Building the soil immune system: do cover crops increase soil health and resistance to climate change?

The project examined the impact of cover crops on soil health, and evaluated the use of decomposition of household items (tea bags, cotton, and birch sticks) as alternative measures of more expensive soil health measurements. As a measurement of soil health, commercially available green and red tea bags were used to create soil decomposition indices for nine Iowa farms with and without replicated cover crop strips

What is soil health, how do we measure it, and why the emphasis on soil biology?

The current interest in soil health is largely due to increased awareness of the importance of soil biology. While there are a variety of biological soil health indices, there is currently no consensus among scientists. The current soil health tests are relatively expensive and show inconsistent results amongst management practices. Further research into calibrating and validating all soil health indicators is needed, especially for biological indicators

A Protocol for 3D Reconstructions from Reduced-quality Serial Histological Sections

Computer-generated 3D reconstructions of anatomy allow the examination of minute and internal structures that cannot be visualized using traditional methods. Digital reconstructions are generated from many sources, including magnetic resonance imaging, computed tomography, and histological serial sections. Of these, serial sections provide the most information, but are difficult to generate because of deformation and misalignment. Protocols to eliminate inconsistencies in a serial section stack could result in informative reconstructions generated efficiently and inexpensively. I describe a protocol I developed to construct 3D visualizations from reduced-quality serial sections. Using this technique, I created a reconstruction of the vertebral column of the spadefoot toad (Spea bombifrons), a species for which the vertebral column has unique morphology and developmental patterns. Results presented here should: 1) provide better methods for creating 3D reconstructions from serial sections, and 2) offer new insights for future studies of the development of the spinal column of S. bombifrons

Evaluation of Humic Fertilizers Applied at Full and Reduced Nitrogen Rates on Kentucky Bluegrass Quality and Soil Health

Soil health and sustainable management practices have garnered much interest within the turfgrass industry. Among the many practices that enhance soil health and sustainability are applying soil additives to enhance soil biological activity and reducing nitrogen (N) inputs—complimentary practices. A two-year study was conducted to investigate if reduced N fertilizer rates applied with humic substances could provide comparable turfgrass quality as full N rates, and whether humic fertilizers would increase biological aspects of soil health (i.e., microbial biomass and activity). Treatments included synthetic fertilizer with black gypsum (SFBG), poly-coated humic-coated urea (PCHCU; two rates), urea + humic dispersing granules (HDG; two rates), urea, stabilized nitrogen, HDG, and a nontreated control. Reduced rates of N with humic substances maintained turfgrass quality and cover, and reduced clipping biomass compared to full N rates. There were no differences in soil physical and chemical properties besides soil sulfur (S) concentration. SFBG resulted in the highest soil S concentration. Fertilizer treatments had minimal effect on microbial biomass and other plant-available nutrients. However, PCHCU (full rate) increased potentially mineralizable carbon (PMC) and N (PMN) by 68% and 59%, respectively, compared to the nontreated control. Meanwhile SFBG and stabilized nitrogen also increased PMC and PMN by 77% and 50%, and 65% and 59%, respectively. Overall, applications of reduced N fertilizer rates with the addition of humic substances could be incorporated into a more sustainable and environmentally friendly turfgrass fertilizer program

Disproportionate CH4 sink strength from an endemic, sub-alpine Australian soil microbial community

Soil-to-atmosphere methane (CH4) fluxes are dependent on opposing microbial processes of production and consumption. Here we use a soil–vegetation gradient in an Australian sub-alpine ecosystem to examine links between composition of soil microbial communities, and the fluxes of greenhouse gases they regulate. For each soil/vegetation type (forest, grassland, and bog), we meas-ured carbon dioxide (CO2) and CH4 fluxes and their production/consumption at 5 cm intervals to a depth of 30 cm. All soils were sources of CO2, ranging from 49 to 93 mg CO2 m −2 h −1. Forest soils were strong net sinks for CH4, at rates of up to −413 µg CH4 m −2 h −1. Grassland soils varied, with some soils acting as sources and some as sinks, but overall averaged −97 µg CH4 m −2 h −1. Bog soils were net sources of CH4 (+340 µg CH4 m −2 h −1). Methanotrophs were dominated by USCα in forest and grassland soils, and Candidatus Methylomirabilis in the bog soils. Methylocystis were also de-tected at relatively low abundance in all soils. Our study suggests that there is a disproportionately large contribution of these ecosystems to the global soil CH4 sink, which highlights our dependence on soil ecosystem services in remote locations driven by unique populations of soil microbes. It is paramount to explore and understand these remote, hard-to-reach ecosystems to better understand biogeochemical cycles that underpin global sustainability

The Effect of Land-Use Change on Soil CH4 and N2O Fluxes

Land-use change is a prominent feature of the Anthropocene. Transitions between natural and human-managed ecosystems affect biogeochemical cycles in many ways, but soil processes are amongst the least understood. We used a global meta-analysis (62 studies, 1670 paired comparisons) to examine effects of land conversion on soil-atmosphere fluxes of methane (CH4) and nitrous oxide (N2O) from upland soils, and determine soil and environmental factors driving these effects. Conversion from a natural ecosystem to any anthropogenic land use increased soil CH4 and N2O fluxes by 234 kg CO2-equivalents ha-1 y- 1, on average. Reversion of managed ecosystems to that resembling natural ecosystems did not fully reverse those effects, even after 80 years. In general, neither the type of ecosystem converted, nor the type of subsequent anthropogenic land use, affected the magnitude of increase in soil emissions. Land-use changes in wetter ecosystems resulted in greater increases in CH4 fluxes, but reduced N2O fluxes. An interacting suite of soil variables influenced CH4 and N2O fluxes, with availability of inorganic nitrogen (i.e. extractable ammonium and nitrate), pH, total carbon, and microclimate being strong mediators of effects of land-use change. In addition, time after a change in land use emerged as a critical factor explaining the effects of land-use change – with increased emissions of both greenhouse gases diminishing rapidly after conversion. Further research is needed to elucidate complex biotic and abiotic mechanisms that land-use change, and in particularly during this initial disturbance when greenhouse gas emissions are increased the most relative to native vegetation. Efforts to mitigate emissions will be severely hampered by this gap in knowledge

Water-saving irrigation is a ‘win-win’ management strategy in rice paddies – With both reduced greenhouse gas emissions and enhanced water use efficiency

Demand for rice will increase with growing global population. Globally, water management and nitrogen (N) application are two key factors influencing rice production and greenhouse gases (GHGs) emissions. In China, one of the world’s largest rice-producing countries, scarcity of water also threatens rice production. Therefore, in order to meet these challenges, it is essential to find water-use efficient irrigation management that also mitigates GHGs emissions from rice paddies. This study was conducted with three N application rates (90, 180, 270 kg N ha−1) under two irrigation regimes: 1) the conventional flooding-midseason drainage-flooding irrigation (FDF), and 2) flooding-moist by alternating wetting and drying (AWD) as the water-saving irrigation. Results showed that AWD irrigation significantly reduced CH4 emissions by 38%, but increased N2O emissions by 34%. Although N2O and CH4 emissions showed a trade-off relationship, the global warming potential (GWP) and greenhouse gas intensity (GHGI) significantly decreased by 22% and 24%, respectively, under water-saving irrigation management. N fertilization significantly enhanced rice grain yield but had no effects on water use efficiency (WUE). Although AWD had no effects on rice grain yield, it significantly enhanced WUE by 40%. Considering the interactive effects of N fertilization and irrigation management, the highest grain yield (7808.38 kg ha−1) occurred in AWD with medium N application rate. Generally, AWD irrigation regime could be used as an effective management for simultaneously saving water and enhancing rice grain yield, while mitigating GHGs emissions from rice paddies

Practice Guideline for the treatment of patients with HIV-AIDS

This guideline addresses psychiatric issues in the care of people with HIV/AIDS. Originally published in November 2000. This guideline is more than 5 years old and has not yet been updated to ensure that it reflects current knowledge and practice. In accordance with national standards, including those of the Agency for Healthcare Research and Quality’s National Guideline Clearinghouse (http://www.guideline.gov/), this guideline can no longer be assumed to be current. The April 2006 Guideline Watch associated with this guideline provides additional information that has become available since publication of the guideline, but it is not a formal update of the guideline

A novel strategy to increase the proliferative potential of adult human β-cells while maintaining their differentiated phenotype

Our previous studies demonstrated that Wnt/GSK-3/β-catenin and mTOR signaling are necessary to stimulate proliferative processes in adult human β-cells. Direct inhibition of GSK-3, that engages Wnt signaling downstream of the Wnt receptor, increases β-catenin nuclear translocation and β-cell proliferation but results in lower insulin content. Our current goal was to engage canonical and non-canonical Wnt signaling at the receptor level to significantly increase human β-cell proliferation while maintaining a β-cell phenotype in intact islets. We adopted a system that utilized conditioned medium from L cells that expressed Wnt3a, R-spondin-3 and Noggin (L-WRN conditioned medium). In addition we used a ROCK inhibitor (Y-27632) and SB-431542 (that results in RhoA inhibition) in these cultures. Treatment of intact human islets with L-WRN conditioned medium plus inhibitors significantly increased DNA synthesis ∼6 fold in a rapamycin-sensitive manner. Moreover, this treatment strikingly increased human β-cell proliferation ∼20 fold above glucose alone. Only the combination of L-WRN conditioned medium with RhoA/ROCK inhibitors resulted in substantial proliferation. Transcriptome-wide gene expression profiling demonstrated that L-WRN medium provoked robust changes in several signaling families, including enhanced β-catenin-mediated and β-cell-specific gene expression. This treatment also increased expression of Nr4a2 and Irs2 and resulted in phosphorylation of Akt. Importantly, glucose-stimulated insulin secretion and content were not downregulated by L-WRN medium treatment. Our data demonstrate that engaging Wnt signaling at the receptor level by this method leads to necessary crosstalk between multiple signaling pathways including activation of Akt, mTOR, Wnt/β-catenin, PKA/CREB, and inhibition of RhoA/ROCK that substantially increase human β-cell proliferation while maintaining the β-cell phenotype

The effect of land-use change on soil CH4 and N2O fluxes: A global meta-analysis

Land-use change is a prominent feature of the Anthropocene. Transitions between natural and human-managed ecosystems affect biogeochemical cycles in many ways, but soil processes are among the least understood. We used a global meta-analysis (62 studies, 1670 paired comparisons) to examine effects of land conversion on soil–atmosphere fluxes of methane (CH4) and nitrous oxide (N2O) from upland soils, and determine soil and environmental factors driving these effects. Conversion from a natural ecosystem to any anthropogenic land use increased soil CH4 and N2O fluxes by 234 kg CO2-equivalents ha−1 y−1, on average. Reversion of managed ecosystems to that resembling natural ecosystems did not fully reverse those effects, even after 80 years. In general, neither the type of ecosystem converted, nor the type of subsequent anthropogenic land use, affected the magnitude of increase in soil emissions. Land-use changes in wetter ecosystems resulted in greater increases in CH4 fluxes, but reduced N2O fluxes. An interacting suite of soil variables influenced CH4 and N2O fluxes, with availability of inorganic nitrogen (that is, extractable ammonium and nitrate), pH, total carbon, and microclimate being strong mediators of effects of land-use change. In addition, time after a change in land use emerged as a critical factor explaining the effects of land-use change—with increased emissions of both greenhouse gases diminishing rapidly after conversion. Further research is needed to elucidate complex biotic and abiotic mechanisms that drive land-use change effects on soil greenhouse gas emissions, but particularly during this initial disturbance when emissions are greatest relative to native vegetation. Efforts to mitigate emissions will be severely hampered by this gap in knowledge