1,721,081 research outputs found
Application of a Formulated Humic Product Can Increase Soybean Yield
Full text linkApplication of humic products to crops remains controversial. We conducted a field study in Iowa over four environments from 2012 to 2014 examining productivity of soybean [Glycine max (L.) Merr.] receiving foliar application of a humic product at one of four application times based on plant development. Humic product application never influenced soybean height at harvest. Soybean yield increased following application of the humic product in two of four environments, but application timing was not completely consistent between these two environments. In one 2012 environment, humic product application at V2, V6, and R2 resulted in greater yield than the untreated control. In the other 2012 environment, application of the humic product at V2 resulted in improved yield over the untreated control. Application of the humic product never influenced seed oil concentration; however, seed protein concentration was decreased following application of humic product at V2 and R2 in a single 2012 environment. Use of the formulated product influenced returns from –171 acre−1, depending on the environment. The environments where humic product application positively influenced yield and seed quality had greater rainfall deficits and air temperatures above the long-term average.This article is published as Lenssen, Andrew W., Dan C. Olk, and Dana L. Dinnes. "Application of a Formulated Humic Product Can Increase Soybean Yield." Crop, Forage & Turfgrass Management 5, no. 1 (2019): 180053. doi: 10.2134/cftm2018.07.0053.</p
Nitrogen fertilization rate and method influences water and nitrogen productivity of forage winter wheat
Full text linkSpring‐seeded annual forages are well adapted to the Great Plains; however, the influence of application rate and method of N fertilization on winter wheat (WW) (Triticum aestivum L.) forage productivity is unknown. A field study was conducted in a factorial design for 3 yr to determine the influence of N application rate and method on water and N productivity of awnletted WW ‘Willow Creek’. Urea was either broadcast or banded at planting using N fertilization rates of 0, 28, 56, and 84 kg N ha−1. The N application rate × method interaction was significant only for WW height. Weed herbage was low at WW forage harvest, 19 kg ha−1. As N fertilization rate increased from 0 to 84 kg N ha−1, wheat stem density and height increased by 70 and 78%, respectively, and herbage increased by 58%. Increased N rate increased WW water use quadratically, but water productivity (kg biomass ha−1 mm−1) was 68% greater at 84 kg N ha−1. However, N application method did not influence water use or productivity. Banded N application increased N accumulation in WW herbage by 11% compared to broadcast N. Increasing N rate reduced N productivity by 24% compared to 0 kg N ha−1. Willow Creek WW produced greater herbage yield as N fertilization rate increased with banded application. Willow Creek is a highly productive fall‐planted forage in this predominantly spring‐planted small grain–grain legume region.This article is published as Lenssen, Andrew W., Upendra M. Sainju, Clain Jones, Kent McVay, and Terry Angvick. "Nitrogen fertilization rate and method influences water and nitrogen productivity of forage winter wheat." Agronomy Journal (2020). doi: 10.1002/agj2.20495.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Diversified crop rotation and management system influence durum yield and quality
Full text linkDiversified crop rotation, sequence of crops within a rotation, and management system may affect durum (Triticum turgidum L.) yield and quality. This study investigated the impact of stacked vs. alternate‐year rotation and conventional vs. ecological management system on dryland durum growth, yield, quality, and N relations from 2008 to 2011 in the northern Great Plains. Stacked rotations were durum–durum–canola (Brassica napus L.)–pea (Pisum sativum L.) (DDCP) and durum–durum–flax (Linum usitatissimum L.)–pea (DDFP). Alternate‐year rotations were durum–canola–durum–pea (DCDP) and durum–flax–durum–pea (DFDP). Continuous durum (CD) was also included for comparison. Conventional management included the combination of tillage, recommended seed rate, broadcast N fertilization, and reduced stubble height; ecological management included no‐tillage, increased seed rate, banded N fertilization, and greater stubble height. Durum height was 4–7 cm taller in the ecological than the conventional management with DCDP, DDCP, and DFDP. Plant height, spike number, grain yield, aboveground biomass, N accumulation, N removal index, and N‐use efficiency were 8–46% greater in the ecological than the conventional management in wet years, but were 15–26% greater in the conventional management in dry years. Plant height, spike number, aboveground biomass, and seed weight varied with crop rotations and years. The ecological management improved durum growth, yield, and N relations in wet years, but the conventional management was superior in dry year. Producers can enhance dryland durum yield and quality by using the ecological management, especially in wet years, rather than relying on crop rotations.This article is published as Lenssen, Andrew W., Upendra M. Sainju, Brett L. Allen, William B. Stevens, and Jalal D. Jabro. "Diversified crop rotation and management system influence durum yield and quality." Agronomy Journal 112 (2020): 4407-4419. doi: 10.1002/agj2.20311.</p
Dryland Corn Production and Water Use Affected by Tillage and Crop Management Intensity
Full text linkManagement strategies to enhance dryland corn (Zea mays L.) production and soil water use are lacking. We evaluated the effect of tillage and crop management intensity on the growth, yield, and water use of dryland corn from 2005 to 2010 in the northern Great Plains. Tillage systems (no-tillage, NT, and conventional tillage, CT) as main-plot and crop management to corn (traditional intensity: conventional seeding rates and reduced wheat, Triticum aestivumL., stubble height; and improved intensity: increased seeding rate for 3 out of 6 yr and wheat stubble height) as split-plot treatments were arranged in a randomized complete block design with three replications. Corn plant stand was greater for CT than NT in 3 out of 6 yr and greater for the improved than the traditional intensity in 3 out of 3 yr. Seed number and grain yield were greater for NT than CT in 4 out of 6 yr. Biomass was greater for NT than CT in 1 out of 6 yr and greater for NT than CT in the traditional intensity. Corn plant height, seed weight, and harvest index as well as preplant and postharvest soil water, water use, and water-use efficiency were not influenced by treatments, but varied with years. Corn yield increased for NT compared with CT during years with below-average precipitation due to increased seed number and by reducing seeding rate and wheat stubble height. No-tillage with reduced seeding rate and wheat stubble height can enhance dryland corn production without affecting soil water.This article is published as Lenssen, Andrew W., Upendra Sainju, Brett L. Allen, Jalal D. Jabro, and William B. Stevens. "Dryland Corn Production and Water Use Affected by Tillage and Crop Management Intensity." Agronomy Journal 110, no. 6 (2018): 2439-2446. doi: 10.2134/agronj2018.04.0267.</p
The Environmental Impact of Ecological Intensification in Soybean Cropping Systems in the U.S. Upper Midwest
Full text linkIntroducing cover crops is a form of ecological intensification that can potentially reduce local, regional and global environmental impacts of soybean cropping systems. An assessment of multiple environmental impacts (global warming potential, eutrophication, soil erosion and soil organic carbon variation) was performed on a continuous soybean system in the U.S. upper Midwest. Four sequences were assessed and compared: a soybean cropping system with winter camelina, field pennycress, or winter rye as cover crop, plus a control (sole soybean). Cover crops were interseeded into standing soybean in Year 1, while in Year 2 soybean was relay-cropped into standing camelina or pennycress. Rye was terminated before sowing soybean. When compared with the control, sequences with cover crops showed lower eutrophication potential (4–9% reduction) and soil erosion (5–32% reduction) per ha year−1, in addition to a lower global warming potential (3–8% reduction) when the cover crop was not fertilized. However, when the economic component was included in the assessment, and the results expressed per USD net margin, the sequences with cover crops significantly reduced their performance in all categories of impact considered. A further optimization of field management for camelina and pennycress is recommended to make the cropping system more sustainable.This article is published as Cecchin, Andrea; Pourhashem, Ghasideh; Gesch, Russ W.; Mohammed, Yesuf A.; Patel, Swetabh; Lenssen, Andrew W.; Berti, Marisol T. 2021. "The Environmental Impact of Ecological Intensification in Soybean Cropping Systems in the U.S. Upper Midwest" Sustainability 13, no. 4: 1696. doi:10.3390/su13041696.</p
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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