Monitoring soil nitrate to estimate cover crop nitrogen contribution in organic vegetable production fields

Organic vegetable growers rely on legume cover crops as an economical source of plant-available N. This research evaluated N contributions to summer vegetable crops by cover crops (CC) residues by monitoring soil nitrate (NO3-N) concentrations during the summer crop growing season. Replicated field plots were established with three CC mixes: solo common vetch (V), phacelia + V (PV), and cereal rye + V (RV), plus a winter fallow (F) control in grower fields in the north Willamette Valley OR. Soil textures were silt loam (7 sites) and sandy loam (2 sites). Cover crops were seeded in a randomized complete block design in mid-October and killed in April (vegetative) or in early May (just prior to flowering). Cover crop biomass was incorporated by tillage 1-3 wk. after CC kill. Soil samples (0-12 in depth, 4 in beside the row) were collected on 2-4 wk. intervals, beginning at summer crop planting (Year 1 sites) and at cover crop kill (Year 2 sites). Net soil NO3-N contribution from CC in the field was estimated by difference in soil test nitrate concentrations (CC treatment minus winter fallow control). Summer crops monitored included winter squash (3 sites), lettuce (2 sites), and table beet, snap bean, kale and popcorn (1 site each). All sites received overhead sprinkler irrigation. Phacelia did not establish reliably as a winter cover crop. It emerged in fall, but did not survive the winter at most sites. At time of cover crop kill in spring, phacelia biomass exceeded 25% of total CC biomass (phacelia + V) at only 2 of 7 sites where it was seeded. Maximum net soil NO3-N contribution was observed near time of crop planting for lettuce, kale, snap bean and table beet, and just prior to the first heavy irrigation for corn and winter squash. Across 9 sites, median net soil NO3-N contribution (treatment minus control) was 28 lb/acre (range = 3 to 95) for RV and 46 lb/acre for V (range = 9 to 130). Soil nitrate monitoring had the most practical value for adjustment of organic fertilizer input rates for crops that receive limited early season irrigation (corn and winter squash), or for short season crops (lettuce and kale) planted in July. Median net soil nitrate contribution in the field was 50 to 80% of that measured in 10-wk laboratory incubation at 22oC. This suggests that N credits based on measuring soil nitrate (0-12 inches) following a cover crop will usually underestimate actual plant-available N supplied by a cover crop.Keywords: nitrate, common vetch, cover crop, cereal rye, phacelia, nitrogen, vegetable, soi

Monitoring soil nitrate to estimate cover crop nitrogen contribution

Organic vegetable growers rely on legume cover crops as an economical source of plant-available N. This research evaluated N contributions to summer vegetable crops by cover crops (CC) residues by monitoring soil nitrate (NO3-N) concentrations during the summer crop growing season. Replicated field plots were established with three CC mixes: solo common vetch (V), phacelia + V (PV), and cereal rye + V (RV), plus a winter fallow (F) control in grower fields in the north Willamette Valley OR. Soil textures were silt loam (7 sites) and sandy loam (2 sites). Cover crops were seeded in a randomized complete block design in mid-October and killed in April (vegetative) or in early May (just prior to flowering). Cover crop biomass was incorporated by tillage 1-3 wk. after CC kill. Soil samples (0-12 in depth, 4 in beside the row) were collected on 2-4 wk. intervals, beginning at summer crop planting (Year 1 sites) and at cover crop kill (Year 2 sites). Net soil NO3-N contribution from CC in the field was estimated by difference in soil test nitrate concentrations (CC treatment minus winter fallow control). Summer crops monitored included winter squash (3 sites), lettuce (2 sites), and table beet, snap bean, kale and popcorn (1 site each). All sites received overhead sprinkler irrigation. Phacelia did not establish reliably as a winter cover crop. It emerged in fall, but did not survive the winter at most sites. At time of cover crop kill in spring, phacelia biomass exceeded 25% of total CC biomass (phacelia + V) at only 2 of 7 sites where it was seeded. Maximum net soil NO3-N contribution was observed near time of crop planting for lettuce, kale, snap bean and table beet, and just prior to the first heavy irrigation for corn and winter squash. Across 9 sites, median net soil NO3-N contribution (treatment minus control) was 28 lb/acre (range = 3 to 95) for RV and 46 lb/acre for V (range = 9 to 130). Soil nitrate monitoring had the most practical value for adjustment of organic fertilizer input rates for crops that receive limited early season irrigation (corn and winter squash), or for short season crops (lettuce and kale) planted in July. Median net soil nitrate contribution in the field was 50 to 80% of that measured in 10-wk laboratory incubation at 22oC. This suggests that N credits based on measuring soil nitrate (0-12 inches) following a cover crop will usually underestimate actual plant-available N supplied by a cover crop.Keywords: nitrate, common vetch, cover crop, cereal rye, phacelia, nitrogen, vegetable, soi

Genome-Wide Profiling and Analysis of Arabidopsis siRNAs

Eukaryotes contain a diversified set of small RNA-guided pathways that control genes, repeated sequences, and viruses at the transcriptional and posttranscriptional levels. Genome-wide profiles and analyses of small RNAs, particularly the large class of 24-nucleotide (nt) short interfering RNAs (siRNAs), were done for wild-type Arabidopsis thaliana and silencing pathway mutants with defects in three RNA-dependent RNA polymerase (RDR) and four Dicer-like (DCL) genes. The profiling involved direct analysis using a multiplexed, parallel-sequencing strategy. Small RNA-generating loci, especially those producing predominantly 24-nt siRNAs, were found to be highly correlated with repetitive elements across the genome. These were found to be largely RDR2- and DCL3-dependent, although alternative DCL activities were detected on a widespread level in the absence of DCL3. In contrast, no evidence for RDR2-alternative activities was detected. Analysis of RDR2- and DCL3-dependent small RNA accumulation patterns in and around protein-coding genes revealed that upstream gene regulatory sequences systematically lack siRNA-generating activities. Further, expression profiling suggested that relatively few genes, proximal to abundant 24-nt siRNAs, are regulated directly by RDR2- and DCL3-dependent silencing. We conclude that the widespread accumulation patterns for RDR2- and DCL3-dependent siRNAs throughout the Arabidopsis genome largely reflect mechanisms to silence highly repeated sequences

Cognitive dysfunction after analgesia and sedation: Out of the operating room and into the pediatric intensive care unit

In the midst of concerns for potential neurodevelopmental effects after surgical anesthesia, there is a growing awareness that children who require sedation during critical illness are susceptible to neurologic dysfunctions collectively termed pediatric post-intensive care syndrome, or PICS-p. In contrast to healthy children undergoing elective surgery, critically ill children are subject to inordinate neurologic stress or injury and need to be considered separately. Despite recognition of PICS-p, inconsistency in techniques and timing of post-discharge assessments continues to be a significant barrier to understanding the specific role of sedation in later cognitive dysfunction. Nonetheless, available pediatric studies that account for analgesia and sedation consistently identify sedative and opioid analgesic exposures as risk factors for both in-hospital delirium and post-discharge neurologic sequelae. Clinical observations are supported by animal models showing neuroinflammation, increased neuronal death, dysmyelination, and altered synaptic plasticity and neurotransmission. Additionally, intensive care sedation also contributes to sleep disruption, an important and overlooked variable during acute illness and post-discharge recovery. Because analgesia and sedation are potentially modifiable, understanding the underlying mechanisms could transform sedation strategies to improve outcomes. To move the needle on this, prospective clinical studies would benefit from cohesion with regard to datasets and core outcome assessments, including sleep quality. Analyses should also account for the wide range of diagnoses, heterogeneity of this population, and the dynamic nature of neurodevelopment in age cohorts. Much of the related preclinical evidence has been studied in comparatively brief anesthetic exposures in healthy animals during infancy and is not generalizable to critically ill children. Thus, complementary animal models that more accurately reverse translate critical illness paradigms and the effect of analgesia and sedation on neuropathology and functional outcomes are needed. This review explores the interactive role of sedatives and the neurologic vulnerability of critically ill children as it pertains to survivorship and functional outcomes, which is the next frontier in pediatric intensive care

Patient/Family Education for Newly Diagnosed Pediatric Oncology Patients

There is a paucity of data to support evidence-based practices in the provision of patient/family education in the context of a new childhood cancer diagnosis. Since the majority of children with cancer are treated on pediatric oncology clinical trials, lack of effective patient/family education has the potential to negatively affect both patient and clinical trial outcomes. The Children’s Oncology Group Nursing Discipline convened an interprofessional expert panel from within and beyond pediatric oncology to review available and emerging evidence and develop expert consensus recommendations regarding harmonization of patient/family education practices for newly diagnosed pediatric oncology patients across institutions. Five broad principles, with associated recommendations, were identified by the panel, including recognition that (1) in pediatric oncology, patient/family education is family-centered; (2) a diagnosis of childhood cancer is overwhelming and the family needs time to process the diagnosis and develop a plan for managing ongoing life demands before they can successfully learn to care for the child; (3) patient/family education should be an interprofessional endeavor with 3 key areas of focus: (a) diagnosis/treatment, (b) psychosocial coping, and (c) care of the child; (4) patient/family education should occur across the continuum of care; and (5) a supportive environment is necessary to optimize learning. Dissemination and implementation of these recommendations will set the stage for future studies that aim to develop evidence to inform best practices, and ultimately to establish the standard of care for effective patient/family education in pediatric oncology

Genome-Wide Profiling and Analysis of Arabidopsis siRNAs

Eukaryotes contain a diversified set of small RNA-guided pathways that control genes, repeated sequences, and viruses at the transcriptional and posttranscriptional levels. Genome-wide profiles and analyses of small RNAs, particularly the large class of 24-nucleotide (nt) short interfering RNAs (siRNAs), were done for wild-type Arabidopsis thaliana and silencing pathway mutants with defects in three RNA-dependent RNA polymerase (RDR) and four Dicer-like (DCL) genes. The profiling involved direct analysis using a multiplexed, parallel-sequencing strategy. Small RNA-generating loci, especially those producing predominantly 24-nt siRNAs, were found to be highly correlated with repetitive elements across the genome. These were found to be largely RDR2- and DCL3-dependent, although alternative DCL activities were detected on a widespread level in the absence of DCL3. In contrast, no evidence for RDR2-alternative activities was detected. Analysis of RDR2- and DCL3-dependent small RNA accumulation patterns in and around protein-coding genes revealed that upstream gene regulatory sequences systematically lack siRNA-generating activities. Further, expression profiling suggested that relatively few genes, proximal to abundant 24-nt siRNAs, are regulated directly by RDR2- and DCL3-dependent silencing. We conclude that the widespread accumulation patterns for RDR2- and DCL3-dependent siRNAs throughout the Arabidopsis genome largely reflect mechanisms to silence highly repeated sequences