Abstracts of Nippon Dojo-Hiryogaku Zasshi 93 - 3

572, 850, and 518 kg-CO 2 eq with high, medium, and low moisture content, respectively. Thus, with low moisture content, emissions were reduced by 9.4% and 39.1% compared with those when moisture content was high and medium, respectively. These results indicate that composting by actively mixing wheat straw into dairy manure to adjust moisture content can lead to swollen and softened compost and accelerated fermentation, which could help reduce greenhouse gas emissions from dairy farms. paddy sites. Comparison by landform revealed a wide variety of trends in soil-type differences, but specific trends, similar to those detected for land use, were not found. Thus, the nation-wide reformation into well-drained paddy fields has apparently lowered the position of the groundwater gley horizon, chan-ging Gley Lowland soils into other soil types, such as Gray Lowland soils. We propose that the present land-use type is an important factor for determining the degree of soil-type change from Gley Lowland soils to other soil types in paddy fields. of increased nitrogen supply and improved soil physical properties, such as air permeability, water retention, and water permeability, in the main root zone (0–40 cm) of onion plants. Onion yields were increased when the soil frost depth in the study fields was 23–37 cm. Considering a possible error of several centimeters in soil frost depth control, we recommend a target frost depth of 30 cm to improve the productivity of onion fields. However, in fields with high nitrogen fertility, soil frost depth control may result in excessive nitrogen supply. In such cases, growth suppression due to salt injury and damage from diseases, such as dry and soft rot, may occur, leading to lower onion yield. Therefore, proper nitrogen management might be required in fields in which soil frost depth is controlled. variables. Furthermore, nitrogen uptake from the panicle formation to full heading stages could be predicted using a multiple regression equation in which the amount of nitrogen in topdressing fertilizer and the amount of nitrogen applied to the surface soil were explanatory variables. These multiple regression equa-tions were adapted to calculate the optimum amounts of basic and topdressing fertilizer nitrogen. According to verifica-tion analysis conducted in a local producer’s field, the more that the amount of applied fertilizer deviated from the calculated amounts of basic and topdressing fertilizer estimated using our formula, the more that the nitrogen uptake from the transplantation to the panicle formation stage and the spikelet number deviated from the target ranges. Thus, the optimum spikelet number of Datemasayume can be obtained if the optimum nitrogen richness, calculated according to our formula, is provided using basic and topdressing fertilizers. significantly higher than that of Akitakomachi, and the rice root activity of Fusaotome was higher. At high temperature, the panicle temperature of Fusaotome was significantly lower than that of Akitakomachi, whereas the relative light intensity of Fusaotome was significantly higher than that of Akitakomachi at each height from 30 to 80 cm. Under normal-temperature conditions, there was no significant difference in the leaf area index (LAI) between the two varieties at each height. However, at high temperature, the LAI of Fusaotome was significantly lower than that of Akitakomachi at >70 cm (top layer), 60–70 cm, and 50–60 cm. With the high-temperature treatment, the occurrence of milky white and basal white rice was significantly lower in Fusaotome than that in Akitakomachi. In contrast, there was no difference in brown rice yield between the two varieties under normal- and high-temperature conditions. These results indicate that the high-temperature-ripening O. sativa variety Fusaotome has vigorous root elongation and activity, relative to that of the conventional variety Akitakomachi, under high-temperature conditions. Moreover, it is a favorable variety for ripening with a reduced increase in LAI in the upper layers of the vegetation community.