Soil moisture gradients shape microbial communities and influence cranberry yield: a case study on subirrigation

Water management is vital in cranberry farming, balancing plant needs and supporting flood-based harvesting. This study examines subirrigation, a technique that reduces water use and enhances yields, by utilizing natural soil moisture gradients in two fields to assess its effects on yield and soil bacteria. Considering 166,551 observation points collected over four years, we confirmed significant differences in soil moisture between the eastern and western sides of the fields, with lower water table depths on the subirrigated sides. Using 16S rRNA sequencing, we examined soil bacterial communities, focusing on nitrogen cycling. Subirrigated areas, with lower moisture levels, showed higher cranberry yields (up to 45.67 t/ha) and a greater abundance of beneficial bacteria such as Burkholderia and Arthrobacter. The results also suggest an increase in predicted bacterial genes linked to nitrogen mineralization, denitrification, and nitrate assimilation as soil moisture levels rise, which, notably, correlates negatively with cranberry yield. Conversely, DNRA (nirD) and ANRA (NasA and NasB) genes appear to be indirectly favored in environments with lower soil moisture. Our findings not only shed light on the intricate relationships between bacterial genera, nitrogen metabolism, and environmental factors but also underscore the potential of sustainable agricultural practices in enhancing soil health.