At the 2025 Niigata Conference of the Japanese Society of Soil Science and Plant Nutrition, held in September 2025, MATSUMURA Nodoka (1st year doctoral student at the Agricultural Chemistry Program, Graduate School of Agriculture), and TAKATERA Muku (4th-year student at the Department of Agricultural Chemistry, School of Agriculture), both from the Laboratory of Soil Science, received the Best Oral Presentation Award for Young Scientists, and NONAKA Yuki (2nd-year doctoral student at the Agricultural Chemistry Program, Graduate School of Agriculture) from the same laboratory received the Best Poster Presentation Award for Young Scientists.
Best Oral Presentation Award for Young Scientists
◆Title: Element leaching behavior from sewage sludge melting slag and phosphorus availability to crops (MATSUMURA Nodoka)
Melting slag obtained through melting treatment is expected for agricultural use owing to its high phosphorus content. However, it is not understood how phosphorus leaches from the melting slag and becomes available to crops. This study attempted to clarify the element leaching mechanism in melting slag while relating it to phosphorus availability. The results revealed that phosphorus leaching associated with melting slag enhances phosphorus availability to crops.
◆Title: Crop growth and phosphorus supply from treated sewage sludge using different heat treatment methods (TAKATERA Muku)
Thermal treatment processes such as melting and incineration are employed in sewage sludge treatment to achieve reduction in volume and weight, resource recovery, and harmless disposal. This study evaluated crop growth and phosphorus supply based on the differences in thermal treatment methods, using the resulting melt and incineration ash as fertilizers. The results indicated that the phosphorus form in the treated materials, as well as plant growth and phosphorus uptake, may vary depending on the type of sewage sludge and the thermal treatment method.
Best Poster Presentation Award for Young Scientists
◆Title: Relationship between root system development and aboveground growth under combined use of woody biochar and organic phosphorus (NONAKA Yuki)
Wood-based biochar, which is expected to be used as a soil conditioner, requires combined application with phosphorus fertilizer. The phosphorus content of biochar is low. This study focused on organic materials, pig manure compost and liquid fertilizer, as phosphorus fertilizers. It compared the effects of using woody biochar alone with the combined use of woody biochar and phosphorus derived from organic materials on available phosphorus in soil, root system development, and above-ground growth. The results showed that combining biochar with these materials promoted root system development and increased phosphorus uptake, leading to higher above-ground growth.
