Tobacco floating growing substrate and preparation method thereof

The invention relates to a tobacco floating growing substrate and a preparation method thereof. The tobacco floating growing substrate comprises 65-80 percent of rotten peanut chaff, 10-20 percent of expanded perlite and 10-20 percent of vermiculite. The preparation method of the tobacco floating growing substrate comprises the following steps of: removing impurities from peanut shells and crushing the peanut shells to obtain peanut chaff of 3-6mm; adjusting the obtained peanut chaff until the water content is 60-70 percent; adding an HM (high methoxyl pectin) decomposition agent and uniformly mixing the HM decomposition agent with urea for stack retting; maintaining the temperature in the decomposition high-temperature stage to be 55-65DEG C; when the temperature in the stack is risen to over 65DEG C, turning stacks and reducing the temperature in time; when the temperature in the stack is recovered to normal temperature without raising, obtaining the rotten peanut chaff, sterilizing the rotten peanut chaff and uniformly mixing the rotten peanut chaff with the expanded perlite and the vermiculite according to the mixture ratio to form the tobacco floating growing substrate. The tobacco floating growing substrate has the advantages of moderate granularity, looseness and permeability, formed aggregated structure, favorable permeability and water retention property and stable physical and chemical properties; and the activities of tobacco nitrate reductase and saccharase can be improved and the development of a tobacco root system is promoted.