Fig. 1. Storage time and treatment effects on headspace ammonia N concentrations. Regression equations fit for (a) dose of N binder (yucca extract) (0–14.9 mg/L) P = 0.0513, hour P < 0.0001 and (b) dose of urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) (0–152 µL/L) P = 0.0131, hour P = 0.0010.