2018 Volume 89 Issue 2 Pages 136-145
Nitrogen mineralization in soil depends on many factors such as time, temperature, and soil fertility. Under soil solarization, a method of disinfecting arable soil using solar heat, the high temperatures achieved may enhance nitrogen mineralization in soil, allowing farmers to use less chemical nitrogen fertilizer. We measured nitrogen mineralization rates in incubation experiments at 30°C, 45°C, and 60°C, and based on the results, we estimated nitrogen mineralization under field conditions. Nitrogen mineralization during incubation was enhanced as soil temperature increased. To evaluate soil fertility, we extracted 28 soils in water at 80°C. The amount of organic carbon extracted was positively correlated with the amount of inorganic nitrogen released during incubation for 21 days at 45°C. We developed a kinetic model to estimate nitrogen mineralization under field conditions in Andosol in Tsukuba in the Ibaraki prefecture. N0, Q, and k0 values were determined from incubation experiments in which soil temperatures were measured at depths of 5 and 15 cm. Results showed that measurement of soil temperature at a depth of 5 cm allows to estimate nitrogen mineralization rates under soil solarization.
