Thursday, May 24, 2012

Mixed rainfall outlook for southeastern Australia

The Australian Bureau of Meteorology is reporting a drier than average winter for South Eastern Australia. This itself is not an issue for horticulture. As long as there is enough soil moisture for grass germination, covercrops will grow and nutrients will cycle through the top soil.

The main concern is for horticultural crops if lower than median winter rainfall occurs over June, July and August. Winter rain is needed so the subsoil will be flushed of sodium that has built up over last summers irrigation season.

The BOM says in its 23/5/2012 update;

probability of exceeding median rainfall - click on the map for a larger version of the map

"The southeast Australian outlook for winter 2012 shows the following:
A drier season is more likely for southwest NSW, northwest Victoria and much of SA. This outlook is mainly influenced by warmer than normal waters in the Indian Ocean. 
Over much of southern and central SA, parts of northwest Victoria, and southwest NSW the chances of receiving above normal rainfall are between 30 and 40%. In other words, the chance of below normal rainfall is between 60 and 70%."

Experience from dry seasons, notably Vintage 2007 and 2008, shows that soil moisture during spring is critical for vine health and in some respects quality. If vineyards are water stressed too early in their life cycle the results are detrimental to both yield and grape quality.

Growers should consider a drought strategy if winter and then spring does prove to be dry.

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