Agriculture Reference
In-Depth Information
of rainfall and potential
ET
(
PET
),providedthatacropcoeicientis
used to adjust the
PET
according to the vineyard's stage of growth and
canopy cover.
12. Both RDI and PRD are most effectively practiced with drip irrigation,
whichcanbedeliveredabovegroundorbelow(bysubsurfacedrip
irrigation)throughsuitableemitters.Othermethodsincludemicrojets,
minisprinklers, overhead sprinklers, flood, and furrow irrigation. The
last two are the least efficient in terms of water delivery but the cheapest
to install and operate.
13. Mid-row cover crops and under vine mulch moderate soil temperatures
and affect soil water storage and biological activity. Permanent grass
swards compete with vines for soil water and on high-potential sites in
higher rainfall regions can help to control excess vigor. They also protect
soil from erosion.
14. Drainage is determined not only by land slope but also by soil texture
and structure, especially of the subsoil. Poor drainage can lead to
waterlogging,withconsequentiallyundesirableefectsonrootgrowth
and soil microbial activity. Drainage can be improved through the
installation of perforated pipes at depth, provided the water collected
can be moved offsite. Pumping may be necessary to keep groundwater
below 2 m depth, especially if the groundwater is saline, because such
water can be drawn to the surface by capillary rise.
15. Somedrainage,calculatedfromtheleachingrequirement(
LR
),is
essential to prevent salt buildup in irrigated soils. The
LR
increases as
theelectricalconductivity(
EC
),asurrogateforthesaltconcentration
of the water, increases. Preferably the
EC
of irrigation water used for
grapevinesshouldbe<0.8dS/m.
