Farmers may soon have a cost-effective solution to prevent excess phosphorus from polluting downstream waterways while also recycling the nutrient as a slow-release fertilizer. Researchers at the University of Illinois Urbana-Champaign have developed a novel method using designer biochar pellets made from sawdust and lime sludge. These pellets have a significantly higher phosphorus-binding capacity compared to traditional materials, making them an efficient solution for capturing phosphorus from tile drainage systems.
In a field study in Fulton County, Illinois, the research team tested the designer biochar pellets in working field conditions for two years. The pellets were placed in phosphorus removal structures in fields with subsurface drainage pipes, where they successfully removed phosphorus from the water flowing through. The study found that smaller 1-centimeter pellets performed much better at removing phosphorus compared to larger pellets, reaching up to 41% removal efficiency.
The economic viability of the system was also evaluated, with the cost to produce designer biochar pellets estimated at $413 per ton – significantly lower than the market cost of alternative materials. The total cost of phosphorus removal using the system was estimated at $359 per kilogram removed, with a two-year replacement timeline being the most cost-effective scenario. Life cycle analysis showed that the system could save 12 to 200 kilograms of carbon dioxide-equivalent per kilogram of phosphorus removed, making it a sustainable and environmentally-friendly solution.
The benefits of the system go beyond just nutrient loss reduction and carbon sequestration. By returning spent biochar pellets to crop fields and reducing the need for additional phosphorus inputs, the system can also help in energy production, reduction of eutrophication, and improving soil quality. While there are currently no regulations requiring farmers to remove phosphorus from drainage water, the system provides an attractive option for conservation-conscious farmers looking to reduce nutrient losses from their fields.
Overall, the research demonstrates that utilizing designer biochar pellets for phosphorus removal in agricultural fields is a viable and environmentally-friendly solution. By combining efficient nutrient capture with cost-effectiveness and sustainability, farmers can help prevent water pollution while also recycling valuable nutrients back into the soil. The system offers a practical and accessible way for farmers to address nutrient runoff issues, contributing to improved water quality and soil health in agricultural landscapes.