1,142 research outputs found
Ecological Weed Management for Field Crop Production
No full textChapter 1 assesses the effect of crop density and nitrogen immobilization on weed suppression and yields in an organic system where soybean [Glycine max (L.) Merr.] was no-till planted into a cereal rye mulch (Secale cereale L.). High soybean seeding rates promoted weed suppression, and yields were unaffected by low-nitrogen environments. Thus, results suggest that crop density is an important lever for optimizing weed suppression and that low soil nitrogen conditions may enhance weed suppression without reducing yields in soybean production.Chapter 2 evaluates the effect of multi-tactic weed management in establishing intermediate wheatgrass [Thinopyrum intermedium (Host) Barkworth & Dewey], a burgeoning perennial grain crop. In this experiment, no single-tactic or combination of tactics suppressed weeds or increased grain yield relative to the untreated control. However, the experimental and analytical approach used in this study provides a framework for evaluating multi-tactic weed management and testing for synergistic interactions. Chapter 3 tests how soybean density and cereal rye mulch biomass suppress weeds and affect the functional diversity of weed communities. It determined that soybean density and cereal rye biomass interacted synergistically to promote weed suppression. However, soybean density and cereal rye biomass had differing effects on weed community functional diversity, suggesting that these management practices represent unique filters during weed community assembly. Consequently, this chapter shows that using multiple weed-management tactics can enable the suppression of diverse weed functional groups. Chapter 4 studies how phylogenetic relatedness affects cover crop-based weed suppression. Findings from this study demonstrate that cover crops can reduce up to 99% of weed biomass and change weed community structure by most intensely suppressing related weeds. However, only cover crops that overwintered affected weed community phylogenetic distance, suggesting that the emergence timing of cover crops relative to weeds might influence whether or not they select for particular weed phylogenetic groups. As such, this study helps develop cover crop-based weed management systems by demonstrating that the suppression of problematic weeds can be improved through the use of phylogenetically related cover crops that are established prior to weed emergence
Winter Wheat (Triticum aestivum L.) Tolerance to Mulch
No full textMulch from cover crops can effectively suppress weeds in organic corn (Zea mays L.) and soybean (Glycine max L.) as part of cover crop-based rotational no-till systems, but little is known about the feasibility of using mulch to suppress weeds in organic winter small grain crops. A field experiment was conducted in central NY, USA, to quantify winter wheat (Triticum aestivum L.) seedling emergence, weed and crop biomass production, and wheat grain yield across a gradient of mulch biomass. Winter wheat seedling density showed an asymptotic relationship with mulch biomass, with no effect at low rates and a gradual decrease from moderate to high rates of mulch. Selective suppression of weed biomass but not wheat biomass was observed, and wheat grain yield was not reduced at the highest level of mulch (9000 kg ha−1). Results indicate that organic winter wheat can be no-till planted in systems that use mulch for weed suppression. Future research should explore wheat tolerance to mulch under different conditions, and the potential of no-till planting wheat directly into rolled-crimped cover crops
Comprehensive behavioral testing in the R6/2 mouse model of Huntington's disease shows no benefit from CoQ10 or minocycline
No full textPrevious studies of the effects of coenzyme Q10 and minocycline on mouse models of Huntington’s disease have produced conflicting results regarding their efficacy in behavioral tests. Using our recently published best practices for husbandry and testing for mouse models of Huntington’s disease, we report that neither coenzyme Q10 nor minocycline had significant beneficial effects on measures of motor function, general health (open field, rotarod, grip strength, rearing-climbing, body weight and survival) in the R6/2 mouse model. The higher doses of minocycline, on the contrary, reduced survival. We were thus unable to confirm the previously reported benefits for these two drugs, and we discuss potential reasons for these discrepancies, such as the effects of husbandry and nutrition
Recommended from our members
Nitrogen dynamics and red pine growth following application of pelletized biosolids in Massachusetts, USA
No full textPelletized biosolids from municipal wastewater treatment were applied to a thinned red pine plantation to determine if there were treatment levels that could produce a fertilization growth response without resulting in unacceptable nitrate leaching. The pellets (total nutrient concentrations of 4.4% N, 1.4% P, 0.2% K) were applied at four levels (0, 200, 400, 800 kg/ha total N). Only 26% of labile organic N in the pellets was mineralized in the first year after application. Foliar N increased with increasing application rate, but other nutrients were unchanged. Red pine basal area growth was unchanged with low and medium levels, but decreased to 50% of control plots with the highest level. A decrease in foliar K/N ratio resulting from high N uptake with little additional K is hypothesized as the cause for the growth decline. The highest treatment level resulted in lysimeter nitrate-N concentrations increasing to 2 mg/L in the first year and 9 mg/L in the second, returning to control levels in the third; no increase occurred in other treatments. These results contrast with those found with liquid sludge applications, in which nearly all N mineralization and the highest nitrate leaching rates occurred in the first year. The slower release of inorganic N from pellets over 2 years may allow higher total N application rates without causing high nitrate leaching.1477-148
A meta-analysis of field bindweed (Convolvulus arvensis L.) and Canada thistle (Cirsium arvense L.) management in organic agricultural systems
No full textSpatial Variation in Germination of Two Annual Brome Species in the Northern Great Plains
No full textDowny brome or cheat grass (Bromus tectorum L.) and field brome (B. arvensis L.; Synonym = Bromus japonicus Thunb. ex Murr.; Japanese brome) are two annual exotic species that have increased the intensity and frequency of fire cycles in the Intermountain West of the United States, with millions of dollars in associated costs (DiTomaso 2000). These invasive brome species have a different impact in the Northern Great Plains of North America where they commonly co-occur in disturbed sites (White and Currie 1983, Haferkamp et al. 1993). In these mixed-grass prairie rangelands, annual bromes compete against other forage species (Haferkamp et al. 1997) and reduce litter decomposition rates (Ogle et al. 2003), which negatively impacts ecosystem services of biomass production and soil nutrient availability. In central plains croplands, downy brome invades alfalfa fields (Kapusta and Strieker 1975), wheat fields (Wicks 1984, Ostlie and Howatt 2013), and perennial grass pastures and seed production areas (Wicks 1984). Downy brome is a regulated plant in Montana (Montana Noxious Weed List, December 2013) and has been found in all counties of Montana since 1950 (Menalled et al. 2008). Field brome is found in all North American states and provinces (USDA Plants Database http://plants.usda.gov). It is used as a winter cover crop in vegetable plots and orchards in the Northeastern United States (NRCS 2006). Field brome has no formal designation in the state of Montana, although downy brome and field brome are commonly grouped together and are referred to colloquially as “cheatgrass” in the state
Supporting Beneficial Insects for Agricultural Sustainability: The Role of Livestock-Integrated Organic and Cover Cropping to Enhance Ground Beetle (Carabidae) Communities
No full textGround beetles (Carabidae) are beneficial insects providing ecosystem services by regulating insect pests and weed seeds. Despite several studies conducted on ground beetles worldwide, there is a lack of knowledge on how these insects are affected by differently managed organic systems (e.g., tillage-based versus grazed-based) compared to that of chemical-based no-tillage conventional cropping systems. In a 5-year (2013–2017) study, we assessed the ground beetle communities in cover crops and winter wheat (Triticum aestivium L.) in Montana, USA, with three contrasting cropping systems: a chemically managed no-tillage, a tillage-based organic, and a livestock-integrated organic with reduced tillage. The first three years (i.e., 2013–2015) corresponded to the transition to organic period, while the last two (i.e., 2016–2017) were conducted in United States Department of Agriculture (USDA) organic-certified tillage-based and livestock-integrated organic systems. The experiment was designed with three management systems across three blocks as the whole plot variable and 5-year rotation of crop phases as the subplot variable. Using pitfall traps, we sampled ground beetles across all cover crop and winter wheat subplots for five years (n = 450). The data were analyzed using mixed effects models and PERMANOVA and visualized with non-metric multidimensional scaling ordination. Our study indicated that organically managed farms, whether tilled or grazed, enhance activity density, species richness, diversity, and evenness of ground beetles in the dryland row crop productions. Also, irrespective of farming system, cover crops supported higher species richness, diversity, and evenness of ground beetles than winter wheat. The ground beetle communities were mostly similar during the transition to organic period. However, during the established organic phase, cropping systems acted as contrasting ecological filters and beetle communities became dissimilar. Cover cropping affected ground beetle communities positively not only in organically managed systems but also in chemical-based conventional systems. Our study provides evidence supporting the adoption of ecologically-based cropping systems such as crop-livestock integration, organic farming, and cover cropping to enhance beneficial insects and their pest-regulation services
Dryland Cropping Systems, Weed Communities, and Disease Status Modulate the Effect of Climate Conditions on Wheat Soil Bacterial Communities
No full textABSTRACT Little knowledge exists on how soil bacteria in agricultural settings are impacted by management practices and environmental conditions in current and predicted climate scenarios. We assessed the impact of soil moisture, soil temperature, weed communities, and disease status on soil bacterial communities in three cropping systems: (i) conventional no-till (CNT) systems utilizing synthetic pesticides and herbicides, (ii) USDA-certified tilled organic (OT) systems, and (iii) USDA-certified organic systems with sheep grazing (OG). Sampling date within the growing season and associated soil temperature and moisture exerted the greatest effect on bacterial communities, followed by cropping system, Wheat streak mosaic virus (WSMV) infection status, and weed community. Soil temperature was negatively correlated with bacterial richness and evenness, while soil moisture was positively correlated with bacterial richness and evenness. Soil temperature and soil moisture independently altered soil bacterial community similarity between treatments. Inoculation of wheat with WSMV altered the associated soil bacteria, and there were interactions between disease status and cropping system, sampling date, and climate conditions, indicating the effect of multiple stressors on bacterial communities in soil. In May and July, cropping system altered the effect of climate change on the bacterial community composition in hotter conditions and in hotter and drier conditions compared to ambient conditions, in samples not treated with WSMV. Overall, this study indicates that predicted climate modifications as well as biological stressors play a fundamental role in the impact of cropping systems on soil bacterial communities. IMPORTANCE Climate change is affecting global moisture and temperature patterns, and its impacts are predicted to worsen over time, posing progressively larger threats to food production. In the Northern Great Plains of the United States, climate change is forecast to increase temperature and decrease precipitation during the summer, and it is expected to negatively affect cereal crop production and pest management. In this study, temperature, soil moisture, weed communities, and disease status had interactive effects with cropping system on bacterial communities. As local climates continue to shift, the dynamics of above- and belowground associated biodiversity will also shift, which will impact food production and increase the need for more sustainable practices
Weed Communities in Winter Wheat: Responses to Cropping Systems under Different Climatic Conditions
No full textUnderstanding the impact of biological and environmental stressors on cropping systems is essential to secure the long-term sustainability of agricultural production in the face of unprecedented climatic conditions. This study evaluated the effect of increased soil temperature and reduced moisture across three contrasting cropping systems: a no-till chemically managed system, a tilled organic system, and an organic system that used grazing to reduce tillage intensity. Results showed that while cropping system characteristics represent a major driver in structuring weed communities, the short-term impact of changes in temperature and moisture conditions appear to be more subtle. Weed community responses to temperature and moisture manipulations differed across variables: while biomass, species richness, and Simpson’s diversity estimates were not affected by temperature and moisture conditions, we observed a minor but significant shift in weed community composition. Higher weed biomass was recorded in the grazed/reduced-till organic system compared with the tilled-organic and no-till chemically managed systems. Weed communities in the two organic systems were more diverse than in the no-till conventional system, but an increased abundance in perennial species such as Cirsium arvense and Taraxacum officinale in the grazed/reduced-till organic system could hinder the adoption of integrated crop-livestock production tactics. Species composition of the no-till conventional weed communities showed low species richness and diversity, and was encompassed in the grazed/reduced-till organic communities. The weed communities of the no-till conventional and grazed/reduced-till organic systems were distinct from the tilled organic community, underscoring the effect that tillage has on the assembly of weed communities. Results highlight the importance of understanding the ecological mechanisms structuring weed communities, and integrating multiple tactics to reduce off-farm inputs while managing weeds
The influence of organic and conventional fertilisation and crop protection practices, preceding crop, harvest year and weather conditions on yield and quality of potato (Solanum tuberosum) in a long-term management trial
No full textThe effects of organic versus conventional crop management practices (fertilisation, crop protection) and preceding crop on potato tuber yield (total, marketable, tuber size grade distribution) and quality (proportion of diseased, green and damaged tubers, tuber macro-nutrient concentrations) parameters were investigated over six years (2004–2009) as part of a long-term factorial field trial in North East England. Inter-year variability (the effects of weather and preceding crop) was observed to have a profound effect on yields and quality parameters, and this variability was greater in organic fertility systems. Total and marketable yields were significantly reduced by the use of both organic crop protection and fertility management. However, the yield gap between organic and conventional fertilisation regimes was greater and more variable than that between crop protection practices. This appears to be attributable mainly to lower and less predictable nitrogen supply in organically fertilised crops. Increased incidence of late blight in organic crop protection systems only occurred when conventional fertilisation was applied. In organically fertilised crops yield was significantly higher following grass/red clover leys than winter wheat, but there was no pre-crop effect in conventionally fertilised crops. The results highlight that nitrogen supply from organic fertilisers rather than inefficient pest and disease control may be the major limiting factor for yields in organic potato production systems
- …
