This study investigated the effect of floating balls （diameter in 80 mm, white color） made of polyester on lotus growth and lotus root yield in a shallow soil cultivation system from April to September 2018. Lotus growth was improved by the increased soil temperature owing to the utilization of floating balls on paddy water, because sensible heat inflow was induced through a thermal insulation effect and by suppressing evaporation of paddy water. Furthermore, increasing soil temperature may enhance the subterranean stem division, thereby, increasing the number of lotus roots resulting in increased lotus root yield. Covering the surface area of the paddy field also contributed to reducing irrigation water requirement. In addition to the utilization of floating balls, application of supplemental nitrogen fertilizer after the blooming stage might further increase lotus root yield, because increasing leaf chlorophyll content in emergent leaves increased lotus root during the thickening stage.

According to the FAO, Japan ranks 11^th among 52 countries in the total production of sweet corn. However, in terms of yield per hectare, Japan ranks 20th in the world. This relatively low production efficiency is likely the result of the conventional Japanese cultivation system, in which the farmers grow only one ear of corn per stalk. In this study we investigate whether drip irrigation and fertigation techniques could yield multiple ears of corn per stalk in open-field culture of sweet corn in Japan. The study used a randomized complete block design and was replicated five times. There were four treatments of different fertigation regimes: 300 gN/10 a/day （N1）, 500 gN/10 a/day （N2）, 700 gN/10 a/day （N3）, and conventional soil application of solid N fertilizer without any irrigation （control）. The result showed that the yield from all fertigation treatments （N1, N2, and N3） were significantly greater than the control treatment. Although yield did not significantly differ among N1, N2, and N3, the average yield increased with increases in the amount of N applied. The average number of marketable fruits produced by N3 was 3.27/stalk, showing that the successful production of multiple ears per stalk can be achieved. Differences in yield among the treatments may have resulted from differences in the amount of N and water applied. IT agriculture is expected to continue developing in the near future using a variety of sensors, satellite imagery, cloud data, and AI technology. Drip fertigation will certainly be an important component of IT agriculture because of the capability of precisely controlling the amount and timing of irrigation water and fertilizers.

Following the 2011 accident at the Tokyo Electric Power Fukushima Daiichi Nuclear Power Station, large amounts of potassium fertilizer were applied to paddy soils to reduce the uptake of radiocesium by rice. The Fukushima Prefectural Government recommended that extra potassium fertilizer be applied before planting with the goal of increasing the soil exchangeable K content (ExK) to above 250 mg K₂O kg^–1 soil. After collecting ExK data for paddy fields in Fukushima Prefecture in 2011 (n = 863), 2014 (n = 730), and 2017 (n = 577), we divided Fukushima Prefecture into 13 regions and investigated the changes in ExK from 2011 onward in these different regions. In addition, we investigated soil chemical properties related to the increase in ExK. In regions where rice with high concentrations of radiocesium was harvested in 2011, supplemental potassium fertilizer (250 kg ha^–1 year^–1) was applied, resulting in an increase in ExK by 313 mg K₂O kg^–1 soil during the period from 2011 to 2014. In 2017, 81% of all sampling sites had ExK greater than 250 mg K₂O kg^–1 soil. Simple linear regression analysis identified effective CEC (ECEC) and Ek (K equivalent/ECEC) as soil chemical properties correlated with the magnitude of ExK increase from 2011 to 2014 in all 13 regions. CEC, however, was not correlated with the magnitude of ExK increase. The coefficient of determination (R²) for the linear model of the relationship between magnitude of ExK increase from 2011 to 2017 and the quantity of additional K fertilizer applied was 0.41. The goodness of fit of the model was improved (R² = 0.52) by multiplying the quantity of additional potassium fertilizer by the reciprocal of Ek, suggesting that Ek (or ECEC, which is used to calculate Ek) may serve as an indicator of ExK maintenance.

A robot tractor is developed to solve the decreasing of farm labors, launched into the demonstrational experiments. The robot tractor can work to coordinate with a manned conventional tractor. To investigate the safety work of the robot tractor, an operator’s view point at the robot tractor operation was analyzed by an eye-mark recorder. In the coordinate working with the robot tractor, the rate of fixation duration to the robot tractor were 51～67%. At this event, the center maker which is attached to a rotary harrow was effective to observe the robot tractor. For the case of the coordinate working with the robot tractor, it seems that the fixation duration and the number of saccade are possible to obtain the amount of visual information for safety work. While the manned conventional tractor was turning and passing by the robot tractor, the rate of fixation duration ahead of the moving direction increased. Consequently, the rate of fixation duration to the robot tractor decreased.