The soil organisms are most active at . . . . . . . . temperature.

The soil organisms are most active at 24° - 35°C. It is the optimum temperature range required for the better functioning of microorganisms.
At very low temperatures they move to an inactive state and high temperatures may harm the structural damage to the microorganisms.
Soil temperature impacts the rate of nitrification. It also influences soil moisture content, aeration and the availability of plant nutrients.