サイレージの調製法に関する研究 (第18報)材料作物に対する窒素施肥量がサイレージの品質におよぼす影響

To find out the extent of influence of N-applied forage crops on the silage fermentation, a continued experiment of the silage-making was made. The oats. Avena sativa L., was cultivated in the field of clay loamy soil, which parceled out into three lots under the same conditions except the levels of N-application were 0(N-0), 10 (N-10) and 20 kg N/10 ares (N-20) respectively (Table 1). Of each sample of the green oats at the three growth stages (leafy, April 17, booting, April 24 and heading, May 1), the influences of nitorogen application on chemical composition was tested, and also the ensilability of the green oats at the heading stage was investigated. The results obtained were summarized as follows: l) As the level of N-application increased, the content of protein and carotene became high, while that of soluble carbohydrated decreased. 2) The fermentative quality of all silages was not satisfactory. The score by the FLIEG'S appraisal method was 48 in the N-10-, 42 in the N-10- and 40 in the N-20-silage. It was suggested that the quality of silages decreased as the level of the N-application increased. 3) The content of nitrate nitrogen of silage became higher as the level of N-application increased. Ten to 29 percent of nitrate nitrogen in the ensiled green oats was removed during the ensiling process. 4) The digestion trials of these silages, carried out by feeding a goat, revealed that the digestibilities of organic matter, crude protein and crude fiber, and TDN (in percent) of dry matter were 71.2, 57.9 and 82.9, and 65.0％ in the N-0-silage; 72.4, 61.9 and 79.1, and 66.3％ in the N 10 sileage; 60.0, 47.9 and 62.3, and 60.0% in the N-20-silage. 5) The nutrient yields, DCP and TDN, were higher at the high level than at the low level of N-application, but it was suggested that the standard level, 10kg N/10 ares, was most beneficial. The results obtained with green oats agreed in principle with those obtained in Italian ryegrass experiments.