Odhiambo J.A.,University of Wyoming |
Norton U.,University of Wyoming |
Ashilenje D.,Manor House Agricultural Center |
Omondi E.C.,1000 E. Uni |
Norton J.B.,1000 E. Uni
PLoS ONE | Year: 2015
Weed competition is a significant problem in maize (Zea mays, L.) production in Sub-Saharan Africa. Better understanding of weed management and costs in maize intercropped with beans (Phaseolus vulgaris, L.) during transition to conservation agricultural systems is needed. Changes in weed population and maize growth were assessed for a period of three years at Bungoma where crops are grown twice per year and at Trans-Nzoia where crops are grown once per year. Treatments included three tillage practices: minimum (MT), no-till (NT) and conventional (CT) applied to three cropping systems: continuous maize/bean intercropping (TYPICAL), maize/bean intercropping with relayed mucuna after bean harvest (RELAY) and maize, bean and mucuna planted in a strip intercropping arrangement (STRIP). Herbicides were used in NT, shallow hand hoeing and herbicides were used in MT and deep hoeing with no herbicides were used in CT. Weed and maize performance in the maize phase of each cropping system were assessed at both locations and costs of weed control were estimated at Manor House only. Weed density of grass and forb species declined significantly under MT and NT at Manor House and of grass species only at Mabanga. The greatest declines of more than 50% were observed as early as within one year of the transition to MT and NT in STRIP and TYPICAL cropping systems at Manor House. Transitioning to conservation based systems resulted in a decline of four out of five most dominant weed species. At the same time, no negative impact of MT or NT on maize growth was observed. Corresponding costs of weed management were reduced by $148.40 ha-1 in MT and $149.60 ha-1 in NT compared with CT. In conclusion, farmers can benefit from effective and less expensive weed management alternatives early in the process of transitioning to reduced tillage operations. © 2015 Odhiambo et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Proctor J.,1000 E. Uni
Journal of Electronic Resources Librarianship | Year: 2013
This article explores the way in which eight academic publishers portray the publication dates of ebooks on their websites and title lists and the need for standard terminology for, and display of, ebook publication dates. Publishers often use terminology that does not accurately describe the dates they are providing, and sometimes they provide only the date of electronic publication, which can be misleading when the print version was published many years prior. Unclear publication dates can force librarians to spend a great deal of time searching for publication dates, and it could potentially lead to unintended purchases or duplication. © 2013 Copyright Taylor and Francis Group, LLC.
Soni K.,1000 E. Uni |
Premnath K.N.,1000 E. Uni
International Journal of Thermal Sciences | Year: 2012
This paper presents a self-similar solution of the coupled problem of magneto-hydrodynamic free convection flow of an electrically conducting fluid arising from melting of a semi-infinite solid substrate. At steady state, buoyancy induced free convection of the electrically conducting fluid is influenced by the Lorentz force. A set of governing PDEs is developed for a two dimensional boundary layer problem including phase change which is simplified to a set of ODEs using a similarity transformation and are solved iteratively using an implicit Keller-box method. An asymptotic analytical solution for melting and heat transport rates is also presented for the case of small Prandtl numbers. The effect of each of the three characteristic parameters, viz., the Prandtl number, the melting parameter and the Lykoudis number on the similarity velocity and temperature profiles in the boundary layer over melting substrate is studied. It is observed that increasing the Lykoudis number or decreasing the Prandtl number lowers the melting rate and heat transfer at the substrate-melt interface. The use of magnetic field in controlling the free convection heat transfer, the melting rate and the thickness of the velocity and thermal boundary layers over melting substrate is elucidated and discussed. © 2011 Elsevier Masson SAS. All rights reserved.