Organic and biodynamic viticulture affect soil quality and soil microbial diversity

Abstract

Context and purpose of the study ‐ The production of organically grown crops developed exponentially in the last few decades based on consumer demands for healthy food as well as environmentally friendly farming practices. Current agricultural and environmental policies are reacting to these demands with initiatives limiting the use of synthetic pesticides and thus promoting organic farming. In viticulture, 316,000 hectares of grapes are grown organically, which is a 4.5 % share of the global grape growing area. The effects of organic and biodynamic viticulture on soil quality and soil microbial diversity in comparison to conventional or integrated viticulture are very controversially discussed. The aim of this review is to summarize the outcomes of scientific trials performed on organic and biodynamic viticulture worldwide and hence to characterize the effects of the respective management systems on soil properties and soil microbial diversity.

Material and methods ‐ Literature searches of peer‐reviewed published literature were conducted to find studies investigating organic and/or biodynamic viticulture which deal with soil properties and biodiversity of the soil microbiota. Only field trials that used replicates of management treatments with representative plots or studies that used a representative number of samples were included in the review in order to avoid bias in individual studies.

Results – For describing the effect of organic and biodynamic viticulture on soil quality and microbial soil life, authors concentrated on reporting the effects of the respective management systems on biological activity of the soil, macronutrient supply, copper levels in the soil and soil microbial diversity. In several studies an increase of the biological activity of the soil under organic management is reported. Biodynamic and organic vineyards show a higher cumulative soil respiration, a higher content of microbial biomass C and a higher ratio of microbial biomass C to organic C, especially after conversion. The contents of organic C, total N, P and S as well as Cu do not differ among treatments in most of the trials. Fungal endophyte colonization of the roots of grapevines under organic management, species richness, diversity indices and arbuscular mycorrhizal spore abundance were higher compared to conventional management. No difference in fungal species richness was assessed in soils of biodynamically and conventionally managed vineyards in New Zealand. In contrast, management systems differed in the types of species present and in the abundance of the single species. These results are supported by a recent study from Germany, where a fungal community shift under organic viticulture was observed without affecting fungal species richness. Bacterial biodiversity was increased in topsoil under organic management compared to conventional viticulture. The links between soil microbial diversity, biological activity of the soil and macronutrient supply will be discussed. Their importance for organic and biodynamic viticulture will be discussed.