Agriculture Reference
In-Depth Information
Figure 4.22 A deep sandy loam
soilundervinesintheSt.Emilion
appellation, Bordeaux region,
France.Notethedeeprooting
and darker moist soil in the lower
profile.
Moist soil at depth
How to Improve Soil Drainage
Poor drainage that results in waterlogging can be caused by compaction and poor
soil structure. Box 2.6, chapter 2, discusses deep ripping to break up compacted
soil when a vineyard is established and methods of alleviating compaction in
the mid-rows of established vineyards. Apart from mechanical intervention, soil
structure and hence drainage can be improved by applying amendments such as
gypsum or by growing a cover crop. Grasses and cereals are most effective because
of their fibrous root systems, but the deep taproots of species such as chicory are
also effective. Mulches and composts also improve structure through the addi-
tion of organic matter that encourages earthworms and stimulates soil biological
activity.
Mounding or hilling soil under vine increases topsoil depth, thereby poten-
tially increasing the rooting volume. As shown in figure 4.23, mounds also help
to shed surface water more rapidly, especially on slopes. Subsurface drainage
may be needed to control waterlogging in flat land. In long-established regions,
porousclaypipes(calledtiles)werelaidinrowsatadepthbetween1and2mto
remove excess water and control the water table. For new vineyards, perforated
PVCpipe(“aggie”pipe)canbelaidbyalaser-guidedmachineonaprecisegradi-
ent without trenches needing to be excavated. The pipe spacing varies between
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