A new study published in Sustainability by Resham B. Thapa, Chandan Shilpakar, and Samir Budhathoki, investigates the potential of carbon-rich products like coal char and 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 as soil amendments in challenging environments. For years, biochar, a product derived from pyrolyzed biomassBiomass is a complex biological organic or non-organic solid product derived from living or recently living organism and available naturally. Various types of wastes such as animal manure, waste paper, sludge and many industrial wastes are also treated as biomass because like natural biomass these More, has been recognized for its ability to improve soil health and water retention. Now, a similar product, coal char, made from the pyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More of coal, is emerging as a potentially valuable alternative, particularly in semiarid regions like Wyoming, USA, where soil degradation and water scarcity threaten crop production.

The two-year field study focused on sugar beet, a crop highly sensitive to poor soil conditions and moisture stress. The researchers compared the effects of coal char and biochar, applied at 22 and 44 Mg ha−1, against traditional inorganic fertilizer and manure treatments on a sandy clay loam soil. Although the char treatments did not significantly change basic soil properties like 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, electrical conductivity (EC), or cation exchange capacity (CEC), they did have a noticeable effect on nutrient dynamics and plant health indicators.

The most significant finding centered on crop yield. Multivariate multiple linear regression analysis showed that applying coal char at either 22 Mg ha−1 or 44 Mg ha−1 increased sugar beet yield by 4.7 and 4.1 (or up to 4.4 t ha−1) tons per acre, respectively, compared to the control. This suggests that coal char, particularly when applied in the range of 22 to 44 Mg ha−1, offers a substantial contribution to crop productivity in this type of soil. The study hypothesized that this increase may be due to the coal char’s ability to retain nutrients, such as the sorption of NO3​, throughout the growing season.

The efficacy of the amendments was also strongly tied to nutrient management. While char treatments alone did not drastically alter individual soil nutrient levels, the use of fertilizer and manure significantly increased collective soil nutrients, particularly soil nitrogen, phosphorus, and potassium. Fertilizer application, especially the double application or combination with manure, enhanced plant health, as measured by a significant increase in the Normalized Difference Red Edge (NDRE) index. NDRE, an indicator of canopy greenness and health, was found to be the strongest overall predictor for higher sugar beet yield in the model, suggesting that improved vegetative growth is key to greater output.

Furthermore, the quality of the sugar beets benefited from the char treatment. Higher NDRE values and increased leaf sulfur (S) concentration were strongly associated with a reduction in sugar loss to molasses (SLM). SLM is a critical quality metric, as lower loss means more sugar is available for commercial use. Given that coal char can be naturally rich in sulfur, its application may have contributed to this observed improvement in quality. Conversely, while fertilizer application increased the sugar content, excessive (double) fertilizer application showed a negative effect on yield, reinforcing the need for precise nutrient management to optimize both yield and quality.

In conclusion, this research supports the potential of coal char as a sustainable and effective 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 for improving sugar beet productivity in challenging semiarid, sandy clay loam soils. The findings highlight that the application of coal char at 22−44 Mg ha−1 is a direct contributor to yield, and when integrated with appropriate nutrient management (fertilizer and manure), it helps maximize both vegetative health and crop quality.

Source: Thapa, R. B., Shilpakar, C., & Budhathoki, S. (2025). Effects of Char and Amendments on Soil Properties and Sugar Beet Yield in Sandy Clay Loam Soil. Sustainability, 17(18), 8132.