Submitted to: Journal of Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/25/2019
Publication Date: 5/10/2019
Citation: Tyler, H.L. 2019. Bacterial community composition under long-term reduced tillage and no till management. Journal of Applied Microbiology. 126:1797-1807.
Interpretive Summary: Tillage, the act of mechanically disrupting soil, is performed to prepare fields for planting, disrupt weeds, and create paths in the field for irrigation water to flow. While this practice is common in row crop production, it has some detrimental effects, such as increased erosion and nutrient loss. Therefore, no till management has been introduced as a way to mitigate some of these negative effects. Scientist from the USDA-ARS Crop Productions Systems Research Unit in Stoneville, MS conducted a field study to examine the microbial community in soils after 14 years of reduced tillage or no till management. Soils collected from no till plots were found to have higher amounts of microbial biomass, as well as greater activities of enzymes linked to phosphate mineralization, organic matter turnover, and general microbial hydrolytic activity compared to reduced tillage. Bacterial diversity was higher in reduced tillage compared to no till soils, while several of the bacterial groups in greater abundance in no till soils are known to possess genes for degradation of plant residues. This study demonstrates how a long-term no till management approach can impact soil bacterial communities involved in organic matter turnover in soils. These results will provide insight to scientists and information to farmers allowing them to weigh the positive and negative effects of no till management in their fields.
Technical Abstract: Aims: The purpose of this study was to assess impacts of long-term reduced tillage and no till management on bacterial communities in agricultural field soils. Methods and Results: Samples from surface soils were collected from field plots maintained under reduced tillage and no till conditions for 14 years. No till soils had significantly higher microbial biomass, as well as ß-glucosidase activity, which is linked to organic matter breakdown. Sequencing of the 16S rRNA gene revealed most variability in bacterial community composition was observed in low abundance members of the community. Diversity estimates (Chao 1, ACE, and Shannon indices) were lower in no till soils, and several bacterial taxa linked to organic matter breakdown were significantly higher in no till compared to tilled soils. Conclusions: Long-term no till management can significantly enhance of the size of soil microbial communities while negatively impacting bacterial diversity, through the lack of soil disturbance and breakdown of crop residues left on soil surfaces. Significance and Impact of the Study: This study provides insights into how no till management can influence the microbial community’s contribution to soil health and suggests that long-term no till field plots may benefit from occasional tillage.