The Effect of Pesticides Dichlorodiphenyl Trichloroeyhane (D.D.Y) and Benzene Hexachroride (BHC) on the Microflora of the Three Types of Soil
CHAPTER ONE
AIM AND OBJECTIVES
- To determine the effect of pesticide dicblorodipheny trichloroethane (DDT) and benzene hexachloride (BHC) on the microflora of three types of soil.
- To isolate soil microflora from the three types of soil.
- To identify soil microflora of the three type of soil.
- To determine the type of soil that is mostly affected by pesticides.
CHAPTER TWO
LITERATURE REVIEW
PESTICIDE LABELING AND SAFETY
among the pesticide now in use, only five have aroused the concern of environmental scientists, who are attempting to consider the long term effects upon the global environment (Moriarty 1975) Pesticide such as aldrin, dieldrin, endrin, heptachlor and Dichlorodipheny trichloroethane (DDT) are extremely toxic and have the capacity to inflict harm upon non- target organisms. Though D.D.T is relatively persistent, much of it is degraded to another derivative compound called D.D.E (Miriarty 1975 ) chronic toxicity: The extent of poisonous effect of a pesticide to man or animal after apparently harmless repeated doses is measured in terms of chronic oral toxicity and chronic inhalation toxicity. A measure of acute toxicity is done which is the poisonous effect of a pesticide after a single exposure. It is measured as acute oral and acute inhalation toxicity. A measure of the 50% lethal dose of the test organisms is done. This is called LD 50. This is the (lethal dose) of toxicant or active ingredient that will kill orallly or dermal 50% of the tested population. The lower the LD 50, the more poisonous the pesticide. It is usually given in milligram per kilogram MG/kg of body weight or pants per million (PPM). Another measure is LC50. This is the lethal concentration in the air necessary to kill 50% of the test organism. LC50 values are measured in mg/per intre (Hoff man (1974)
VARIOUS CLASS AND TYPES OF PESTICIDES
All pesticides act alike in blocking some metabolic activities of the organisms the came in contact with. They differ however in composition, potential mode of action, speed of effects dosage requirement, and stage of pest against which they may be used. They may often differ according to the type of organism they are principally intended to kill or control more than 800 biocidal compound are now used as pesticides. These compounds includes the chlorinated hydrocarbons, organophosphous insecticides and carbamates (Mc grawhill 1982) he further says that some insecticides are naturally occuring while other are said to be synthetic organic matter.
EFFECTS OF PESTICIDE ON POPULATION OF INVERTEBRATES IN SOIL.
ACCORDING TO (Edward and Arnold (1966) (Pvivka (1951) and (wgate (1966), the numbers and kind of organisms depend upon its physical and chemical characteristic. Most soil are derived from rock and other bioorganic matter by weathering a combination of physical chemical and biological processes e.g sandy soil. Soil animals are very diverse in form and habital and the effects of pesticide on each animal group are discussed below.
EARTHWORMS
Earthworms (inmbriocode) are important in the promotion and maintains of soil structures and fertility, so it is important that they should not be killed by pesticides. Fortunately not many pesticides are toxic to the invertebrates at doses normally applied but organochlorine that usually kill earthworms mostly found include chlordane, endrion and heptachlor
CHAPTER THREE
MATERIAL AND METHODS
MATERIALS (SEE APPENDIX)
METHODS
STERILIZATION
Already, properly washed petridishes, byour bottles, test tubes, conical flask, beakers, universal bottle, pipettes, spatulas, wirelopps, maculating needles 50 ml capacity bottles Durham tubes were sterilized in hot air oven at 160c0 for I hour in their respective canisters and stored at 40 c
COLLECTION OF PESTICIDES
The two pesticides Dichlorodiphemy trichlroethane (DDT) and benzene hexachloride (BHC) were obtained at Ogbete main market.
COLLECTION OF THREE TYPES OF SOIL LOAMY CLAY AND SANDY)
Different soil type namely loamy clay and sandy soil were collected with sterile containers, loamy soil samples were collected from secretarial quarter ogui Enugu. And clay and sandy soil samples were collected from different location at Ninth mile corner, Enugu.
PREPARATION OF MEDIA
The media for culturing were aseptically prepared as when necessary according to the manufacturers instruction and autoclaved at 121c for 15 min at 151bs pss. Remaining media in flask were stored at 4c
PLATING TECHNIQUES (SERIAL DILUTION)
The serial dilution techniques was employed ig of loamy soil was dissolved in 9 ml of water and dilution up to 10 –3 were made this process was also made separately for both clay and sandy soil. Nutrient agar potato dextrose agar (PDA) and sabourand agar plates were prepared in this order 2 plate for untreated soil and then 2 plate for same soil treated with DDT and BHc. And this was done for all the chlutions. The same treatment was applied separately to clay and sandy soils. Then imi from each serial dilution up to 10-3 was taken from the treated and untreated sample of each soil type and was run into the agar plate when still mollen. The plate were surled clockwise and anticlockwise for even distribution. The plates were allowed to solidify inverted and incubated for 24 hours at 37oc. also duplicate plate were prepared from each serial dilution up to 103 for each soil types, for both treated and untreated and incubated for 28c. 50 sample were performed for each soil type separately for treated and untreated sample were examined counted and record recorded.
CHAPTER FOUR
RESULT
KEY :
- Greenish blue coloration
- Greyish white coloration
- White cream coloration
- Bluish green coloration
CHAPTER FIVE
DISCUSSION
The effect of pesticide chichlorodipheny trichlorethane (DDT) and benzene hexachloride (BHC) on the microflora of three types of soil was conducted. ‘The highest bacterial load before the soil types were treated with DDT and BHc was got in loamy soil with 133 per ml followed by clay soil with 78 per ml and least was sandy soil with 42 per ml. And the highest bacterial isolates before the three soil types were treated with D.D.T and BHc was pseudomonas species which was 40 per ml in clay soil and 12 per ml in sandy soil the next bacterial organism was Actinomyces species which was 30 per ml in loamy soil 18 per ml in clay soil and 10 per ml in sandy soil. The next bacterial organism was Actinomyces species which was 30 per ml in loamy soil 18 per ml in clay soil and 10 per ml in sandy soil. Where as the least isolated bacterial organism was Rhizobum species which was 25 per ml in loamy soil 15 per ml in clay and 8 per ml in sandy soil.
From the above result loamy soil gave the highest number of bacterial organisms with 133 per ml with pH7.1 followed by clay soil with 78 per ml with pH 4.5. while sandy soil had the lowest bacterial organisms with 42 per ml having pH 4.4.
The microbial count of the three soil types after treatment with D.D.t gave on the average the highest count of 105 per ml for loamy soil, followed by clay soil with 51 per ml and the least isolation was obtained from sandy soil with 28 per ml. Also the microbial count after treatment with BHc was still highest in loamy soil with 127 per ml, followed by clay soil with average count of 64 per ml and least is sandy soil with 37 per ml and also fungal organisms were isolated such as Aspergillus species penicillum sycophalastrum species mucor species with their different morphological appearance.
The result of this project have shown that there was reduction in microbial load after treatment separately with the two pesticides the effect on the microflora was more with diphemy trichloroethane (DDT) where the microbial load of loamy which 133 per ml reduced to 105 per ml and clay soil which was 78 reduced to 52 per ml while sand soil which was 40 per ml reduced to 22. Where as after treatment with BHc the microbial load of loamy which was 133per ml before treatment reduced to 127 per ml, and clay soil which was 78 before treatment reduced to 64 per ml and sandy soil which was 42 before treatment reduced to 37 per ml.
The result of this project work were in conformity with (moriarty in 1975) who stated that bacteria mostly grow in loamy and clay soils. This project also aggress with the views of (macclanby 1970) who state that D.D.T among other pesticides are extremely toxic and can inflict harm upon non- target organisms
However, this project work shows that the average microbial counts of the individual soil types and the individual isolated organisms are not shared affected. This view is share by wall work (1970) and Helling (1971) who state that the over all levels of bacteria in the soil as generally not seriously affected by pesticides.
CONCLUSION
The result obtained from this project work showed that both pesticides diphenyi trichloroethane (D.D.T) and benzene hexachloride (B.H.C) have no serious effect on the microbial flora of the three soil types (loamy clay and sandy). However, the effect on the micro flora of the three soil types was mox with D.D.T than with BHc. Also, the effect of the two pesticides separately was highest on sandy soil followed by clay soil, and least in loamy soil. The study further reveled that the population of micro organisms was highest in loamy soil, followed by clay soil least in sandy soil moreover, the highest bacterial isolate from the three types of soil was pseudonas species followed by Bacillus species, next was Actinomycetes species and least isolated organism was Rhizobum species.
RECOMMENDATION
The adequate concentration of pesticides should be applied to the soil or if higher than normal for a particulars pesticide, it may drastically reaccelerate or reduces the microflora
REFERNCES
- BURGES, A and RAW,F.C.S (1967) Effect of Insecticides in the soil Rothanisted press London. PP.185-186
- CHERRET, J.M and SAGAR, G.R (1977) origin of pest parasite disease and weed problem: black week scientific Pub. Oxford pp.39
- Dobson R.M and lofty, jr. (1956) observation on effect of BHc on the soil science public Paris pp.203-205.
- DONAHUE, K. CHRISTENSEN, V.AND EVANS N.(1974) Exploring Agriculture An introduction to food and Agriculture; 5th Edt. Prentice Hall inc U.K pp. 57-68.
- EDWARD, C.A. (1965) Effect of pesticides resiques on soil invertebrate and plant; 5th Edith. Deker publication N York PP 23g-260.
- EDWARD, C.A. and ARNOLD, M.K (1965) Effects of insecturdes on soil fauna; Rothamsted press London. PP158.
- EDWARD, C.A and DENNIS, E.B 1960 some effect of aldrin and DDT on the soil fauna of arable land Nature study inc. PP 188.167
- EDWARD, C.A DENNIS E.B and EMPSON D(1967) pesticide and the soil fauna; effect of aldrin and DDT in an arable field Deker scientific pib. New York PP11-22.
