Farkesht technical guide
Applying fertiliser correctly, and avoiding fertiliser burn
Fertiliser burn is usually not the result of a bad product. It is the result of the right amount in the wrong place, or all at once. This page answers the three questions no label answers: how much, where, and in how many goes.
- Salt gap between the saltiest and mildest common fertiliser
- 12×
- Applications that keep the peak under the threshold
- 3applications
- Minimum clearance from a young tree’s collar
- 30cm
Updated September 1, 2026Farin Kesht Taban Co.
Chapter one
Three different things we all call "fertiliser burn"
The first is physics, the second chemistry, and the third never touches a root. Until you know which one happened, the rescue chapter cannot help you — because leaching only answers the first.
Osmotic pull: the root gives water back
Dissolved fertiliser raises the concentration of the soil solution. Past a point the direction of water movement reverses, and the root loses water instead of taking it. The same thing a saline soil does over years, compressed into one week.
- What you see:
- Wilting in moist soil, marginal leaf scorch starting low in the tree, and growth that stops abruptly.
- What actually answers it:
- Leaching with plenty of water — provided there is drainage, or the salt simply stays where it is.
Ammonia: the gas that never reached a root
Urea and ammonium fertilisers on a dry surface, and on calcareous soil, convert to free ammonia. Part of your nitrogen goes into the air, and that same gas scorches the young tissue nearest it.
- What you see:
- A sharp ammonia smell while spreading, scorch on young trees and tissue near the soil surface, and a response smaller than the amount applied.
- What actually answers it:
- Incorporation or irrigation immediately after spreading; fertiliser that gets into the soil never takes this route.
Direct contact: a chemical scald
A granule on a wet leaf, a pile against the collar, or a foliar spray mixed too strong. The root is not involved at all here; the tissue that touched the material is what burns.
- What you see:
- Localised burn marks exactly where the material sat, and dark sunken bark at the collar.
- What actually answers it:
- Rinse the tissue and remove the material quickly; leaching the soil does nothing for this one.
If nothing was applied and only the leaf colour and pattern changed, that is another dossier:The nutrient deficiency dossier
Chapter two
Which fertiliser burns hardest?
The left column is the figure printed in tables. The right column is the figure that changes a decision — and once the division is done, the ranking turns over.
- KPotassium chloride60 % nutrientSalt index116Salt per unit of nutrient193
- NAmmonium nitrate34 % nutrientSalt index105Salt per unit of nutrient309
- NUrea46 % nutrientSalt index75Salt per unit of nutrient163
- KPotassium nitrate46 % nutrientSalt index74Salt per unit of nutrient161
- NAmmonium sulfate21 % nutrientSalt index69Salt per unit of nutrient329
- NCalcium nitrate16 % nutrientSalt index53Salt per unit of nutrient331
- KPotassium sulfate50 % nutrientSalt index46Salt per unit of nutrient92
- PDiammonium phosphate46 % nutrientSalt index34Salt per unit of nutrient74
- PMonoammonium phosphate52 % nutrientSalt index30Salt per unit of nutrient58
- PTriple superphosphate46 % nutrientSalt index10Salt per unit of nutrient22
The ranking turns over
The tinted rows are the ones that stand higher in the right column than in the left. Ammonium sulfate and calcium nitrate look mild in an ordinary table, but because they carry little nutrient they put more salt into the soil to deliver the same nitrogen. Urea is the opposite: its index is high, yet at forty-six per cent nitrogen it is milder per unit of nitrogen than all three.
Manure is not in this table, and its absence does not mean it is safe. Well-composted manure has a very low salt index. Fresh manure has both a high soluble salt load and free ammonia as it breaks down — that is mechanisms one and two of the previous chapter together. "Natural" and "harmless" are not the same word.
Which fertiliser to buy in the first place is a separate question with a dossier of its own:The fertiliser types dossier
Chapter three
The same amount, in one go or in three
Growers argue about how much fertiliser and almost never about how many times. The second question decides whether the roots ever meet a damaging concentration. The area under all three curves is identical; only the peaks differ, and only the peak burns.
- crosses the line
One go, the whole amount
The commonest practice and the riskiest. The entire load enters the soil solution in one week, and much of it leaches before it can be taken up.
Peak concentration:100
- crosses the line
Two applications
Better, but in this model the peak still crosses the line. On light soil with generous irrigation, two is often not enough.
Peak concentration:56
- under the line
Three applications
The same total, without ever reaching a damaging concentration. Uptake improves too, because supply now lines up with what the tree is doing.
Peak concentration:43
Where does the amount come from?
Each of these four is a step away from the habit this page exists to break: a number you heard from a neighbour.
A soil test
The starting point and the cheapest part of the whole business. Without it you buy and spread fertiliser the soil did not need.
Tree age and size
A first-year tree and a ten-year-old bearing tree want completely different amounts. Most burns happen on young trees, because a mature tree’s dose was used on them.
Last season’s crop
A tree that carried a heavy crop took more out of the soil and has more to replace. One that had an off year does not need the same.
Irrigation water quality
If the water is itself saline, part of the allowable salt load is already spent. A water analysis matters as much here as a soil test.
You will deliberately find no figure in kilograms on this page. The dose depends on species, rootstock, age, soil texture, water analysis and yield target, and any number written without those is the neighbour’s number in a smarter font. What this page gives you is the structure of the decision: start from the test, split it, and put it in the right place.
Chapter four
The same amount, in four different places
Two meters ride on each card because they do not move together: how much of it actually reaches the tree, and how likely it is to burn on the way. A method can be both safe and useless.
Around the collar
The commonest mistake there is. There are no absorbing roots there to take it up, and the only living tissue in contact with it is the collar bark — which also stays damp underneath.
Broadcast without incorporation
Safe, but much of the nitrogen volatilises and the phosphorus never reaches rooting depth. A method that does little harm and little good.
Pits under the canopy edge
Several pits at the drip line, fertiliser in them, soil back on top. It sits right beside the absorbing roots, away from the collar, and stays in the soil.
Fertigation
Dissolved and delivered at a concentration the emitter dictates rather than one a granule creates. The highest uptake and the lowest risk — given a system and a correctly set concentration.
One simple rule removes most nursery burns: keep granular fertiliser at least 30 cm away from a young tree’s collar — and further on a mature tree, because the canopy is wider. Fertiliser belongs in a ring under the canopy edge, not in a circle around the trunk.
Chapter five
What turns a survivable dose into a burn
Same amount, same product, same place — and a completely different outcome on two different days. These eight are ranked rather than weighted: nobody can put an honest coefficient on them, but the ordering is not in dispute, and the ordering is what tells you whether today is the day.
Dry soil
In dry soil the same fertiliser dissolves in less water and the soil solution is several times more concentrated. Fertiliser on a thirsty soil is the worst combination available.
high risk
No irrigation afterwards
Watering after fertilising does two things: it dilutes the concentration and it carries the fertiliser down to rooting depth. Skipping it loses both.
high risk
Young trees and the establishment year
A young tree’s root volume is small, so the dose a mature tree tolerates is several times more concentrated for it. This is where most burns happen.
high risk
Extreme heat
High transpiration and surface evaporation concentrate the soil solution, and heat speeds up the conversion of urea to ammonia. Midsummer noon is not fertilising time.
moderate risk
Light, sandy soil
Low holding capacity means the concentration climbs faster and the fertiliser leaches faster. On sand, splitting the dose is not optional.
moderate risk
Foliar spraying in the sun
A droplet on a hot leaf evaporates fast and the salt left behind is more concentrated than the solution you mixed. Foliar work is a dawn and dusk job.
moderate risk
Un-composted manure
A high soluble salt load plus free ammonia. Fresh manure is one of the commonest causes of young-tree burn, precisely because it is assumed to be "natural".
high risk
Saline irrigation water
If the water brings salt of its own, part of the allowance was spent before you fertilised. Both a smaller dose and more splits are needed.
moderate risk
These conditions do not add, they multiply. A young tree, in sandy soil, in July heat, with no irrigation after, and fresh manure — none of those five is a disaster on its own, and all five together lose the tree. If more than two of this list are true today, postpone the application.
Chapter six
A burned tree: what to do and what not to
The order of these seven steps matters in two places: leaching before the surface granules are cleared washes the rest of them straight in, and feeding again before a soil test is how a tree gets burned twice.
Seven steps to rescue
The first step is not doing something. The grower’s most natural reaction — "let us help it" — is exactly what makes it worse.
- 01
Stop every other application
No compensatory feed, no stimulant, no foliar spray. The tree has a concentration problem, not a shortage; anything added is added to that concentration.
Nothing on this week’s programme
- 02
Clear the fertiliser off the surface
Collect and remove undissolved granules from the soil and around the collar. Done after watering rather than before, the water carries them straight into the roots.
Soil surface and collar cleared
- 03
Leach with plenty of water
Several heavy irrigations that dilute the concentration and take the salt below the root zone. One is not enough, and a single long flood suffocates the roots.
Several irrigations, not one flood
- 04
Make sure the water leaves
If the water has nowhere to go, leaching only moved the salt and it comes back with the first hot week. Drainage is the condition on the previous step.
A route for water out of the profile
- 05
Wait, and do not prune
Do not cut the burned tissue straight away; until new growth shows where the live wood is, every cut is a guess. Waiting here is an action, not inaction.
No pruning until new growth appears
- 06
Take a soil test
While there is time, find out what is left in the soil. The next decision — and next year’s amount — should come off that sheet rather than out of memory.
A test sheet with EC and nutrients
- 07
Reassess once new growth appears
When the new leaves come, you can see how much of the root system was lost. Only then can you decide about cutting out dead tissue and a light feeding programme.
Judgement made on new growth, not burned tissue
It takes about 4 weeks before new growth tells you how much of the root system survived. Until then, any verdict on the outcome is premature.
Three things not to do: no compensatory feed (it raises the concentration further), no immediate pruning of burned tissue (you still do not know where the live boundary is), and no growth stimulant while the roots are still sitting in a concentrated solution — the tree has no capacity to grow right now, it needs room to recover.
Leaching and the drainage condition it depends on are the main subject of another dossier, with the formula and the volume:The soil salinity dossier
Chapter seven
Farkesht products for lower-risk feeding
Two groups that sit at the low-salt end of the range: one that releases gradually, and one dissolved and applied at a concentration you control.
Organic fertilisers
Organic fertilisers: very low salt and gradual release. Instead of one concentrated hit, a supply spread across the season — which is what chapter three achieves by splitting the dose, done here inside the product itself.
Chelated fertilisers
Chelated fertilisers: for fertigation and foliar work, where the concentration is set by you rather than by a granule. The chelate keeps the element available without needing much salt in the soil to do it.
Plainly: we sell fertiliser, and this page is asking you to buy less of it. But fertiliser that half leaches away, or goes on in one go and burns the tree, is a sale for us and a lost season for you. Before any purchase, take a soil test — it is the cheapest thing you will buy in this whole business.
Chapter eight
The Farkesht fertiliser and burn-prevention course
What you have read is the structure of the decision. The course walks the same route on real ground: reading a soil test sheet, turning it into a dose, digging and filling the pits, and setting the concentration on a fertigation line.
Young trees and the establishment year
Where most burns happen, because a mature tree’s dose gets used on a small root system. The course focuses on the young-tree dose and the clearance from the collar.
Bearing orchards
Where the amounts are large and splitting and timing have the greatest effect. The course builds a seasonal programme lined up with growth stages.
Greenhouses and confined media
In a limited volume the concentration climbs several times faster. The course covers solution EC control, flushing the medium and managing drainage water.
What the course covers
Every module ends in something you can do, not something you can recite. If you finish a module unable to do the thing written beside it, that module has not done its job.
- 01
Reading the label and the analysis
What the numbers on the bag mean, the difference between element and compound, and what to pull out of a soil test sheet.
Read a soil test sheet
- 02
Calculating the dose
From the soil test, tree age and last season’s crop to a real amount per tree. Worked on several real examples.
Calculate your own trees’ dose
- 03
Pit placement and fertigation
Where and how many pits, at what depth, and how to set and check the concentration on a fertigation line.
Execute a correct pit placement
- 04
Splitting across the season
How many applications, at what interval, and lined up with which growth stage. Building a fertiliser calendar for your own species.
Write the season’s fertiliser calendar
- 05
Foliar spraying without scorch
Safe concentrations, the right hour, a test on a few branches before the whole block, and mixtures that must not go on together.
Spray foliar feed without burning leaves
- 06
Managing a burned tree
Working out which mechanism happened, running the leaching properly, and deciding about pruning and later feeding.
Manage a burned tree through recovery
- Sectioned curriculumEach course is divided into sections and lessons, so you can go straight to the part you need.
- Pick up where you left offProgress is saved per lesson and the player resumes from the point you stopped.
- Free preview lessonsSome lessons are open before purchase, so you can judge the depth and the tone first.
- Permanent accessA course you buy stays open in your account. There is no time limit on watching it.
- Phone or desktopThe player runs in the browser. Nothing to install.
- Ask an adviserStuck anywhere along the way, post the question in the forum and get an adviser’s answer.
Courses available now
This list is read straight from the Farkesht library — every course published appears here.
- Almond
سرمازدگی و گلدهی بادام
انتخاب رقم دیرگل، تغذیه بور قبل از گل، و کارهایی که بعد از سرمای دیررس بهاره هنوز باغ را نجات میدهد.
- 1 sections
- 1 lessons
- 9:00
Watch
- Pomegranate
ترکیدگی میوه و کرم گلوگاه انار
آبیاری یکنواخت در سخت شدن پوست، پوشش توری، و زمان برداشت برای کم کردن ترکیدگی و خسارت گلوگاه.
- 1 sections
- 1 lessons
- 8:00
Watch
چطور دفترچه باغ را نگه دارید
ثبت آبیاری، تغذیه و سمپاشی طوری که فصل بعد قابل مقایسه باشد. این درس به گونهٔ خاصی وابسته نیست.
- 1 sections
- 1 lessons
- 6:00
Watch
Chapter nine
Everything on the site is free
Every lesson and tool here is free; sign in to your account and start.
Questions
Common questions about applying fertiliser
The eight asked most often in the forum.
What exactly is fertiliser burn, and what does it look like?
Three different events under one name. The commonest is osmotic: the fertiliser raises the soil solution concentration so far that the root loses water instead of taking it — and the sign is wilting on moist soil, which is the most confusing symptom available. The other two are scorch from ammonia gas and direct contact burn. Which one happened decides whether leaching helps at all.
How much fertiliser should each tree get?
This page deliberately gives no number, because any figure without a soil test, tree age, soil texture and water analysis is the neighbour’s guess in a smarter font. What you can do today: take a soil test — the cheapest part of the whole business — and whatever amount is finally settled on, spread it across three applications rather than one.
Manure is natural, so it is safe, isn’t it?
No, and this is one of the commonest causes of young-tree burn. Fully composted manure has a very low salt index and is safe. Fresh manure has both a high soluble salt load and releases ammonia as it breaks down — that is both of the main burn mechanisms at once. Manure should be fully composted, applied preferably in autumn, and kept away from the collar.
Why should fertiliser not go around the trunk?
For two reasons. First, there are no absorbing roots there; the fine roots that take fertiliser up are concentrated at the canopy edge, not against the trunk. Second, the only living tissue in contact with it is the collar bark, which also holds moisture underneath the fertiliser and burns. It belongs in a ring under the canopy edge.
Do I have to irrigate after fertilising?
Yes, and it is close to the most important habit on this page. Watering after fertilising does two things at once: it dilutes the soil solution and it carries the fertiliser from the surface down to rooting depth. Without it, urea loses part of its nitrogen as ammonia and the rest sits concentrated on the surface.
Why does a foliar spray scorch leaves?
Because what stays on the leaf is more concentrated than what you mixed: the water evaporates and the salt stays. That is why the hour matters more than the concentration — early morning or evening, out of direct sun, and not on a water-stressed leaf. And always test on a few branches and wait a few days before doing the block.
Will a burned tree recover?
It depends how much of the root system was damaged, and that cannot be known until new growth appears about a month later. What improves the odds: clear the remaining fertiliser, leach several times, make sure the water drains, and then stop. What destroys the odds is feeding it again "to make up for it".
Can I write my orchard’s fertiliser programme from this page?
The structure of the decision is here and it is enough to start. What a page cannot give you is two things: reading a real soil test sheet and turning it into a number, and executing pit placement and setting fertigation concentration on the ground. Those two affect the outcome more than the brand of fertiliser, and they are exactly what the video course shows.
Before the next fertiliser purchase, one soil test
Start with the video course — or request a consultation if you want an adviser to look at your soil and water analysis and write the season’s fertiliser programme.