ABSTRACT
Department of Microbiology and Plant Pathology, University of Pretoria, Pretoria, South Africa
Unifrutti SA Pty Ltd., Kirkwood, Eastern Cape, South Africa
CONTENTS
38.1 Soil Profile Modification as an Intervention............................................................... 548
38.2 Soil Compaction .............................................................................................................. 550
38.3 Relationship between Soil Compaction and Root Diseases..................................... 550
38.4 Soil Profile Modification in Citrus Orchards in South Africa ................................. 551
38.4.1 Plowing as a Stimulus for Root Growth and Soil Biota.............................. 552
38.4.2 Results from Deep Plowing ............................................................................. 552
38.4.3 Impacts on Roots ............................................................................................... 553
38.4.4 Other Observations ........................................................................................... 554
38.4.5 Nutrient Mobilization and Microbial Activity ............................................. 554
38.5 Discussion ........................................................................................................................ 555
Acknowledgments ..................................................................................................................... 555
References ................................................................................................................................... 555
This chapter is based on a case study in South Africa of the relationship between soil
compaction and root disease of citrus, and conversely, of the beneficial effects that deep
tillage can have to improve root development and suppress root rot caused by
Phytophthora nicotianae. It focuses on soil profile modification (SPM) as a means of
improving root growth and root health and of suppressing soil-borne pathogens. It does
not undertake a review of the various methods and mechanisms of SPM which have
previously been reviewed by Eck and Ungerer (1985). We focus on this case because we
have good and extensive data to examine within the larger context of soil profile
modification.
