Impact of land use patterns and agricultural practices on water quality in the Calapooia River Basin of western Oregon

Agricultural practices, including tillage, fertilization, and residue management, can affect surface runoff, soil erosion, and nutrient cycling. These processes, in turn, may adversely affect (1) quality of aquatic resources as habitat for amphibians, fish, and invertebrates, (2) costs of treating surface and ground water to meet drinking water standards, and (3) large-scale biogeochemistry. This study characterized the surface water sources of nitrogen (N) (total, nitrate [NO₃⁻], ammonium [NH₄⁺], and dissolved organic N) and sediment active within 40 subbasins of the Calapooia River Basin in western Oregon in monthly samples over three cropping years. The subbasins included both independent and nested drainages, with wide ranges in tree cover, agricultural practices, slopes, and soils. Sediment and N form concentrations were tested against weather and agricultural practice variables. Subbasin land use ranged from 96% forest to 100% agriculture. Average slopes varied from 1.3% to 18.9%, and surface water quality ranged from 0.5 to 43 mg L⁻¹ (ppm) total N maxima and 29 to 249 mg L⁻¹ suspended sediment maxima. Total N during the winter was positively related to percentage landcover of seven common agricultural crops (nongrass seed summer annuals, established seed crops of perennial ryegrass [Lolium perenne L.], tall fescue [Schedonorus phoenix {Scop.} Holub], orchardgrass [Dactylis glomerata L.], clover [Trifolium spp.], and newly planted stands of perennial ryegrass and clover) and negatively related to cover by trees and one seed crop, Italian (annual) ryegrass (Lolium multiflorum). Results for NO₃⁻ and total N were highly similar. Sediment concentrations were most strongly related to rainfall totals during periods of 4 and 14 days prior to sampling, with smaller effects of soil disturbance. Fourier analysis of total N over time identified four prominent groups of subbasins: those with (1) low, (2) medium, and (3) high impacts of N (up to 2, 8, and 21 mg L⁻¹, respectively) and a strong cyclical signal peaking in December and (4) those with very high impact of N (up to 43 mg L⁻¹) and a weak time series signal. Preponderance of N in streams draining agriculturally dominated subbasins was in the form of the NO₃⁻ ion, implying mineralization of N that had been incorporated within plant tissue following its initial application in the spring as urea-based fertilizer. Since mineralization is driven by seasonal rainfall and temperature patterns, changes in agronomic practices designed to reduce prompt runoff of fertilizer are unlikely to achieve to more than similar to ~24% reduction in N export to streams.This is the publisher’s final pdf. The published article is copyrighted by Soil and Water Conservation Society and can be found at: http://www.jswconline.org/Keywords: Ecosystem services, Geographically weighted regression, Water quality, Fourier time series analysi

Environmental Noise in Advanced LIGO Detectors

The sensitivity of the Advanced LIGO detectors to gravitational waves can be affected by environmental disturbances external to the detectors themselves. Since the transition from the former initial LIGO phase, many improvements have been made to the equipment and techniques used to investigate these environmental effects. These methods have aided in tracking down and mitigating noise sources throughout the first three observing runs of the advanced detector era, keeping the ambient contribution of environmental noise below the background noise levels of the detectors. In this paper we describe the methods used and how they have led to the mitigation of noise sources, the role that environmental monitoring has played in the validation of gravitational wave events, and plans for future observing runs

Genotypic Variability in Mineral Composition of Switchgrass

Switchgrass (Panicum virgatum L.) is a warm season perennial grass with great potential as an energy crop in the USA. It is widely adapted to many regions of the country, produces large amounts of biomass, serves as a useful forage grass, and provides ecosystem services that benefit soil and water quality and wildlife. Biological and thermochemical technologies are being developed to convert herbaceous biomass, including switchgrass, to energy. The objective of this research was to determine the effect of genotype and production environment on the concentration of minerals that affect the suitability of switchgrass for thermochemical conversion and to quantify the amount of potassium (K) and phosphorus (P) removed from the production system by harvest of the aboveground biomass, a measure of the sustainability of the practice. Straw dry biomass contained from 1.3 to 6.4 kg Mg-1 and from 6.2 to 15.8 kg M-1 of P and K, respectively. Variability in aluminum (Al), calcium (Ca), chloride (Cl), K, P, silicon (Si), and sulfur (S) concentrations across locations was relatively high, ranging from twofold (Al) to eightfold (CI). Location had a strong impart on mineral concentrations among switchgrass genotypes evaluated in this study. Latitude of origin imparted the CI and Si concentrations measured in plant tissues, but none of the other minerals analyzed in this study. Upland and lowland cytotypes explained some of the observed differences, but population x location interactions were the primary source of variability in the concentration of these minerals

Overproduction of Cytokinins in Petunia Flowers Transformed with P(SAG12)-IPT Delays Corolla Senescence and Decreases Sensitivity to Ethylene

Plant senescence is regulated by a coordinated genetic program mediated in part by changes in ethylene, abscisic acid (ABA), and cytokinin content. Transgenic plants with delayed senescence are useful for studying interactions between these signaling mechanisms. Expression of ipt, a cytokinin biosynthetic gene from Agrobacterium tumefaciens, under the control of the promoter from a senescence-associated gene (SAG12) has been one approach used to delay senescence. We transformed petunia (Petunia x hybrida cv V26) with P(SAG12)-IPT. Two independently transformed lines with extended flower longevity (I-1-7-22 and I-3-18-34) were used to study the effects of elevated cytokinin content on ethylene synthesis and sensitivity and ABA accumulation in petunia corollas. Floral senescence in these lines was delayed 6 to 10 d relative to wild-type (WT) flowers. Ipt transcripts increased in abundance after pollination and were accompanied by increased cytokinin accumulation. Endogenous ethylene production was induced by pollination in both WT and IPT corollas, but this increase was delayed in IPT flowers. Flowers from IPT plants were less sensitive to exogenous ethylene and required longer treatment times to induce endogenous ethylene production, corolla senescence, and up-regulation of the senescence-related Cys protease phcp1. Accumulation of ABA, another hormone regulating flower senescence, was significantly greater in WT corollas, confirming that floral senescence was delayed in IPT plants. These results extend our understanding of the hormone interactions that regulate flower senescence and provide a means of increasing flower longevity

Removal of molluscicidal bait pellets by earthworms and its impact on control of the gray field slug (Derocerus reticulatum Mueller) in western Oregon grass seed fields

Slugs are common pests of grass seed fields in western Oregon and the current focus of repeated, and often unsuccessful, efforts by growers to control them using molluscicides. Here we document rapid loss of molluscicidal bait pellets to earthworms and the resulting adverse effects on slug control. Three years of field studies were conducted at 17 locations with contrasting crops, soil types, residue levels, and tillage management programs. Baits were isolated in covered, sunken, open bottom arenas in the field to exclude removal by slugs, rodents, or birds. Forty hours of nighttime field observations and photographic documentation were collected to support the hypothesis that earthworms were removing slug bait before it had the opportunity to kill slugs. Greenhouse studies were conducted on the gray field slug (Derocerus reticula turn Mueller), in screen-topped arenas to determine the effects on mortality, seedling survival, and egg fecundity in a bait-depleting environment. Field data showed that an average of 17% of all bait pellet types were removed nightly by earthworms, with a range of 5.1-6.4 days until 100% disappearance. Individual earthworms in the field were observed removing up to three bait pellets per hour. Earthworms removed a 5% metaldehyde formulation significantly faster than either 4% metaldehyde or 1% iron phosphate pellet baits, possibly because of the smaller physical pellet size. Seedling survival in the greenhouse >= 65% was achieved by the highest rate of 4% metaldehyde bait pellets, the two highest rates of 7.5% metaldehyde granules, and the two highest rates of 25% metaldehyde liquid formulation. Earthworms showed no behavioral interest in the granular or liquid formulations, providing growers with attractive alternatives to the ineffectual pelleted baits currently in widespread use. Published by Elsevier Ltd.Keywords: Lumbricus terrestris, Grass seed production, Crop residue

Leaf senescence is delayed in tobacco plants expressing the maize homeobox gene knotted1 under the control of a senescence-activated promoter

Leaf senescence is an active process involving remobilization of nutrients from senescing leaves to other parts of the plant. Whereas senescence is accompanied by a decline in leaf cytokinin content, supplemental cytokinin delays senescence. Plants that overexpress isopentenyl transferase (ipt), a cytokinin-producing gene, or knotted1 (kn1), a homeobox gene, have many phenotypes in common. Many of these phenotypes are characteristic of altered cytokinin physiology. The effect of kn1 on leaf senescence was tested by driving its expression using the promoter of the senescence-associated gene SAG12. SAG:kn1 tobacco plants showed a marked delay in leaf senescence but otherwise developed normally. The delay in senescence was revealed by an increase in chlorophyll content in SAG:kn1 leaves relative to leaves of the control plants and by a decrease in the number of dead leaves. Senescence was also delayed in detached leaves of SAG:kn1 plants. Delayed senescence was accompanied by increased leaf cytokinin content in older leaves expressing kn1. These experiments extend the current understanding of kn1 function and suggest that in addition to mediating meristem maintenance, kn1 is capable of regulating the onset of senescence in leaves