Research Center for Global Agromedicine, Obihiro University of Agriculture and Veterinary Medicine帯広畜産大学グローバルアグロメディシン研究センター

In order to achieve high crop yield while minimizing environmental impact in agricultural production, it is fundamental to understand the soils capacity to retain nutrients and water, and manage the crop according to the soil conditions. Yield potential of a crop is primarily determined by weather conditions and genetic potentials but soil’s ability to supply water and nutrients determine how much of the potential is achieved (Fig. 1). Currently, only 20-30% of the yield potential is achieved in many of crop growing areas across the world. Even in Hokkaido, depending on environmental conditions and growers management strategies, the degree of yield potential achieved is highly variable.

The characteristics of agricultural soils are variable depending on the parent materials (rocks, volcanic ash, plant residue…), climate conditions and other factors. In order for a grower to properly manage their crop, we need to understand the inherent characteristics of the soil. In our laboratory, we conduct soil profile assessment in various places in the world (Fig. 2). We incorporate the knowledge of geology to evaluate the soils in field. We also use laboratory assessment in combination with the field survey to understand the characteristics of the soil.

After understanding the inherent characteristics of the soil, we need to evaluate soil conditions of each field and within field. I have been conducting soil survey at a regional scale from various grower fields to understand the soil physical and chemical conditions. I have been assessing farm field soils at regional scale when I lived in United States where maize and soybeans are mainly grown. In my current research, I have been conducting soil survey in Kenya in East Africa (Fig. 3). In these regions, soil testing has not been incorporated in their agricultural practices. I have been working on building models to use infrared spectroscopy techniques as a rapid and low-cost soil testing method. In Tokachi Hokkaido, farm fields are getting larger and we have been finding high spatial variation of soil properties even at within-field scale. Therefore, some of my work is on the use of satellite and drone images to estimate soil properties at within-field scale (Fig. 4).

Also, we have been conducting field trials to grow potatoes at grower’s fields (Fig. 5). I have been trying to combine the knowledge of soil information that can be gained from various technologies and field trial information to derive crop production systems that is suited to particular soil environmental conditions.

• Evaluation of within-field variable soil phosphorus fertility and soil water holding capacity using satellite and drone information
• Use of infrared spectroscopy for soil evaluation
• Development of phosphate fertilizer application guidelines for improving yield and quality of potatoes in Kenya
• Influence of traditional slash-and-burn agriculture on carbon accumulation and soil fertility in Sabah, Malaysia
• Effects of various fertilizers and soil conditioners on crop growth in various soil types
• Effects of Chinese yam cultivation on soil fertility and ways for improvements
• Influence of land use change on soil physical, chemical, and biological characteristics