Subject: [SANET-MG] Arbuscular mycorrhizal fungi and organic farming

From: jcummins <[email-masked]>
Date: Wed, 11 Jan 2006 18:10:13 -0500

Agriculture, Ecosystems & Environment
Article in Press
doi:10.1016/j.agee.2005.09.009
 Review
Arbuscular mycorrhizal fungi and organic farming

P. Goslinga, , , A. Hodgeb, G. Goodlassc and G.D. Bendinga
Abstract
Symbiotic associations between arbuscular mycorrhizal fungi and plant 
roots are widespread in the natural environment and can provide a range 
of benefits to the host plant. These include improved nutrition, 
enhanced resistance to soil-borne pests and disease, improved resistance 
to drought, tolerance of heavy metals and better soil structure. Many 
agricultural crops are mycorrhizal and there is widespread if equivocal 
evidence that crop plants benefit from the arbuscular mycorrhizal (AM) 
association in the same way. However, many agricultural practices 
including use of fertilisers and biocides, tillage, monocultures and the 
growing of non-mycorrhizal crops are detrimental to arbuscular 
mycorrhizal fungi (AMF). As a result, agroecosystems are impoverished in 
AMF and may not provide the full range of benefits to the crop. Organic 
farming systems may be less detrimental to AMF because they exclude the 
use of water-soluble fertilisers and most biocides and generally have 
diverse rotations. The evidence available suggests that this leads to 
increased AMF inoculum in soils, greater crop colonisation and enhanced 
nutrient uptake. AMF might therefore be able to substitute for reduced 
fertiliser and biocide inputs in organic systems, though there is little 
evidence for increased yield resulting from high rates of AMF 
colonisation in organic systems. This review examines the benefits that 
the AM association can have for agroecosystems and how farm management 
practices influence the AM association. Management options that may be 
employed to increase the benefits that AMF can bring to this type of 
farming system, such as changes to the rotation and careful use of 
tillage, are discussed.

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