Intermediate soil acidification induces highest nitrous oxide emissions.

Global potent greenhouse gas nitrous oxide (N2O) emissions from soil are accelerating, with increases in the proportion of reactive nitrogen emitted as N2O, i.e., N2O emission factor (EF). Yet, the primary controls and underlying mechanisms of EFs remain unresolved. Based on two independent but complementary global syntheses, and three field studies determining effects of acidity on N2O EFs and soil denitrifying microorganisms, we show that soil pH predominantly controls N2O EFs and emissions by affecting the denitrifier community composition. Analysis of 5438 paired data points of N2O emission fluxes revealed a hump-shaped relationship between soil pH and EFs, with the highest EFs occurring in moderately acidic soils that favored N2O-producing over N2O-consuming microorganisms, and induced high N2O emissions. Our results illustrate that soil pH has a unimodal relationship with soil denitrifiers and EFs, and the net N2O emission depends on both the N2O/(N2O + N2) ratio and overall denitrification rate. These findings can inform strategies to predict and mitigate soil N2O emissions under future nitrogen input scenarios.

The effect of transvaginal prolapse surgery on anorectal function

Objective: Pelvic floor dysfunction can manifest as a spectrum including anorectal dysfunction, vaginal prolapse, and urinary incontinence. Sacrospinous fixation is a procedure performed by gynecologists to treat vaginal prolapse. The present study aims to evaluate the impact of transvaginal prolapse surgery on anorectal function. Materials and Methods: We conducted a retrospective review of patients undergoing sacrospinous fixation surgery for vaginal prolapse between 2014 to 2020. Those with anorectal dysfunction who had also been evaluated by the colorectal service preoperatively and postoperatively were included for analysis. These patients were assessed with symptom-specific validated questionnaires. The effect of surgery on constipation and fecal incontinence symptoms was analyzed. Results: A total of 22 patients were included for analysis. All patients underwent transvaginal sacrospinous fixation, and 95.4% also had posterior colporrhaphy for vaginal prolapse. There were a statistically significant improvements in the Fecal Incontinence Severity Index (FISI), the St. Mark's Incontinence Score (Vaizey), the embarrassment and lifestyle components of the Fecal Incontinence Quality of Life Score, the Constipation Scoring System, the Obstructed Defecation Score, and components of the Patient Assessment of Constipation Quality of Life score. Conclusion: Transvaginal prolapse surgery leads to a favorable effect on anorectal function, with improvements in both obstructed defecation and fecal incontinence scores in this small series. (AU)

Arbuscular Mycorrhizae Shift Community Composition of N-Cycling Microbes and Suppress Soil N2O Emission.

Mycorrhizae are ubiquitous symbiotic associations between arbuscular mycorrhizal fungi (AMF) and terrestrial plants, in which AMF receive photosynthates from and acquire soil nutrients for their host plants. Plant uptake of soil nitrogen (N) reduces N substrate for microbial processes that generate nitrous oxide (N2O), a potent greenhouse gas. However, the underlying microbial mechanisms remain poorly understood, particularly in agroecosystems with high reactive N inputs. We examined how plant roots and AMF affect N2O emissions, N2O-producing (nirK and nirS) and N2O-consuming (nosZ) microbes under normal and high N inputs in conventional (CONV) and organically managed (OM) soils. Here, we show that high N input increased soil N2O emissions and the ratio of nirK to nirS microbes. Roots and AMF did not affect the (nirK + nirS)/nosZ ratio but significantly reduced N2O emissions and the nirK/nirS ratio. They reduced the nirK/nirS ratio by reducing nirK-Rhodobacterales but increasing nirS-Rhodocyclales in the CONV soil while decreasing nirK-Burkholderiales but increasing nirS-Rhizobiales in the OM soil. Our results indicate that plant roots and AMF reduced N2O emission directly by reducing soil N and indirectly through shifting the community composition of N2O-producing microbes in N-enriched agroecosystems, suggesting that harnessing the rhizosphere microbiome through agricultural management might offer additional potential for N2O emission mitigation.