Elemental interactions in soil and their impact on soil fertility under the influence of treated wastewater and biosolid

Treated wastewater and biosolids are increasingly used in agriculture as alternatives to well irrigation water and as organic fertilizers. While these practices offer benefits, they also present challenges. Both treated wastewater and biosolids contain essential plant nutrients and heavy metals, which vary based on their source. When applied to soil, these elements interact with each other and with soil properties, potentially affecting soil fertility. To investigate these interactions, a greenhouse pot experiment was conducted using a simulated soil, based on a randomized block design with 12 treatment combinations, four replications, and 48 pots. The goal was to examine how heavy metals, nutrients and soil properties such as pH, clay content, organic matter, and electrical conductivity influence soil fertility when treated with wastewater and biosolids. The interactions were classified into six groups, and their nutrient contributions were analyzed using regression analysis. The study found several significant interactions, with the highest contributions observed in macronutrients, particularly from the interactions between “soil properties x macronutrients” and “micronutrients x macronutrients.” Significant contributions included nitrate (1016.05 mg/kg), potassium (783.07 mg/kg), calcium (4014.52 mg/kg), magnesium (475.46 mg/kg), and micronutrients like boron (2.02 mg/kg), zinc (11.98 mg/kg), copper (16.78 mg/kg), and iron (29.76 mg/kg).  The present study offers new insights into how elemental interactions affect soil fertility, under the influence of treated wastewater and biosolids. It highlights the importance of understanding these interactions for the effective management of the interactively contributed plant nutrients in the presence of the applied wastewater and biosolids.