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Relationship between soil temperature and N release in organic and conventionally managed vineyards

Davenport, J.R., K.E. Bair and R.G. Stevens. 2012. Communications in Soil Science and Plant Analysis 43:464-470


Soil temperature is a very easily measured parameter that influences nutrient availability in vineyards. We monitored soil temperature and plant-available nitrogen (N) in a study evaluating the potential of legumes as an interrow cover crop to supply N to Concord grape (Vitis labruscana Baily). Nitrogen sources used were hairy vetch (Vicia villosa subsp. villosa L.) and yellow sweet clover [Melilotus officinalis (L.) Lam] as green manure sources and either blood meal (in a certified organic vineyard) or urea (in a conventional vineyard) as soluble sources. Plant-available N was measured both continuously using ion exchange membranes (PRS™) and point in time by soil sampling at regular intervals; both were analyzed for nitrate (NO3) N and ammonium (NH4) N, although negligible concentrations of NH4-N were detected. PRS™ NO3-N concentration varied by treatments because of differences in the chemical composition of the N source. Soil NO3-N concentration reached a peak between 520 and 550 degree-days with no significant differences by treatment or site. These findings are similar to results from incubation and field mineralization studies of organic amendments and suggest that N availability from organic sources in vineyards can be predicted using a degree-day-type model.

Key Words

Nitrogen release, organic management, soil temperature