Estimating the spatial variability of water needs using the soil ECa, rooting depth, and fruit developmental stage in sweet cherry orchard

In the future, agriculture has to produce more fruit with less water. Therefore, irrigation management must be adapted to the actual water needs of fruit trees aimed at more sustainable irrigation scheduling. In a semi-humid climate, spatially resolved analysis of water deficit was carried out in a sweet cherry orchard (Prunus avium L. 'Regina'). A weather station daily recorded the meteorological data. The apparent soil electrical conductivity (ECa) was measured at field capacity with a Wenner array. In 20 locations with varying ECa, the root depth was measured to contrast the field-uniform root depth commonly used in water balancing according to the FAO guidelines. Actual evapotranspiration was estimated daily considering the crop coefficients, soil water stress, and soil surface evaporation in low, medium, and high ECa. Consequently, two ETa cases and subsequent water balance were compared for ECa regions: K-c timing according to the FAO and field-uniform root depth of 1 m (WBRF), and considering the Kc timing according to the measured fruit developmental stage and root depth (WBRD). The total available water content in the root zone was positively correlated with the ECa (r=0.68). In parallel, ECa was negatively correlated (r=-0.72) with the root depth pointing to the adaptation capacity of the trees, which may partly jeopardize the spatial soil water content variability. The WBRF revealed 11.45 mm more water use compared to WBRD, in low ECa regions during harvest. Although no water deficit stress was displayed by the two models in high ECa areas, WBRD differed by approximately 28.6 mm from WBRF during the harvest period. Consequently, the water balance adjustment considering the rooting depth and fruit developmental stages can lead to more sustainable fruit production in cherry orchards.

Automated summary

In the future, agriculture needs to produce more fruit with less water. This study focused on adapting irrigation management to the actual water needs of sweet cherry orchards, aiming for more sustainable irrigation scheduling. The researchers found that adjusting the water balance by considering the rooting depth and fruit developmental stage can lead to more sustainable fruit production.