An analytical device includes a heat output portion for heating an interior of a housing with which an analyzing portion is surrounded; a first temperature sensor for measuring a temperature of the analyzing portion; a second temperature sensor for measuring a temperature of an interior of the housing; and a control portion. The control portion determines a setting value of the temperature in the housing according to a transfer function of a PID control based on a difference between a preset temperature of the analyzing portion and the temperature measured by the first temperature sensor. Further, the control portion determines an output value of the heat output portion according to a transfer function of PID control based on a difference between the setting value of the temperature in the housing and the temperature measured by the second temperature sensor.

A system and method for nematode extermination in lawns using an array of insulated heat blankets (2) placed on the lawn, and energized in a controlled sequence to raise the soil temperature to an effective degree and depth to exterminate nematodes. An electric current controller such as a programmable logic controller (PLC) activates a first subset of the blankets (2) until they reach an upper setpoint temperature, then maintains the blanket temperature within a desired range with reduced current while activating additional blankets. The heat penetrates the soil over a period of about 20 to 50 hours to raise the temperature to at least about 52.degree. C. (125.degree. F.) at a sufficient depth such as at least 12 cm (4.7 inches) to kill at least most nematodes.