Se. Spayd et al., NITROGEN-FERTILIZATION OF WHITE RIESLING GRAPES IN WASHINGTON - MUST AND WINE COMPOSITION, American journal of enology and viticulture, 45(1), 1994, pp. 34-42
Nitrogen (N) fertilizer was applied to White Riesling grapevines throu
gh the drip irrigation system at rates of 0, 56, 112, or 224 kg N/ha f
or three years. Attainment of 21% soluble solids was delayed as rate o
f N fertilization increased. Juice and wine titratable acid and organi
c acid concentrations did not vary due to N fertilization rate. Juice
pH increased linearly with increasing N fertilizer rate and was relate
d to juice titratable acid and ammonia concentration. Juice potassium
concentrations were not affected by N fertilizer rate, while wine pota
ssium concentrations increased linearly with increasing N. Wine pH inc
reased with N fertilizer rate and was related to tartrate and to a les
ser extent to potassium concentration. Juice total N, ammonia, free am
ino nitrogen, arginine, and proline concentrations increased linearly
with increasing N fertilizer rate. Wine urea concentrations after four
to six years of storage at 15-degrees-C was low (highest concentratio
n was less than 10 mg/L), but increased linearly with increasing rate
of N fertilization.