Soil Quality in Vineyards - Soils for Fine Wines - page 203

Examples of Potential Nitrate Leaching from Vineyards
Mean NO 3
Concentration in

Table 7.6

Winter Rainfall Winter Quantity of

Drainage a N Leached b

Drainage Water over 4 Months Evapotranspiration

(mg N/L) (mm) (mm) (mm) (kg N/ha)

10 150 175 c 0 0

250 175 75 7.5

350
150

175
100 d

175
50

17.5
5

250 100 150 15

350 100 250 25

a 1 mm

1 L/m 2
b These quantities would increase in proportion to an increase in the drainage NO 3 concentration.
c Vines with a cover crop
d Vines without a cover crop

Summary Points

7.7

In this chapter, factors that affect the soil quality in vineyards were discussed. The
major points follow.
■ Good soil quality depends on maintaining a favorable physical, chemical, and bi-
ological environment for the growth of vines and beneficial soil organisms.
■ Important physical properties are infiltration rate 50 mm/hr; minimal com-
paction, especially in the subsoil (soil strength 2 MPa at the field capacity); an
AWC 60 mm/m for a sandy soil and 120 mm/m for a clay loam; and an air
capacity 10%.
■ The supply of macro- and micronutrients should be adequate, with no element
imbalances or toxicities. Vine nutrition can be assessed by soil testing , for exam-
ple, for pH, because of its effect on exchangeable Al 3 (damaging to roots), and
for the availability of the micronutrients Fe, Mn, Zn, Cu, Mo, and B. Plant anal-
ysis is most useful for measuring N, P, K, Ca, and Mg.
■ Soil salinity should be monitored in inland areas and where irrigation is used. EC
is a simple measure of the total concentration of salts in the soil or in water. The
salinity hazard of water is low at an EC 0.25 dS/m (ca. 160 mg/L), but very
high at an EC 2.25 dS/m (ca. 1440 mg/L). Irrigation water is concentrated
two- to threefold in the soil as a result of evaporation. A leaching requirement
should be used to maintain a salt balance in soil being irrigated.
■ Bulk soil salinity is measured using electromagnetic radiation techniques, as with
an EM38. This kind of instrument should be calibrated against EC measured on
soil extracts, such as the saturation extract EC e or the 1:5 soil:water extract (used
in Australia). A soil with an EC e 4 dS/m is considered saline .
■ High Na and Cl concentrations in grape juice are undesirable for wine making.
Vitis vinifera varieties are moderately sensitive to salinity; where salinity is a prob-
lem, rootstocks such as Ramsey, Schwarzmann, 140Ru, Rupestris du Lot, and
99R should be used.