How are nematode communities affected during a conversion from conventional to organic farming in southern French vineyards?

Abstract

The rate of conversion from conventional vineyards to organic farming practices is increasing. Organic farming improves some soil properties, although some organic practices have negative effects on soils. The objective of this work was to study the long-term effects of organic farming through the use of soil nematodes as bio-indicators of soil processes. Our experimentation was conducted in a commercial vineyard where plots belonged to two types of viticulture: conventional viticulture and organic viticulture (for 7, 11 and 17 years). The nematode community structure and nematode indices were determined. The main result was that organic practices increased soil nematode density. An increase in the available resources, as measured by a higher enrichment index (EI), led to an increase in the microbial feeder density and mainly opportunistic fungal-feeding nematodes. A greater density of plant-feeding nematodes was attributed to the presence of a grass cover. The functioning of the soil was shifted with the decomposition channel of the soil organic matter becoming more fungal than bacterial. Even though changes were observed in the nematode community structure following the conversion, the maturity index (MI), the plant-parasitic index (PPI) and the structure index (SI) remained constant. Consequently, the organic practices did not improve the soil food web length or complexity even though the biological activity, as measured by microbial biomass and total nematode density, increased

Soil Properties and Olive Cultivar Determine the Structure and Diversity of Plant-Parasitic Nematode Communities Infesting Olive Orchards Soils in Southern Spain

“…Furthermore, SOM, organic C, organic N, C:N ratio were significantly higher in organic as compared to conventional management in the same orchards of this study [ 10 ]. Our results agree with previous reports of the existence of a higher number and diversity of PPNs in fields managed organically [ 46 – 49 ], however the lack of clear differences in abundance or diversity indexes of soil biota in other studies is attributed to the fact that soil type in general had a much stronger effect on the soil biota compared to orchard or farm management type [ 48 , 50 – 51 ].…”

Physicochemical composition, minerals, and pesticide residues in organic grape juices

“…The international bibliography concerning the production of organic grapes covers different aspects of this field, such as those related to a) minimize the use and effect of copper application (Dagostin et al, 2011); b) search alternative products for different diseases (Crisp et al, 2006); c) control nematodes (Coll et al, 2012); d) fertilization and mineral nutrition (Coll et al, 2011); e) the impact and evaluation of the organic viticulture (Reeve et al, 2005;Fragoulis et al, 2009). Serra Gaúcha, the most important Brazilian viticultural region was also influenced by this scientific and technological development with the use of different agricultural inputs − such as fungicides, insecticides, herbicides, growth regulators, fertilizers −, and enological -such as yeasts, enzymes, stabilizers, antioxidants.…”

Vineyard Management and Its Impacts on Soil Biodiversity, Functions, and Ecosystem Services

“…Nematodes are not necessarily adversely affected by cultivation practices and are, for example, less sensitive to tillage than larger soil animals (Wardle, 1995). As reported by Coll et al (2012), compaction reduces nematode abundance and disturbs omnivores and predators in vineyards.…”