Earthworms enhance the inhibition efficiency of 3,4-dimethylpyrazole phosphate on soil nitrification by altering soil AOB communities and gut denitrifier communities

• DOI: 10.1007/s00374-023-01744-2
• Publication Date: 2023-05-26T07:01:49Z
• Authors: Bing-Jie Jin; Xi-Peng Liu; Miao Zhang; Yan Hu; Cheng-Liang Sun; Gang Li; Yong-Guan Zhu; Xian-Yong Lin
• Keywords: DMPP; Denitrifier; 0401 agriculture, forestry, and fisheries; Earthworm gut microbiota; 04 agricultural and veterinary sciences; NO emission; Nitrifier

Earthworms can significantly accelerate soil nitrification and N2O emissions by stimulating microbial communities in the soil and their gut. However, the response of earthworm-mediated N transformation to nitrification inhibitors (e.g., 3,4-dimethylpyrazole phosphate, DMPP) is mostly unknown. In this study, soils with or without earthworms were treated with four different concentrations of DMPP (0%, 1%, 2%, and 3%), and samples were collected at six different time points (days 3, 5, 7, 14, 21, and 30 of incubation). The presence of earthworms resulted in the highest soil NH4+ content and lowest NO3– content in DMPP-treated soil, which could be attributed to the highest ureC gene abundance and lowest soil ammonia-oxidizing bacteria (AOB) abundance. Approximately 75% of the earthworm-induced N2O emission could be suppressed by DMPP application, and earthworms also resulted in weak correlations between soil N-related gene abundance (bacterial amoA and nirK) and N2O emission, while such correlations could be strengthened when both DMPP and earthworms were applied. Besides, DMPP application could also significantly suppresses the nitrification and denitrification functions of earthworm gut microbiota, suggesting that the earthworm-induced N2O emission might be mainly produced by the denitrifier communities within their gut. In addition, the earthworm-induced fluctuations in soil NO3− and NH4+ content further resulted in significant losses of earthworm gut microbial diversity, while such losses could be alleviated by DMPP application, which enhanced the C-, P-, and S-cycling capacities of gut microbiota. Altogether, we suggest that DMPP can effectively inhibit nitrification in earthworm-treated soil, subsequently enhancing the earthworm gut microbiota’s metabolic capacities.