Abstract: A field experiment was carried out in the experimental field of Water Conservancy Institute of Shenyang Agricultural University in May-September 2019. There were two planting modes (maize/soybean intercropping, MS; maize/peanut intercropping, MP) crossed with three biochar application doses (0, T0; 15 t·hm^-2, T1; 30 t·hm^-2, T2). We investigated the effects of biochar application on hydrothermal, nutrient absorption and yield in the maize/soybean and maize/peanut intercropping systems. Results showed that biochar application did not affect soil water storage of 0-30 cm in the early stage of crop growth. Influenced by the rainfall, the biochar application significantly increased soil water storage at 0-30 cm soil layer with crop growth. The maximum increment (15.49%) was observed under the MPT₂ treatment during the tassel stage. Biochar application did not affect water storage at 30-60 cm soil layer at the seedling stage and jointing stage due to the low rainfall. While biochar application increased water storage at 30-60 cm soil layer at the tassel stage, the magnitude of such effect was less than that at the 0-30 cm soil layer. Biochar application significantly increased the effective accumulated soil temperature at the seedling stage and jointing stage. The greatest increment occurred in the MPT₂ treatment at the seedling stage, reaching up to 20.97%. The effects of biochar application on the effective accumulated temperature were weakened at the middle and late stages, while such effect was least at the tasseling stage and filling stage. After biochar application, soil mineral nitrogen content was significantly reduced at the early stage of crop growth, but significantly increased by 25.19%-48.82% at the middle and late stages of crop growth. The total yield of MS increased by 12.79%-13.71% and the total yield of MP by 15.86%-18.01%. Therefore, biochar application effectively regulated soil water, nutrient and heat conditions during the critical stage of crop growth, improved the water and heat environment of soil and crop growth in the intercropping systems, which together facilitated the positive effects of intercropping on crop yield.

Key words: biochar, intercropping, water storage, effective accumulated temperature, mineral nitrogen.