Soil Microbial Community Dynamics during the Decomposition Period of Winter Cover Crops

Across the Midwest United States, there is an increasing number of agriculturalists incorporating cover crops and reduced tillage residue management into sustainable nutrient management plans. However, the impact of these treatments on the soil microbial community, and subsequently, on soil nutrient cycling and inorganic nitrogen (N) availability, is largely unknown. Therefore, this research had two objectives: i) to determine the impact of cover crop species on soil and litter enzyme activity and soil nitrogen supply during the cover crop decomposition period, and ii) to evaluate the impact of cover crops and reduced tillage on the soil microbial community diversity and composition during the cover crop decomposition period. Enzyme activity was measured through β-glucosidase and urease activity assessments on soil and cover crop litter. Soil microbial communities were characterized using the small subunit (16S) rRNA gene sequences determined using the Illumina MiSeq system and analyzed with the QIIME bioinformatics pipeline. Results indicate that cover crops and tillage treatment significantly influenced soil and litter enzyme activity and inorganic N availability during the decomposition period. Specifically, soil β-glucosidase activity peaked in all cover crop treatments in 2016 and 2017 within six decomposition degree-days (DCDs) following cover crop termination. Both seasons, peak inorganic N availability occurred within seven DCDs from peak β-glucosidase activity. In addition, this study revealed that the structure of the soil microbiome changed during the decomposition period. This was evident through changes in microbial community ɑ- and β-diversity, and these differences were greater as the decomposition period progressed, most notably after DCD 2.9 when a majority of the cover crop decomposition occurred. Residue management treatment was also a significant determinant of the soil microbial community structure, and the impact of these treatments was greatest at DCD 6.4. The variation of the soil microbiome structure at the beginning and end of the decomposition period was greater than the variation during peak cover crop decomposition. Overall, it was concluded that DCD, cover crop treatment, and residue management treatment were important variables in explaining the variance of the genus level observations. This study increases our understanding of how the soil microbial community responds to carbon inputs during the decomposition of winter cover crops, leading to the identification of bacteria that are highly responsive to management practices during the cash crop growing season and having the largest effect in differentiating cover crop species. Understanding the abundance patterns of the microbiota that are influenced by management practices has the potential to help optimize agriculture management practices to promote beneficial microorganisms as the adoption of management practices such as cover cropping and reduced tillage residue management treatments continues

Screening disability insurance applications

This paper investigates the effects of stricter screening of disability insurance applications. A large-scale experiment was setup where in two of the 26 Dutch regions case workers of the disability insurance administration were instructed to screen applications more stringently. The empirical results show that stricter screening reduces long-term sickness absenteeism and disability insurance applications. We find evidence for direct effects of stricter screening on work resumption during the period of sickness absence and for self-screening by potential disability insurance applicants. Stricter screening seems to improve targeting efficiency, without inducing negative spillover effects to the inflow into unemployment insurance. The costs of stricter screening are only a small fraction of the monetary benefits.Disability insurance; experiment; policy evaluation; sickness absenteeism; self-screening

Domains and prominence in nasal harmonization of Maxakalí loanwords

We examine the patterns of loanword adaptation in Maxakalí, a Macro-Jê language of Brazil, in importing loans from Brazilian Portuguese, with respect to the introduction of nasality and nasal harmony, based on a corpus of 18 speakers. Employing MaxEnt modeling of quantitative trends enabled the comparison and analysis of certain recurrent trends, even if not exceptionless, and the potentially additive effects of their interaction. The results reveal that nasal harmonization, modeled as set of markedness constraints, is greatly enforced within syllable rimes, and strongly enforced within syllables, but shows little role for syllable-to-syllable harmony, demonstrating that harmonization is preferred within tighter prosodic domains. Word-initial consonants always retain their nasality or orality from Portuguese, and stressed vowels always preserve their nasality. These latter effects uphold the role of prominent positions in maintaining contrasts within loanword phonology. The overall patterns of loanword harmonization find convergence with certain characteristics within Maxakalí phonology itself

Twenty-five years of recombinant human growth factors rhPDGF-BB and rhBMP-2 in oral hard and soft tissue regeneration.

Contemporary oral tissue engineering strategies involve recombinant human growth factor approaches to stimulate diverse cellular processes including cell differentiation, migration, recruitment, and proliferation at grafted areas. Recombinant human growth factor applications in oral hard and soft tissue regeneration have been progressively researched over the last 25 years. Growth factor-mediated surgical approaches aim to accelerate healing, tissue reconstruction, and patient recovery. Thus, regenerative approaches involving growth factors such as recombinant human platelet-derived growth factor-BB (rhPDGF-BB) and recombinant human bone morphogenetic proteins (rhBMPs) have shown certain advantages over invasive traditional surgical approaches in severe hard and soft tissue defects. Several clinical studies assessed the outcomes of rhBMP-2 in diverse clinical applications for implant site development and bone augmentation. Current evidence regarding the clinical benefits of rhBMP-2 compared to conventional therapies is inconclusive. Nevertheless, it seems that rhBMP-2 can promote faster wound healing processes and enhance de novo bone formation, which may be particularly favorable in patients with compromised bone healing capacity or limited donor sites. rhPDGF-BB has been extensively applied for periodontal regenerative procedures and for the treatment of gingival recessions, showing consistent and positive outcomes. Nevertheless, current evidence regarding its benefits at implant and edentulous sites is limited. The present review explores and depicts the current applications, outcomes, and evidence-based clinical recommendations of rhPDGF-BB and rhBMPs for oral tissue regeneration

Does Chemical Leaf Burn of Double Crop Soybeans Reduce Yield?

Most farmers who have applied acifluorfen (sold as Blazer or Tackle) for postemergence control of broadleaf weeds in soybean fields are aware that leaf crinkling, bronzing, and necrosis can result. Despite this, studies in Kentucky, Illinois, Arkansas, and South Carolina have shown that full season soybeans have plenty of time to recover from leaf burn caused by this herbicide, and no yield losses have been found. However, double crop soybeans are usually planted much later than the full season crop. This delay in planting may reduce the time for plants to complete vegetative growth before beginning the seed production process. Therefore, double crop soybeans may be limited in their ability to recover from acifluorfen injury in time to produce as much grain as nonsprayed soybeans. Our objective was to determine if yields of double crop soybeans are reduced by leaf burn due to the use of acifluorfen