The response of nitrifier, N-fixer and denitrifier gene copy numbers to the nitrification inhibitor 3,4-dimethylpyrazole phosphate

Abstract

A laboratory incubation experiment was conducted to examine the effects of 3,4-dimethylpyrazole phosphate (DMPP) on the transformation of urea-N and associated microbial communities in a low-fertility brown soil. The soil was supplied with urea at 180 kg N/ha and DMPP at 0, 1.8 or 18 kg/ha, while soil that was not supplied with urea and DMPP was treated as the control. Soil mineral nitrogen (NH 4 + -N and NO 3 --N) was measured at regular intervals, and temporal variations in the population sizes of nitrogen-cycling microbes were determined using realtime PCR. Compared to the urea-alone treatment, the additional application of DMPP maintained significantly higher (P < 0.05) NH 4 + -N concentrations and lower NO 3 --N (P < 0.05) concentrations in the soil and decreased the population sizes of ammonia oxidizing and denitrifying microbes but promoted the growth of nitrogen-fixing bacteria. The results suggest that the application of DMPP is beneficial in improving the availability of fertilizer-N for plant uptake. This study is the first comprehensive investigation to examine the effects of DMPP on the functional microorganisms that are important in nitrogen-cycling processes.

The Effects of Long-Term Application of Stabilized and Coated Urea on Soil Chemical Properties, Microbial Community Structure, and Functional Genes in Paddy Fields

“…The experimental treatments included the following: (1) no fertilizer (CK); (2) Conventional granular urea (N), containing 46% nitrogen; (3) Urea fertilizer supplemented with 1% hydroquinone (HQ), containing 45.55% nitrogen; (4) Urea fertilizer supplemented with 0.5% N-butylthiophosphoric triamide (NBPT), containing 45.77% nitrogen; (5) Urea fertilizer supplemented with 3% dicyandiamide (DCD), containing 44.66% nitrogen; (6) Urea fertilizer supplemented with 1% 3,4-dimethylpyrazole phosphate (DMPP), containing 45.55% nitrogen; (7) Urea fertilizer supplemented with 1% HQ and 3% DCD (HQ+DCD), containing 44.23% nitrogen; (8) Urea fertilizer supplemented with 0.5% NBPT and 1% DMPP (NBPT+DMPP), containing 45.32% nitrogen; (9) Sulfur-coated urea fertilizer (SCU) (120-day release period) produced by Han Feng Company in Canada, containing 34.00% nitrogen; (10) Resin-coated urea fertilizer (PCU) (120-day release period) produced by Shandong Jin Zheng Da Group, containing 43.00% nitrogen. Each treatment was replicated three times, with a plot area of 20 m 2 .…”

“…As a result, soil nitrate reductase and denitrification enzyme activities decrease, leading to a reduction in nitrate leaching and N 2 O emissions [9]. Furthermore, research has shown that the use of nitrification inhibitors like 3,4-dimethylpyridyl phosphate (DMPP) markedly decreases the abundance [10] and transcript activity of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB), which in turn alters the composition of AOB communities with respect to NH 4 + -N, NO 3 − -N, N 2 O, and pH [11][12][13]. By temporarily inhibiting urease-mediated urea decomposition, urease inhibitors extend the soil's retention time for ammonium ions, resulting in reduced ammonia volatilization and increased availability of NH 4 + for plant absorption [14].…”

Effect of a urea and urease/nitrification inhibitor combination on rice straw hydrolysis and nutrient turnover on rice growth

“…Stabilized fertilizer showed a noticeably higher protease activity, which means that the inhibitor promoted the PG metabolisms and the microorganisms still had higher activity, and N turnover capacity, mainly due to the availability of nitrogen substrates by microorganism's absorption and utilization still be high compared with urea alone. Research showed that the nitrification inhibitor NBPT impeded the growth of ammoniaoxidizing archaea (AOA), and DMPP significantly reduced the ammonia oxidizing bacterial abundance, which significantly inhibited urea hydrolysis indirectly affecting nitrification (Dong et al 2013;Meng et al 2020). Geisseler et al (2010) showed that the N turnover was determined by the amount and species of N source.…”