Organic Highbush Blueberries (Vaccinium corymbosum L.) Production: Long-Term Effect of Cultivation System and pH Regulation on Plant Growth, Yield and Root Distribution and Biomass with Two Cultivars

Summary

In recent years, an increasing market for blueberries has developed in Switzerland. Blueberries are well suited for organic production because few disease and insect pests are currently found under Swiss conditions. Soil conditions present the greatest obstacle to blueberry cultivation in that Swiss soils are often too alkaline and have low soil organic matter content. During a nine-year (1998–2006) field
experiment on an alkaline soil, we tested the feasibility and plant performance of three peat-free cultivation systems (deep ditch, flat ditch, raised bed) and two
acidification methods (sulfur or citric acid versus an untreated control). Cultivars were ‘Bluecrop’ and ‘Reka’. The vegetative growth of the bushes was not
significantly affected by the cultivation systems. However, the deep ditch system obtained produced significantlyhigher yields (6.04 kg) compared with the raised bed
system (5.13 kg). The yield in the flat ditch system (5.96 kg) was not significantly different from either of the other two systems. Lowering pH levels in the substrate
sufficiently (pH<4.8) was achieved only with sulfur (30 g/plant/y). The acidification treatments affected the shrub development and yields significantly. Compared with
the untreated control, shrub volume (+43%) and accumulated yield (+55%) were greater in the treatment with application of sulfur. With the citric acid treatment, shrub volume and yield were increased by 12% and 9%, respectively. Root growth and biomass showed no differences between the cultivation systems. A flat ditch with pine sawdust combined with acidification by sulfur offers good plant growth and yield performance and is cheaper to install compared with deep ditch. Based on these results, we have recommended this cultivation system with sulfur applications
for commercial blueberry production in regions with alkaline soils in Switzerland since 2005.