https://theses.gla.ac.uk/ Theses Digitisation: https://www.gla.ac.uk/myglasgow/research/enlighten/theses/digitisation/ This is a digitised version of the original print thesis. Copyright and moral rights for this work are retained by the author A copy can be downloaded for personal non-commercial research or study, without prior permission or charge This work cannot be reproduced or quoted extensively from without first obtaining permission in writing from the author The content must not be changed in any way or sold commercially in any format or medium without the formal permission of the author When referring to this work, full bibliographic details including the author, title, awarding institution and date of the thesis must be given Enlighten: Theses https://theses.gla.ac.uk/ [email protected] EFFECTS OF PESTICIDES ON SOIL MICROBIOLOGICAL PROCESSES MD. AZIZUR RAHMAN MAZUMDER (M.Sc.Ag.) Thesis submitted for the Degree of Master of Science (M.Sc.) February 1992 Agricultural Food and Environmental Chemistry University of Glasgow U.K. ProQuest Number: 11011439 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a com plete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. uest ProQuest 11011439 Published by ProQuest LLC(2018). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States C ode Microform Edition © ProQuest LLC. ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106- 1346 ACKNOWLEDGEMENTS I am extremely grateful to Dr. T.H. Flowers for his kind assistance, interest and supervision throughout the course of this work. Without his ever-lasting helpful encouragement and careful attention this work would never have been completed. I also wish to thank Dr. H.J. Duncan for his encouragement and making my stay more enjoyable. I am indebted to Isabella Boyd for her kind help and fruitful discussions. In addition I wish to express my sincere thanks to all staff and colleagues for their help in various ways. I wish to thank Mrs. Elizabeth A. Pulford for her skill in typing the manuscript of this thesis. -VI # I am extremely grateful to the British Coucil for financial support during the period of this study. Finally my sincere and heartful thanks go to my parents and all my family back home for their patience, help and understanding. (i) CONTENTS Page No. ACKNOWLEDGEMENTS (i) CONTENTS (ii) SUMMARY 1 CHAPTER ONE: GENERAL INTRODUCTION 5 Importance of pesticide use 5 Effects of pesticides on soil 8 microorganisms Effects of pesticides on bacteria 12 Effects of pesticides on fungi 16 Effects of pesticides on actinomycetes 19 Effects of pesticides on soil algae 20 Effects of pesticides on organic 22 matter breakdown Effects of pesticides on soil 24 respiration Effects of pesticides on ammonification 27 Effects of pesticides on nitrification 31 Page No. 1.7 Effects of pesticides on 38 denitrification 1.8 Effects of pesticides on 43 nitrogen fixation 1.9 Effects of pesticides on 51 transformation of other elements 1.10 Effects of pesticides on urease 54 activity in soil 1.11 Effects of pesticides on 60 phosphatase activity in soil 1.12 Effects of pesticides on 63 dehydrogenase activity in soil 1.13 Aim of the thesis 66 CHAPTER TWO: METHODS AND MATERIALS 71 2.1 Soil sampling sites 71 2.2 Collection and preparation of soil 72 samples 2.3 Determination of soil pH 72 2.4 Determination of moisture content 7 3 (iii) Page No. 2.5 Determination of moisture content at 7 3 -0.5 bar 2.6 Soil properties 74 2.7 Method of pesticide application to 75 soils 2.8 Method for phosphatase activity 75 2.8.1 Reagents 77 2.8.2 Procedure 78 2.9 The method for dehydrogenase activity 79 2.9.1 Reagents 81 2.9.2 Procedure 81 2.10 Incubation procedure for measurement 82 of nitrification of added ammonium 2.11 Extraction of inorganic nitrogen 83 from soil 2.11.1 Washing of glassware 85 2.11.2 Washing of filter papers 85 2.11.3 Preparation of 0.5M potassium 86 sulphate solution (iv) Page No . 2.11.4 Procedure for extraction of inorganic-N 86 2.12 Automated determination of soil 87 inorganic nitrogen 2.12.1 Determination of ammonium nitrogen 87 2.12.1.1 Reagents 88 2.12.1.2 Procedure 89 2.12.2 Nitrate and nitrite nitrogen 91 determination 2.12.2.1 Reagents 91 2.12.2.2 Procedure 93 2.13 Steam distillation methods for 96 determination of inorganic-N 2.13.1 Apparatus 97 2.13.2 Reagents 98 2.13.3 Procedure 101 2.13.3.1 Standardization of 0.005N sulphuric 101 acid 2.13.3.2 Determination of NH^-N 101 2.13.3.3 Determination of NO^'-N+NC^'-N 102 (v) Page No. 2.13.3.4 Determination of NO^'-N 102 2.13.3.5 Calculation 103 CHAPTER THREE: A COMPARISON OF THE 104 STEAM DISTILLATION AND TECHNICON AUTOMATED METHODS FOR DETERMINATION • OF INORGANIC NITROGEN 3.1 Introduction 104 3.2 Methods 107 3.2.1 Steam distillation methods 108 3.2.2 Technicon method 108 3.3 Results and discussion 112 CHAPTER FOUR: EFFECT OF THREE 129 PESTICIDES ON SOIL MICROBIAL PROCESSES 4.1 Introduction 129 4.2 Methods 132 4.2.1 Experimental design 132 4.2.2 Treatment of soil with pesticides 132 4.2.3 Phosphatase activity 132 (vi) Page N o . 4.2.4 Dehydrogenase acitivity 133 4.2.5 Nitrification 133 4.3 Results and discussion 135 4.3.1 Phosphatase and dehydrogenase 135 activities 4.3.2 Nitrification 151 <4' 3 * 3 ^ ‘.scM-ssifrK 16 3 \=> M • F 'u rth L 'T ^ REFERENCES 170 (vii) SUMMARY The thesis can be divided into two parts. The first part is devoted to a comparison of the two methods, the steam distillation and Technicon automated methods, used for the determination of inorganic nitrogen. To test the precision and accuracy of the two methods, a 5 ppm standard of both ammonium and nitrate nitrogen was used for the steam distillation method and a 1 ppm standard of both ammonium and nitrate nitrogen was used for the Technicon method. By the steam distillation method the % recovery for the NH^-N standard was 95.2% and for NO^-N 94%. The major factor affecting the recovery of nitrogen was the loss of ammonia at the joint between the spray trap and the distillation flask. The joint on the apparatus was modified and tests achieved the recoveries for NH^-N of 99.6% and N03~N of 99.6%. The inorganic-N was then determined by the Technicon AutoAnalyzer II. 1 ppm standards of both ammonium and nitrate-N prepared in water and 2M KC1 were analysed. Standard deviations were 0.0275 and 0.0025 in water and KC1 respectively for NH^-N and 0.0056 and 0.0051 in water and KC1 for NO^-N. The standard deviation of NH^-N in water was very high. One source of variability was identified in that particular flasks consistently gave low results. - 1 - A possible reason for the variability is due. to the adsorption of NH4 ion by negative sites on the glass walls of the volumetric flasks. NOg” ion would not be affected by such negative adsorption sites and in KC1, K+ + + would be adsorbed in preference to NH. as K would be present at a much higher concentration. Both steam distillation and Technicon methods are found suitable in their own places. Though distillation procedures are time consuming they are simple, accurate and less expensive and not affected by the various organic and inorganic substances present in soil extracts. Using the Technicon AutoAnalyzer II a concentration as low as 0.001 pg/ml can be detected and large numbers of samples can be analysed quickly with a high degree of reproducibility. But these automated methods are very sophisticated and it is very difficult to run such complex systems which require a skilled operator and well furnished laboratories. So for developing countries steam distillation methods are more preferable. The second part of the thesis is devoted to testing the effects of three pesticides, captafol, carbaryl and malathion on three selected microbial processes, the phosphatase, dehydrogenase activities and nitrification in two soils of different properties. The two soils used were Darvel Series, a sandy clay loam of pH 6.4 and 8.82% organic matter content and Dreghorn Series, a sandy soil - 2 - of pH 6.8 and 5.64% of organic matter content. Phosphatase activity involved the colorimetric estimation of p-nitrophenol released from p-nitrophenyl phosphate after incubation at 37°C for one hour. Dehydrogenase activity involved the reduction of 2,3,5- triphenyl tetrazolium chloride to the red coloured triphenyl formazan after incubation at 37°C for 24 hours. A significant decrease was observed in the activity of both enzymes with captafol and malathion at both levels of application (10 and 100 mg/kg) for both soils. Carbaryl at both levels of application significantly reduced both enzymic activities in Darvel soil. The low level of carbaryl did not affect either of the enzymic activities in Dreghorn soil while at high level this compound affected the dehydrogenase activity but not the phosphatase activity of the same soil. Nitrification involved the incubation of soils treated with ammonium sulphate at 25°C, subsampling at intervals, extraction of inorganic-N using potassium sulphate followed by analysis by Technicon AutoAnalyzer II.