Nitrogen Utilization Rate and Nitrogen Contribution Ratio of Fertilizer in the Two-rowed Barley Cultivar ‘Haruka Nijo’ for Food

Abstract

¹⁵N-labeled ammonium sulfate was used as fertilizer to construct a labor-saving fertilization system for two-rowed barley for food, and the soil fertility in barley plants and the content, contribution ratio, and utilization rate of nitrogen for each fertilization were clarified. The nitrogen content of the basal dressing, topdressing at tillering stage, and topdressing at panicle formation stage was 1.52-1.80 g m^-2, 2.58-2.60 g m^-2, and 2.62-3.25 g m^-2, respectively. The nitrogen content from soil fertility was 4.90-5.82 g m^-2, and was higher than that from each fertilizer application. The nitrogen contribution rate of grain containing nitrogen from the basal dressing, topdressing at tillering stage, and topdressing at panicle formation stage was 12-14%, 20-21%, and 21-27%, respectively. The nitrogen contribution rate of soil fertility was 40-45%, and was the highest, suggesting the importance of soil fertility. The fertilizer nitrogen utilization rate for basal dressing, topdressing at tillering stage, and topdressing at panicle formation stage was 30-36%, 65%, and 66-81%, respectively. The nitrogen composition of barley grain during the maturity period was 86-87%, within which 54-60% was derived from the fertilizers applied. Fertilization of barley plant is a system applied during the first half of growth, and the nitrogen composition ratio of two-rowed barley at 54-60% fertilizer application was high. Therefore, in constructing a labor-saving fertilization system, a controlled availability fertilizer, from which nitrogen is eluted in the first half of growth, should be selected to ensure stable yield.