Innovative spatio-temporal irrigation strategies improve soil-water management in kiwifruit orchards

Kiwifruit has high water-requirements, but it can also suffer from poor soil oxygenation and structure, which is worsened by improper irrigation practices. In the Mediterranean area, frequent and relatively high levels of irrigation are necessary to meet the water need of vines. Irrigation water is generally distributed across a confined soil volume, exacerbating the impact of irrigation on soil properties. An innovative irrigation system with four independent drip lines was implemented in a Mediterranean kiwifruit orchard to achieve a dynamic spatio-temporal distribution of irrigation water. This system was compared with a conventional two drip lines irrigation system. The daily irrigation requirement was split and distributed alternately to different root zones, according to soil water availability, to satisfy the vines’ water needs and yet allow the soil to oxygenate. The influence of different irrigation water distribution strategies on root water-uptake dynamics was evaluated through the continuous monitoring of soil water content at different depths. The different irrigation systems were compared in terms of soil oxygenation and respiration. The preliminary results showed that the dynamic management of irrigation volumes allowed some soil zones to dry out and root water uptake to shift predominantly toward the irrigated soil zones. Relative soil oxygen concentrations were found to be lower (close to critical levels of ~10%) in the irrigation system with two drip lines. The dynamic distribution of irrigation water over time and space could be an effective way of addressing the increasing need for precision irrigation in kiwifruit, ensuring improved soil conditions, root development and uptake activity.