Soil Solarization

• Almost all plant pathogens are killed at 82 oC after 30 minutes.
• The coldest part of the bed must reach the above.
• TMV is a resistant virus that requires almost boiling temperatures for eradication.
• Manganese salts and ammonia can reach toxic levels at "high heat" for "prolonged periods."
• Benefits of soil sterilization are only if < 200 oF.

Calculations

Bed Volume: 5ft * 5ft * 18in = 64800in^3 
                           ~1060L
Specific heat of wet soil: 1.48 KJ/Kg*oC
Specific heat of water:    4.19 KJ/Kg*oC
Density of soil:           ~0.5g/mL ?

Vol * Specific Heat * Density =
1060L * (1.48KJ/Kg*oC) * 0.5g/mL = 784kJ/oC = 0.22 kWh/oC

So to raise bed from 0oC to 82oC (assuming no heat loss):
0.22 kWh/oC * 82oC ~ 18kWh

At $0.05/kWh, only costs about $1 for above treatment.

Measured 20ft of 0.659 ohms/ft 20ga nichrome wire.
In practice, after hookup, 15A measured with 240V:
Power = 240V*15A = 3.6kW
Or time = 18kWh/3.6kW = 5h

Started 6PM with almost frozen soil, then warmed with approx 40gal hot water.
Assuming temperature around freezing after hot water temp.
Temperature measured at 12:30AM: