Sprayer maintenance and calibration through the season

Why sprayer accuracy matters more than ever

A sprayer puts costly chemicals onto your crop. Get the rate wrong and you either waste product or fail to control the pest or weed. Both cost money, and the second can cost a whole crop. In 2026, with inputs still expensive, accuracy is a direct saving.

Accuracy also keeps you on the right side of the law. Rules in both the US and UK set out how products must be applied, and over-application can pollute water or harm wildlife. A well-kept, well-set sprayer protects your crop, your budget and your licence to farm.

Before the season starts, it helps to know your machine's spec well. Use FarmFleets to check sprayer specs and capacities so your calibration starts from the right baseline figures.

Start the season with a full service

A sprayer that sat over winter needs waking up properly. Drain any antifreeze, flush the tank and lines with clean water, and look for splits in hoses that frost can cause. A leak found in the yard is far better than one found in the field.

Check the pump, the agitation and the pressure gauge. The gauge is the heart of accurate spraying, so if it reads wrong everything else will too. Replace a doubtful gauge before you trust it for a whole season of application.

Open and clean every filter, from the tank line down to the nozzle filters. Blocked filters cause uneven output and stress the pump. A clean start makes the rest of the season far easier to manage.

Test the booms unfold and fold smoothly, and check that all the section controls work. A jammed section or a bent boom found in the yard is a cheap fix. The same fault found mid-field can mean a missed weather window and a half-sprayed crop.

Understanding calibration

Calibration means making sure the sprayer puts out the rate you intend, evenly across the boom. It links three things: your forward speed, the pressure, and the nozzle output. Change one and the applied rate changes too.

The simplest method is to measure how much each nozzle delivers in a set time, then check that against the rate you want for your speed and boom width. Modern rate controllers help, but they still rely on good nozzles and correct settings underneath them.

Check your forward speed too, since wheel slip or the wrong tyre size can make the real speed differ from the dial. If speed is out, the applied rate is out, however good the nozzles are. A quick measured run over a known distance confirms your true working speed.

Do not calibrate once and forget it. Output drifts as nozzles wear and conditions change. A quick check every few tank loads catches problems early, before they cost you a field of poor control.

Keep your calibration figures written down. Knowing last season's settings gives you a starting point and lets you spot when something has changed. It also backs you up if anyone ever questions the rate you applied to a crop.

Nozzles: the part that wears fastest

Nozzles are small, cheap and easy to ignore, yet they decide how well the whole machine works. As they wear, the hole opens up and output rises, often by far more than people expect. A worn set can apply much more chemical than the label says.

Check nozzle flow against the maker's rated figure. If a nozzle delivers well above its rating, replace it. Replace the whole set together so output stays even across the boom, rather than swapping one tired nozzle at a time.

Match the nozzle to the job. Coarser droplets cut drift, which matters for careful weed control, while finer droplets give better cover for some products. Keep spares of the types you use most.

Store nozzles carefully and never clean them with anything that could scratch the orifice. A pin or wire opens up the hole and ruins the rate. A soft brush and water, or a blast of clean air, is all a blocked nozzle should ever need.

Mid-season checks that keep you honest

The busy spraying weeks are exactly when checks slip, and that is when errors creep in. Build a short routine into each day. A five-minute walk around the booms before filling can catch a blocked nozzle or a dripping joint that would otherwise spoil a pass.

Watch the spray pattern as the booms unfold. Streaks, fans that point the wrong way or nozzles that dribble are easy to spot once you look. Fix them on the spot rather than spraying a whole field with a fault.

Keep an eye on the weather too. Drift in wind wastes product and risks neighbouring crops. Pairing a well-set sprayer with drone scouting helps you spot where control worked and where it did not.

• Walk the booms and check every nozzle before each fill.
• Watch the spray fan shape as booms unfold.
• Clean nozzle and line filters when output looks uneven.
• Check pressure holds steady at your working speed.
• Stop spraying if wind rises enough to cause drift.

Cleaning out between products

Chemical left in a tank can damage the next crop you spray. A trace of a strong herbicide in a tank later used on a sensitive crop can cause real harm. Cleaning out properly between products is not optional, it is part of safe spraying.

Follow the cleaning steps on the product label. Usually that means rinsing the tank, lines and nozzles several times, often with a cleaning agent, and spraying the rinse onto a suitable area. Do not tip residue down a drain or near water.

Triple-rinse empty containers and store them as the rules require. Good clean-out habits protect your crops, the environment and your standing if an inspector ever calls.

Keep a clean-out routine the same every time so nothing gets skipped when you are tired and rushing. A written checklist on the shed wall is a simple way to make sure the tank, lines, filters and nozzles all get flushed before the next product goes in.

Record keeping and end-of-season care

Write down what you sprayed, where, when, at what rate and in what weather. In both the US and UK these records can be required, and they also help you compare results year to year. Good records turn a busy season into useful learning.

At the end of the season, clean the machine thoroughly inside and out. Store it dry, protect the pump from frost and note any repairs needed before next spring. Owning the data behind your decisions matters as much as the kit, as our farm data guide explains.

A sprayer that is put away clean and recorded is ready to work when the weather turns. The half hour spent now saves a stressful start when the first spray window opens.

What buyers should check

If you are buying a used sprayer, the same care that keeps a machine accurate also tells you whether one is worth the money. A tidy sprayer with records behind it is usually a safer buy than a cheap, neglected one.

• Compare tank size, boom width and pump specs on FarmFleets before viewing.
• Check the boom for repairs, bends and worn nozzles.
• Ask for service and calibration records, and any recall notices.
• Test that the pressure gauge and rate controller read steady.
• Look at photos closely and weigh the source confidence of the listing.
• Inspect filters and tank for old chemical residue or damage.

Sources and method

This guide is written for the 2026 season and explains good sprayer practice in plain English. It does not name any chemical, brand or data provider, and it avoids specific figures because correct rates depend on the product label and local rules in your country.

FarmFleets gathers specs, photos, recall notices and a confidence rating on each listing so you can judge a sprayer before you buy. Always follow the product label and your national rules on application, cleaning and record keeping.