To establish dry direct seeding rice cultivation techniques that can be implemented in the double cropping area of Kyushu, Japan, the following steps were undertaken: development of a technique to prevent water leakage from dry direct seeding fields using a compaction roller; construction of dry direct seeding cultivation system with roller compaction; and development of a ridging direct seeder with water leak prevention function and wet damage avoidance function. Based on the observed results, the following were confirmed: in the gray lowland soil field, the developed three-point link type roller can effectively prevent water leakage under conditions of high moisture content more than the plastic limit; during the dry direct seeding of paddy fields after barley production, leakage can be prevented by compaction using the vibratory roller, thereby ensuring stable cultivation; and, the developed ridging direct sowing seeder requires lesser power even under high moisture conditions, and the labor saving and cost effective nature of this machine was verified in the field verification test.

It is important to increase the yield of wheat (Triticum aestivum L.) in Japan. To develop a high-yielding wheat production system in the warm Tokai region, we analyzed the effects of rolling, the plant growth regulator ethephon, and the foliar fungicide metconazole under a high nitrogen condition on the agronomic characteristics and grain quality of early-sown ‘Satonosora’ winter wheat in 2016–17 and 2017–18. Early sowing of winter wheat avoided both frost injury in early spring and preharvest sprouting in the rainy season. Rolling at the spikelet differentiation stage reduced lodging without shortening culm length, and ethephon at the start of heading reduced lodging by shortening culm length; rolling plus ethephon reduced lodging the most. Metconazole at both the third-leaf-below-flag-leaf and flag-leaf stages reduced foliar disease. The effect of rolling on yield varied with the year (probably with soil moisture condition). Ethephon and metconazole did not affect yield, probably because lodging and disease were mild. The combination of rolling, ethephon, and metconazole produced 750 g m^–2 in 2016–17 and 676 g m^–2 in 2017–18, and the grain satisfied most standard values for noodle quality. Large-plot experiments confirmed the high yield and quality. The results show that this system for the intensive production of early-sown winter wheat achieves high productivity and quality in the warm Tokai region of Japan.

This study aimed to develop a technique for raising middle rice-seedlings under pooled conditions with application of organic fertilizer. We set up experimental plots in which rapeseed oil cake and ground fish were mixed with forest surface soil to prepare nursery soil in 2013 and 2014. Plots were kept fallow for 0, 1, 2 or 4 weeks. As fallow duration increased, the amount of mineralized nitrogen （N） within the nursery soil, which is mainly composed of ammonium-N, increased. The N contents of the seedlings, which were significantly （P<0.05） correlated with the mineralized N, showed a significant （P<0.05） positive correlation with rice seedling height, weight, and irregular seedling growth. All plots showed satisfactory growth for middle rice-seedlings based on leaf age. The plant height in the nursery boxes of the 4-weeks plot exceeded the standard value of 14 cm for representative middle rice-seedlings, although irregular seedling growth was observed. In contrast, the plant height in the 0-week plot was below 12 cm, the standard value for young rice-seedlings, and little irregular seedling growth was observed. It was concluded that rice seeding was the most appropriate in the 1-week plot, because leaf age was ranged from 3.4 to 4.5 of the standard value of middle-rice seedlings, the plant height exceeded 12 cm and there was little irregular growth. This indicated that the effect of fallow duration on the growth of organic middle rice-seedlings and mineralized N in organic fertilizer-amended soil could be used to set a guideline for the organic rice farmers in an Andosol area of Tochigi Prefecture.

In this study, we developed three element technologies （HPS, roll-damper, and high-rigid slide boom） to reduce boom displacement. The three element technologies were placed in a vehicle for crop management. Two tests were performed （boom displacement reducing test, adhesion test）, and the following results were obtained. In the boom displacement reducing test, the developed machine reduced the vertical boom displacement （full amplitude） by approximately 63% relative to the control machine （equipped with only high-rigidity slide boom）. In the adhesion, the performance of the developed machine was similar to that of the control machine, even when the developed machine performed work at twice （1.0 m/s） the velocity of the conventional control machine. As we determined from the two tests, when equipped with the three devices, the machine reduced the vertical displacement of the boom, matching the performance levels of adhesion. Consequently, we concluded that the developed machine can work at a high velocity in the field.