Abstract
Cultivation of paddy rice by applying the whole fertilizer as basal dressing in the nursery box and planting sparsely is a low cost and labor-saving cultivation technique. The number of nursery boxes per unit area can be reduced by sparse planting, but the amount of fertilizer per nursery box must be increased when combined with application of whole fertilizer as basal dressing. With the increase in the amount of fertilizer in the nursery box, there is concern about the influence on the growth and yield. This study was conducted using “Asahi-no-yume” in Tatebayashi city, Gunma prefecture. The fertilizer was “Naebako-makase” (NK301-100). The plant density in the paddy field was 11.1, 18.1, 24.2 hill/m2 in the sparse, medium and dense plots, respectively. We decided the amount of fertilizer per nursery box from the amount of nursery boxes in the paddy field and the percentage of fertilizer to reduce. In 2010 and 2011, to reduce the fertilizer 50%, we applied to the sparse, medium and dense plots, 1280 g, 800 g and 580 g fertilizer, respectively, and in 2012, 1400 g, 800 g and 650 g, respectively. We carried out the cultivation experiment in the paddy field for three years from 2010. In addition, we applied chemical fertilizer by spilt application in the standard plot. As a result, the sparse plot which had the most fertilizer per nursery box, gave comparable results compared with the medium (standard) plot for growth and yield, and was not considered a problem for practical use.
