soil structure/soil biota S€M λ interrelationships International Workshop on Methods of Research on Soil Structure/Soil Biota Interrelationships, held at the International Agricultural Centre, Wageningen, The Netherlands, 24-28 November 1991 Edited by L. Brussaard Department of Soil Science and Geology, Agricultural University, P.O. Box 37, 6700 AA Wageningen, The Netherlands and Department of Soil Biology, DLO—Institute for Soil Fertility Research, RO. Box 30003, 9750 Haren, The Netherlands and M.J. Kooistra Department of Soil Structure and Micromorphology, DLO—The Winand Staring Centre for Integrated Land, Soil and Water Research, P.O. Box 125, 6700 AC Wageningen, The Netherlands Reprinted from Geoderma, Vol. 56, Nos. 1-4 and Vol. 57, Nos. 1-2 OECD OCDE ELSEVIER, Amsterdam — London — New York —Tokyo 1993 ELSEVIER SCIENCE PUBLISHERS B.V. Sara Burgerhartstraat 25 P.O. Box 211, 1000 AE Amsterdam, The Netherlands Library of Congress Cataloging-in-Publication Data International Workshop on Methods of Research on Soil Structure/Soil Biota Interrelationships (1991 : International Agricultural Centre) Soil structure/soil biota interrelationships : International Workshop on Methods of Research on Soil Structure/Soil Biota Interrelationships, held at the International Agricultural Centre, Wageningen, The Netherlands, 24-28 November 1991 / edited by L. Brussaard and M.J. Kooistra. p. cm. "Reprinted from Geoderma, vol. 56, nos. 1-4 and vol. 57, nos. 1-2." Includes bibliographical references and index. ISBN 0-444-81490-6 (alk. paper) 1. Soil biology-Research—Methodology—Congresses. 2. Soil structure—Research—Methodology—Congresses. I. Brussaard, L. (Lijbert) II. Kooistra, M. J. III. Title. QH84.8.I58 1991 93-15218 631.4'6~dc20 CIP ISBN 0-444-81490-6 © 1993 Elsevier Science Publishers B.V. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the publisher, Elsevier Science Publishers B.V., Copyright and Permis- sions Department, P.O. Box 521, 1000 AM Amsterdam, The Netherlands. Special regulations for readers in the USA - This publication has been registered with the Copyright Clearance Center Inc. (CCC), Salem, Massachusetts. Information can be obtained from the CCC about conditions under which photocopies of parts of this publication may be made in the USA. All other copyright questions, including photocopying outside of the USA, should be referred to the publisher. No responsibility is assumed by the publisher for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any meth- ods, products, instructions or ideas contained in the material herein. This book is printed on acid-free paper. Printed in The Netherlands V Editors' Introduction The aim of the conference on Methods of Research on Soil Structure/Soil Biota Interrelationships, which we organized 24-28 November, 1991, was to provide a thorough review of established and innovative methods of study and assessment at the microscopic scale, that can be used in all aspects of research on this subject in soil ecology and soil science. It appears that much research on the transformation and transport of elements such as carbon and nitrogen is either concerned with soil biota/plant relationships or with soil structure/plant relationships, but very few studies explicitly take the interre- lationships between soil structure and soil biota into account: plant; land qualities soil structure; organic matter; texture soil microbes and fauna Since both in reduced input agriculture and in (semi-)natural ecosystems the plant depends on the contribution of the soil biota to the formation of soil structure and to the release of nutrients, it is obvious that all aspects of the triangle deserve adequate consideration. This calls for interdisciplinary re- search among soil microbiologists, soil zoologists, soil micromorphologists, soil physicists and root ecologists. It appears, however, that state-of-the-art research in these disciplines is often carried out on different scales, depending, e.g., on the size of the biota that is studied or, rather trivial, on the technical equipment available. There is also insufficient knowledge on techniques used in sister disciplines and on the prospects of using those in one's own field of expertise. So one of the chal- VI EDITORS' INTRODUCTION lenges we face is to develop an adequate methodology for the study of soil structure/soil biota interrelationships and for the translation of results from such research to plant performance and land qualities, as indicated in the figure. Dealing with this challenge different levels of adequate methodology can be distinguished: \ identification observations location & features distribution description/ interrelations tables etc. quantification / reflect identification — strength/frequency processes interpretation -^ interrelations -*- actuality result in \ function/properties extrapolation/ effects generalization > synthesis models predictions / The first level concerns the collection of the basic data: observation, de- scription and quantification of primary features. Focussing on methodology the question is: how do we observe, describe and quantify these features, the interaction between soil structure and soil biota, in situ. The second level deals with the arrangement of diagnostic features into processes. The question here is: how do we translate observed soil features into biologically mediated pro- cesses. The third level concerns the translation of processes into effects. The basic question is: how to evaluate effects of the features and processes on soils and plants. This set-up was chosen for the workshop and the articles in the proceedings are arranged accordingly. EDITORS' INTRODUCTION Vll Although the conference was on innovative methodology in the first place, we also received a number of excellent contributions in which conventional methods were applied. It was therefore decided not to restrict the proceedings entirely to methodology. The response we have had from the scientific community, both in terms of participation and in terms of manuscripts received, has convinced us that the conference was timely and relevant. The financial support of the sponsors, mentioned elsewhere in this volume, created the possibility to participate for most of the invited speakers and for a considerable number of scientists from developing countries. Finally, we are confident that the proceedings, like the conference itself, will stimulate co-operation among scientists interested in soil structure and soil biota, to the benefit of application of knowledge in environmentally sound plant production and use of land qualities. Wageningen, 19 November 1992 L. BRUSSAARD M.J. KOOISTRA Vlll Sponsors h Wageningen Agricultural University Co-operative Research Project on ®@®S Biological Resource Management of the Organisation for Economic Co-operation and Development (OECD) ©tie® Netherlands Integrated Soil Research Programme / «-ir>\ !M Royal Netherlands Academy of Sciences Diürt: Netherlands Ministry of Agriculture, Nature Management and Fisheries MM Netherlands Council for Agricultural Research Foundation for Biological Research ^ΙΟΝ Netherlands Soil Science Society \& International Agricultural Centre IX Preface Reductions of chemical and energy inputs to agriculture could lead to more economical production systems while minimising pollution. This might be achieved by modifying farming systems (e.g. reduction of tillage), the use of improved efficiency organic fertilisers, and the partial replacement of crop protection chemicals with micro-organisms (including those which have been genetically modified). Theme 1 of the OECD Co-operative Research Project on Biological Re- source Management 1990-1994, Modification of plant/soil/microbial inter- actions to reduce inputs in farming systems, focuses on the role of micro- organisms in these managed ecosystems and their relevance to crop produc- tion and protection. Particular priorities are to: - Improve existing and develop new detection and assessment methodologies for microbes. - Identify physicochemical aspects of the soil environment which regulate microbial function. - Determine population dynamics and survival of soil and rhizosphere communities. - Analyse the potential of sustainable agriculture systems using inter-discipli- nary approaches. In a planning meeting which was held in Wageningen in the summer of 1990, the following topics were identified as priorities for the Theme to fund fellowships and workshops: (1) The soil environment and microbes. (2) Plant effects on micro-organisms. (3) The soil and plant environment in relation to fertilizer use. (4) Food webs and soil fauna. (5) Soil quality and biodiversity. (6) Biocontrol of pests and diseases. When it was indicated that Professor Lijbert Brussaard and colleagues were to arrange a workshop on the Topic in Wageningen in 1991, it was obvious that this should be supported by OECD. From the programme arranged, I am sure that our decision to finance the attendance of a large proportion of the overseas speakers was fully vindicated. In future workshops, we will be endeavouring to cover the remaining topics X PREFACE and will meet at varying locations with the network of participating countries (Australia, Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Japan, Netherlands, New Zealand, Norway, Portugal, Spain, Sweden, Switzerland, Turkey, United Kingdom, United States at the time of this publication). It is critical that sustainability of agricultural systems be addressed on in- terdisciplinary and international bases. Hopefully then reduction in inputs will be achieved in a manner which maintains profitability for farmers whilst protecting the environment, particularly the soil itself on which agricultural productivity depends. J.M. LYNCH Horticulture Research International, Littlehampton, West Sussex, BN17 6LP, UK (Scientific co-ordinator of theme 1) The International Workshop on Methods of Research on Soil Structure/Soil Biota Inter- relationships was sponsored, in part, by the Organisation of Economic Co-operation and Development (OECD). Financial support for this workshop came from the Co-operative Research Project on Biological Resource Management, a four-year endeavour that involves creating fellowships to encourage exchange among scientists in the field, and the organisa- tion of workshops and publications on the proceedings. For more information, please con- tact the OECD - Directorate for Food, Agriculture and Fisheries, 2, rue Andre Pascal, 75775 Paris Cedex 16, France. XI Opening address Ladies and gentlemen, It is a great pleasure and honour for me to welcome you today on behalf of Wageningen Agricultural University. Together with the research institutes of the ministry of Agriculture, Natural Resource Management and Fisheries, our University has made the small town of Wageningen known in many parts of the world as a centre for agricultural research. Ironically, this has not only contributed to a reputation of some degree. Today, agricultural research is under severe attack. A production-oriented approach in agricultural science has been, and still is, successful in leading to the production of abundant, cheap food of good quality. Current production methods, however, have also led to food surpluses in large parts of the industrialized world, to inefficient use of resources, and to environmental pollution and health hazards. In con- trast, adequate technology for sufficient food production in less-endowed countries is not yet provided for to an acceptable degree. Although the problematic nature of these issues should not be denied, they present at the same time challenges and responsibilities for the scientific com- munity to work on. A major shift is now occurring within the agricultural sciences from a production-oriented to an environmental safety-oriented ap- proach. Sustainable land use and sustainable agriculture are key issues in this respect. They require research on efficient use of external inputs wherever these are scarce, such as in large parts of the developing countries, and wher- ever outputs should be reduced, such as in some parts of the industrialized world. Efficient use of resources is easier said than done. It calls for a lot of basic knowledge on the functioning of natural and managed ecosystems both from a production and an environmental point of view. Soil research is of prime importance in this context, first because supply of water and nutrients depend mainly on soil factors, and second because sooner or later human ac- tivities aboveground have repercussions belowground. Soil research has always been one of the strengths of Wageningen but, until recently, the biological aspects have received relatively little attention. Truly interdisciplinary and basic research is now needed, involving soil biologists, physicists, chemists and plant scientists to unravel the functioning of soils as ecosystems, a prerequisite for an operational approach towards sustainable Xll OPENING ADDRESS land use and agriculture. Such basic soils research is at the heart of the man- date of Wageningen Agricultural University and an important reason to spon- sor your workshop. I wish you every success over the next few days and I hereby declare this work- shop open. H.C. VAN DER PLAS Rector Magnificus Wageningen Agricultural University