Agriculture Reference
In-Depth Information
Figure 4.23
Steepmoundingofagranite-derivedsoilinanewvineyardintheWestern
CapeProvinceregion,SouthAfrica.
10 and 40 m, depending on the depth at which the pipes are laid and the soil's
hydraulicconductivity.Subsoildrainagewithpipeshasbeenused,forexample,
in Pomerol, France, the Tuscany region, Italy, and the Carneros subregion of the
NapaValley,California.Althoughtheinstallationofsubsoildrainageisexpen-
sive,itisoftenworththeinvestmentwhenamortizedoverthecommerciallifeof
a vineyard.
SubsoildrainageissometimesnecessaryinirrigatedvineyardsoftheRiverina
regioninAustraliatopreventsalinegroundwaterrisingintotherootzone.In
some cases, groundwater pumping and discharge into evaporation basins may also
berequired.
Leaching, Salinity, and Sodicity Control
Irrigation supplies both water and salts to vines. Because most of the applied water
is transpired by the vines and only some of the salts absorbed, the salt concentra-
tion in the soil gradually increases as it passes through repeated wetting and dry-
ing cycles. This salt increase can be monitored by measuring
EC
at the bottom of
therootzone,preferablybyobtainingasampleofthesoilsolutionwithasuction
sampler,suchastheSoluSAMPLER(igure4.24).Signiicantsaltaccumulation
occurs even with low
EC
irrigationwater(<0.8dS/m),buttheproblemisworse
