Soil fertility is a major challenge in tropical regions, where acidic and nutrient-poor soils limit crop productivity. In a recent study published in Agronomy, Ana Rita de Oliveira Braga and colleagues explored how biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More made from açaí fruit waste can improve phosphorus (P) availability and enhance the growth of cowpea (Vigna unguiculata), a staple legume.

The researchers tested five doses of açaí biochar (0, 7.5, 15, 30, and 60 t/ha) combined with four levels of phosphorus fertilizer (0, 40, 80, and 120 kg/ha) in a greenhouse experiment. The results were promising. Adding biochar increased soil pHpH is a measure of how acidic or alkaline a substance is. A pH of 7 is neutral, while lower pH values indicate acidity and higher values indicate alkalinity. Biochars are normally alkaline and can influence soil pH, often increasing it, which can be beneficial More, improved nutrient retention, and reduced toxic aluminum levels—all key factors for better plant growth in acidic soils. Higher biochar doses combined with phosphorus fertilizer boosted available soil P by up to 2.3 times, significantly increasing phosphorus uptake in cowpea plants.

However, biochar’s impact on phosphorus use efficiency (PUE) was more modest, with a maximum increase of 7.7%. This suggests that while biochar helps retain phosphorus, additional optimization is needed to maximize its efficiency as a fertilizer enhancer. The study also found that biochar raised levels of potassium (K), calcium (Ca), and total nitrogen (N) while decreasing magnesium (Mg) and aluminum (Al).

These findings highlight açaí waste biochar as a sustainable soil amendmentA soil amendment is any material added to the soil to enhance its physical or chemical properties, improving its suitability for plant growth. Biochar is considered a soil amendment as it can improve soil structure, water retention, nutrient availability, and microbial activity.   More, especially in phosphorus-deficient regions. By repurposing agricultural waste into biochar, farmers can enhance soil fertility, reduce reliance on chemical fertilizers, and promote sustainable farming. Future studies could refine biochar formulations for even greater impact on crop productivity.

SOURCE: Braga, A. R. d. O., John, V., Danielli, C. K. A. d. O., Sousa, H. M., Danielli, F. E., Marques-dos-Santos, C. S. d. C., Oliveira, D. M. d., & Falcão, N. P. d. S. (2025). Açaí waste biochar combined with phosphorus fertilizer and phosphorus use efficiency in cowpea (Vigna unguiculata (L.) Walp). Agronomy, 15(393). https://doi.org/10.3390/agronomy15020393