Recording soil temperature
Chose a maintained grass site that is level, freely drained, unshaded and with the soil unobstructed by stones or severe induration to a depth of 300 mm (12 in). Purchase from an ironmonger or garden centre a 300 mm (12 in) long, metal-sheathed soil thermometer and make up, or purchase, a 12 mm (1/2 in) wide, 300 mm (12 in) long, strong metal probe fitted with a handle—an old fashioned, long chisel is ideal. The probe is required to create the hole into which the thermometer is to be neatly inserted to 250 mm (10 in) depth without risk of damage, the idea being to enable close contact to be maintained between the metal sheath and the soil.
Measure soil temperature at 250 mm (10 in) depth weekly (or twice ...