Soil management as a key factor on vineyard behavior under semiarid conditions: effects on soil biological activity, plant water and nutrient status, and grape yield and quality

Aims: Viticulture practices linked with soil management, as cover crops and deficit irrigation, can help to regulate the vineyard behavior reducing in most cases plant vigor and modifying plant water and nutrient status, and as a consequence, grape yield and quality. Also, these practices can modify the soil biological activity mostly related to microbiome diversity and functionality. However, the overall effect of these agricultural practices depends on the soil water availability, the soil fertility, and the grape cultivar response. Under semiarid conditions, the intensity of competition for water and nutrients associated to cover crop practice can be a handicap for a regulation of grape yield and quality. Also, the effect of cover crops on soil biology under those conditions is poorly understood.

Methods and Results: In the present work we present results of a three year’s experiment studying the effect of combining natural green cover and deficit irrigation on soil microbiome, plant water and nutritional status, and grape yield and quality, in two contrasting genotypes. Changes in functional diversity of microbiomes were mainly associated with soil moisture and also changed throughout the vegetative period. Nevertheless, organic matter decomposition assays determined that the maintenance of the cover implies not only a higher rate of decomposition of organic matter but also that a less fraction of it is degraded, favoring the accumulation of carbon in the soil. Under our experimental conditions, green cover reduced plant growth and yield due to an excess of competition for water regardless of genotype. However, the cover crop had a positive effect on grape quality increasing sugar and phenolic content. 

Conclusions: 

The maintenance of cover crop in vineyards under semiarid areas such as the Mediterranean basin, generates a balance between positive effects such as the increase of organic C in the soil or the improvement of the quality of the grape and negative effects such as the decrease in the availability of water in the soil or the decline of yields.

Significance and Impact of the Study: This study has shown that more sustainable soil management practices can have clear positive effects on the environmental services of the agroecosystem and yield quality. These results open a window to explore this type of management in less studied environments such as the Mediterranean.