What type of pipe conveys water from a source ditch to a furrow without using a pump?

The type of pipe that conveys water from a source ditch to a furrow without using a pump is a siphon tube. Siphon tubes utilize the principle of siphoning, which relies on gravity and atmospheric pressure to move water from a higher elevation to a lower elevation. By placing one end of the siphon tube in the water source and the other end in the furrow, the water can flow downhill through the tube, enabling irrigation without the need for a mechanical pump.

Siphon tubes are particularly effective in applications where there is sufficient elevation difference and the water can flow freely as long as the setup allows for the creation of a siphon. This method is often used in surface irrigation systems where gravity can be utilized to distribute water evenly to crops.

Other types of pipes listed do not serve this specific function effectively. Drainage pipes are primarily used to remove excess water from an area rather than convey it for irrigation purposes. Pressure pipes are designed to carry water under pressure, typically in pressurized irrigation systems rather than relying on gravity. Plastic tubing is a versatile option for irrigation but often needs to be connected to a water source under pressure and doesn't function like a siphon tube without additional equipment.