Agriculture Reference
In-Depth Information
Figure 4.20
AstrawmulchinvinerowsintheBarossaValleyregion,SouthAustralia.
25tofdrymatter)isrequiredforanundervinestrip50cmwideand5cmdeepat
2500 vines per hectare.
Mulches have several beneficial effects, including
• Shadingthesoil,therebyreducingsoilevaporation
• Suppressingweeds,therebyreducingtheneedforherbicides
• Preventingraindropsfromimpactingdirectlyonthesoilsurface,thereby
maintaining soil structure and water infiltration
• Encouragingbiologicalactivity,especiallyofearthworms,throughthe
added organic matter and by keeping the soil moist
The effect of mulch on soil evaporation is more important while the vines
are dormant and before the canopy begins to develop in spring and early sum-
mer. Also, the row spacing is an important factor because this affects the degree of
shadingofthesoilbythecanopy.Whentheproportionofshadedgroundisless
than10%,soilevaporationmaycompriseasmuchas70%oftotalvineyard
ET
.
This is the period when mulches can have a significant effect in reducing waste-
ful losses of water through soil evaporation. However, as the canopy develops to
shade40%ormoreoftheground,soilevaporationisamuchsmallerfraction
of total
ET
, especially for drip-irrigated vineyards when it can be as low as 10 to
20%.Nevertheless,infurroworloodirrigatedvineyardsevenwithmaturecano-
pies,soilevaporationhasbeenestimatedtobeasmuchas41%(furrow)to77%
(lood)of
ET
(Kooletal.,2013).
