Farkesht technical guide
How to diagnose and reduce soil salinity
Salt does three completely different injuries and we call all three "salinity" — which is why gypsum gets spread every season on ground whose problem is something else. This page separates them first, then measures, then corrects.
- ECe above which most fruit trees start losing yield
- 2dS/m
- Share of water that must pass the roots on saline ground
- 15%
- Tonnes of salt irrigation water brings to a hectare in a season
- 4t/ha
Updated September 1, 2026Farin Kesht Taban Co.
Chapter one
Three injuries, three different remedies
These three are nearly always lumped together as "salt damage" and they do not share a cure. Separating them is the only thing that makes the correction chapter usable.
Osmotic stress
Dissolved salt holds water in the soil. The higher the concentration, the more force a root must spend to take the same water — and past a point it cannot.
Symptom: Midday wilt in moist soil, slow growth with no clear leaf symptom at all.
Remedy: Leaching: taking the salt out of the root zone with surplus water and drainage.
Specific ion toxicity
Chloride, sodium and boron are taken up, carried up the vascular system and accumulate at the leaf margin until the tissue burns.
Symptom: Marginal leaf scorch, even across the whole tree and unrelated to leaf age.
Remedy: Leaching, a tolerant rootstock, and not spraying with saline water.
Sodicity (structure)
Sodium disperses the clay particles; the pores close and water stops moving through the profile. This is the only injury gypsum has anything to do with.
Symptom: Water ponds and will not infiltrate; the soil is like rock dry and like putty wet.
Remedy: Gypsum to displace the sodium, then drainage and organic matter to hold the structure.
Chapter two
Four numbers from the laboratory, and one of them is the right one
Confusing these four is the most expensive mistake in this subject: a leaching fraction worked out from a 1:5 extract is out by a factor of three or four, and a season of water goes past the roots for nothing.
ECw
on a water sample
The salinity of the irrigation water. The first thing to know, because it is the main source of the salt arriving in the orchard every year.
ECe
on a soil sample
The salinity of the saturated soil paste extract. The figure every published threshold is written against — ask the laboratory for this one.
1:5 extract EC
on a soil sample
Cheaper and commoner, but diluted. It reads about a third to a quarter of ECe and cannot be compared to any table directly.
TDS
on a water sample
Total dissolved solids, in mg/L. The same information as EC in another unit; it converts by a fixed factor.
The standard conversion
TDS (mg/L) ≈ EC (dS/m) × 640
The factor from a 1:5 extract to ECe moves with soil texture — about three on sand and about four on clay. Which is why the best move is to ask the laboratory for ECe directly and never enter this arithmetic at all.
Where, when, and how many
A salinity reading without these four is a number with no meaning: salt concentrates at the edge of the wetted zone and at the surface, so the same field reads twice as salty from the wrong spot on the wrong day.
- Depth: the whole root profileAt least two depths: zero to thirty and thirty to sixty centimetres. The difference between them says whether salt is rising or moving down.
- Position: wetted centre and edgeOne from the middle of the wetted zone and one from its edge. Under drip the edge is several times saltier than the centre, and that is exactly where roots are damaged.
- Timing: before an irrigationStraight after watering the figure is diluted and optimistic. Sample at the end of the interval, when the soil is at its most concentrated.
- Number: a composite sampleFrom several points spread through the same block, combined. And if you have saline patches, sample those separately rather than mixing them in.
Chapter three
How much of your crop is salinity taking?
The FAO threshold-and-slope model. Each species holds a hundred per cent of yield up to its own threshold and then loses a fixed percentage per unit above it. This chart answers the question a grower actually has.
Yield remaining at 4 dS/m
- Date palm100 %
- Olive95 %
- Pomegranate95 %
- Fig95 %
- Grape76 %
- Pistachio80 %
- Apple63 %
- Peach52 %
- Almond53 %
- Apricot42 %
If you have not planted yet, species and rootstock are the cheapest answer to salinity:The sapling selection dossier
Chapter four
Leaching: move the salt past the roots, not around them
Three frames of one soil profile. The third carries this chapter’s condition with it: the same water with no drainage under it is a bath with the plug in.
1as it stands
Where the salt is
Exactly where the water stopped: a crust at the surface and a band at the edge of the wetted zone. Sampling the centre never sees that band at all.
2no use
An ordinary irrigation
The band shifts a little and stays within reach of the roots. The following week evaporation brings it back up.
3works
Leaching with drainage
Surplus water carries the band past rooting depth and the drain takes it off the land. Without a drain, the same work only raises the water table.
Leaching requirement
LR = ECw ÷ (5 × ECe − ECw)
- 2 dS/m
- Your irrigation water salinity
- 2 dS/m
- Target salinity in the root zone
- 25 %
- Share of water that must pass the roots
The steady-state formula, written for ordinary orchard conditions. ECw is your water’s salinity and ECe the salinity you want to hold in the root zone — usually the threshold of the species you planted.
Before you apply one extra litre
If any of these four is not true, the leaching water is wasted. This chapter is why the page does not simply end at "irrigate more".
Drainage, before anything else
If the water has nowhere to go, the salt stays where it is and returns with the first hot week. Subsurface drainage or a permeable layer is the first condition, not the last.
Uniform application
With a system that is not uniform, half the block leaches and half does not — and you have paid for all the water.
The right season
During dormancy or outside the sensitive period. Leaching in peak heat suffocates roots in saturated soil and creates a second problem.
A calculated amount
The amount comes from the formula, not from feel. Less than required simply spreads salt through the root zone; more is waste and leached fertiliser.
Chapter five
Correction: which remedy for which injury
Gypsum is spread on saline-but-not-sodic ground every season by growers who were told it "fixes salt". It fixes sodium; on a soil whose problem is osmotic it changes nothing but the invoice.
Drainage
For: Sodicity (structure)
The dearest and the most fundamental. Without a way for water to leave, none of the other remedies survives more than a season.
- Time to effect
- Relative cost
Without this the rest do not work
Leaching
For: Osmotic stress
The fastest tangible effect, provided there is drainage underneath. The amount comes from the formula in the previous chapter.
- Time to effect
- Relative cost
Without this the rest do not work
Gypsum (calcium sulphate)
For: Sodicity (structure)
Calcium displaces sodium on the clay particles and the structure returns. For sodic soil only, and only after a test confirms it.
- Time to effect
- Relative cost
Organic matter
For: Sodicity (structure)
Holds the structure and raises infiltration. The slowest and the most durable; it complements gypsum rather than replacing it.
- Time to effect
- Relative cost
A tolerant rootstock
For: Specific ion toxicity
The cheapest answer to salinity, and available only before planting. On an established block it is an option for replanting.
- Time to effect
- Relative cost
Changing the irrigation method
For: Specific ion toxicity
Short-interval drip pushes salt to the edge of the wetted zone and keeps roots in the low-salinity part of it. High capital cost, immediate effect.
- Time to effect
- Relative cost
Before buying gypsum, get an SAR or exchangeable sodium percentage test. If the soil is saline but not sodic, gypsum does nothing and you have lost the money and a season. That one test is what settles this decision.
A season’s correction programme
Seven jobs in a set order. The order genuinely matters: leaching before drainage is water poured into a bath with the plug in.
- 01
Test the soil and the water
ECe from two depths, ECw from the source, and SAR or exchangeable sodium percentage. Without those three, the next decision is a guess.
A test sheet with ECe and SAR on it
- 02
Diagnose: saline, sodic, or both
Saline is high EC and low SAR; sodic is low EC and high SAR; saline-sodic is both. Three states, three different programmes.
One of three states, written down
- 03
Solve the drainage
If water has nowhere to go, stop here and fix that first. Every rial spent before this is wasted.
A route for water out of the profile
- 04
Amend, if it is sodic
Gypsum at the rate calculated from the test, spread and mixed into the surface layer. If it is not sodic, skip this step.
Gypsum applied at the calculated rate
- 05
Leach the calculated amount
In dormancy or outside the sensitive period, split across several applications rather than one flood. Splitting improves infiltration.
Leaching volume applied and recorded
- 06
Manage it permanently
A shorter irrigation interval, a leaching fraction in every application, and never letting the soil dry out completely. Salinity is not finished in one correction; it is managed.
A leaching fraction in the irrigation plan
- 07
Test again after a season
The same two depths, the same points, the same point in the irrigation interval. Comparison against the first sheet is the only trustworthy verdict.
An ECe trend over two consecutive seasons
Chapter six
Farkesht products for saline ground
Two groups, in the order saline soil requires: first a structure that lets water through, then something that holds that structure.
Soil conditioners
Soil conditioners: to restore structure and infiltration on sodic ground, and to make leaching possible at all.
Organic fertilisers
Organic fertilisers: they raise holding capacity and aggregate stability. The slowest and the most durable, and a complement to a conditioner rather than a substitute.
No micronutrient or biostimulant is on this list, because neither touches salinity. If the diagnosis is salt, a product aimed at a nutrient deficiency is money wasted — and if the drainage is unsolved, even these two will not survive more than a season.
Chapter seven
The Farkesht salinity management course
What you have read so far is the frame of the decision. The course walks the same route with a camera on saline ground: sampling from the right spot, reading the laboratory sheet, and running one leaching application start to finish.
Orchards on saline ground
A block that has lived with salt for years and gets a little worse each one. The course covers telling saline from sodic and building a multi-year plan.
Before planting
The cheapest time to solve salinity is before the first tree goes in: species and rootstock choice, drainage design and land preparation.
Greenhouses and confined media
In a confined substrate salinity 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 define. If you finish a module unable to do the thing written beside it, that module has not done its job.
- 01
Reading the ground: salinity symptoms
Telling the three injuries apart on real trees, identifying saline patches in a block, and separating salt from drought and from deficiency.
Separate salinity from three impostors
- 02
Measuring and sampling
Where, at what depth and when to sample, which test to ask for, and how to read ECe and SAR off the sheet.
Take a valid sample and read the sheet
- 03
Calculating the leaching fraction
From ECw and target ECe to a volume of water, and from volume to system run time. Worked on several real examples.
Calculate your own orchard’s leaching volume
- 04
Drainage: assessment and options
Finding where water stops, surface and subsurface drainage options, and when it simply does not pay.
Assess your own land’s drainage
- 05
Gypsum and amendments
Calculating the gypsum requirement from SAR, spreading and incorporation, and why it should not be used on non-sodic ground.
Make the gypsum decision on a number, not a habit
- 06
Living with residual salinity
Permanent management: interval, a leaching fraction in every application, species choice on replant, and annual monitoring.
Write a multi-year management plan
- 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.
- Pistachio
مراقبت فصلی باغ پسته
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- 1 sections
- 1 lessons
- 12:00
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- 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.
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- 9:00
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- Pomegranate
ترکیدگی میوه و کرم گلوگاه انار
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ثبت آبیاری، تغذیه و سمپاشی طوری که فصل بعد قابل مقایسه باشد. این درس به گونهٔ خاصی وابسته نیست.
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Chapter eight
Plans and how to get in
There are two routes to these lessons: buy the single course you need, or take a plan that opens the whole library at once.
Buy one course
You buy a course and it stays open in your account permanently. Right when you know exactly which subject you need.
See courses and pricesFarkesht plan
Opens every video course, the technical knowledge base and the species files together — and any course published while the plan runs is included too.
Compare plans
Basic
Register your orchard and keep its record
150,000 Toman90 days
Includes
- Ask questions in the forum
- Orchard records and care sheets for your species
- Our pick
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The expert knowledge base, and every species
350,000 Toman180 days
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- Care sheets for every species
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Complete
Everything, for a year
600,000 Toman365 days
Includes
- Ask questions in the forum
- Priority placement for your questions
- Orchard records and care sheets for your species
- Care sheets for every species
- Expert knowledge base
- Recorded video courses
- Private consultation with an agronomist
Questions
Common questions about soil salinity
The eight asked most often in the forum.
How do I know whether my soil is saline?
From the surface there are three signs: a white crust on the soil, even marginal leaf scorch regardless of leaf age, and midday wilt in soil that is moist. But all three are confused with other things; the only certain route is measuring EC of the saturated soil extract and of the irrigation water. Two numbers, and both are cheap.
The laboratory gave several numbers. Which is the right one?
ECe, the EC of the saturated soil paste extract. Every published threshold and every leaching formula is written against it. If your sheet gives a 1:5 extract EC, that figure is diluted and reads three to four times lower than ECe — do not make any decision directly from it. Best of all, ask for ECe from the start.
Does gypsum reduce salinity?
No, unless the soil is sodic. Gypsum supplies calcium to displace sodium on the clay particles and restore structure; that is a sodicity problem, not a salinity one. On soil that is merely saline, gypsum does nothing but add a line to the invoice. Measure SAR or exchangeable sodium percentage before buying any.
How much water does leaching need?
It comes out of the leaching fraction formula: ECw divided by five times target ECe minus ECw. For water at two and a target of two, about eleven per cent on top of the crop’s water requirement. But that figure only means anything if there is drainage; without it, the same water simply raises the water table.
On saline ground, is drip better than flood?
For day-to-day management, short-interval drip: it keeps the soil continuously moist, holds salt concentration in the root zone down and pushes salt to the edge of the wetted zone. But periodic leaching needs a volume of water drip alone will not deliver. In practice, both: drip through the season and one heavy leaching in dormancy.
Which species tolerate salt best?
Date palm is the most tolerant, then olive, pomegranate and fig. Pistachio and grape sit in the middle, and almond, apricot, peach and apple at the sensitive end. But the threshold is only half the story: the slope of loss matters too. Chapter three shows both together, and for a pre-planting choice see the sapling dossier.
How long before salinity comes down?
With drainage in place, one properly calculated leaching can lower root-zone ECe measurably within the same season. Correcting sodicity with gypsum takes one to two seasons. But salinity is never "finished": as long as the irrigation water carries salt, it arrives again every year. What you get is a managed balance, not a cure.
Can I manage my orchard’s salinity from this page?
The framework and the formulas are here and it is enough to start. What a page cannot give you is practice sampling from the right spot and assessing drainage on real ground — and those two affect the outcome more than any calculation. That is exactly what the video course shows, on saline land.
Get two numbers before next season
Start with the video course — or request a consultation if you want an adviser to look at your own soil and water test and write the correction programme.