Although the application of Organic Waste Products (OWP) has an economical interest [1], there is a need to assess both potential positive and negative impacts. Indeed, the use of OWP can spread pollutants that reduce cultivated soils quality, in particular their biological component [2]. To study the possible impact on soil macrofauna, and especially earthworms, we monitored earthworm communities (abundance and biomass) in open field conditions on the QualiAgro site. We also studied the functional impact in soil by assessing earthworm related microporosity using X-ry tomography.

Main results

Before using different solid waste composts at large scale in agricultural fields, it is necessary to prove that these composts do not have harmful effects on soil fauna, especially on earthworms that play important roles in the soil ecosystem. This study carried out the effect of two particular composts (municipal solid waste compost (OMR) and sludge compost (DVB)) on earthworm communities under field conditions. This study was conducted on the “QualiAgro” site (near Paris, France), an agricultural field where these composts are disposed every two years since 8 years and compared to controls (with (TN) or without (T0) N fertilisation). OMR had significant and lasting effects increasing earthworm abundances and biomass whereas DVB had limited and transitory positive effects (figure 1).

Figure1: Earthworm biomass (means and standard deviations). Symbols with different values are significantly different at the 5% theshold level. Absence of a letter for a date means absence of significant difference. Non-significant differences between controls (T0 and TN) are not reported.

The positive effects observed on abundance were not due to difference in the number of immature earthworms. Moreover we found that in OMR (and DVB for one of the date), adults of A. caliginosa species had higher weights. Moreover, 6 soil cores were sampled in March of 2006 and analysed with X-ray tomography and showed that earthworm burrow systems were more developed and deeper in OMR plots. Globally only positive effect on earthworm communities after disposal of these composts were observed. However, only OMR seems to have significant effects that last between two successive disposals.

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References

1. Houot S, Francou C, Vergé-Leviel C, Michelin J, Bourgeois S, Linères M, Morel P, Parnaudeau V, Le Bissonais Y, Dignac MF, Dumat C, Cheianb A, Poitrenaud M, 2003 - Valeur agronomique et impacts environnementaux de composts d’origine urbaine : variation avec la nature du compost. In : « Agriculture et épandage de déchets urbains et agro-industriels » (M. Tercé, Ed.). Les Dossiers de l’environnement de l’INRA, 25, Paris, pp. 107-124.

2. Barrerra I, Andrès P, Alcaniz JM, 2001 - Sewage sludge application on soil : effects on two earthworm species. Water, Air and Soil Pollution, 129, pp. 319-332

Affiliations

1) UR 1115 INRA « Plantes et Systèmes Horticoles », 84914 Avignon cedex 09, France
2) Laboratoire de Toxicologie Environnementale, UMR 406 « Écologie des Invertébrés » INRA / Université d’Avignon
et des Pays du Vaucluse, 84914 Avignon cedex 09, France
3) CreeD, Veolia Environnement, 78520 Limay, France
4) UMR INRA / INAPG « Environnement et Grandes Cultures », 78850 Thiverval-Grignon, France