Furrow Irrigation

• Furrows are formed between raised rows, typically at the same time as bed formation or planting
• Water is released at the head of each furrow from a supply channel, gated pipe, or siphon
• Water advances down the furrow by gravity, infiltrating into the soil as it flows
• Flow is cut off once sufficient water has been applied along the furrow length
• Water may recede and continue infiltrating after cutoff, depending on furrow slope and length

Furrow irrigation is used for row crops on land that is level or can be economically graded to a gentle, uniform slope, and it is closely associated with cotton, sugarcane, and maize production in many established irrigation regions. It is generally less suited to closely spaced or broadcast crops without distinct rows.

Efficiency and uniformity in furrow irrigation depend heavily on furrow length, slope, inflow rate, and cutoff timing: water that reaches the end of a long furrow quickly may over-water the head end, while too little inflow may leave the tail end under-watered. Techniques such as surge irrigation (applying water in pulses) and precise field levelling are used in some systems to improve uniformity.

As with other surface methods, furrow irrigation efficiency is a function of management and design rather than an inherent, fixed property of the method itself.

Surge irrigation

Applies water to a furrow in intermittent pulses rather than a continuous stream, which can improve advance uniformity on some soils

Alternate furrow irrigation

Irrigates every other furrow in a given cycle, reducing the wetted area and total water applied

Gated pipe or siphon delivery

Common methods for releasing a controlled flow into the head of each furrow from a supply line or channel

On poorly drained soils, furrow irrigation can contribute to waterlogging in low spots or, over time, to secondary salinity if drainage and leaching are inadequate. Maintaining furrow shape and grade requires periodic re-forming, particularly after tillage or heavy rain.