Nitrogen-fixing bacterial communities differ between perennial agroecosystem crops

Area of Science:

• Microbial ecology
• Soil science
• Agricultural science

Background:

• Biocrusts are microbial communities on soil surfaces, crucial in natural ecosystems.
• Agroecosystem biocrusts exhibit nitrogen fixation but their community composition under agricultural management is understudied.

Purpose of the Study:

• To investigate how agricultural management influences the bacterial and diazotrophic communities of biocrusts.
• To compare biocrusts from citrus orchards, vineyards, and apple orchards differing in management, climate, and soil type.

Main Methods:

• Examined total bacterial and diazotrophic communities in biocrusts from diverse agricultural settings.
• Compared microbial composition across different management systems (citrus, vineyard, apple orchard).

Main Results:

• Agroecosystem biocrusts were dominated by proteobacteria, unlike natural biocrusts, with lower cyanobacteria abundance.
• Diazotroph communities in all studied agroecosystems were dominated by Nostocales cyanobacteria, similar to natural biocrusts.
• Vineyard and citrus orchard biocrust composition was linked to irrigation and fertilizer inputs, while apple orchard biocrusts varied with soil and climate.

Conclusions:

• Agricultural management, alongside climatic and edaphic factors, significantly shapes soil biocrust community composition and function.
• Seasonality did not appear to affect the bacterial and diazotrophic communities in these agroecosystem biocrusts.