Effects of maize straw-derived biochar application on soil temperature, water conditions and growth of winter wheat

Biochar application to soil has been widely accepted as an approach to enhance soil carbon sequestration, promote nutrient use efficiency and improve crop yields. Maize straw-derived biochar application is also a novel practice for the sustainable use of straw waste. However, it remains unclear whether biochar modifies soil temperature, thereby influencing winter wheat growth. Field experiments were conducted for 2 years to answer this question. Maize straw-derived biochar was applied at rates of 0 (B0), 20 (B20), 40 (B40) and 60 (B60) t ha⁻¹ in the field plots. Biochar application increased the soil temperature compared to the unamended control plot for all growth stages. The highest soil temperatures occurred at 40-cm depth in the B40 treatment and 20-cm depth in the B60 treatment. Biochar application also enhanced the soil water content of the winter wheat fields during the growing seasons, with a maximum effect achieved at a rate of biochar application of 40 t ha⁻¹. However, water content did not increase with increasing rate of application. Biochar application decreased the soil bulk density, and this effect was enhanced with increasing rates of biochar application. The largest grain yield was obtained in the B40 treatment, resulting from an increase in aboveground biomass and effective spike number. Our study suggests that biochar application potentially improves the grain yield of winter wheat from the increased soil temperature. This conclusion needs to be confirmed by a long-term study on biochar application. Highlights: The effects of rates of biochar application on wheat growth and yield were evaluated. Response of soil temperatures to biochar application improves understanding of underlying mechanisms involved. Warmer soil temperature and lower soil bulk density with large rates of biochar were unfavourable for water storage and wheat growth. Biochar application at a rate of 40 t ha⁻¹ was optimal to enhance wheat growth and grain yield.