Enhancing Clay Soil Productivity with Fresh and Aged Biochar: A Two-Year Field Study on Soil Quality and Wheat Yield

Biochar application has gained attention as an effective soil amendment for improving soil quality and increasing crop productivity, particularly in clay-rich soils facing challenges such as compaction, poor drainage, and nutrient limitation. This two-year field study evaluated the effects of fresh and artificially aged biochar on soil chemical, physical, and biological properties and wheat (Triticum aestivum) yield. The experiment was conducted on clay soil with treatments including no biochar application as a control (CK), 5 and 10 t ha −1 fresh biochar (B5, B10) and 5 and 10 t ha −1 aged biochar (AB5, AB10). The results showed significant improvements in soil pH, soil organic carbon, cation exchange capacity, total nitrogen, and plant-available water capacity, particularly with higher doses of biochar. In both years, the effects of the treatments on the soil quality index area (SQI-area) were found to be statistically significant. The AB10 treatment increased SQI-area by 19% compared to the CK in the first year and by 33% in the second year. In the first year, the highest grain yield was obtained from the AB10 treatment, reaching 5.25 t ha −1 , which was 13% higher than the CK. In the second year, the highest yield was obtained from the B10 treatment, reaching 4.09 t ha −1 , which was 24% higher than the CK. Despite these positive changes, the correlation between SQI and yield was not statistically significant, suggesting that crop yield may also depend on other interacting variables. These results highlight the potential of biochar, particularly aged biochar, as a sustainable practice to improve soil health and productivity in clay soils.