Effects of co-application of lime and biochar on physicochemical properties of albic soil and maize yield.

Obstacles in the albic layer of albic soil, such as hardening and acidification, are key factors restricting crop yield in albic soil areas. In this study, we conducted a field manipulative microplot experiment, included lime alone (900 kg·hm^-2, C), and combinations of lime with 4.5 t·hm^-2(B1) and 9 t·hm^-2 biochar (B2), control (no amendment, CK), to investigate effects of amendments on soil physical and chemical properties, maize growth characteristics, and yield. The results showed that lime application significantly increased soil pH value of the albic layer, with the three treatments increasing by 0.26-0.69 units compared to CK. Soil bulk density of treatment C increased by 7.6% compared to CK. The addition of biochar could effectively mitigate the risk of increased soil bulk density caused by lime addition, and soil bulk density of B1 and B2 decreased by 4.6% and 3.9% respectively compared to treatment C. Compared to CK, lime application increased soil total calcium content of the albic layer by 4.7%-22.7%, but it led to a decrease in soil organic matter content, which decreased by 17.6% in treatment C compared to CK. However, biochar application effectively reduced the risk of organic matter content decline and increase organic matter content of the albic soil layer by 15.0%-15.3% compared to treatment C. The application of all amendment formulations showed a tendency to increase maize plant height, but had no significant effect on leaf chlorophyll content. Compared to CK, grain yield of treatment C increased by 9%, but the difference was not significant, while that of B1 and B2 significantly increased by 19.3% and 18.0% respectively. There was no significant difference between B1 and B2. Mantel test analysis showed that grain yield was mainly regulated by soil pH of albic layer. In conclusion, the combined application of 4.5 t·hm^-2 and 9 t·hm^-2 biochar with 900 kg·hm^-2 lime could effectively alleviate the acidification of albic layer and significantly increase maize yield. Among them, the combined application of 4.5 t·hm^-2 biochar and 900 kg·hm^-2 lime demonstrates the highest application value.