To clarify the effects of pond excavation and field elevation combined with biochar application on soil improvement and maize growth in cold-soaked fields in northern China, a two-year field experiment was conducted using maize as the test crop under five biochar application rates: 0, 7.5, 15, 22.5, and 30 t/ha. The effects of biochar application on soil water characteristics, maize root development, plant growth, and yield formation were investigated. The results showed that, under the pond excavation and field elevation treatment, the application of 22.5 t/ha biochar (B3) achieved the best overall improvement effect and significantly improved soil moisture conditions. At the heading stage, the soil water content in the 0–90 cm soil layer under the B3 treatment increased by 6.18% and 27.72% in the two experimental years, respectively, compared with the 0 t/ha biochar treatment (B0). In 2025, compared with the B0 treatment, root length density, root surface area density, and root volume density under the B3 treatment increased by 38.56%, 109.31%, and 65.35%, respectively, while the average diameter of maize fine roots decreased by 8.50%. Meanwhile, the leaf area index, plant height, stem diameter, kernels per ear, 100-kernel weight, and maize yield were all significantly increased, with grain yield reaching 13,991.10 kg/ha in 2025. Correlation analysis showed that the biochar application rate was significantly positively correlated with maize plant height, stem diameter, leaf area index, root morphological traits, and grain yield, indicating that biochar application promoted maize growth and yield by optimizing canopy structure and root architecture. These results demonstrate that pond excavation and field elevation combined with an appropriate biochar application rate can effectively improve cold-soaked fields in northern China and achieve stable and high maize yields, thereby providing technical support for the management of medium- and low-yield farmlands.
Tang et al. (Tue,) studied this question.