Progress in the Regulation Effects of Biochar on Continuous Cropping Obstacles in Tobacco

Tobacco is a crop avoiding from continuous cropping. A continuous cropping for long-term will intensify pests and diseases of tobacco, accelerate accumulation of harmful microorganisms in soil, and make pathogens predominate in soil, which would cause imbalance of soil nutrient elements, aggravation of crop autotoxicity, imbalance of soil microbial flora, and changes of enzymes activity. The imbalance of soil microhabitats is the basic reason of continuous cropping obstacles of tobacco. The biochar with porous, alkaline and special nutrient characteristics, makes it an important way to adjust rhizosphere microbial population characteristics directionally, to recover and rebuild healthy rhizosphere ecosystems, and to overcome continuous cropping obstacles in tobacco. Through physical, chemical, and biological processes, the biochar could directionally regulate the population characteristics of rhizosphere microbes, restore and rebuild healthy rhizosphere ecosystems, increase the number of beneficial microbes and bacteria in the soil, and transfer soil microbes dominate by fungi to the ones dominate by bacteria. The transformation can make the pathogen to lose the dominant advantage in the soil ecosystem, maintain the soil microhabitats balance, and ultimately alleviate and eradicate continuous cropping obstacles. In this paper, we analyzed the reasons for continuous cropping obstacles in tobacco-planting soil, reviewed the regulation effects of biochar on continuous cropping obstacles in tobacco, and then interpreted the acting mechanism of biochar on continuous cropping obstacles of tobacco.