Relationships between Soil Physico-chemical Properties and Nitrogen Fixing, Nitrifying and Denitrifying under Varying Land-use Practices in the Northwest Region of Argentina

PÉREZ BRANDÁN C.; MEYER A.; MERILES J. M.; HUIDOBRO J.; SCHLOTER M.; VARGAS-GIL S.

SOIL AND WATER RESEARCH

Czech Academy of Agricultural Sciences

Año: 2018 vol. 14 p. 1 - 9

1801-5395

The aim of this work was to evaluate the response pattern of diazotrophic microbes, denitrifiers and nitrifiers towards different types of land use management, such as soybean monoculture during 5 and 24 years (M5 and M24) and soybean-corn rotation during 4 and 15 years (R4 and R15) in two subsequent years at the time point of flowering. As control soil samples from a site recently introduced into agriculture (RUA) and a pristine soil under native vegetation (NV) were used. Abundances of the different functional groups of microbes were assessed using the direct quantification of marker genes by quantitative real time PCR using extracted DNA from rhizosphere samples. In addition, soil chemical and physical properties were analyzed and correlated the abundance data from the functional microbial groups under investigation. Overall, the results indicate that the abundance of nifH genes was higher under R treatments compared to M treatments. The abundance of AOA was generally higher under rotation systems and decreased under M24. RUA evidenced a negative effect on the establishment and development of AOA communities. The influence of land use on nirS abundance was inconsistent. However, R treatments showed high abundance of nirK genes compared to M treatments. In both growing seasons, the abundance of nosZ genes was higher under NV compared with the other treatments. Furthermore, M24 treatment was related to strongly changed chemical and physical soil properties compared to the other sides. As expected, soil samples from RUA showed a strongly dynamic of the measured parameters indicating the high sensitivity of soils under transition for environmental parameters. Our results also indicated that long-term crop rotation modified the abundance of the investigated microbial groups compared to the monoculture and increased soil chemical and physical quality. Therefore, our results provide evidence for a stimulatory effect of long-term crop rotation on the abundance of microbes involved in N transformation.