Objectives The effects of biochar on enhancing crop productivity and soil fertility is limited by soil and biochar properties. In this study, we explored the suitable utilization mode of biochar according to different soil conditions.
Methods A pot experiment was conducted in loam and clay fluvo-aquic soils. The soils were treated with wheat straw biochar (WBC) and maize straw biochar (MBC), and the same treatment without biochar was prepared as a control (CK). The physicochemical characteristics and extracellular enzyme activity of rhizosphere soil and maize growth, resistance, and nutrient absorption were examined.
Results 1) WBC enhanced maize seedling growth and improved root architecture in loam fluvo-aquic soil (P<0.05). Shoot biomass increased by 43.7%, and total root length increased by 34.3% in WBC under loam fluvo-aquic soil (P<0.05), compared with CK. In the clay fluvo-aquic soil, biochar treatment showed little effects on maize seedling biomass and root system architecture. Our results showed that biochar amendment could promote maize seedling growth in loam fluvo-aquic soil, and WBC was better than MBC. 2) Biochar soil amendment could improve maize resistance at the seedling stage. The two biochars decreased MDA content in maize leaf by 32.7%−55.3% in a similar manner. MBC increased the SOD activity in clay fluvo-aquic soil (P<0.05), while WBC had no effect. In contrast, SOD activity did not differ among the treatments in loam fluvo-aquic soil. 3) Biochar could promote the nutrient absorption of maize at the seedling stage. The two bioachar treatmens did not affect maize N content but increased P and K content in loam fluvo-aquic soil. Specifically, WBC increased P and K content by 23.5% and 28.7%. In clay fluvo-aquic soil, biochar showed no effects on maize N and P content, while MBC increased K content. 4) Biochar amendment improved soil fertility and increased extracellular enzyme activity. Compared with CK, MBC increased available phosphorus content by 25.4% in loam fluvo-aquic soil. Both MBC and WBC treatments inceased available phosphorus content by 15.03% in clay fluvo-aquic soil, and soil CEC was significantly increased (P<0.05). Biochar increased the activity of extracellular enzymes related to C, N, and P cycling. There was no significant difference in extracellular enzymes activity in clay fluvo-aquic soil (P>0.05). Conversely, WBC recorded higher extracellular enzymes activity than MBC in loam fluvo-aquic soil.
Conclusions The application of biochar to fluvo-aquic soil could improve maize productivity at the seedling stage, increase maize root architecture, and regulate soil nutrient cycling in the rhizosphere. This effect was better in loam fluvo-aquic soil than in clay fluvo-aquic soil, and WBC had a higher effect than MBC.
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