2022 Volume 57 Issue 3 Pages 145-153
This study aimed to clarify the work performance of harvesting corn grains by the axial-flow combine equipped with a corn header, because the sale of corn headers began in Japan in response to the growing interest in corn grain production in upland fields that were converted from paddy fields. An evaluation of the harvesting operation accuracy conducted in the forage field of NARO revealed lower head losses when a corn header was used as compared to when a reel header was used, whereas the total threshing losses, the damaged grains, and impurities remained similar for both the headers. The effective field capacities measured in the upland fields converted from paddy fields were in the range of 42–59 a h-1 under weed-free conditions, which are 1.2–1.6 times higher than those reported in a prior study involving the use of a reel header. This effectiveness could be estimated based on corn grain moisture content of less than 30%, in contrast to less than 25% recommended by combine harvester manufacturers, for harvesting using a reel header. We believed that the 5％ increase in the upper limit of the corn grain moisture content, when harvesting using the corn header, can alleviate the risk of stem lodging during Japanese typhoon season. This is because it allows harvesting to be advanced by approximately 10 days as compared with the conventional schedule using the reel header, which depends on the cultivation condition. However, compared with other grains, damaged corn grains and impurities were observed when harvesting using either the corn header or the reel header. Therefore, studies focusing on factors such as variety selection and improvements in threshing and separation methods to reduce damaged grains and impurities should be conducted in the future.
