Biochar made from rice straw can help soil retain nutrients and improve fertility, but it doesn't hold onto nutrients well on its own. Scientists modified the biochar with different chemicals to increase its ability to hold onto both positively and negatively charged nutrients. The modified biochar significantly reduced the leaching of important nutrients like nitrogen, phosphorus, and potassium from the soil, while also increasing the retention of these nutrients. One particular type of modified biochar, RBC-O-Cl, was the most effective at increasing nutrient retention in the soil. This engineered biochar could help plants use nutrients more efficiently and reduce the need for harmful chemical fertilizers.