Soil Fertility as a Contingent Rather than Inherent Characteristic - Principles of Sustainable Soil Management in Agroecosystems - page 141

6 Soil Fertility as a

Contingent Rather than
Inherent Characteristic:
Considering the
Contributions of Crop-
Symbiotic Soil Microbiota

Norman Uphoff, Feng Chi, Frank B. Dazzo,
and Russell J. Rodriguez

CONTENTS
6.1 Introduction .................................................................................................. 141
6.2 Biological Actors within Soil Systems ......................................................... 142
6.3 High Crop Productivity from “Poor Soils” in Madagascar .......................... 14 4
6.4 Increases of Beneficial Microorganisms in Rhizospheres in Response to
Management Practices .................................................................................. 148
6.5 Evidence on the Beneficial Effects of Root Endophytes .............................. 151
6.6 Effects of Soil Microbial Endophytes in Plant Canopies ............................. 152
6.7 Effects of Seed Endophytes for Root Emergence and Growth ..................... 154
6.8 Influence of Soil Microbes on Gene Expression in the Plant Canopy .......... 157
6.9 Implications for Advancement of Soil Science ............................................. 160
6.10 Conclusion .................................................................................................... 161
Abbreviations ......................................................................................................... 161
References .............................................................................................................. 162

6.1 INTRODUCTION
Usually soil fertility is assessed in terms of certain inherent, fixed properties at
the time of sampling, rather than over a period of time and reflecting the dynamic
interaction of multiple factors. Also, soil fertility assessments are made as a rule in
terms of specific chemical properties of the mineral portion of the soil, mostly the
concentrations of essential plant nutrients in plant-available or unavailable forms,

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