Amending soil with duckweed enhances mineralization of plant nutrients and induces shifts in composition of soil microbiome

Abstract

Duckweed, with its high levels of protein and nutrient contents, is a viable option for use as a soil amendment. This research investigated using duckweed to enhance the properties of soil with low nitrogen content and to observe any associated changes in the soil bacterial community. The 8 duckweed samples were identified as either Lemna aequinoctialis or Landoltia punctata. Notably, Lemna aequinoctialis BK01 exhibited rapid multiplication (approximately six-fold within 7 d) when cultivated in Hoagland medium. Duckweed proved effective in soil enhancement, leading to a 10.5% increase in organic matter after 30 d of soil incubation, triggering mineralization and release into the soil of ammonium (4.95 mg L−1), nitrate (3.29 mg L−1), and available phosphorus (73.46 mg kg−1). Furthermore, the soil amended with duckweed showcased the dominance of 3 bacterial phyla: the Actinobacteriota (24.9%), Proteobacteria (20.9%), and Planctomycetota (10%). Ammonium was positively correlated with Tumebacillus and nitrate was positively correlated with Pullulanibacillus, while the organic matter and available phosphorus were positively correlated with Dyella. These results demonstrated that duckweed has a potential not only to improve the soil quality in nitrogen-deficient soil, such as the Hup Krapong soil series, but also to induce shifts in bacterial communities.