribution coefficient suggests that nano-phosphorus fertilizers are more concentrated in specific areas within the soil, leading to slower and more controlled nutrient distribution. Additionally, the leachate's observed total phosphorus concentration and the soil profile's phosphorus concentration support the study findings. The results indicate that the transport mechanism of nano and bulk fertilizers in soil is distinct and should be treated separately. This study's findings will contribute to developing optimal fertilizer application strategies for nano-phosphorus fertilizers.