PARENT SESSION
Poster Session #74: Agroecology.
Friday, August 9. Presentation from 8:00 AM to 9:30 AM. Exhibit Hall B & C, TCC

Water redistribution by transverse hydraulic conductance in a vineyard ecosystem.

Smart, David^*,1, Carlisle, Eli¹, ¹ University of California, Davis, CA

ABSTRACT- Hydraulic lift by roots can raise water from deep, moist soil zones in an upward direction to drier surface soils. Limited information also suggests that precipitation onto surface soils can be immediately and rapidly redistributed to depth by either hydraulic conductance through roots or channeling along roots. Our question in the current investigation concerned the possibility that water can be redistributed in a transverse direction out of the drip irrigation wet-up zone to drier soils in a vineyard. In other words, from one side of a grapevine through the trunk to the opposite, dry side of the vine. We used water labeled with deuterium oxide and found that water is rapidly redistributed from the drip wet-up zone to roots in surface soils on the opposite side of the vine. We used an isotope mixing model to estimate that 6-10% of the water in these surface roots was supplied from the wet-up zone within 24 h. It is estimated that over 150,000 vineyard hectares are currently grown in California using micro-, or drip irrigation systems. Such systems concentrate resources like water and nutrients in a very restricted soil zone, but our results suggest that redistributed water probably sustains roots in dry soil zones as well.

KEY WORDS: hydraulic lift, roots, vineyard