Effect of different concentrations of some agrochemicals on soil microbial density and crop growth
Date
2021-05
Authors
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Publisher
Federal University of Technology, Owerri
Abstract
The effects of insecticide and herbicide pollution on soil nutrients, soil microbes as well as Pinto beans (Phaseolus vulgaris) and maize cultivated on the soil was studied. Insecticide herbicide were used to impact soil samples across concentration gradients. Pinto beans (Phaseolus vulgaris) and maize seeds were planted in separate experiments to monitor the effects of the agrochemicals on the cultivars. The microbial load, diversity and the physicochemical characteristics of the soil before and after pollution were determined using standard methods. Chlorophyll contents of the leaves were also determined after planting. Results shows that Bacterial isolates namely Enterococcus sp 54(44%), Staphylococcus sp 8(7%), Bacillus sp 46(37%) and Micrococcus sp 15(12%) and fungal isolates such namely Penicillium sp 41(35%), Saccharomyces sp 67(56%), Yeast sp 4(3%), Geotrichum sp 6 (5%) and Aspergillus sp 1(1%) were recovered from treated and untreated soil with the percentages representing after planting. The findings from the study showed that the herbicide treated
soils indicated that the total heterotrophic bacterial count (THBC) increased after cultivation, while the total heterotrophic fungal count (THFC) decreased after cultivation. On the other hand, insecticides treated soils recorded a general decrease in THFC and THBC after cultivation. The total nitrogen (TN), available phosphorus (AP) and exchangeable potassium (EP) had significant differences before and after planting. The cultivars generally had poor growth characteristics recorded as well as chlorophyll content. This study demonstrates the negative effects of the use of insecticides and herbicides against non-target species and call for the need for strict regulations against their use especially against permissive threshold concentrations.
Description
This thesis is for the award of Master of Science (MSc) Degree in Environmental Microbiology
Keywords
Heterotrophic fungal count (THFC), total nitrogen (TN), available phosphorus, pinto beans (phaseolus vulgaris), total heterotrophic bacterial count (THBC), Department of Microbiology
Citation
Oparah, J. U. (2021). Effect of different concentrations of some agrochemicals on soil microbial density and crop growth [Unpublished Master's Thesis]. Federal University of Technology, Owerri, Nigeria