PurposeThe effects of different previous crops on the soil biochemical properties were studied.
MethodUsing chemical, enzymatic analysis and 16S diversity sequencing techniques, the soil nutrient, enzyme activity and bacterial community structure of tobacco fields with fagopyrum (FB), rape (FR), wheat (FW) and green manure (FG) were analyzed after seven years.
Results(1) The contents of organic matter, total nitrogen, alkali-hydrolyzed nitrogen and available phosphorus were the highest in FR tobacco field, which respectively were 30.04 g/kg, 1.62 g/kg, 143.50 mg/kg and 88.09 mg/kg, followed by FG tobacco field, but the content of available potassium was 240.10 mg/kg, and the activities of protease and phosphatase in FG tobacco field were the highest, which were 709.02 μg/(g·d)(tyrosine) and 306.60 μg/(g·h)(p-nitroph), respectively. (2) The activities of urease and invertase were lower than those of FW tobacco field, and there was no significant difference (P>0.05). In terms of bacterial community composition, 770, 670, 654 and 597 genera were detected in FB, FG, FW and FR tobacco fields, belonging to 36 taxa, including Actinobacteria, Proteobacteria, Chloroflexi and Acidobacteria. Among them, the abundance of Actionbacteria and Proteobacteria were the highest, respectively ranging from 26.87% to 45.21% and 25.82% to 30.69%. Antagonistic bacteria such as Treptomyces, Bradyrhizobium, Bacillus and Mycobacterium and nitrogen-bacteria such as Bradyrhizobium, Rhizobium and Paenibacillus had the highest relative abundance of bacterial community in FB tobacco field soil.
ConclusionThe effects of different preceding cropping on the soil physical and chemical properties, enzyme activities and bacterial community structure were different. Green manure improved soil organic matter, nutrients and enzyme activities, while buckwheat improved soil bacterial population structure and diversity, and the relative abundance of probiotics was higher.
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