1985 Volume 31 Issue 2 Pages 241-247
Whole crop maize was applied with fresh poultry manure at levels of 0, 5, 10, 15 or 20t/10a, respectively (Expts 1 and 2) or with urea at levels of 0, 10 or 20kg (or 30kg)/10a, respectively (Expts 3 and 4) as a basal dressing. They were harvested at silking or yellow-ripe stages and ensiled in bag silos for about 90 days. Nitrate nitrogen contents were determined both in whole crop maize and their silages, and effects of level of nitrogen fertilizer on nitrate accumulation in whole crop maize and disappearance of nitrate during ensilage were studied. The results obtained were as follows: 1. Nitrate nitrogen contents in whole crop maize harvested at silking stage increased with increasing amounts of nitrogen fertilizer and they reached the maximum of 0.22% of dry matter at levels of 15-20t/10a of poultry manure or 30kg/10a of urea. Nitrate nitrogen contents in yellow-ripe stage materials were entirely much lower than those in silking stage irrespective of levels of nitrogen fertilization. 2. In all silking stage silages except for the controls in each experiment, nitrate nitrogen contents were more than about 0.1% of dry matter. The rates of nitrate disappearance in silages made from materials containing relatively high levels of nitrate nitrogen (more than 0.19%) were 21.1-54.5%. 3. Most of silking stage silages were of fairly good quality characterized by a high lactic acid and a low acetic acid. Most of yellow-ripe stage silages also were of good quality, although contents of lactic and acetic acids were lower than those in silking stage. The qualities of silages were not affected by levels of nitrogen fertilizers.
