Influence of reducing nitrogen application rate with coated fertilizer in combination with irrigation water saving on yield of east Indian Lotus (Nelumbo nucifera) and nitrogen effluent
2007
Orimoto, Y.(Ibaraki-ken. Agricultural Center, Kasama (Japan). Horticultural Inst.) | Takei, M.
East Indian Lotus (Nelumbo nucifera) is mainly cultivated in the Lake Kasumigaura and Kitaura Basin in Ibaraki Prefecture, and the effluent nitrogen from the fields is considered one of the causes of nutrient enrichment of the lakes. Two experimental plots were set up to develop a method for reducing the nitrogen effluent: 1) a conventional plot, where 240 kg/ha/year of nitrogen divided into three portions of 80 kg/ha a basal dressing with 2 top-dressings-was applied and an irrigation gate was controlled manually to keep the soil surface flooded throughout the year to prevent rhizome rot; 2) a low-input plot, where the nitrogen rate was reduced to 29% of the conventional rate with a single application of coated fertilizer as the basal dressing, and the irrigation gate was controlled automatically with an auto-irrigator for water saving. The yield and nitrogen balance of each plot were examined. The yield of East Indian Lotus at the low-input plot was almost equal to that at the conventional plot. The net nitrogen input to the low-input plot during the crop period (341 d) was 210 kg/ha, 30% less than that to the conventional plot. Thus, the effluent nitrogen from the low-input plot during the crop period was 68 kg/ha, 41% less than that from the conventional plot. The decrease in effluent nitrogen at the low-input plot was due mainly to the decrease in the amount of surface drainage as an effect of irrigation water saving.
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