To improve sugarcane yield in Kitadaito Island, we investigated the effect of molasses, a sugarcane byproduct, on soil fertility, yield, and economical balance in a field experiment. Experimental plots included the control (no molasses application), 20-Mg (20 Mg ha⁻¹ molasses application), and 50-Mg plots (50 Mg ha⁻¹ molasses application). Sugarcane was cultivated for two cropping periods of spring planting and ratoon planting. Molasses were applied before spring planting. The total yield of sugarcane for the two cropping seasons was 87.2 Mg ha⁻¹ in the control plot, 101.3 Mg ha⁻¹ in the 20-Mg plot, and 111.9 Mg ha⁻¹ in the 50-Mg plot, which significantly increased with the molasses application. Available nitrogen in the soil significantly increased with the amount of molasses applied during spring planting, and the available nitrogen increased the yield. The exchangeable potassium in the soil significantly increased with the molasses application compared with the control throughout the test period. Accumulation of exchangeable potassium in the soil was thought to suppress magnesium uptake through competitive inhibition, but there was no difference in leaf magnesium content at harvest, and there was also no difference in sugar content among the treatments. The estimate of profitability by the molasses application showed an increase of 364,000 yen ha⁻¹ in the 20-Mg plot and 544,000 yen ha⁻¹ in the 50-Mg plot compared with the control plot.

We evaluated the anti-caking effect of bulk blending (BB) fertilizer, which has various powdery anti-caking agents to resolve caking, the most problematic fertilizer quality. Caking tendency was evaluated when 0.5％ of powdered anti-caking material was added to the main BB raw materials, i.e., ammonium sulfate, DAP, and potassium chloride, and stored for 4 weeks at 30°C and 85％ RH.

Among talc, silica fume, and diatomaceous earth, talc has the lowest percentage and hardness of lumps. Talc has a higher anti-caking effect than does blending 1％ of spherical silica gel, which is used to prevent consolidation of BB fertilizer. In addition, the added talc has high adhesion to fertilizer and has the effect of reducing powdering by reducing abrasion of BB fertilizers.

Therefore, 0.5％ of 12 types of talc were added to BB fertilizer, and the anti-caking effect of talc particle size and purity was investigated. Results showed that talc with a small grain size and high purity (SiO₂+MgO) had greater anti-caking effect. Furthermore, talc with a particle size of ≤8 µm and a purity of ≥90％ achieved sufficient anti-caking effect, even when as small an amount as 0.1–0.2％ was added.

Elementary school and junior high school students in three different areas (a rural area, a new town area, and an old urban area) of Yamaguchi city were surveyed using a questionnaire to investigate their perception of soil. Results showed that the typical perception of the need for soil was that it would be best to have a little soil and there was no difference among the student of the three areas. Most reasons given to have soil in the surroundings were linked to having trees, grass, and “greens” in all areas. The recognition that soil is needed for food production was higher in rural areas. Playgrounds, parks, and playing sports afforded students a major opportunity to touch soils in all areas. Furthermore, there were only a few students, even in rural areas, who touched soil when engaged in agricultural activities. Interest in soils declined each year. It was suggested that opportunities to touch soils would increase interest in soils. Even when participants’ knowledge of the functions of soil was great, very few recognized these functions as a need for soils. Even when using the same text books, opportunities to touch soils during classes were different among schools and among teachers.