Comparison of Two High-Yielding Rice Varieties, Kita-aoba and Tachijobu, for Hokkaido, Northern Japan, and Effects of Swine Compost Application on the Growth and Grain Yield of Tachijobu

Abstract

The grain yield of two high-yielding rice varieties, Kita-aoba and Tachijobu, was examined in a field experiment by using swine compost at a rate of 0, 1 and 2 kg m^-2 and chemical fertilizer at a rate of 5.25, 7.35, and 10.5 g N m^-2 in 2010, and 5.25 and 10.5 g N m^-2 in 2011 (Exp. 1). The grain yield of Tachijobu was also evaluated by applying compost at a rate of 0 or 2 kg m^-2 and chemical fertilizer at a rate of 5.25, 10.5, and 15.75 g N m^-2 from 2011 to 2013 (Exp. 2). Tachijobu had a lower grain yield than Kita-aoba under the same fertilizer management in Exp. 1 due to its lower sink production efficiency, but it showed the highest grain yield of 1085 g m^-2 at the highest fertilizer level in Exp. 2. A significant interaction between compost application and nitrogen fertilizer level was observed in grain yield and nitrogen uptake in Tachijobu in Exp. 2, and the nitrogen uptake in Tachijobu reached its maximum at around 15 g m^-2 at maturity. In addition, the apparent nitrogen use efficiency of compost (NUE_compost) was higher at a lower nitrogen fertilizer level. From the nitrogen uptake and NUE_compost at each fertilizer level, the optimum rates of compost and fertilizer were discussed. The compost also increased the concentration of protein in Tachijobu (significantly in 2013).