Under wine fermentation conditions, a lack of available nitrogen has also been shown to limit yeast growth and fermentation. If it is added at the end of fermentation, it will have no effect on the H 2 S produced. During the past vintage we added DAP to several wines within 24 hours after an H 2 S off-odor was noticed. In all cases the off-odor disappeared and did not reappear. Nitrogen supplementation therefore may also help to produce wines with cleaner, more characteristic aromas.
More samples are necessary to make specific recommendations.
However already this limited overview shows that in most years the available nitrogen in New York musts is critically low and likely causes reduced sulfur off-odors and incomplete fermentations which could be avoided with additions of nitrogen nutrients to the must.