Explore the potential for improving phosphorus availability in calcareous soil through electrokinetic methods

Abstract

Phosphorus (P) is a key nutrient that limits plant growth. The world's supply of phosphorus is limited, making it vital to maximize soil phosphorus consumption and minimize P inputs. This study was motivated by these challenges to examine in-depth soil electrokinetics (SEK), which supports the theory of electro-agric technology (A. Abou-Shady & El-Araby, 2021) that was introduced to overcome agricultural problems in arid and semi-arid regions. Our goal is to optimize P availability/use efficiency and significantly diminish P losses in agroecosystems via intensive fertilization. Our search turned up limited literature on the topic of enhancing soil nutrient availability through the application of electric fields. This involves studying the relevant factors of SEKs, such as applied voltage (0.5, 1, and 1.5 V), experimental time (3, 7, and 10 days), and SEK design change (regular, provided with anode reservoir, and with hydrostatic head) by applying the Taguchi technique (L₉OA). Calcareous soil was chosen as a target soil owing to its high pH that reduces P availability. The results indicate that short period (3 days), applied voltage (1 V cm⁻¹), and SEK design with an anode reservoir are the best characteristics for enhancing P availability in calcareous soil. After the SEK tests were finished, four samples were obtained from the calcareous soil at equal intervals. In the four sections, the available P concentration ratios from anode to cathode were 1.51 (50.51 % increase), 1.16 (16.01 % increase), 1.15 (14.90 % increase), and 0.65, (34.65 % drop), indicating a greater availability of P adjacent to the anode. Taguchi's analysis revealed that the SEK method increases P availability in calcareous soil without being time-dependent, which is advantageous because it requires less energy. The pH decreases around the anode in the soil were less than the cathode's surrounding increases. Because of the water electrolysis on the anode surface, which lowers the pH of the water, the P content in the anode reservoir was higher than that of the hydrostatic head. Two future visions to help SEK applications for improving nutrient availability would be 1) process intensification and optimization, and 2) integrated acid and hydrogen production.