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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/8446

Title: Effect of some commonly used herbicides on soil microbial population
Authors: Adomako, Michael Opoku
Issue Date: 4-Apr-2016
Abstract: Herbicide application has become an integral part of vibrant agricultural productivity in the whole world since its benefit has been overwhelming over the years. However, its toxic impact on the non-target soil microorganisms which play roles in degrading organic matter, nitrogen and nutrient recycling and decomposition needs to be considered. In the present study, the effect of four (4) most commonly used herbicides in Ghana; Atrazine, 2, 4-D amine, Glyphosate and Paraquat on soil microorganisms was assessed over a period of fifteen continuous days (exposure period). The herbicide treatments were the normal recommended field rate, (6.67 mg active ingredient per gram of soil for Atrazine, 6.17 mg for 2, 4-D amine, 5.56 mg for Glyphosate, and 2.46 mg for Paraquat), half the recommended field rate and double the rate. Bacterial and Fungal population were then determined at a five-day interval up to the 15th day after treatment. The data gathered from bacterial enumeration was logarithmically transformed before graphs of mean bacterial were plotted against the exposure period for each selected herbicide. Bacterial population and percentage organic matter did not show any significant differences relative to the exposure period in this study (p < 0.05). However, the deleterious impact of the herbicides was seen as Paraquat treatment resulted in reduction in the bacterial population for five, ten and fifteen Days after treatment (DAT) in treatment halved the recommended field rate. Glyphosate follows with 69.3%, 12.7%, and 18.0%; 2,4-D amine had 44.8%, 33.5%, and 21.6%; and lastly Atrazine had 41.8%, 44.5% and 13.6% bacterial population 5DAT, 10DAT and 15DAT respectively. The inhibition effect on the fungal population was very specific as some fungi (such as A. Niger, Trichoderma viride, Collectotrichum gloeosporioides, A. flavus, Mucor, Penicillium, Curvularia lunata) which were present in the baseline (control) did not appear in the treatment and vice versa. Percentage organic matter for the treatment did not vary much with the baseline determination (control) but the impact was observed in the various levels of treatments for all the herbicides. A similar study should be conducted on a normal field condition where herbicide treatments would be carried out on a normal field condition since most of the previous studies had the herbicide treatment carried out under laboratory condition. It will also be very appropriate if further research work is carried out to identify the specific components of these herbicides which favour the growth and development of certain beneficial microorganisms such as fungi and bacterial.
Description: A thesis submitted to the Department of Theoretical and Applied Biology, Kwame Nkrumah University of Science and Technology in partial fulfillment of the requirements Master of Science degree in Environmental Science, 2015
URI: http://hdl.handle.net/123456789/8446
Appears in Collections:College of Science

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