Weed suppression and rice production by mechanical weeding and rice bran application work in organic rice cultivation system
2015
Miura, S. (NARO Agricultural Research Center (Japan)) | Uchino, A. | Nozoe, T. | Tazawa, J. | Yoshida, T. | Mizukami, T. | Jeong, B. | Wan, X.C. | Nakagawa, A. | Nakatani, K. | Shibuya, T. | Shiraishi, A. | Imaizumi, T. | Aoki, D. | Matsuoka, H.
From 2008 to 2013, field experiments were conducted to investigate the effects of organic rice cultivation on weed control and rice production at Tsukubamirai, Ibaraki, Japan. On the 10th and 20th days after transplanting, weeding was carried out with a riding-type weeder used in organic cultivation. From 2008 to 2010, rice bran was applied at each weeding time, but after 2011, it was applied at the time of transplanting and the first weeding. At the 6th week after transplanting, the weed dry weight after weeding was less than 2% compared with the weight when weeding on the interrow space was not conducted. However, for interhill space, the ratio varied between 6% and 35%, irrespective of weeding times. In particular, the weed dry weight at harvesting time greatly decreased after 2011. The average of the vacant hill rate after weeding was 6% throughout the trials. Plant height and leaf color (SPAD) were overall higher with organic than conventional cultivation; however, stem number tended to be lower. At the harvest time, the stem length was longer and the panicle number was significantly lower with organic cultivation. The average rice yield from organic cultivation was approximately 96% of the yield with conventional cultivation. It is concluded that the organic cultivation system used in this experiment is useful, because the weeding was effective and the rice yield was almost same as with conventional cultivation. It is also considered that an increase in panicle number is a more important factor to stabilize organic rice production.
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