Sodium Azide as a Possible Nitrification Inhibitor in a Bentgrass Putting Green.

Abstract

 Nitrification inhibitors have been found to be beneficial in reducing nitrification of NH₄⁺ under field conditions.  Their use in sand-based turfgrass soils (eg:  putting greens) may help increase N uptake efficiency and reduce N loss via nitrate leaching.  The objective of this research was to examine a granular formulation of sodium (Na) azide, evaluating its effectiveness as a nitrification inhibitor.  This material has previously been shown to control soil borne pests (nematodes).  Studies were conducted in 2006 and 2007 at Grand National Golf Club in Opelika, Alabama on a sand-based ‘Dominant’ creeping bentgrass putting green.  A randomized complete block split plot design was used with 4 replications.  A granular formulation of Na azide was applied to the entire plot, and urea was applied to the split plot, at the N rate supplied in the Na azide. Urea was also applied alone. Treatments included 0, 5.6, 11.2, and 16.8 kg ai/ha of Na azide and 10.8 kg ai/ha urea (46-0-0).  Treatments were applied three times.  Soil samples (0-7 cm depth) were collected weekly for nitrate and ammonium (2M KCl extract) analysis.  At most sampling dates the addition of Na azide resulted in more 2M KCl extractable ammonium in the soil than in comparable urea-only plots.  Plots receiving only urea had a greater soil nitrate level, indicating that, in addition to its' nematicidal properties, Na azide may also offer use as a nitrification inhibitor.