Long-term agrichemical use leads to alterations in bacterial community diversity

Bacterial communities are key drivers of soil fertility and agriculture productivity. Understanding how soil bacterial communities change in response to different conditions is an important aspect in the development of sustainable agriculture. There is a desire to reduce the current reliance on high inputs of chemicals and fertilisers in agriculture, but limited data are available on how this might impact soil bacterial communities. This study investigated the bacterial communities in a spring barley monoculture site subjected to two different input regimes for over 12 years: a conventional chemical/fertiliser regime, and a reduced input regime. A culture independent approach was performed to compare the bacterial communities through 16S rRNA gene PCR-DGGE. PCO analysis revealed that the rhizosphere has a strong structuring effect on the bacterial community. Moreover, high inputs of agrichemicals lead to an increase of phosphorus level in the soil and a concomitant reduction of the bacterial diversity. These results may help to evaluate the environmental risks associated with agrichemical usage.