Question 1

How do I calibrate a boom sprayer?

Accepted Answer

The standard field calibration method: (1) Fill the tank with clean water. (2) Set your normal spraying pressure and speed. (3) Hold a 2-litre measuring jug under one nozzle for exactly 60 seconds and record the output in ml. (4) Enter that figure as your nozzle output in this calculator along with your forward speed and nozzle spacing. The result is your application rate in L/ha. Repeat the nozzle catch on 3–4 nozzles across the boom — if any differ by more than 10% from the average, replace or clean that nozzle.

Question 2

What is the formula for calculating sprayer application rate?

Accepted Answer

L/ha = (nozzle output in ml/min × 60) ÷ (forward speed in km/h × nozzle spacing in cm). For example: nozzle output 800 ml/min, speed 8 km/h, nozzle spacing 50 cm → (800 × 60) ÷ (8 × 50) = 48,000 ÷ 400 = 120 L/ha. The formula works for any consistent set of units — the key is that nozzle spacing in cm cancels with the speed correctly to give litres per hectare.

Question 3

How many litres per hectare should I spray?

Accepted Answer

This depends on the product, target pest, and application type. Fungicides are typically applied at 100–200 L/ha. Herbicides may require 80–200 L/ha depending on the product label. Glyphosate for desiccation is often applied at 150–200 L/ha. Insecticides may be as low as 50–100 L/ha. Always follow the product label — it will specify the water volume range. Higher water volumes generally give better coverage and penetration into the crop canopy.

Question 4

What nozzle size should I use for 100 L/ha?

Accepted Answer

At 8 km/h forward speed with 50 cm nozzle spacing, a blue (03) nozzle at 3 bar outputs approximately 1,200 ml/min giving 180 L/ha. To hit 100 L/ha at the same speed you would need approximately 667 ml/min — a yellow (02) nozzle at 3 bar (800 ml/min) would give approximately 120 L/ha. Increasing speed reduces the rate; reducing speed increases it. Use the target speed calculator in this tool to find the exact speed required for any combination.

Question 5

How do I check if my nozzles need replacing?

Accepted Answer

Catch the output from every nozzle on the boom (or a representative sample) into a measuring jug for exactly 60 seconds at normal spraying pressure. Calculate the average output across all nozzles. Any individual nozzle that differs from the average by more than 10% should be replaced. Also check for: dripping nozzles when the boom is shut off (failed diaphragm check valve), streaking or uneven spray pattern (worn nozzle), and off-angle sprays (blocked nozzle). Most manufacturers recommend replacing nozzles every 50,000 hectares or if wear is detected.

Question 6

What is the difference between flat fan, air inclusion and hollow cone nozzles?

Accepted Answer

Flat fan nozzles (110° or 80°) produce a fan-shaped spray and are the most common type for herbicides and fungicides. They give good coverage at moderate droplet sizes. Air inclusion (drift reduction) nozzles mix air into the spray to produce larger, heavier droplets that are less prone to drift — these are LERAP-rated and can reduce buffer zone requirements near watercourses. Hollow cone nozzles produce a ring-shaped spray pattern with very fine droplets, giving excellent penetration into the crop canopy — used for systemic fungicides and insecticides where coverage of undersides of leaves is important.

Question 7

How do I convert nozzle output from L/min to ml/min?

Accepted Answer

1 litre per minute = 1,000 ml per minute. If your nozzle chart shows output in L/min (as ISO nozzle charts do), multiply by 1,000 to get ml/min for use in this calculator. For example, a blue (03) nozzle at 3 bar has an output of 1.2 L/min = 1,200 ml/min. The ISO nozzle colour reference table below the calculator shows both L/min and the ml/min equivalent.

Question 8

What forward speed should a tractor travel when spraying?

Accepted Answer

Most arable boom sprayers operate at 6–12 km/h. Slower speeds (6–8 km/h) give more time for droplets to penetrate a dense canopy and reduce the risk of boom bounce. Higher speeds (10–12 km/h) increase output but require larger nozzles or higher pressure to maintain the correct water volume. On uneven ground, reduce speed to minimise boom bounce — poor boom height control degrades spray distribution significantly. The target speed calculator in this tool shows the exact speed needed to hit any target water volume.

Colour	ISO	L/min @ 3 bar	ml/min	Typical use
Orange	01	0.40	400	Very fine mist, pre-emergence herbicides
Green	015	0.60	600	Fine sprays, low-volume fungicides
Yellow	02	0.80	800	Most fungicide and insecticide work at 100–200 L/ha
Purple	025	1.00	1000	Standard fungicide/herbicide at moderate speed
Blue	03	1.20	1200	Most common — versatile for 100–200 L/ha at 8 km/h
Red	04	1.60	1600	Higher volumes, herbicides, soil-applied products
Brown	05	2.00	2000	High-volume applications, glyphosate, desiccation
Grey	06	2.40	2400	Very high volume, soil incorporation treatments
White	08	3.20	3200	Maximum volume applications

Sprayer Calibration Calculator

Calibration

Job Planner

Target Speed Calculator

ISO Nozzle Colour Codes — Flat Fan Reference

Frequently Asked Questions — Sprayer Calibration