Nutrient Management Research Database

The timing and amounts of nitrogen fertilizer applications are critical in optimizing nitrogen uptake to avoid leaching below the root zone and possible groundwater contamination. This study quantified the uptake of nitrogen and potassium as a function of winegrape variety, rootstock, and location from 1997-1998. This research was designed to determine fertilizer use efficiency in four different vineyards (two Chardonnay, two Cabernet Sauvignon) at different locations in California. Nitrogen and potassium budgets were to be determined on those vines and compared to more conventional means to determine vine nutritional status. Nitrogen labeled fertilizer was applied to six, individual vine replicants for each rootstock at all locations two to four weeks after bloom. The amount of nitrogen applied was dependent on yield estimates for each site. Tissue samples were taken from each site to determine nutrient status to develop nitrogen and potassium budgets for each site. Results show that across vineyards, the amount of nitrogen removed by the vines was equal to between 1 to 1.5 kg nitrogen per tonne fruit, and in 1997 only, 2 to 3 kg potassium per tonne of fruit.

• During the 1997 growing season, nitrogen fertilizer was applied to vines two to four weeks after bloom grafted to various rootstocks at four vineyard locations.
• Vineyard nitrogen application varied, as applications were based on yield estimations from each site;
  • applications ranged from 30 to 45 kg nitrogen/hectare. Two Chardonnay and two Cabernet Sauvignon vineyards were tested.
• Sixrootstocks were used:
  • 5C
  • 110R
  • Freedom
  • 3309C
  • 140Ru
  • 1103P
• Tissue samples were collected in 1997 and 1998 to monitor nutrient status and yields were measured at each site. Leaf and berry analyses were done to determine total nitrogen fertilizer uptake by each vine and potassium levels to calculate both nitrogen and potassium budgets.

• Results indicated that the amount of nitrogen in the clusters at harvest, the leaves, and the pruning canes ranges from a low value of 23.7 to a high value of 64.5 kg nitrogen/hectare over the two growing seasons.
• The amount of nitrogen removed from the vineyards via harvesting fruit ranged from 23 to 38 kg nitrogen/hectare; in 1997, the amount of potassium removed from the vineyards via harvesting fruit ranged from 31 to 72 kg potassium/ hectare.
• These numbers are equal to 1 to 1.5 kg nitrogen per tonne of fruit and 2 to 3 kg potassium per tonne of fruit.
• Location and rootstock have considerable effect on nitrogen concentrations in the petioles and fertilizer use efficiency (FUE).
• When averaged across rootstocks, FUE was 10.3% at Carneros, 3.81% in Gonzales, 3.45% in Paso Robles, and 11.5% in Oakville.
• However, within each site, rootstocks made very little difference on FUE.
• It appears that vine growth drove the uptake of nitrogen fertilizer, with larger crop loads using more nitrogen and potassium.