The Impact of Soil Biota and Crop Management Practices on Soil-Borne Plant Pathogens and Diseases in Agricultural Systems

T. VATCHEV
Department of Plant Pathology, Plant Protection Institute, BG-2230 Kostinbrod, Bulgaria

Abstract

VATCHEV, T.D., 2004. The impact of soil biota and crop management practices on soil-borne plant pathogens and diseases in agricultural systems. Bulg. J. Agric. Sci., 10: 71-87

Long before the interdependent relationships between crop plants, soil-borne plant pathogens, and other soil organisms, all influenced by humans' activity have been noticed and scientifically documented they themselves had produced a prominent, often dramatic effect on agricultural systems. Numerous systematic groups including soil fungi, nematodes, bacteria, viruses, phytoplasmas and rickettsiae can cause diseases in cultivated plants and therefore, are considered detrimental from anthropocentric viewpoint and economic perspective. Unlike earlier tenets, recent concepts tend to consider crop diseases and pests as counterbalancing mechanisms to restore the biological equilibrium disturbed in some way through replacing the natural plant ecosystems with the agricultural ecosystems. Likewise, soil biota, mainly soil microorganisms might limit the population growth of soil-borne plant pathogenic organisms and/or provide an efficient natural biocontrol of diseases they incite. Pathogen- or disease-suppressive effects or both may occur in soil defined as naturally suppressive or biologically buffered. While a relatively stabile habitat, the soil environment is vulnerable to manipulation, so that disease-suppressive soil ecosystem can be developed by various agricultural or horticultural practices. A speculation deeply encroached among scientifically literate public is that mechanisms thought to regulate diseases in nature must be utilized in agricultural systems, particularly where the sustainable farming is the major goal. This line of thinking still remains disputable in literatures. However, the inconsistent performance of biological control based on introduction of specific antagonists over last decades has illustrated the needs for detailed understanding of biological interrelationships and processes that might take place in cultivated soils.
Be it non-exhaustive, this paper considers areas of interest associated with development of environmentally benign control strategies, which promote soil quality and health.

Key words: agroecosystems, biological control, soil suppressiveness, polyculture, crop rotation, intercropping, monoculture, tillage, sanitation, soil disinfestation, organic amendments