Does No-Tillage Mitigate Stover Removal in Irrigated Continuous Corn? A Multi-Location Assessment

No-tillage (NT) may ameliorate negative effects on soil properties from corn (Zea mays L.) stover harvest, but few long-term irrigated continuous corn production systems have been evaluated to test this hypothesis. We evaluated three long-term no-tillage sites (4–13 yr) in Nebraska and Colorado that spanned a range of precipitation and soil organic carbon (SOC) levels. We measured SOC, d13C of SOC, soil microbial biomass (SMB) and composition (i.e., phospholipid fatty acids, PLFAs), and water stable aggregation at all sites under stover retention vs. removal (~60%). Surface SOC stocks (0–30- cm depth) increased across the gradient and were 46.4, 57.4, and 63.1 Mg C ha–1 for Colorado, central Nebraska, and eastern Nebraska, respectively. Overall, residue removal decreased SOC stocks by 6% and soil aggregation by 12% in the 0- to 30-cm depth. The d13C signature of SOC indicated less new surface C storage under residue removal in Colorado, but not at the two Nebraska sites. Residue harvest did not decrease SMB or change soil microbial community structure, suggesting that high plant productivity buffered community composition from stover harvest impacts under NT but stimulated microbial activity levels that led to SOC loss. The high rates of stover removal used in this study decreased SOC stocks and aggregation at all sites compared to residue retained treatments, suggesting that no-tillage alone was not sufficient to maintain erosion protection and soil function

N fertilizer and harvest impacts on bioenergy crop contributions to SOC

Below ground root biomass is infrequently measured and simply represented in models that predict landscape level changes to soil carbon stocks and greenhouse gas balances. Yet, crop-specific responses to N fertilizer and harvest treatments are known to impact both plant allocation and tissue chemistry, potentially altering decomposition rates and the direction and magnitude of soil C stock changes and greenhouse gas fluxes. We examined switchgrass (Panicum virgatum L.) and corn (Zea mays L.,) yields, below ground root biomass, C, N and soil particulate organic matter-C (POM-C) in a 9-year rain fed study of N fertilizer rate (0, 60, 120 and 180 kg N ha-1) and harvest management near Mead, NE, USA. Switchgrass was harvested with one pass in either August or postfrost, and for no-till (NT) corn, either 50% or no stover was removed. Switchgrass had greater below ground root biomass C and N (6.39, 0.10 Mg ha-1) throughout the soil profile compared to NT-corn (1.30, 0.06 Mg ha-1) and a higher below ground root biomass C:N ratio, indicating greater recalcitrant below ground root biomass C input beneath switchgrass. There was little difference between the two crops in soil POM-C indicating substantially slower decomposition and incorporation into SOC under switchgrass, despite much greater root C. The highest N rate decreased POM-C under both NT-corn and switchgrass, indicating faster decomposition rates with added fertilizer. Residue removal reduced corn below ground root biomass C by 37% and N by 48% and subsequently reduced POM-C by 22% compared to no-residue removal. Developing productive bioenergy systems that also conserve the soil resource will require balancing fertilization that maximizes above ground productivity but potentially reduces SOC sequestration by reducing below ground root biomass and increasing root and soil C decomposition

N fertilizer and harvest impacts on bioenergy crop contributions to SOC

Below ground root biomass is infrequently measured and simply represented in models that predict landscape level changes to soil carbon stocks and greenhouse gas balances. Yet, crop-specific responses to N fertilizer and harvest treatments are known to impact both plant allocation and tissue chemistry, potentially altering decomposition rates and the direction and magnitude of soil C stock changes and greenhouse gas fluxes. We examined switchgrass (Panicum virgatum L.) and corn (Zea mays L.,) yields, below ground root biomass, C, N and soil particulate organic matter-C (POM-C) in a 9-year rain fed study of N fertilizer rate (0, 60, 120 and 180 kg N ha-1) and harvest management near Mead, NE, USA. Switchgrass was harvested with one pass in either August or postfrost, and for no-till (NT) corn, either 50% or no stover was removed. Switchgrass had greater below ground root biomass C and N (6.39, 0.10 Mg ha-1) throughout the soil profile compared to NT-corn (1.30, 0.06 Mg ha-1) and a higher below ground root biomass C:N ratio, indicating greater recalcitrant below ground root biomass C input beneath switchgrass. There was little difference between the two crops in soil POM-C indicating substantially slower decomposition and incorporation into SOC under switchgrass, despite much greater root C. The highest N rate decreased POM-C under both NT-corn and switchgrass, indicating faster decomposition rates with added fertilizer. Residue removal reduced corn below ground root biomass C by 37% and N by 48% and subsequently reduced POM-C by 22% compared to no-residue removal. Developing productive bioenergy systems that also conserve the soil resource will require balancing fertilization that maximizes above ground productivity but potentially reduces SOC sequestration by reducing below ground root biomass and increasing root and soil C decomposition

Seasonal switchgrass ecotype contributions to soil organic carbon, deep soil microbial community composition and rhizodeposit uptake during an extreme drought

The importance of rhizodeposit C and associated microbial communities in deep soil C stabilization is relatively unknown. Phenotypic variability in plant root biomass could impact C cycling through belowground plant allocation, rooting architecture, and microbial community abundance and composition. We used a pulse-chase 13C labeling experiment with compound-specific stable-isotope probing to investigate the importance of rhizodeposit C to deep soil microbial biomass under two switchgrass ecotypes (Panicum virgatum L., Kanlow and Summer) with contrasting root morphology. We quantified root phenology, soil microbial biomass (phospholipid fatty acids, PLFA), and microbial rhizodeposit uptake (13C-PLFAs) to 150 cm over one year during a severe drought. The lowland ecotype, Kanlow, had two times more root biomass with a coarser root system compared to the upland ecotype, Summer. Over the drought, Kanlow lost 78% of its root biomass, while Summer lost only 60%. Rhizosphere microbial communities associated with both ecotypes were similar. However, rhizodeposit uptake under Kanlow had a higher relative abundance of gram-negative bacteria (44.1%), and Summer rhizodeposit uptake was primarily in saprotrophic fungi (48.5%). Both microbial community composition and rhizodeposit uptake shifted over the drought into gram-positive communities. Rhizosphere soil C was greater one year later under Kanlow due to turnover of unlabeled structural root C. Despite a much greater root biomass under Kanlow, rhizosphere δ13C was not significantly different between the two ecotypes, suggesting greater microbial C input under the finer rooted species, Summer, whose microbial associations were predominately saprotrophic fungi. Ecotype specific microbial communities can direct rhizodeposit C flow and C accrual deep in the soil profile and illustrate the importance of the microbial community in plant strategies to survive environmental stress such as drought

Bidirectional Psychoneuroimmune Interactions in the Early Postpartum Period Influence Risk of Postpartum Depression

More than 500,000 U.S. women develop postpartum depression (PPD) annually. Although psychosocial risks are known, the underlying biology remains unclear. Dysregulation of the immune inflammatory response and the hypothalamic–pituitary–adrenal (HPA) axis are associated with depression in other populations. While significant research on the contribution of these systems to the development of PPD has been conducted, results have been inconclusive. This is partly because few studies have focused on whether disruption in the bidirectional and dynamic interaction between the inflammatory response and the HPA axis together influence PPD. In this study, we tested the hypothesis that disruption in the inflammatory-HPA axis bidirectional relationship would increase the risk of PPD. Plasma pro- and anti-inflammatory cytokines were measured in women during the 3rd trimester of pregnancy and on Days 7 and 14, and Months 1, 2, 3, and 6 after childbirth. Saliva was collected 5 times the day preceding blood draws for determination of cortisol area under the curve (AUC) and depressive symptoms were measured using the Edinburgh Postpartum Depression Survey (EPDS). Of the 152 women who completed the EPDS, 18% were depressed according to EDPS criteria within the 6 months postpartum. Cortisol AUC was higher in symptomatic women on Day 14 (p = .017). To consider the combined effects of cytokines and cortisol on predicting symptoms of PPD, a multiple logistic regression model was developed that included predictors identified in bivariate analyses to have an effect on depressive symptoms. Results indicated that family history of depression, day 14 cortisol AUC, and the day 14 IL8/IL10 ratio were significant predictors of PPD symptoms. One unit increase each in the IL8/IL10 ratio and cortisol AUC resulted in 1.50 (p = 0.06) and 2.16 (p = 0.02) fold increases respectively in the development of PPD. Overall, this model correctly classified 84.2% of individuals in their respective groups. Findings suggest that variability in the complex interaction between the inflammatory response and the HPA axis influence the risk of PPD

Gender and sexual orientation differences in cognition across adulthood : age is kinder to women than to men regardless of sexual orientation

Despite some evidence of greater age-related deterioration of the brain in males than in females, gender differences in rates of cognitive aging have proved inconsistent. The present study employed web-based methodology to collect data from people aged 20-65 years (109,612 men; 88,509 women). As expected, men outperformed women on tests of mental rotation and line angle judgment, whereas women outperformed men on tests of category fluency and object location memory. Performance on all tests declined with age but significantly more so for men than for women. Heterosexuals of each gender generally outperformed bisexuals and homosexuals on tests where that gender was superior; however, there were no clear interactions between age and sexual orientation for either gender. At least for these particular tests from young adulthood to retirement, age is kinder to women than to men, but treats heterosexuals, bisexuals, and homosexuals just the same

Seasonal switchgrass ecotype contributions to soil organic carbon, deep soil microbial community composition and rhizodeposit uptake during an extreme drought

The importance of rhizodeposit C and associated microbial communities in deep soil C stabilization is relatively unknown. Phenotypic variability in plant root biomass could impact C cycling through belowground plant allocation, rooting architecture, and microbial community abundance and composition. We used a pulse-chase 13C labeling experiment with compound-specific stable-isotope probing to investigate the importance of rhizodeposit C to deep soil microbial biomass under two switchgrass ecotypes (Panicum virgatum L., Kanlow and Summer) with contrasting root morphology. We quantified root phenology, soil microbial biomass (phospholipid fatty acids, PLFA), and microbial rhizodeposit uptake (13C-PLFAs) to 150 cm over one year during a severe drought. The lowland ecotype, Kanlow, had two times more root biomass with a coarser root system compared to the upland ecotype, Summer. Over the drought, Kanlow lost 78% of its root biomass, while Summer lost only 60%. Rhizosphere microbial communities associated with both ecotypes were similar. However, rhizodeposit uptake under Kanlow had a higher relative abundance of gram-negative bacteria (44.1%), and Summer rhizodeposit uptake was primarily in saprotrophic fungi (48.5%). Both microbial community composition and rhizodeposit uptake shifted over the drought into gram-positive communities. Rhizosphere soil C was greater one year later under Kanlow due to turnover of unlabeled structural root C. Despite a much greater root biomass under Kanlow, rhizosphere δ13C was not significantly different between the two ecotypes, suggesting greater microbial C input under the finer rooted species, Summer, whose microbial associations were predominately saprotrophic fungi. Ecotype specific microbial communities can direct rhizodeposit C flow and C accrual deep in the soil profile and illustrate the importance of the microbial community in plant strategies to survive environmental stress such as drought

Pre-Operative Cognitive Functioning and Inflammatory and Neuroendocrine Responses to Cardiac Surgery.

BACKGROUND: Cognitive functioning is linked to cardiac mortality and morbidity, but the mechanisms underlying this relationship are unclear. PURPOSE: To examine the relationship between pre-operative cognitive functioning and post-operative inflammatory and neuroendocrine responses in patients undergoing coronary artery bypass graft (CABG) surgery. METHODS: One-hundred ninety-three outpatients were screened to assess their cognitive function using the Montreal Cognitive Assessment (MoCA) on average 30 days prior to CABG surgery and provided blood samples for the measurement of interleukin (IL)-6 and C-reactive protein (CRP) and saliva samples for the measurement of diurnal cortisol. Participants were followed-up 4-8 days following surgery for the repeat measurement of IL-6 and CRP and 60 days after surgery for the measurement of diurnal salivary cortisol. RESULTS: Patients with low cognitive function (MoCA < 26) prior to surgery reached higher IL-6 concentrations in the days after surgery (β = -0.212, p = 0.021) and had greater cortisol output across the day 2 months after surgery (β = -0.179, p = 0.044). CONCLUSIONS: Low cognitive functioning is associated with a more negative pattern of biological response to surgery, indicative of poorer physical recovery. These pathways may contribute to the links between cognitive function and cardiovascular pathology