2007 Volume 76 Issue 2 Pages 171-180
We studied the possibility of introducing the single fertilizer application in an area of paddy rice culture by early planting and normal season culture in Gunma prefecture. The fertilizer was applied exclusively only to the nursery box to save labor. The seedlings were grown in the condition of pool raising, which is the standard method in Gunma prefecture. The commercialized fertilizer named "Naebako-makase" was used and a field experiment was conducted for 4 years. We found that the maximum of seedling-rearing period was 20 days due to spindly growth of seedlings by excessive dissolution of fertilizer, and injury by a high fertilizer concentration appeared sometimes after transplanting to the field. However, over-3cm-depth-flooding reduced the injury, and later these problems were almost solved by improving the fertilizer. Growth after rooting showed a pattern typical for that caused by the conventional controlled availability fertilizer. Early growth was slightly reduced and stem number was decreased. However, the percentage of ripened grains and productive stems was increased. The application of fertilizer with 34-40%-reduced nitrogen resulted in equal or higher yield and quality than in the standard fertilizer application. Therefore, we considered that this method could be introduced to the area of early planting and normal season culture in Gunma prefecture.
