Question

Why do the farmers fill their fields with water to protect the crops from frost?

Answer 1

In severe winter, if the highest temperature falls below 0${}^o$C, the water in the fine capillaries would freeze causing the veins to burst due to increase in volume of water on freezing resulting in the death of the plants. When the fields are filled with water, then due to its high specific heat capacity, it prevents the temperature in the surrounding areas from falling below 0${}^o$C.