Tuesday, February 24, 2009

Questions about Irrigation - Q&A

Post harvest vines.

When running short of water can you skip post harvest irrigations?

The short answer is no, it is not ideal given the type of dry seasons we have been having. Salt levels are building up in soils and vine vigour is generally decreasing. This is especially noticeable on hard, cracking clays.
The period between the fruit being picked and the leaf fall is important to the continued health of vines. This period;
  • Allows vines to recover from the season,


  • Allows replenishment of carbohydrate reserves,


  • Stimulates some new root growth and nutrient uptake,


  • Can help to flush salts from the soil if irrigation is applied in a large enough amounts to cause leaching.
Therefore you need to maintain healthy canopy in most cases irrigation is vital to do this.

Can we wait until next Spring before giving fertiliser?


Post harvest fertiliser is timed when the vines have a flush of new root growth. Root growth after harvest in dry soil is obviously going to be less than root growth in Spring, when the soil is moist.


While you could catch up with fertiliser in Spring, there is no guarantee weather conditions next Spring will be idea for growth. The last few seasons have been notable for a lack of Spring rainfall. We may be chasing our tail.


Also, post-harvest uptake of phosphorus important, and nitrogen is needed to repleshing amino acids and proteins to help with a good bud burst next year.

Conclusions.

In the shorter term,
  • Vines can tolerate a few poor post-harvest periods, but we have had two out of the last three years with very dry conditions, and many vineyards are at a point of low vigour.

  • Have we been running vineyards too lean during the droughts?
In the longer term,
  • Salinity management a key issue.

  • Consider your water supply, variety, rootstocks and location. Give priority for blocks that have the most potential to make you a return next year.
For more information visit:
http://waterandvine.gwrdc.com.au/

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