Abstract:

As a porous material rich in stable organic carbon，biochar exhibits significant potential in improving soil structure，enhancing aggregate stability，and increasing soil organic carbon content，and has become an important technical means for alleviating continuous cropping obstacles. This paper systematically reviews the research progress on the effects of different biochar application rates on aggregate stability and organic carbon in continuous cropping soils. It first elaborates on the basic characteristics of biochar and its application basis in the improvement of continuous cropping soils；then analyzes the effect patterns arising from differences in biochar application rates from three aspects：aggregate stability，organic carbon content and compositional changes，and physicochemical protection mechanisms. On this basis，it summarizes the intrinsic mechanisms by which biochar alleviates continuous cropping obstacles through the synergistic effects of structural improvement and carbon input. Existing studies indicate that biochar application can significantly increase the proportion of macroaggregates，mean weight diameter，and geometric mean diameter in soils，while also raising soil organic carbon content；most of these effects are positively correlated with application rate，but aggregate stability may show a trend of initially increasing and then decreasing at excessively high rates. Combined with meta-analysis results and typical case studies，this paper further summarizes the appropriate application rate ranges for different soil types and crop systems.

Key words: biochar, continuous cropping soil, aggregate stability, organic carbon