Dynamics of biochemical properties associated with soil nitrogen mineralization following nitrification inhibitor and fungicide applications

Abstract

Agrochemical applications may have side effects on soil biochemical properties related to soil nitrogen (N) mineralization and thus affect N cycling. The present study aimed to evaluate the effects of nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) and fungicide iprodione on soil neutral protease (NPR), alkaline protease (APR), chitinase (CHI), and their functional genes (nprA, aprA, and chiA) related to soil N mineralization. The following four treatments were included: blank control (CK), single DMPP application (DAA), weekly iprodione applications (IPR), and the combined applications of DMPP and iprodione (DI). Compared with the CK treatment, DMPP application significantly inhibited the CHI activity in the first 14 days of incubation, and iprodione applications, particularly when applied alone, decreased the NPR, APR, and CHI activities. Relative to the IPR treatment, extra DMPP application had the potential to alleviate the inhibitory effects of iprodione on the activities of these enzymes. DMPP application significantly increased aprA gene abundances after 14 days of incubation. However, repeated iprodione applications, alone or with the DMPP, decreased nprA and chiA gene abundances. Relative to the CK treatment, DMPP application generated negligible effects on the positive/negative correlations between soil enzyme activities and the corresponding functional gene abundances. However, the positive correlation between the CHI activity and chiA gene abundance was changed to negative correlation by repeated iprodione applications, alone or together with the DMPP. Our results demonstrated that agrochemical applications, particularly repeated fungicide applications, can have inadvertent effects on enzyme activities and functional gene abundances associated with soil N mineralization.

Blame It on the Metabolite: 3,5-Dichloroaniline Rather than the Parent Compound Is Responsible for the Decreasing Diversity and Function of Soil Microorganisms

“…3). In a series of studies, Zhang et al (21,24) observed a significant reduction in the activity of Bglu, AcP, alkaline phosphomonoesterase (AlkP), Leu, and Chit upon repeated applications of the recommended dose of iprodione (4 ϫ 1.5 g g Ϫ1 ). These effects became evident at the later stages of the incubation (from 14 days onward) and probably reflected the gradual accumulation of iprodione and/or the formation of 3,5-DCA.…”

“…3.5-DCA is neurotoxic (16), and it is considered the most recalcitrant (17) and toxic (18) dichloroaniline isomer. Previous studies have reported significant reductions in the abundance, activity, and diversity of soil microorganisms in response to iprodione application (19)(20)(21). However, the effects observed were attributed entirely to the parent compound, while the transformation of iprodione in soil and the potential contribution of its TPs were not explored.…”

Drought Effects on Nitrogen Provisioning in Different Agricultural Systems: Insights Gained and Lessons Learned from a Field Experiment

“…During proteolysis, proteins are hydrolyzed into smaller fragments [45], a process in which extracellular proteolytic enzymes (proteases) secreted by microbes are crucial [45]. Molecular tools such as quantitative polymerase chain reaction and amplicon-based sequencing allow us to quantify the abundance and diversity of gene regions encoding for extracellular proteases such as alkaline and neutral metallopeptidases, as well as serine peptidases [46], and to describe the genetic potential of proteolytic communities [8,17,45,47,48]. The genetic potential for N mineralization was found to correlate with direct measurements of protease activity [45,49,50], yet not always [48].…”

“…Molecular tools such as quantitative polymerase chain reaction and amplicon-based sequencing allow us to quantify the abundance and diversity of gene regions encoding for extracellular proteases such as alkaline and neutral metallopeptidases, as well as serine peptidases [46], and to describe the genetic potential of proteolytic communities [8,17,45,47,48]. The genetic potential for N mineralization was found to correlate with direct measurements of protease activity [45,49,50], yet not always [48]. Therefore, direct measurements of the soil extracellular enzyme activity potential should be performed, e.g., by spectrophotometry [51,52] or by fluorescence analysis [53].…”

Metagenomic insight into antagonistic effects of a nitrification inhibitor and phosphate‐solubilizing bacteria on soil protease activity

“…the responses of soil protease to nitrification inhibitor were generally ignored (Li et al, 2018;Meng et al, 2021). The study found that nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) addition significantly stimulated N cycling-related genes nprX and aprA encoding protease and accelerated N cycling (Zhang et al, 2017). However, rare investigations were conducted to explore how nitrification inhibitors affected protease activity and to analyze the quantitative contributions of functional genes, microbial communities, and soil physiochemical properties to soil protease activities (Guo et al, 2013;Zhang et al, 2017).…”