TABLE CONTENTS

SESSION TWENTY-FOUR – CLIMATE CHANGES, SOIL HEALTH
MONITORING AND NEMATODE BIOINDICATORS
CONVENORS: ROY NEILSON & THOMAÉ KAKOULI-DUARTE
Nematofauna Analysis for Assessment of Soil Ecosystem Functioning in
No-till versus Conventional Agricultural Systems
Villenave, C. (1), B. Rabary (2), J-L. Chotte (1), E. Blanchart (1) & D. Djigal (3)
(1) IRD UR179 SEq-Bio SupAgro, 2 place Viala, Batiment 12, 34060 Montpellier cedex; (2) FOFIFA, UPR
Système de Culture et Riziculture Durable, BP 230, 110 Antsirabe, Madagascar; (3) IRD URS Seq-Bio,
LEMSAT-BP 1386 Dakar, Sénégal
Soil fauna through its activities driven by key species or by complex assemblages of
organisms realizes several life-supporting functions such as the decomposition of organic
matter, the mineralization and recycling of nutrients, the regulation of diseases and pests, the
formation of soil structure. In conventional agriculture most of these functions are achieved
through the inputs (structure and weed control: tillage -and herbicides-, availability of
nutrients: mineral fertilizers, control of pests and disease: pesticides). In integrated or organic
agriculture, parts of these functions are achieved by the biological actors.
The aim of our study was to determine how soil nematofauna reflect the soil biological
functioning in cropping systems with or without tillage and with or without organic and/or
mineral fertilizers.
During three years, we analyzed the effect of no-tillage and permanent cover crops on
nematode functional diversity in two long-term (15 years and 9 years) trials in Antsirabé
(Madagascar) under a subtropical climate (16°C, 1 200 mm y -1 ) and in a clayey soil.
Correlations between nematofauna and other soil organisms (micro-organisms and
macrofauna) were assessed, as well as relations with soil physico-chemical parameters
(mineral Nitrogen, C and N content, Nirs spectrum) in the rhizosphere, and crop parameters
(yields, quality of the litters). The potential of indicators of soil functioning of different
nematode functional groups and indices was demonstrated.
5 th International Congress of Nematology, 2008 89