Flooding effects on soil properties, heavy metals, and microbial communities in tea plantations

The flooding of tea plantation caused by natural rainfall is a common natural disaster, which has adverse effects on the soil quality of tea plantation, the growth of tea trees, and the yield and quality of tea. This article systematically studied the multidimensional effects of natural rainfall (flood conditions) on tea plantation soil for the first time. In this study, the physicochemical properties, heavy metals, and microbial communities of tea plantation soil samples were analyzed at six time points after natural rainfall (flood conditions) at 0, 15, 18, 21, 24, and 27 days. The results showed that natural rainfall (flood conditions) had a significant impact on soil nutrients and heavy metal concentrations in tea plantations. With the extension of flooding time, compared with the pre-flooding control (0 days), soil pH, organic matter, available potassium, available phosphorus, alkali-hydrolyzable nitrogen, and the concentrations of eight heavy metals first increased and then decreased with prolonged flooding, and the concentrations of all heavy metals were lower than the limits of soil environmental quality standards. After flooding, Proteobacteria was the dominant group of bacterial community, and Acidobacterita, Chloroflexi, and Actinobacteriota were also abundant. The fungal community is dominated by Ascomycota and Basidiomycota. Soil components were significantly correlated with microbial community, in which organic matter, available potassium, and pH value had the greatest impact on bacterial community, while fungal community was mainly affected by available potassium, organic matter, Cr, and As. In general, natural rainfall (flood conditions) will reduce the content of nutrients and heavy metals in tea plantation soil and change the soil microbial community structure, which provides a scientific basis for evaluating the impact of natural rainfall on tea plantation soil health.