Abstract
In the mountain valley Martelltal (Bolzano province, Italy), a classical area for strawberry cultivation in high mountain areas, the interest for organic production is increasing. Due to the very limited availability of land, strawberries have been grown very intensively and with very narrow crop rotations. In order to understand soil heath in these areas, a survey was carried out in four long term strawberry fields which had been subjected to different crop rotation in the past. Three of them have been intensively cultivated with strawberry since more than 25 year, whilst one since only 7 years. A greenhouse growth test on soil samples from the selected fields was performed in greenhouse using young strawberry plants. Plant growth parameters and root fungal colonization were evaluated aiming at investigating the effect of different crop rotations on plant health. Plants grown on soil samples coming from the three older strawberry fields did not differ in plant growth and strawberry production, although one of them had been left fallow over the last 4 years. Conversely, plants grown on soil samples taken from the more recent strawberry cultivation (7 years), showed significantly higher plant vigour and production than those grown in soil from the other fields. In addition, strawberry plants of the more recent specialized cultivations also showed the highest diversity of root-colonizing fungi and a slightly, though not significantly lower incidence of the agents of strawberry root rot (spp., like fungi and binucleate) as compared those of the fields cultivated with strawberry over a long term. Findings of this study suggest that leaving a field fallow for four years does not result in a significant modification of fungal community composition in long-term strawberry cultivations. Therefore, in rural areas devoted to high quality crops, which play a key role for local economy, rotation and cropping practices aiming at preserving soil diversity should be planned since the beginning in both conventional and organic agriculture.