1,720,972 research outputs found
Root and shoot biomass and nutrient composition of winter rye cover crop following corn and soybean
Full text linkWinter cereal rye (Secale cereale L.), a commonly used cover crop in corn (Zea mays L.) systems, has potential to scavenge soil NO3–N through a fibrous root system. This study aimed to quantify root and shoot biomass, carbon (C), and nitrogen (N) partitioning in rye cover crop at the time of termination in spring. This was a 1-year study conducted at a site with a no-till corn–soybean [Glycine max (L.) Merr.] rotation, rye drilled following grain crop harvest, and three N rates applied to corn (0, 135, and 225 kg N ha−1, respectively). Rye root biomass to 60-cm depth following corn and 30-cm depth following soybean was estimated using ingrowth tubes installed in the fall after rye seeding and removed at the time of rye termination in the spring. For rye, 48% and 62% of the total root biomass were present in the top 15-cm depth, following corn and soybean, respectively. Overall, the shoot biomass, C, and N were significantly greater than for roots, with approximately two times more shoot than root material and only 33%–36% of total plant C and 17%–18% of total plant N in the root biomass. The C:N ratio of root biomass was consistently high (47–52) and at least double that of the shoot (16–23). With high C, low N, and high C:N ratio of the rye roots, inorganic-N from soil or degrading shoot biomass could be immobilized with root degradation and reduce potential N recycling.This article is published as Patel, Swetabh, Arshdeep Singh, John E. Sawyer, and John P. Lundvall. "Root and shoot biomass and nutrient composition of winter rye cover crop following corn and soybean." Agrosystems, Geosciences & Environment 7, no. 4 (2024): e70017. doi:10.1002/agg2.70017.USDA-NIF
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
Winter oilseed pollinators in IA and MN in 2017 and 2018
No full textData include observations of insect pollinators visiting flowers of two winter oilseed crops (field pennycress and winter camelina) at three sites during the flowering seasons of 2017 and 2018. Two sites were in Minnesota and one site in Iowa each year.Data include observations of insect pollinators visiting flowers of two winter oilseed crops (field pennycress and winter camelina) at three sites during the flowering seasons of 2017 and 2018. Two sites were in Minnesota and one site in Iowa each year.
The value of these data are that they document an important agroecosystem service provided by the two novel winter oilseed crops.
The purpose of saving the data files in the Digital Conservancy is to abide by new journal requirements that call for universal access to data used in professional qualifications.USDA-National Institute of Food and Agriculture-Coordinated Agricultural ProgramForcella, Frank; Patel, Swetabh; Lenssen, Andrew W; Hoerning, Cody; Wells, M Scott; Gesch, Russ W; Berti, Marisol T. (2020). Winter oilseed pollinators in IA and MN in 2017 and 2018. Retrieved from the University Digital Conservancy, https://doi.org/10.13020/22bd-zk88
Interseeded pennycress and camelina yield and influence on row crops
Full text linkField pennycress (Thlaspi arvense L.) (PC) and winter camelina [Camelina sativa (L.) Crantz] (WC) have the potential to provide ecosystem services and economic incentives when adopted as an oilseed cover crops in corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotations. However, PC and WC establishment and yield in the northern Corn Belt and their subsequent impact on row crops are not well known. This study was conducted to determine the effects of interseeding dates (R4, R5, and R6; and R6, R7, and R8 development stages for corn and soybean, respectively) and cover crop species (PC, WC, and winter rye [Secale cereale L.]) on seed yield and oil content of interseeded oilseeds (PC and WC) and relay soybean, and 3rd‐year corn grain yield and quality. Study sites were initiated near Ames, IA; Morris and Rosemount, MN; and Prosper, ND. Late interseeding of PC and WC resulted in greater oilseed yield. Overall yields of PC (218–880 kg ha–1) and WC (15–770 kg ha–1), averaged across interseeding dates, were low when interseeded in corn and soybean. The PC and WC reduced relay‐soybean grain yield by 13–32% and 13–42%, respectively. Corn grain yield and quality following relay soybean were not affected by the residual effects of oilseed cover crops. Based on the results of our study, we do not recommend relay cropping soybean with PC and WC in the upper Midwest.This article is published as Patel, Swetabh, Andrew W. Lenssen, Kenneth J. Moore, Yesuf A. Mohammed, Russ W. Gesch, M. Scott Wells, Burton L. Johnson, Marisol T. Berti, and Heather L. Matthees. "Interseeded pennycress and camelina yield and influence on row crops." Agronomy Journal (2021). doi:10.1002/agj2.20655.</p
Rye cover crop biomass, nutrient composition and crop management practices to enhance corn yield
Full text linkWinter cereal rye (Secale cereal L.), a commonly used cover crop in corn (Zea mays L.) systems has potential to scavenge soil NO3–N through a fibrous root system. The objective of this study was to quantify root and shoot biomass, C, and N partitioning in rye cover crop at the time of termination in spring. This was a one–year study conducted at a site with a no-till corn–soybean [Glycine max (L.) Merr.] rotation, rye drilled following grain crop harvest, and three N rates applied to corn (0, 135, and 225 kg N ha–1). Rye root biomass to 60-cm depth following corn and 30-cm depth following soybean was estimated using ingrowth tubes installed in the fall after rye seeding and removed at the time of rye termination in the spring. For rye following corn and soybean, 48 and 62 %, respectively, of the total root biomass was present in the top 15-cm depth. Overall, the shoot biomass, C, and N was significantly greater than for roots, with approximately two times more shoot than root material and only 33–36 % of total plant C and 17–18 % of total plant N in the root biomass. The C:N ratio of root biomass was consistently high (47–52), and at least double the shoot (16–23). With high C, low N, and high C:N ratio of the rye roots, inorganic-N from soil or degrading shoot biomass could be immobilized with root degradation and reduce potential N recycling.
Cereal rye (Secale cereal L.) cover crops (RCC) have good potential to take up residual NO3 between grain crops and reduce loss to surface waters. However, studies in Iowa have shown a 5–6% corn (Zea mays L.) yield reduction when grown following a RCC. The objective of this research was to study agronomic practices that have potential to improve corn yield in a RCC system. This study was conducted at four sites in 2013 through 2015 with corn grown in rotation with soybean [Glycine max. (L.) Merr.]. Treatments included cereal rye aerially broadcast into soybean before leaf drop and no RCC, tillage or no-till, and starter N fertilizer (34 kg N ha–1) or no starter. The aerial RCC sowing, especially with dry fall conditions the first year and planned RCC termination in the spring at 15–20 cm height, resulted in non-uniform RCC stand and low biomass and N uptake at termination (154–335 kg ha–1 and 6–14 kg N ha–1). Across site-years, V6 corn plant height and V10 sensing indexes were greater with the tilled system and starter N. Overall, corn yield was slightly reduced with the RCC (2.4%), however, tillage (3.3%) and the high N starter (1.6%) consistently increased yield. Soybean yield was not influenced by the aerial seeded RCC or the prior year treatments for corn. While the RCC generally resulted in lower corn yield, starter N and tillage did help offset that reduction and would be expected to help improve corn production in a RCC system.</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
Intercropping and relay cropping to increase productivity, resilience, and long-term sustainability of corn and soybean cropping systems in Iowa
Full text linkSoil erosion and nutrient loss as a result of lack of ground cover in conventional corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] cropping systems in the U.S. Midwest warrant use of cover crops to provide improved protection to the soil. There are needs for alternate cropping systems and management practices capable of protecting our resources without sacrificing existing and future crop yield goals. Field pennycress (Thlaspi arvense L.) and winter camelina [Camelina sativa (L.) Crantz] are short season annual oilseed crops having the potential to be integrated into corn and soybean systems as cash cover crops. Alfalfa (Medicago sativa L.) also has the potential to be intercropped with corn to accelerate its establishment period compared to conventional spring seeding while acting as a cover crop in fall following corn harvest. We interseeded pennycress, camelina, and winter cereal rye (Secale cereale L.) in corn and soybean at late reproductive stages. Soybean was relay planted the next year with an objective to (i) determine the effect of cover crops on row crop grain yield, (ii) assess the survival, biomass and seed yield of cover crops, and (iii) determine the effect of cover crops on soil moisture and weed density. In another study, corn was intercropped with alfalfa with and without the application of prohexadione with an objective to (i) determine the effect of intercropped alfalfa on corn grain yield, (ii) estimate the survival and biomass production of intercropped alfalfa, and (iii) determine the overall productivity of the intercropping system. Corn and soybean yields were not affected by interseeding cover crops from mid-August to late Sept. but soybean yield when relay planted into oilseed cover crops was reduced by 12 to 32%. Overall seed yield of pennycress and winter camelina was 218-880 kg ha-1 and 15-770 kg ha-1, respectively. Corn yield was reduced by 23-26% when intercropped with alfalfa in a dry year whereas intercropped alfalfa stand density was reduced by 36-68% in the establishment year. Despite the reduction in corn yield, the overall productivity of a corn and alfalfa intercropping system was greater than the conventional system where alfalfa is spring seeded following corn harvest.</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
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