Physical structure and chemical quality of waterlogged soils in an Italian kiwifruit orchard

In the last years, kiwifruit vines have been affected by the kiwifruit vine decline syndrome (KVDS), which is damaging the Italian kiwifruit industry. We hypothesize that soil compaction and asphyxia could have a priming effect in the emergence of KVDS. On this basis, we characterized soils from three areas of a kiwifruit orchard in Latina (Lazio region, Italy): one with vines showing severe symptoms of KVDS (K_field), another with vines having intermediate symptoms (I_field), and the last with healthy vines (C_field) as control. Soils were characterized physically showing a gradient of compaction, clay/silt content and water content, with the highest values in K_field and the lowest in C_field, while soil chemical properties were not significantly different. The soil gas redox potential after the onset of waterlogging was significantly lower in K_field than in the other treatments. This parameter indicates reducing soil conditions and it is negatively correlated to oxygen concentration. Higher CO₂ and CH₄ concentrations, two indicators of anoxic soil conditions, were found in K_field, compared to C_field. The microscope analysis of the soils showed that K_field soils had fewer macropores than C_field, whose number is positively correlated to the oxygen content. Implementation of soil and water management strategies could improve kiwifruit roots growth and vine productivity, and also help reduce symptoms of KVDS in impacted vineyards.