速成堆肥の製造に関する研究 : レンゲとオガクズ混入牛糞の混入割合が堆積中の炭素率の変化に及ぼす影響

The effect of the mixing ratio of Chinese Milk Vetch (Astragalus sinicus) and barnyard manure containing sawdust on the carbon content, nitrogen content and carbon-nitrogen ratio in compost was investigated in the Honjo Farm attached to the Department of Agriculture, Shimane University by adding Chinese Milk Vetch to the barnyard manure containing sawdust as a nitrogen source for the purpose of effectively utilizing barnyard manure containing sawdust as a raw material of artificial farmyard manure. Chinese Milk Vetch and the barnyard manure containing sawdust were mixed in various ratios on a raw weight basis to prepare the first group (30 : 0), the second group (20 : 10), the third group (10 : 20) and the forurth group (0 : 30) and the respective groups were packed in a columnar pot by 30 kg to be matured for 73 days. Turning was performed 14 days after packing in all of the groups and the temperature in compost was measured every day, and the carbon and nitrogen contents were analyzed at every two weeks.
As a result, compost temperature was high at an initial stage as the mixing ratio of chinese Milk Vetch increased and reached about 50 ℃ on the fourth fifth days in the first and second groups but only a slight rise in temperature was shown in the group 4 and, with respect to the change of the carbon content, sudden reduction was shown at an initial stage but no marked change was confirmed in the test groups. With respct to nitrogen content, a tendency to reduce at the initial stage was confirmed in the first group but a tendency to gradually rise during the test period was confirmed in the test groups. The carbon-nitrogen ratio was not markedly changed in the first and second groups but gradually lowered in the third and fourth groups. From the foregoing, it was suggested that the barnyard manure containing sawdust was not necessarily suitable for a raw material of artificial farmyard manure but could be effectively utilized by adding about 30% of Chinese Milk Vetch.