Relationships between soil physico-chemical properties and nitrogen fixing, nitrifying and denitrifying under varying land-use practices in the northwest region of Argentina

CAROLINA PEREZ BRANDÁN; ANNABEL MEYER; JOSÉ MERILES; JORGELINA HUIDOBRO; MICHAEL SCHLOTER; SILVINA VARGAS GIL

Soil and water research

Czech Academy of Agricultural Sciences

Año: 2019

1801-5395

The aim of this work was to evaluate the response patternof diazotrophic microbes, denitrifiers and nitrifiers towards different typesof land use management, such as soybean monoculture during 5 and 24 years (M5and M24) and soybean-corn rotation during 4 and 15 years (R4 and R15) in twosubsequent years at the time point of flowering. As control soil samples from asite recently introduced into agriculture (RUA) and a pristine soil undernative vegetation (NV) were used. Abundances of the different functional groupsof microbes were assessed using the direct quantification of marker genes byquantitative real time PCR using extracted DNA from rhizosphere samples. Inaddition, soil chemical and physical properties were analyzed and correlated theabundance data from the functional microbial groups under investigation. Overall,the results indicate that the abundance of nifH genes was higher under R treatmentscompared to M treatments.The abundance of AOA was generally higherunder rotation systems and decreased under M24. RUA evidenced a negative effecton the establishment and development of AOA communities. The influence of land use on nirS abundancewas inconsistent. However, R treatments showed highabundance of nirK genes compared to M treatments. Inboth growing seasons, the abundance of nosZ genes was higher under NV compared with the other treatments. Furthermore, M24 treatment wasrelated to strongly changed chemical and physical soil properties compared tothe other sides. As expected, soil samples from RUA showed a strongly dynamicof the measured parameters indicating the high sensitivity of soils undertransition for environmental parameters. Our results also indicated thatlong-term crop rotation modified theabundance of the investigated microbial groups compared to the monoculture andincreased soil chemical and physical quality. Therefore, our results provide evidence for astimulatory effect of long-term crop rotation on the abundance of microbes involved in N transformation.