Furrow Irrigation & Down the Rows
Runs water to the rows
Enter field width, furrow spacing, stream flow and set time to get the number of furrows, the water applied, the depth in mm and the total flow you need.
Enter your field
Next: run 40 L/s for 30 min to apply ~12 mm; cut back if water ponds at the tail, or use shorter furrows on sandy soil.
Real application has runoff and deep-percolation losses (efficiency 50–70%); cutback or surge flow improves uniformity.
Furrow irrigation — key facts
- Method
- Surface — water down channels between rows
- Furrows
- field width ÷ furrow spacing
- Water applied
- flow/furrow × set time × furrows
- Depth
- volume ÷ field area (mm)
- Set time
- water reaches tail, not over-watered head
- Efficiency
- ≈ 50–70% (runoff + percolation)
- Light soil
- shorter furrows; cutback/surge helps
- Privacy
- Runs in your browser; nothing uploaded
Gravity does the work, if you size it right
Furrow irrigation is as old as farming itself: cut channels between the rows, let water run down them, and the soil wicks it sideways into the beds. No pumps under pressure, no emitters to clog — just a stream of water and gravity. The catch is uniformity. The head of the furrow drinks first and longest, the tail last and least, so the whole skill is matching the stream size and the set time to the furrow length and soil so water reaches the tail without drowning the head.
This tool does the arithmetic — the number of furrows, the water applied, the depth in mm, and the total flow you need to supply — from your field width, furrow spacing, stream flow and set time. Remember real furrow efficiency is only about 50–70% because of runoff and deep percolation; cutback or surge flow and shorter furrows on sandy soil improve it. Pair it with the Pump Run Time, Soil Infiltration and Water Use Efficiency tools to run the set well.
Size the set
Furrows, water and depth for one irrigation.
Hit the right depth
Match the applied depth to the crop's need.
Reach the tail
Tune set time so water gets to the far end.
Supply the flow
Know the total stream the field demands.
Frequently Asked Questions
What is furrow irrigation?+
Furrow irrigation is a surface method where water runs down small channels — furrows — cut between crop rows, soaking sideways and downwards into the beds as it flows. It's a simple, low-energy way to irrigate row crops like maize, cotton, vegetables and sugarcane using gravity rather than pumps and pipes.
How many furrows will my field have?+
Furrows = field width ÷ furrow spacing. If the field is 100 m wide and furrows are 0.75 m apart, that's about 133 furrows. The tool computes this from your width and spacing, which sets how the stream flow and set time translate into total water applied.
How is the water applied calculated?+
Applied volume = flow per furrow × set time × number of furrows. The set time is how long water runs in each furrow. Multiply the stream rate by that time and by the furrow count and you get the total volume the field receives in one irrigation event.
How do I find the depth applied?+
Depth (mm) = applied volume ÷ field area. Expressing water as a depth lets you compare it to the crop's water requirement and to other irrigation methods. The tool reports the depth in mm so you can check whether the irrigation matches what the crop actually needs.
How long should I run each furrow?+
Match the set time so water just reaches the tail end of the furrow without ponding or over-watering the head. Too short and the far end stays dry; too long and the head end is waterlogged and water runs off the tail. Adjust the stream size and set time together for the furrow length and soil.
How efficient is furrow irrigation?+
Real-world furrow efficiency is often only about 50–70% — water is lost to runoff at the tail and deep percolation at the head. Good design, land levelling, and matching stream size to soil and length push it toward the upper end. The tool's depth is the gross applied depth, before those losses.
What are cutback and surge flow?+
Both improve uniformity. Cutback uses a larger initial stream to advance water quickly down the furrow, then reduces it once water reaches the tail to cut runoff. Surge flow pulses the water on and off, which seals the surface and speeds advance. Both reduce the head-to-tail difference in how much water soaks in.
Does soil type change the design?+
Yes. Sandy soils take water in fast and laterally little, so they need shorter furrows and faster streams to reach the tail before too much soaks in at the head. Heavy clay soils take water slowly and can use longer furrows. Always shorten furrows on light, fast-draining soil.
Can I use this for any row crop?+
Yes — the geometry (width ÷ spacing, flow × time × furrows, volume ÷ area) applies to any furrow-irrigated row crop. Enter your own spacing, stream flow and set time for your crop and field, and the tool gives the furrows, water applied, depth and total flow you need to supply.