Sprinkler Spacing & Beat the Wind, Wet Every Row

The tool sets the spacing as a percentage of the sprinkler's wetted diameter, and that percentage falls as wind rises: about 65% in calm air (under 4 km/h), 60% in a light breeze (4–8 km/h), 50% in a moderate wind (8–16 km/h) and 40% in a strong wind (above 16 km/h). Spacing in metres is then the wetted diameter times that percent, and the area each sprinkler covers is that spacing squared. Closer spacing in wind keeps the overlap that fills the gaps.

Wind blows the spray downwind, distorting the circular wetted pattern into an oval and thinning the coverage on the windward side. If sprinklers stay on a calm-air grid, the wind opens dry stripes between them. Bringing the sprinklers closer increases the overlap so that even a wind-shifted pattern still covers the whole field, which is why spacing is reduced as a fraction of the wetted diameter when wind picks up.

In calm air a common rule is to space sprinklers at about 60–65% of the wetted diameter, which gives enough overlap for good uniformity without wasting sprinklers. That is why the tool uses 65% below 4 km/h. As soon as a steady breeze sets in you should tighten that figure; the calculator does it for you so you do not have to remember the bands.

The percentage it gives is the along-the-lateral and between-lateral spacing on a square grid, which is the usual starting layout. In strong or consistent wind, designers often use a rectangular grid — closer spacing across the prevailing wind and slightly wider along it. The tool's square spacing is the conservative basis; tighten the across-wind direction further if your site has a dominant wind.

The wetted diameter is the full diameter of the circle a single sprinkler wets at its operating pressure, taken from the manufacturer's chart for that nozzle and pressure. It shrinks if pressure is low, so use the value for the pressure the sprinkler will actually run at in the field. Everything else in the calculation scales off this number, so getting it right matters most.

Spacing sets how much ground each sprinkler must wet: tighter spacing means more sprinklers per hectare, so the same nozzle discharge is spread over less area and the application rate in mm/h rises. That is good for uniformity but you must check the rate does not exceed the soil's infiltration rate, or you will get runoff. Use a sprinkler-system or infiltration-rate tool to confirm the rate after you set the spacing.

Spacing too wide in wind is the classic cause of striped, patchy crops, where rows between sprinklers stay dry and stressed while others are over-watered. The cost of a few extra sprinklers is far less than the yield lost to poor uniformity. The bands in this tool — down to 40% of the wetted diameter in strong wind — keep the overlap that protects uniformity even on a windy site.

Above roughly 16–20 km/h, even tight spacing struggles, drift and evaporation losses climb steeply, and uniformity suffers no matter the layout — so the best move is often to irrigate at a calmer time of day, usually early morning or evening when wind drops. Use the calculator to set the right spacing for the wind you do irrigate in, and schedule around the windiest hours where you can.