Pattern of water extraction by grapevines on two soils in the Waikato, New Zealand

Abstract

The water extraction patterns of grapevines ( Vitis vinifera) growing on two Waikato soils of contrasting properties were investigated. One soil, the Horotiu silt loam, consisted of silt loam on gravelly coarse sand. In this soil 50% of the water extraction occurred in the top 40 cm of soil. Extraction was highest in the top 20 cm and gradually reduced down to c. 70 cm depth which corresponded to the change from silt loam to gravelly coarse sand. The measured rate of water extraction by the vine corresponded to the predicted evapotranspiration rate up to 62 mm of extraction. Above 62 mm the measured rate of extraction from the soil fell off rapidly but all the vine's water needs were supplied by deep subsurface roots. The second soil studied, the Te Kauwhata clay loam, consisted of clay on a firm sandy clay pan at 110 cm. Fifty percent of water extraction occurred in the top 80 cm of soil. Water extraction was highest in the top 10 cm and also in the 70–110 cm zone. Water moving downslope above the pan was able to supply water to the plant.

Keywords:

• Vitis vinifera
• grapevines
• water use
• water extraction
• soil water
• roots
• soil morphology