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Alan Uchrinscko

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Geology, Nitrogen & Winemaking

by Alan Uchrinscko » Sat Apr 29, 2006 8:14 am

Anyone want to take a stab at this one:

"Soil organic content has a marked positive effect on the nitrogen content of the must, and hence on wine style"...
http://www.wynboer.co.za/recentarticles/1200geology.php3

What effect does Nitrogen have on wine style?
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Howie Hart

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Re: Geology, Nitrogen & Winemaking

by Howie Hart » Sat Apr 29, 2006 9:24 am

The only thing I can think of is the amount of nitrogen compounds present in the must effect the yeast. For example, in '04, I made a Cab Franc from grapes grown in the Niagara Peninsula and I used a yeast strain that required a high amount of nitrogen. I was supposed to supplement the nitrogen content by using yeast nutrient, but failed to do so, as I was unfamiliar with the yeast strain recommended to me. As a result, the yeast, being nitrogen starved, went through a reduction reaction and produced mercaptans, very foul smelling aromatics. I have no idea how this relates to geology, but there is a connection between nitrogen and winemaking. Perhaps the same grapes from a different terroir would have had enough nitrogen, but adding the yeast nutrient or using a less nitrogen dependent yeast strain would have also solved my problem.
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Thomas

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Re: Geology, Nitrogen & Winemaking

by Thomas » Sat Apr 29, 2006 9:42 am

Howie is dead right.

The proper level of nitrogen in the soil is crucial to the nutrition of the grapes. Poor nutrition can lead to bad fermentations. In fact, hydrogen sulfide and mercaptan can often be traced to poor nitrogen levels in the must.
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Alan Uchrinscko

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Re: Geology, Nitrogen & Winemaking

by Alan Uchrinscko » Sun Apr 30, 2006 1:43 am

Thanks everyone for your insightful responses.

John,

I've seen the yellow leaves many times but I never knew esactly what caused them...

Alan
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