Mark Krasnow,* Allison Haywood, and Danielle McMillan
*Thoughtful Viticulture Ltd., PO Box, 312, 7201, New Zealand (thoughtfulviticulture@gmail.com)

A two-year trial was established in two regions of New Zealand where dripline was buried 30 cm off the vine trunk and 30 cm below the surface. Lines were specifical­ly designed for subsurface use, with vacuum breakers to prevent soil being sucked into the line and root intrusion protection built into the drippers. In Hawkes Bay, the trial was carried out in Syrah vineyards and in Marlborough, the trial was carried out in Sauvignon blanc vineyards. The trials were set up as a split plot design in a single irrigation zone. All vines received the same irrigation amounts, fertilization, and cultural practices. Applying irrigation below the surface and off the vine row did not consistently affect vine canopy development, yield, berry weight, or fruit composi­tion. Effects on vine water potential were mixed. There was a clear and significant reduction in weed growth in the vine row when water was applied below ground and off the vine row. Weeds could still access applied water, but grew where they could be mowed with a normal midrow mowing pass, rather than necessitating a slow, undervine weeding pass with specialized equipment. Other trials have shown a 30% water reduction with no negative effect on yield, though that was not part of the present study. Subsurface irrigation offers several benefits, including moving weeds to an easier-to-control area, reducing damage to irrigation lines and infrastructure by machinery and grazing animals, and offering the potential of increased water efficien­cy, especially if lines are buried deeper than the 30 cm in the present study, so weeds could not access the applied water.

Funding Support: New Zealand Winegrowers