Durham E-Theses An ecological evaluation of three systems of farm management using eld beans Parsons, M. How to cite: Parsons, M. (1975) An ecological evaluation of three systems of farm management using eld beans, Durham theses, Durham University. Available at Durham E-Theses Online: http://etheses.dur.ac.uk/8296/ Use policy The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in Durham E-Theses • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. Please consult the full Durham E-Theses policy for further details. Academic Support Oce, Durham University, University Oce, Old Elvet, Durham DH1 3HP e-mail: [email protected] Tel: +44 0191 334 6107 http://etheses.dur.ac.uk AN ECOLOGICAL EVALUATION OF THREE SYSTEMS OF FARM MANAGEMENT USING FIELD BEANS By MICHAEL . J. PARSONS (B.Sc. Dunelm) A Thesis submitted for the Degree of Doctor of Philosophy at the University of Durham July 1975 To the memory of my mother^ who first inspired me with an interest in Botany. This thesis is entirely the result of my o\m v7ork, apart from some of the water analysis.which was done in conjunction with Mr A.Y.Basahy. This work has not been accepted for any other degree, and is not being submitted for aiijuother degree. CONTENTS page no. ACKNOWLEDGEMENTS i AbstrsLct ••• •«• ii Conventions follovfed in the thesis iv Introduction 1 The Biosphere 1 The Ecosystem 2 The Development of Agriculture 3 Nutrient and Energy input li Eutrophication 6 Nitrogen 7 Organic iManures versus Inorganic Fertili zers 9 The Research Project ••• 10 Overall aims of the Research Project 13 Section 1. SOIL ... ... ... ... 17 1:1 Background ... 17 :1.5 Management of farm sections ... 19 .5'1 Organic section 19 .5«2 Mixed section ... 20 ,5.3 Stockless section 20 .5.I1 Commercial section 21 1:2 Analysis of Manures and Fertilizers 22 1:3 Soil Analysis 28 1:3.1 Physical 28 1:3.2 Chemical 31 Section 2. WATER CHEJ'IISTRY 66 2:1 Introduction 66 2:2 Background to Methods 67 2:3 Aim ... ... ... ... 70 2:k Method 70 2:5 Addition to the system 71 2:6 Loss from system 73 2:7 Overall conclusions 100 page no. Section 3- ANALYSIS OF CROP GROWTH ... 103 3:1 Introduction 103 3:2 Method of Growth Analysis 105 3:3 An assessment of the effect of farm management upon the growth of Vicia faba 109 Section h. CROP GEOCHE!'«STRY 151 1+:1 Background 151 k:2 Investigation of• the geochemistry of thehea n plant 157 k:3 1970-19T1 Greenhouse Trial * • 158 k:k 1971 Field Trial 162 k:5 1972 Field Trial 178 h:6 1973 Field Trial 188 hif Overall conclusions from the Geochemistry Section 191 Section 3- NITROGEN FIXATION ... 193 5:1 Introduction .. 193 5:2 Aim ... ... ... 19^ 5:3 Method 195 5:U Development of Technique 196 5:5 Effect of farm management upon nodulation 208 5:6 The effect of farm management upon nitrogen fixation 216 FINAL DISCUSSION 225 1. The overall picture of the agricultural ecosystem . 225 2. The most important features of the research results 232 FINAL CONCLUSIONS 239 3. Recommendations for future research 2kO BIBLIOGR/iPHY 2U2 APPENDIX -i- -1- ACKIJO^-JLEDGEMENTS I must thank the Directors of the. Haughley Research Farm, and the Pye Research Centre at Haughley, Suffolk, for all their help in the planning and operation of the field experiments, and for making available seed stocks, water samples and the past records of the Farms. My thanks are extended to Professor D Boulter for the provision of research facilities in the Department of Botany. I am very grateful to Durham University for their financial support in the form of a three year Research Studentship. I wish to express my special gratitude and appreciation for the guidance and encouragement which I have received from my research Supervisor, Dr David Bellamy, who has shorn great interest in every aspect of the research project. My thanks are also due to Abdullah Basahy for his assistance throughout the study. It is a pleasure to thank Jean Chisholm of the Durham University Library for her patience and perseverance in securing copies of almost all the research papers quoted in this thesis, through the Inter-Library Loan Service. I am indebted to Mrs Nora Allen for providing hours of thought- provoking discussion and for typing the first draft of the thesis, and I am most grateful to Miss M Berryman and Mrs R L Reed for their efficiency in coping with the final typing of the tables and the text. AAA************* -11- Abstract - An evaluation and comparison of the flow of geochemicals through three systems of farm management is made, using Vicia faba L. as a crop phytometer. Organic manures form the only nutrient addition to one system (Organic), artificial fertilizers alone are applied to the second (Stockless), and the third system receives a mixture of the two nutrient sources (Mixed). The influence of the farm management upon each of the main components of the agricultural ecosystem is determined, and these are discussed separately in the five main sections of the text. Crude balance sheets are constructed to demonstrate the magnitude of the annual flow of geochemicals through each system. - The soil of the three farms is compared by chemical analysis. It is shown that where organic manures have been used, the content of available plant nutrients is significantly higher than in the soils where only inorganic fertilizers have been applied. feThe flow of water through the ecosystem is determined by the use of lysimeters. A study of the chemical composition of the leachate shows that the.system receiving both manures and fertilizers provides the greatest threat of eutrophication. The maximum loss of plant nutrients from the soil is shown to occur during the season of the greatest rainfall. The rate of the fixation of energy into the system is determined by a study of the growth and yield of the crop phytoneter. It is found that the long-term practice of growing separate stocks of seed on each farm, (imprinting), does not cause any physiological evolution to occur by which each plant type could become better suited to its own farm type. It is demonstrated that, the magnitude of the growth of the bean plants does not show any significant effect of farm management, despite the differences in nutrient availability from the three soils. It is suggested that this lack -111- of growth response is due to the high background level of nutrients in all the soils. The only effect of nutrient availability is shown by the size of the bean seed yield, but this effect is seen to be drastically modified by weed competition. The flow of geochemicals into the standing crop is investigated by detailed chemical analysis of the plants throughout the season. Corresponding to the lack of growth response to the farm management, no significant effect of soil treatment can be shown to be influencing the chemical composition of the crop. There is no evidence to show any eutrophication of the crop by nitrates, but a marked death reaction is demonstrated to be causing high concentrations of lead in the bean seeds. Due to a greater biomass on the Mixed section, it was this management which incurred the greatest flow of geochemicals into the standing crop. The phenomenon of symbiotic nitrogen fixation by the phytometer is investigated. A close relationship between the rate of fixation, the extent of nodulation and the availability of soil nitrogen is determined. The former two characteristics are sho™ to provide an accurate assay of the level of nitrogen in the soil. Calculation of the probable annual fixation of nitrogen shows that this is maximal on the farm where no organic manures are supplied. From the construction of the balance sheets, and the discussion in the text, it is indicated that the management system, which is the most geo- chemically and economically viable, is the Mixed system. This farm produces the highest yield of bean seeds, and permits a reasonable level of nitrogen fixation by the legume, but also poses the most serious threat of eutrophic• ation to other ecosystems. Even so, the concentration of nitrates in the leachate never exceeded the maximum safe limit suggested by the World Health Organization. -IV- Conventions followed in the thesis 1. Measurements : All measurements were made in SI units according to the metric scale. Where reference figures are quoted from the literature, all values are converted to the metric scale. The abbreviations used : yg or ygm = microgramme mg or mgm = milligramme mm = millim^etres kg = kilogramme cm = centimetres m = metres ha = hectares 2. Numbering : - Tables and Graphs - Section number - sequential number for.that section ie 4—.9 = the ninth graph in Section 4. - Text - paragraphs numbered according to the Universal Decimal Classification, "eg Section number :1.1.2-3(1) 3. Abbreviations : where several elements are m.entioned together in the text, and in all the tables they are listed by symbols (according to the Periodic Table) Farm management and imprint types : 0 = Organic M = Mixed S = Stockless C = Commercial - Vioia faba L. varieties : Tic Thro, Throw = Throws - Plot treatment : 1971 Field Trial : NF = No fertilizer 3F = 375 Kg fertilizer/ha 6F = 625 Kg fertilizer/ha : 1972 Field Trial : NFLys = Normal fertilizer lysimeter S+ = HFLys = High fertilizer lysimeter : 1973 Field Trial : PPKK = double normal rate of phosphorus and potassium NNPPKK = double normal rate nitrogen, phosphorus and potassium NNPK = double norm.al nitrogen added to normal rate phosphorus and potassium 4.