Kingdom of Saudi Arabia · Ministry of Environment, Water and Agriculture · National Study

National Agricultural
Land Evaluation

A national assessment of where agriculture is physically possible, adequately watered, legally permitted, and suited to a named crop. The Kingdom is screened, then evaluated hectare by hectare, then grouped into developable zones. This page explains how that works before any module is opened.

Assessed64 elements · 19 groups
Unit of Assessment1 hectare
MethodNation → Hectare → Zone
BasisSatellite & desk-based
FrameworkFAO land evaluation
01 · The Method
Four questions, four separate answers

Every hectare in the Kingdom is asked four independent questions. Each is answered by its own module, in its own notation, against its own evidence. They are never combined into a single score — because a hectare that is physically excellent but legally barred is not “averagely good”. It is unavailable, and only one of the four answers tells you so.

Can the land support it?
Capability
The physical ground — soil, terrain, climate, drainage. Assessed once, independent of what is grown on it.
C1 C2 C3 C4 CN
Will the water bear it?
Water
Source, volume, quality, sustainability and basin allocation. Assessed separately from the land, never folded inside it.
W1 W2 W3 W4 W0
Does the law allow it?
Land Rights & Constraints
Protection, ownership, zoning and competing designations. Six checks against six separate registers held by different authorities.
E1 E2 E3 E0
How well would this crop do?
Suitability
The same measurements read again — this time against one named crop’s own tolerances rather than a general threshold.
S1 S2 S3 N1 N2

Three gates must all open. A hectare must be capable, watered and permitted before suitability is worth asking. Any one of the three failing stops the hectare — and the assessment records which one, because a military exclusion cannot be moved while an unrecorded title can.

02 · Depth of Analysis
What is evaluated, and how much of it

Each module assesses a defined set of elements, organised into groups. The individual elements are specified in each module — what matters here is the scale of the analysis: sixty-six separate determinations on every hectare that reaches assessment, drawn from nineteen analytical groups across four independent evaluations.

Soil Physical4
Soil Chemical4
Water & Drainage3
Topography & Erosion4
Climate4
Capability
17 land qualities · 5 groups
Source & Availability3
Sustainability3
Water Quality5
Access & Delivery2
Basin Allocation2
Water
15 parameters · 5 groups
Environmental Status2
Land Rights & Tenure2
Restrictions & Exclusions2
Land Rights & Constraints
6 checks · 3 groups
Soil Physical6
Soil Chemical6
Water & Drainage3
Topography & Erosion4
Climate5
Crop-Specific2
Suitability
26 diagnostic factors · 6 groups
64 elements  ×  1 hectare  =  64 determinations
64 elements  ×  [ assessment area, pending ] hectares  =  the national computation
… and the 26 suitability factors are re-read against each candidate crop’s own thresholds, so the crop layer multiplies again by the number of crops assessed.
91
measured parameters in the crop requirement library
1,268
crop threshold records loaded and source-validated
63
crops registered in the national crop library
7
separate authorities screened for the legal answer
03 · Where the Study Starts, and Where it Lands
Nation → Hectare → Zone

The study begins at national scale and ends at the scale a decision is actually made. First the Kingdom is screened to remove land that is definitionally unavailable. What survives is assessed one hectare at a time. Adjacent hectares carrying the same answers are then grouped into zones — blocks large enough and uniform enough to be developed under a single plan.

Step 1 · Nation
Screen the Kingdom
Remove land already allocated to other activities, land that is not land, terrain that is physically impossible, and ground that is legally barred.
Output — the assessment area
→
screen
Step 2 · Hectare
Assess every hectare
Each 1-hectare cell is evaluated against all 64 elements and emerges carrying four independent results — capability, water, legal and, per crop, suitability.
Output — C2s · W1 · E1
→
group
Step 3 · Zone
Group into zones
Adjacent hectares sharing the same capability, water and legal answer merge into one block, large enough to develop under a single management plan.
Output — the zone map and area ledger
Why one hectare
ResolutionSentinel-2 imagery at 10 m aggregates cleanly into a 1-hectare cell without resampling artefacts.
PrecisionFine enough that a zone boundary follows a real change in the ground rather than an arbitrary grid line.
TractabilityCoarse enough that a full national run across 64 elements remains computable.
PracticeIt is the unit in which land is allocated, transacted and reported.
04 · Step 1 in Detail
National exclusion — what is removed before anything is assessed

The first pass removes only land that is definitionally unavailable — not land that scores poorly. Nothing here is a judgement: it is a filter. A slope of twelve percent is not excluded, because that is a capability question. Land with no water within economic reach is not excluded, because that is a water question. Only ground that cannot be agricultural under any assessment comes out at this stage.

StageArea (ha)ShareReversible
Total national area
Kingdom of Saudi Arabia
215,000,000
100.0%
—
−Allocated to other activities
Urban and built-up · roads, rail, airports and ports · industrial cities and MODON zones
pending
pending
NO
−Not land
Water bodies · permanent wetland · active sabkha flats
pending
pending
NO
−Physically impossible
Cliff and escarpment · exposed rock outcrop · active dune fields
pending
pending
NO
−Legally barred
NCW gazetted protected areas · military exclusion zones · petroleum blocks · active mining concessions
pending
pending
BY AUTHORITY
=Assessment area
Every hectare here is evaluated against all 64 elements
pending
pending
—
What was removed matters as much as what remains. Three of these four families are permanent — a city, a cliff and a lake will not become farmland. The fourth is different: land that is legally barred is not gone, it is held by another authority. A petroleum block expires, a mining concession lapses, a designation is revised. On a ten-year planning horizon that is a materially different proposition from a coastline, and the assessment records it separately for exactly that reason.
What is deliberately not excluded here
Steep slopeAssessed as a capability class, not a bar — terrain limits what can be grown and how, but rarely removes land entirely.
No nearby waterAssessed by the Water module as a distance and conveyance question, which changes when infrastructure changes.
Unrecorded ownershipRecorded as E2 — resolvable. This is the most common finding in the Kingdom and it is a paperwork constraint, not a land one.
Saline or gypsum soilA class, not a bar. Severe soil chemistry limits crop choice; it does not make the ground unassessable.
05 · Reading a Result
One hectare, four answers

Every assessed hectare carries its four results in four separate notations. Each answer names not only its class but the reason for it — the subclass letter identifies which family of limitation governed the outcome, so a finding can be acted on rather than merely recorded.

C2s·W1·E1·S2z
C2s
Capable, with a moderate limitation
Class 2 of five. The subclass s names the cause — a soil physical quality is what held it back.
W1
Water usable without constraint
Source, volume, quality and allocation all pass. No subclass, because nothing limited the result.
E1
Legally clear
All six checks pass across six registers. Rarer than it looks nationally — unrecorded tenure alone puts most non-urban land at E2.
S2z
Moderately suitable for the named crop
The subclass z names salinity as the governing limitation for this crop specifically.
The four series are never mixed. A hectare is not described as “C2/S3” in a single token. Each notation answers a different question and carries a different meaning, so each is reported in its own series. Only the Suitability module uses S1–N2; only Capability uses C1–CN.
06 · From Assessment to Decision
The zone — where the study becomes usable

No decision is made about a single hectare. A zone is a contiguous group of hectares sharing the same capability, water and legal answer — uniform enough that one management plan works across all of it, and large enough to be worth developing.

assessed hectares
→
ZONE
one geometry
+
S2z Date palm — irrigated orchard
S3c Wheat — centre pivot
S1 Tomato — protected
N1z Tomato — open field
crop verdicts as attributes

Zones are crop-agnostic by design. Their boundaries come from capability, water and legal state only. Crop suitability attaches to a zone as an attribute rather than a boundary — so the Kingdom has one stable zone map, not one map per crop. Adding crops adds columns, not geometry, and every crop becomes directly comparable because all of them are measured on the same block.

The Zoning module sets out the rules in full — how zone boundaries are drawn, the minimum viable area for each production system, and the administrative hierarchy from nation to province to governorate to zone.
07 · How a Capability Class is Decided
Every land quality is rated. The worst one becomes the class.

FAO Bulletin 32 defines the capability classes. It does not prescribe the arithmetic. The framework establishes what C1 to CN mean, what a land quality is, and how land is matched against a land use requirement — but the method for combining seventeen individual ratings into a single class is left to the evaluator, and the literature offers two distinct families.

Limitation methods take the most severe constraint as the class. Parametric methods — the Storie index, the square-root method, the Sys land index — convert each rating to a percentage and combine them arithmetically. Both are established, and both appear in Sys et al. (1993). This study applies the maximum limitation method, for the reasons set out below.

This section concerns capability only — the 17 land qualities and the C1–CN classes. The Suitability module applies the same limitation rule to its own 26 diagnostic factors and the S1–N2 classes; the reasoning is identical and is not repeated there.

Start with one hectare. Its 17 land qualities sit in five groups. Group A is expanded below — click any row to see how its class and rating were obtained.

Capability assessment — one hectare17 land qualities · 5 groups
Click any group to expand its qualities — then click a quality to see how its class and rating were derived.
ASoil Physicalsubclass s4 qualitieslimited by rootingC4▾
LQ-SP-01Available water capacity147 mm/m90%C1
LQ-SP-01 · Available water capacity — how the class and rating are obtained
i
How much water the soil can hold for the plant to use between waterings.
A soil that holds more water needs watering less often and carries a crop through a missed irrigation. Sandy soils hold little; loams hold a lot.
1 · Class table for this quality — in mm/m  (higher is better)
C1
> 120
C2
90–120
C3
60–90
C4
30–60
CN
< 30
147 mm/m falls in band C1. This is the assessment result — the study stops here.
2 · The same bands on a common 0–100 scale
85–100%
60–85%
40–60%
25–40%
0–25%
band C1 = 120–200 mm/m  maps to  85–100%
position in band = ( 147 − 120 ) ÷ ( 200 − 120 ) = 0.338
rating = 85 + ( 0.338 × 15 ) = 90%
Why a percentage exists at all. Depth is in centimetres, salinity in dS/m, slope in percent — they cannot be combined until they share a scale. This conversion is required only by the scoring methods compared below. The method this study applies never uses it.
LQ-SP-02Soil workability88 index91%C1
LQ-SP-02 · Soil workability — how the class and rating are obtained
i
How easy the soil is to plough, level and prepare a seedbed in.
Hard, cloddy or sticky soils cost more fuel and machinery time, and a poor seedbed means uneven germination.
1 · Class table for this quality — in index  (higher is better)
C1
> 80
C2
60–80
C3
40–60
C4
20–40
CN
< 20
88 index falls in band C1. This is the assessment result — the study stops here.
2 · The same bands on a common 0–100 scale
85–100%
60–85%
40–60%
25–40%
0–25%
band C1 = 80–100 index  maps to  85–100%
position in band = ( 88 − 80 ) ÷ ( 100 − 80 ) = 0.400
rating = 85 + ( 0.400 × 15 ) = 91%
Why a percentage exists at all. Depth is in centimetres, salinity in dS/m, slope in percent — they cannot be combined until they share a scale. This conversion is required only by the scoring methods compared below. The method this study applies never uses it.
LQ-SP-03Rooting conditions42 cm35%C4
LQ-SP-03 · Rooting conditions — how the class and rating are obtained
i
How deep roots can actually grow before hitting something they cannot pass.
Rock, hardpan or calcrete stops roots. A shallow root zone means the plant reaches less water and less nutrient, whatever else is favourable.
1 · Class table for this quality — in cm  (higher is better)
C1
> 100
C2
75–100
C3
50–75
C4
25–50
CN
< 25
42 cm falls in band C4. This is the assessment result — the study stops here.
2 · The same bands on a common 0–100 scale
85–100%
60–85%
40–60%
25–40%
0–25%
band C4 = 25–50 cm  maps to  25–40%
position in band = ( 42 − 25 ) ÷ ( 50 − 25 ) = 0.680
rating = 25 + ( 0.680 × 15 ) = 35%
Why a percentage exists at all. Depth is in centimetres, salinity in dS/m, slope in percent — they cannot be combined until they share a scale. This conversion is required only by the scoring methods compared below. The method this study applies never uses it.
LQ-SP-04Surface sealing & crusting92 index94%C1
LQ-SP-04 · Surface sealing & crusting — how the class and rating are obtained
i
Whether the soil surface forms a hard crust after watering.
A crust blocks water from soaking in and can physically trap emerging seedlings underneath it.
1 · Class table for this quality — in index  (higher is better)
C1
> 80
C2
60–80
C3
40–60
C4
20–40
CN
< 20
92 index falls in band C1. This is the assessment result — the study stops here.
2 · The same bands on a common 0–100 scale
85–100%
60–85%
40–60%
25–40%
0–25%
band C1 = 80–100 index  maps to  85–100%
position in band = ( 92 − 80 ) ÷ ( 100 − 80 ) = 0.600
rating = 85 + ( 0.600 × 15 ) = 94%
Why a percentage exists at all. Depth is in centimetres, salinity in dS/m, slope in percent — they cannot be combined until they share a scale. This conversion is required only by the scoring methods compared below. The method this study applies never uses it.
Group A resolves to C4. Three of its four qualities are excellent. Rooting conditions at 42 cm is not. The group takes the worst of its members.
BSoil Chemicalsubclass z / n4 qualitiesno limitationC1▾
LQ-SC-01Salinity (ECe)1.6 dS/m88%C1
LQ-SC-01 · Salinity (ECe) — how the class and rating are obtained
i
How salty the soil is.
Salt makes it harder for roots to draw water, even when water is present. Above a crop’s tolerance, yield falls and eventually the crop fails.
1 · Class table for this quality — in dS/m  (lower is better)
C1
< 2
C2
2–4
C3
4–8
C4
8–16
CN
> 16
1.6 dS/m falls in band C1. This is the assessment result — the study stops here.
2 · The same bands on a common 0–100 scale
85–100%
60–85%
40–60%
25–40%
0–25%
band C1 = 0–2 dS/m  maps to  85–100%
position in band = ( 2 − 1.6 ) ÷ ( 2 − 0 ) = 0.200
rating = 85 + ( 0.200 × 15 ) = 88%
Why a percentage exists at all. Depth is in centimetres, salinity in dS/m, slope in percent — they cannot be combined until they share a scale. This conversion is required only by the scoring methods compared below. The method this study applies never uses it.
LQ-SC-02Sodicity (ESP)4.7 %93%C1
LQ-SC-02 · Sodicity (ESP) — how the class and rating are obtained
i
How much sodium is held on the soil particles.
Sodium breaks down soil structure. The soil seals up, water stops soaking in, and the surface turns to a hard pan.
1 · Class table for this quality — in %  (lower is better)
C1
< 10
C2
10–15
C3
15–25
C4
25–40
CN
> 40
4.7 % falls in band C1. This is the assessment result — the study stops here.
2 · The same bands on a common 0–100 scale
85–100%
60–85%
40–60%
25–40%
0–25%
band C1 = 0–10 %  maps to  85–100%
position in band = ( 10 − 4.7 ) ÷ ( 10 − 0 ) = 0.530
rating = 85 + ( 0.530 × 15 ) = 93%
Why a percentage exists at all. Depth is in centimetres, salinity in dS/m, slope in percent — they cannot be combined until they share a scale. This conversion is required only by the scoring methods compared below. The method this study applies never uses it.
LQ-SC-03Nutrient availability72 index86%C1
LQ-SC-03 · Nutrient availability — how the class and rating are obtained
i
Whether the soil can supply and hold the nutrients a crop needs.
Poor soils can be fertilised, but low-fertility soils also lose fertiliser quickly, which raises the running cost every season.
1 · Class table for this quality — in index  (higher is better)
C1
> 70
C2
50–70
C3
30–50
C4
15–30
CN
< 15
72 index falls in band C1. This is the assessment result — the study stops here.
2 · The same bands on a common 0–100 scale
85–100%
60–85%
40–60%
25–40%
0–25%
band C1 = 70–100 index  maps to  85–100%
position in band = ( 72 − 70 ) ÷ ( 100 − 70 ) = 0.067
rating = 85 + ( 0.067 × 15 ) = 86%
Why a percentage exists at all. Depth is in centimetres, salinity in dS/m, slope in percent — they cannot be combined until they share a scale. This conversion is required only by the scoring methods compared below. The method this study applies never uses it.
LQ-SC-04Toxicity (boron)0.2 mg/L97%C1
LQ-SC-04 · Toxicity (boron) — how the class and rating are obtained
i
Whether boron in the soil or water is high enough to poison the crop.
Boron is needed in trace amounts and toxic slightly above them. The safe range is narrow, and it differs sharply between crops.
1 · Class table for this quality — in mg/L  (lower is better)
C1
< 1.0
C2
1.0–2.0
C3
2.0–4.0
C4
4.0–6.0
CN
> 6.0
0.2 mg/L falls in band C1. This is the assessment result — the study stops here.
2 · The same bands on a common 0–100 scale
85–100%
60–85%
40–60%
25–40%
0–25%
band C1 = 0–1 mg/L  maps to  85–100%
position in band = ( 1 − 0.2 ) ÷ ( 1 − 0 ) = 0.800
rating = 85 + ( 0.800 × 15 ) = 97%
Why a percentage exists at all. Depth is in centimetres, salinity in dS/m, slope in percent — they cannot be combined until they share a scale. This conversion is required only by the scoring methods compared below. The method this study applies never uses it.
Group B resolves to C1. Every quality in this group rates C1. The group carries no limitation and does not constrain the hectare.
CWater & Drainagesubclass w / f3 qualitiesno limitationC1▾
LQ-W-01Drainage condition82 index89%C1
LQ-W-01 · Drainage condition — how the class and rating are obtained
i
How quickly excess water drains away from the root zone.
Roots need air as well as water. Slow-draining soil suffocates them and invites root disease.
1 · Class table for this quality — in index  (higher is better)
C1
> 75
C2
55–75
C3
35–55
C4
18–35
CN
< 18
82 index falls in band C1. This is the assessment result — the study stops here.
2 · The same bands on a common 0–100 scale
85–100%
60–85%
40–60%
25–40%
0–25%
band C1 = 75–100 index  maps to  85–100%
position in band = ( 82 − 75 ) ÷ ( 100 − 75 ) = 0.280
rating = 85 + ( 0.280 × 15 ) = 89%
Why a percentage exists at all. Depth is in centimetres, salinity in dS/m, slope in percent — they cannot be combined until they share a scale. This conversion is required only by the scoring methods compared below. The method this study applies never uses it.
LQ-W-02Flood hazard0.3 events/10 yr96%C1
LQ-W-02 · Flood hazard — how the class and rating are obtained
i
How often the site is likely to flood.
Flooding can drown a crop, wash away topsoil, and damage irrigation infrastructure. In spate systems it is a resource instead.
1 · Class table for this quality — in events/10 yr  (lower is better)
C1
< 1
C2
1–2
C3
2–4
C4
4–7
CN
> 7
0.3 events/10 yr falls in band C1. This is the assessment result — the study stops here.
2 · The same bands on a common 0–100 scale
85–100%
60–85%
40–60%
25–40%
0–25%
band C1 = 0–1 events/10 yr  maps to  85–100%
position in band = ( 1 − 0.3 ) ÷ ( 1 − 0 ) = 0.700
rating = 85 + ( 0.700 × 15 ) = 96%
Why a percentage exists at all. Depth is in centimetres, salinity in dS/m, slope in percent — they cannot be combined until they share a scale. This conversion is required only by the scoring methods compared below. The method this study applies never uses it.
LQ-W-04Waterlogging risk5 days/yr92%C1
LQ-W-04 · Waterlogging risk — how the class and rating are obtained
i
How long water sits in the root zone after rain or irrigation.
Short waterlogging is survivable. Sustained saturation starves roots of oxygen and kills the plant from below.
1 · Class table for this quality — in days/yr  (lower is better)
C1
< 10
C2
10–25
C3
25–50
C4
50–90
CN
> 90
5 days/yr falls in band C1. This is the assessment result — the study stops here.
2 · The same bands on a common 0–100 scale
85–100%
60–85%
40–60%
25–40%
0–25%
band C1 = 0–10 days/yr  maps to  85–100%
position in band = ( 10 − 5 ) ÷ ( 10 − 0 ) = 0.500
rating = 85 + ( 0.500 × 15 ) = 92%
Why a percentage exists at all. Depth is in centimetres, salinity in dS/m, slope in percent — they cannot be combined until they share a scale. This conversion is required only by the scoring methods compared below. The method this study applies never uses it.
Group C resolves to C1. Every quality in this group rates C1. The group carries no limitation and does not constrain the hectare.
DTopography & Erosionsubclass t / e / d4 qualitiesno limitationC1▾
LQ-T-01Terrain / slope0.5 %96%C1
LQ-T-01 · Terrain / slope — how the class and rating are obtained
i
How steep and even the ground is.
Steep or uneven ground blocks machinery, prevents centre-pivot irrigation, and makes water run off instead of soaking in.
1 · Class table for this quality — in %  (lower is better)
C1
< 2
C2
2–5
C3
5–10
C4
10–16
CN
> 16
0.5 % falls in band C1. This is the assessment result — the study stops here.
2 · The same bands on a common 0–100 scale
85–100%
60–85%
40–60%
25–40%
0–25%
band C1 = 0–2 %  maps to  85–100%
position in band = ( 2 − 0.5 ) ÷ ( 2 − 0 ) = 0.750
rating = 85 + ( 0.750 × 15 ) = 96%
Why a percentage exists at all. Depth is in centimetres, salinity in dS/m, slope in percent — they cannot be combined until they share a scale. This conversion is required only by the scoring methods compared below. The method this study applies never uses it.
LQ-T-02Water erosion hazard2.3 t/ha/yr93%C1
LQ-T-02 · Water erosion hazard — how the class and rating are obtained
i
How fast rain and runoff strip topsoil from the site.
Topsoil is where the fertility and the water-holding capacity live. Once it is gone it takes centuries to replace.
1 · Class table for this quality — in t/ha/yr  (lower is better)
C1
< 5
C2
5–10
C3
10–25
C4
25–50
CN
> 50
2.3 t/ha/yr falls in band C1. This is the assessment result — the study stops here.
2 · The same bands on a common 0–100 scale
85–100%
60–85%
40–60%
25–40%
0–25%
band C1 = 0–5 t/ha/yr  maps to  85–100%
position in band = ( 5 − 2.3 ) ÷ ( 5 − 0 ) = 0.540
rating = 85 + ( 0.540 × 15 ) = 93%
Why a percentage exists at all. Depth is in centimetres, salinity in dS/m, slope in percent — they cannot be combined until they share a scale. This conversion is required only by the scoring methods compared below. The method this study applies never uses it.
LQ-T-03Wind erosion hazard16 index88%C1
LQ-T-03 · Wind erosion hazard — how the class and rating are obtained
i
How fast wind strips soil from the site.
Wind removes the fine fraction, sandblasts young seedlings, and buries irrigation lines. Windbreaks reduce it but cost money.
1 · Class table for this quality — in index  (lower is better)
C1
< 20
C2
20–40
C3
40–60
C4
60–80
CN
> 80
16 index falls in band C1. This is the assessment result — the study stops here.
2 · The same bands on a common 0–100 scale
85–100%
60–85%
40–60%
25–40%
0–25%
band C1 = 0–20 index  maps to  85–100%
position in band = ( 20 − 16 ) ÷ ( 20 − 0 ) = 0.200
rating = 85 + ( 0.200 × 15 ) = 88%
Why a percentage exists at all. Depth is in centimetres, salinity in dS/m, slope in percent — they cannot be combined until they share a scale. This conversion is required only by the scoring methods compared below. The method this study applies never uses it.
LQ-T-04Sand encroachment0.7 m/yr90%C1
LQ-T-04 · Sand encroachment — how the class and rating are obtained
i
How fast mobile sand is advancing onto the site.
Moving dunes bury crops, roads and canals. Holding them back is a permanent, recurring cost on the operation.
1 · Class table for this quality — in m/yr  (lower is better)
C1
< 1
C2
1–3
C3
3–6
C4
6–12
CN
> 12
0.7 m/yr falls in band C1. This is the assessment result — the study stops here.
2 · The same bands on a common 0–100 scale
85–100%
60–85%
40–60%
25–40%
0–25%
band C1 = 0–1 m/yr  maps to  85–100%
position in band = ( 1 − 0.7 ) ÷ ( 1 − 0 ) = 0.300
rating = 85 + ( 0.300 × 15 ) = 90%
Why a percentage exists at all. Depth is in centimetres, salinity in dS/m, slope in percent — they cannot be combined until they share a scale. This conversion is required only by the scoring methods compared below. The method this study applies never uses it.
Group D resolves to C1. Every quality in this group rates C1. The group carries no limitation and does not constrain the hectare.
EClimatesubclass c2 qualitiesno limitationC1▾
LQ-C-02Thermal regime3500 GDD91%C1
LQ-C-02 · Thermal regime — how the class and rating are obtained
i
Whether the site accumulates enough warmth for the crop to complete its cycle.
Too little heat and fruit never ripens. Too much and flowers drop. Every crop has its own window.
1 · Class table for this quality — in GDD  (higher is better)
C1
> 2500
C2
1800–2500
C3
1200–1800
C4
800–1200
CN
< 800
3500 GDD falls in band C1. This is the assessment result — the study stops here.
2 · The same bands on a common 0–100 scale
85–100%
60–85%
40–60%
25–40%
0–25%
band C1 = 2500–5000 GDD  maps to  85–100%
position in band = ( 3500 − 2500 ) ÷ ( 5000 − 2500 ) = 0.400
rating = 85 + ( 0.400 × 15 ) = 91%
Why a percentage exists at all. Depth is in centimetres, salinity in dS/m, slope in percent — they cannot be combined until they share a scale. This conversion is required only by the scoring methods compared below. The method this study applies never uses it.
LQ-C-03Radiation28 MJ/m²/day98%C1
LQ-C-03 · Radiation — how the class and rating are obtained
i
How much sunlight energy reaches the crop each day.
Sunlight drives photosynthesis and therefore yield. Saudi Arabia is among the sunniest places on earth, so this rarely limits.
1 · Class table for this quality — in MJ/m²/day  (higher is better)
C1
> 18
C2
14–18
C3
10–14
C4
6–10
CN
< 6
28 MJ/m²/day falls in band C1. This is the assessment result — the study stops here.
2 · The same bands on a common 0–100 scale
85–100%
60–85%
40–60%
25–40%
0–25%
band C1 = 18–30 MJ/m²/day  maps to  85–100%
position in band = ( 28 − 18 ) ÷ ( 30 − 18 ) = 0.833
rating = 85 + ( 0.833 × 15 ) = 98%
Why a percentage exists at all. Depth is in centimetres, salinity in dS/m, slope in percent — they cannot be combined until they share a scale. This conversion is required only by the scoring methods compared below. The method this study applies never uses it.
Group E resolves to C1. Every quality in this group rates C1. The group carries no limitation and does not constrain the hectare.
Total assessed 17 qualities worst group governs C4s
?
This hectare is excellent at almost everything.
One quality is not. So what class does it get?

Sixteen of seventeen land qualities rate favourably. The soil holds water well, the chemistry is sound, drainage is adequate, the terrain is nearly flat, the climate suits cultivation, and there is no erosion or encroachment hazard. By almost every measure this is good agricultural ground.

One quality is not favourable. Effective rooting depth is 42 cm — a calcrete horizon sits just below. No crop assessed in this study can establish a working root system in 42 cm of soil. Not date palm, not wheat, not tomato, not forage. The constraint is not partial and it does not vary by sector: it closes off every agricultural activity the study evaluates.

So the question the classification method must answer is simple, and everything below turns on it:

Does sixteen favourable qualities out of nineteen make this good land — or does the one that fails decide it?

This is not a rhetorical question. Established land evaluation methods answer it differently, and the same hectare can emerge as C1 or C4 depending purely on which is applied. The five below are worked against these identical readings.

Five ways to answer it. Each is defined below with its formula and reference, worked against the identical 17 readings from the hectare above. Four are published alternatives; the fifth is the method this study applies.

01
Arithmetic mean
Simple averaging — not a published land-evaluation method
FAILS
Definition. Every quality rating is summed and divided by the number of qualities. All qualities count equally. This is the method most readers assume when they see seventeen ratings, which is why it is shown first.
Formula
LI = ( Σ Ri ) ÷ n
where Ri = rating of quality i as % of optimal  ·  n = 17
= ( 90 + 91 + 35 + 94 + 88 + … + 89 ) ÷ 17  =  1,506 ÷ 17
Reference
No primary reference — arithmetic averaging is not an established land-evaluation method. It is included here as the intuitive baseline that the limitation and parametric families both reject.—
FAO Bulletin 32 rejects simple averaging implicitly by defining classes through limitation rather than aggregate score.
Open source
Result88.6% C1 The single C4 quality is diluted by sixteen favourable ones. The hectare reports as highly capable when a crop cannot root in it.
02
Weighted mean
Weights as implemented in ALUES 0.2.1 (scale 1–3)
FAILS
Definition. Each rating is multiplied by an importance weight before averaging, so qualities judged more critical carry greater influence. The ALUES database loaded in this study carries exactly such a weight column. The test below gives rooting conditions the maximum weight of 3 — the most favourable possible case for the method.
Quality (first six of 17)RwR × w
Available water capacity903270
Soil workability912182
Rooting conditions353105
Surface sealing942188
Salinity (ECe)883264
Sodicity (ESP)932186
… 11 more  ·  Σ(R×w) = 3,217  ·  Σw = 37
Formula
LI = Σ( Ri × wi ) ÷ Σ wi
where wi = importance weight, 1 (minor) to 3 (critical)
= 3,217 ÷ 37
Reference
ALUES: Agricultural Land Use Evaluation System, v0.2.1 — Mariano, A.J. et al. CRAN R package. Implements weighted parametric scoring; the weight column is present in every crop requirement record loaded by this study.CR-03
See also the ALUES Reference Manual and the suit function vignette for the scoring implementation.
Open source
Result86.9% C1 Weighting does not rescue averaging. Even with the limiting quality at maximum weight the result moves only 1.5 points and the class is unchanged. The failure is in the averaging operation, not the weights.
03
Storie index
Parametric — multiplicative
AGREES
Definition. Ratings are expressed as decimal fractions of optimal and multiplied rather than averaged. Because multiplication compounds, any single low factor pulls the whole product down regardless of how favourable the others are. Storie applies it across four governing factor groups.
Formula
SI = A × B × C × X  × 100
each factor expressed 0–1 as a fraction of optimal
= 0.90 × 0.35 × 0.88 × 0.96 × 100
Reference
Storie Index Soil Rating — Storie, R.E. (1978). Special Publication 3203, Division of Agricultural Sciences, University of California. The original multiplicative parametric soil rating.ST-78
Method also summarised in O’Geen, A.T. et al. (2008), Revised Storie Index for Use with Digital Soils Information, UC ANR Publication 8335.
Open source
Result26.6% C4 Reaches the correct class — the 0.35 factor dominates the product. But the output is a number that does not say which factor produced it.
04
Square-root method
Parametric — anchored on the minimum
AGREES
Definition. The index is anchored on the lowest rating, then modified by the square root of the next two lowest. Widely applied in arid-zone land evaluation because it retains the severity of the worst constraint while allowing secondary constraints to moderate the result.
Formula
LI = Rmin × √( Ra/100 × Rb/100 )
where Rmin = lowest rating  ·  Ra, Rb = next two lowest
= 35 × √( 0.86 × 0.88 ) = 35 × 0.869
Reference
Assessment of the agricultural potential of the soils of Sudan — Khiddir, S.M. (1986). PhD thesis, State University of Ghent, Belgium. Origin of the square-root parametric method.CR-02
The method is set out and applied in Sys, C., Van Ranst, E. & Debaveye, J. (1991), Land Evaluation Part II: Methods in Land Evaluation, Agricultural Publications No. 7, Brussels.
Open source
Result30.4% C4 Also reaches C4, because it is built on the minimum. Closest of the parametric family to the limitation result — still a value rather than a diagnosis.
05
Maximum limitation
Limitation family — applied in this study
IN USE
Definition. No arithmetic is performed. Each quality is classified against its own thresholds, each group takes the worst class among its members, and the hectare takes the worst class among the groups. The subclass letter of the governing quality group is appended to the result.
Rule
Chectare = max( C1, C2, … C17 )
where max selects the most severe class, not the largest number
= max( C1, C1, C4, C1, … C1 ) = C4
subclass = letter of the governing quality group = s
Reference
A Framework for Land Evaluation — FAO (1976). FAO Soils Bulletin No. 32. Defines the class and subclass structure and the limitation principle by which a class is assigned.LE-01
Applied through Land Evaluation Part III: Crop Requirements — Sys, C., Van Ranst, E., Debaveye, J. & Beernaert, F. (1993), which presents the limitation tables alongside the parametric alternatives.
Open source
ResultC4s C4 Same class as both parametric methods, and the only result that names the limiting quality. A planner reads not just how limited the land is, but what to address.

Applying it to the hectare. The chosen method resolves each group to the worst class among its members, then the hectare to the worst class among the groups.

Rolling up to the hectare class
A → C4· B → C1· C → C1· D → C1· E → C1→ HECTARE = C4s

Four of the five groups return C1. One returns C4. The hectare is C4s — class 4, subclass s for a soil physical limitation. Eighteen of seventeen qualities are favourable and none of them changes the outcome, because no crop can establish a root system through calcrete at 42 cm.

Step 1
Each quality has its own class table
All 17 land qualities carry an independent set of thresholds. Rooting depth has one, salinity another, slope another. A measurement is looked up against its own bands, in its own units — never against a shared scale.
Step 2
Rate every quality, then every group
Each quality is classified individually. Each of the five groups then takes the worst class among its own members. At the end of this step there are five group results and still no hectare class.
Step 3
The hectare takes the worst group
The hectare adopts the most severe of the five group classes, and the subclass letter records which group produced it — C4s is class 4, limited by a soil physical quality.

What the comparison actually shows

The three methods that reach the correct class do so because each is governed by the minimum — the square-root method anchors on it, multiplication is compounded downward by it, and maximum limitation takes it outright. Only the averaging methods fail, and they fail because averaging is the one operation that permits a severe constraint to be paid for by favourable conditions elsewhere. Weighting does not repair this: raising the limiting quality to the maximum weight moved the result by 1.5 points and left the class unchanged.

So the choice is not about which method reaches the right class — on this hectare three of five agree. The choice is about what the result tells you. A parametric index returns 26.6. The limitation method returns C4s: class four, limited by a soil physical quality. One is a number; the other is an instruction.

01
Severe constraints are not compensated
A crop cannot root through calcrete at 42 cm because the radiation is excellent. The binding constraint binds, whatever else is favourable.
02
The class names its own cause
The subclass letter travels with the class, so a planner reads not only how limited the land is, but which group of qualities is limiting it.
03
A reviewer can verify it
Any class can be checked by locating the single worst quality. A parametric result requires reproducing the entire calculation to audit.
Where these methods are set out
A Framework for Land EvaluationFAO (1976) · Soils Bulletin 32
Defines the class and subclass structure, land qualities, and the matching principle. Does not prescribe an aggregation arithmetic — the choice of method rests with the evaluator.
Land Evaluation Part III: Crop RequirementsSys, Van Ranst, Debaveye & Beernaert (1993)
Presents both families — limitation tables and a parametric land index. The source of the threshold tables used in this study, and the reason both approaches are treated here as legitimate.
Storie Index Soil RatingStorie (1978) · University of California
The original multiplicative parametric rating. Factor fractions are multiplied rather than averaged, which is why a single low factor governs the product.
Square-root parametric methodKhiddir (1986)
Anchors the index on the minimum rating, modified by the square root of the next two lowest. Widely applied in arid-zone land evaluation.
Guidelines: Land Evaluation for Rainfed AgricultureFAO (1983) · Soils Bulletin 52
Applies the framework through limitation-based matching of land use requirements against land qualities.
One consequence must be stated plainly. Because a single quality decides the class, the assessment is sensitive to any one erroneous input — an incorrect soil depth value moves a hectare from C1 to C4 on its own, with no other reading to offset it. This is agronomically correct behaviour and it raises the stakes on data quality rather than lowering them. It is why every input layer carries a recorded source and validation status, and why the class always names the quality that produced it: a surprising result can be traced immediately to the single measurement responsible.

Note on the ALUES weight values. The crop threshold records loaded in this study carry a weight column, because the ALUES package implements a parametric method. Those weights are retained in the database for provenance but are not applied — weighting belongs to the parametric family, and mixing the two approaches would produce a class that is neither.
Sample · 01 · The Hectare
One hectare, end to end

Every number the assessment produces for a single hectare — all 64 elements across the four questions, then what those numbers mean for someone deciding what to do with the land. Click any element for a plain-language explanation of what is measured and why it matters. The readings are illustrative and internally consistent; they are not measurements from a surveyed site.

C2nz
Capability
W2qy
Water
E2(ET)
Legal
S1
🌴 Date palm
S3n
🌾 Wheat
S3n
🍅 Tomato
Cell
H-0417-2286
Setting
Inland alluvial plain
Source
Deep confined aquifer
Elements
64 assessed
Basis
Satellite & desk
Question 1 — Can the land support it?
Capability · 17 land qualities · 5 groups
C2nz Moderately capable
CodeLand qualityMeasuredClassSub
A · Soil PhysicalC1
LQ-SP-01Available water capacityⓘ132 mm/mC1s
How much water the soil can hold for the plant to use between waterings.
A soil that holds more water needs watering less often and carries a crop through a missed irrigation. Sandy soils hold little; loams hold a lot.
Reading 132 mm/m → class C1 · subclass s
LQ-SP-02Soil workabilityⓘ86 indexC1s
How easy the soil is to plough, level and prepare a seedbed in.
Hard, cloddy or sticky soils cost more fuel and machinery time, and a poor seedbed means uneven germination.
Reading 86 index → class C1 · subclass s
LQ-SP-03Rooting conditionsⓘ118 cmC1s
How deep roots can actually grow before hitting something they cannot pass.
Rock, hardpan or calcrete stops roots. A shallow root zone means the plant reaches less water and less nutrient, whatever else is favourable.
Reading 118 cm → class C1 · subclass s
LQ-SP-04Surface sealing & crustingⓘ88 indexC1s
Whether the soil surface forms a hard crust after watering.
A crust blocks water from soaking in and can physically trap emerging seedlings underneath it.
Reading 88 index → class C1 · subclass s
B · Soil ChemicalC2
LQ-SC-01Salinity (ECe)ⓘ3.5 dS/mC2z
How salty the soil is.
Salt makes it harder for roots to draw water, even when water is present. Above a crop’s tolerance, yield falls and eventually the crop fails.
Reading 3.5 dS/m → class C2 · subclass z
LQ-SC-02Sodicity (ESP)ⓘ8.5 %C1z
How much sodium is held on the soil particles.
Sodium breaks down soil structure. The soil seals up, water stops soaking in, and the surface turns to a hard pan.
Reading 8.5 % → class C1 · subclass z
LQ-SC-03Nutrient availabilityⓘ74 indexC1n
Whether the soil can supply and hold the nutrients a crop needs.
Poor soils can be fertilised, but low-fertility soils also lose fertiliser quickly, which raises the running cost every season.
Reading 74 index → class C1 · subclass n
LQ-SC-04Toxicity (boron)ⓘ3.5 mg/LC2n
Whether boron in the soil or water is high enough to poison the crop.
Boron is needed in trace amounts and toxic slightly above them. The safe range is narrow, and it differs sharply between crops.
Reading 3.5 mg/L → class C2 · subclass n
C · Water & DrainageC1
LQ-W-01Drainage conditionⓘ79 indexC1w
How quickly excess water drains away from the root zone.
Roots need air as well as water. Slow-draining soil suffocates them and invites root disease.
Reading 79 index → class C1 · subclass w
LQ-W-02Flood hazardⓘ0.4 events/10 yrC1f
How often the site is likely to flood.
Flooding can drown a crop, wash away topsoil, and damage irrigation infrastructure. In spate systems it is a resource instead.
Reading 0.4 events/10 yr → class C1 · subclass f
LQ-W-04Waterlogging riskⓘ7 days/yrC1w
How long water sits in the root zone after rain or irrigation.
Short waterlogging is survivable. Sustained saturation starves roots of oxygen and kills the plant from below.
Reading 7 days/yr → class C1 · subclass w
D · Topography & ErosionC1
LQ-T-01Terrain / slopeⓘ1.1 %C1t
How steep and even the ground is.
Steep or uneven ground blocks machinery, prevents centre-pivot irrigation, and makes water run off instead of soaking in.
Reading 1.1 % → class C1 · subclass t
LQ-T-02Water erosion hazardⓘ3.1 t/ha/yrC1e
How fast rain and runoff strip topsoil from the site.
Topsoil is where the fertility and the water-holding capacity live. Once it is gone it takes centuries to replace.
Reading 3.1 t/ha/yr → class C1 · subclass e
LQ-T-03Wind erosion hazardⓘ18 indexC1e
How fast wind strips soil from the site.
Wind removes the fine fraction, sandblasts young seedlings, and buries irrigation lines. Windbreaks reduce it but cost money.
Reading 18 index → class C1 · subclass e
LQ-T-04Sand encroachmentⓘ0.8 m/yrC1d
How fast mobile sand is advancing onto the site.
Moving dunes bury crops, roads and canals. Holding them back is a permanent, recurring cost on the operation.
Reading 0.8 m/yr → class C1 · subclass d
E · ClimateC1
LQ-C-02Thermal regimeⓘ3900 GDDC1c
Whether the site accumulates enough warmth for the crop to complete its cycle.
Too little heat and fruit never ripens. Too much and flowers drop. Every crop has its own window.
Reading 3900 GDD → class C1 · subclass c
LQ-C-03Radiationⓘ26 MJ/m²/dayC1c
How much sunlight energy reaches the crop each day.
Sunlight drives photosynthesis and therefore yield. Saudi Arabia is among the sunniest places on earth, so this rarely limits.
Reading 26 MJ/m²/day → class C1 · subclass c
Two qualities tie at C2 and both are named. Salinity at 3.5 dS/m carries subclass z; boron at 3.5 mg/L carries subclass n. The other seventeen are C1 and do not affect the class. C2nz = moderately capable, limited by soil chemistry on two counts.
Question 2 — Will the water bear it?
Water · 15 parameters · 5 groups
W2qy Usable, constrained
CodeParameterValueStateSub
A · Source & AvailabilityW1
WP-A-01Source TypeⓘWF — deep confined aquiferW1v
Which kind of water body the hectare would draw from.
Six source types are recognised: renewable aquifer (WR), fossil/confined (WF), managed reserve (WM), treated wastewater (WT), desalinated (WD) and surface/wadi (WS). The source type alone never disqualifies — it only sets which sustainability questions follow.
Reading WF — deep confined aquifer → state W1 · subclass v
WP-A-02Available Volumeⓘ14,200W1v
How much water can actually be delivered to this hectare each year.
Measured against the crop's requirement. Date palm needs 10,000–15,000 m³/ha/yr, so 14,200 covers full demand. Below the requirement, deficit irrigation applies and yield falls.
Reading 14,200 m³/ha/yr → state W1 · subclass v
WP-A-03Distance to Sourceⓘ3.4W1v
How far the water has to travel to reach the field.
Distance drives conveyance capital cost and transmission loss. Under 5 km is generally unconstrained; beyond 20 km the economics usually fail unless the crop value is high.
Reading 3.4 km → state W1 · subclass v
B · SustainabilityW2
WP-B-01Water-Level Trendⓘ−0.8 (declining)W2y
Whether the water table is rising, stable or falling.
This is the parameter that governs the result on this hectare. A declining level means abstraction exceeds recharge. It does not stop irrigation today, but it puts a finite clock on it — which is why the class is W2 and not W1.
Reading −0.8 (declining) m/yr → state W2 · subclass y
WP-B-02Aquifer TypeⓘNon-renewable (fossil)W2y
Whether the aquifer is being naturally replenished.
Fossil aquifers were filled in past wetter climates and receive effectively no modern recharge. Water drawn is not replaced. This is a permanent characteristic of the source, not a management failure.
Reading Non-renewable (fossil) → state W2 · subclass y
WP-B-03Remaining Supply Horizonⓘ28 at current rateW2y
How many years the source can sustain the planned abstraction.
Calculated from saturated thickness, storativity and current abstraction. 28 years is long enough for a date palm planting to reach and complete productive life, but not long enough to treat as indefinite.
Reading 28 at current rate years → state W2 · subclass y
C · Water QualityW2
WP-C-01Salinity (ECw)ⓘ2.1W1q
How salty the irrigation water is.
Irrigation water salinity accumulates in the root zone over time. 2.1 dS/m requires a leaching fraction but is workable for salt-tolerant crops. Above 3.0 the management burden rises sharply.
Reading 2.1 dS/m → state W1 · subclass q
WP-C-02Sodium Adsorption Ratio (SAR)ⓘ6.4W1q
How much sodium the water carries relative to calcium and magnesium.
High SAR degrades soil structure — the soil seals and infiltration collapses. 6.4 is moderate and manageable with gypsum amendment; above 9 with low salinity, structural damage becomes likely.
Reading 6.4 ratio → state W1 · subclass q
WP-C-03Chlorideⓘ340W1q
Chloride concentration, which is toxic to sensitive crops.
Chloride causes leaf burn in sensitive species, particularly under sprinkler irrigation where it contacts foliage directly. 340 mg/L is acceptable for tolerant crops under drip or basin irrigation.
Reading 340 mg/L → state W1 · subclass q
WP-C-04Boronⓘ3.5W2q
Boron concentration in the irrigation water.
This is the same reading that governs the crop verdicts. Boron is a micronutrient at trace levels and toxic slightly above them. It cannot be removed by leaching, which makes it a permanent property of the supply.
Reading 3.5 mg/L → state W2 · subclass q
WP-C-05Treated Wastewater TierⓘNot applicableW1q
If treated wastewater is the source, which health-safety tier it meets.
Applies only to WT sources. WHO (2006) tiers govern which crops may be irrigated with which treatment level. Not applicable here, since the source is groundwater.
Reading Not applicable → state W1 · subclass q
D · Access & DeliveryW1
WP-D-01Pumping Liftⓘ185W1a
How far the water must be raised from the aquifer to the surface.
Lift drives the energy cost of every cubic metre pumped. 185 m is deep but routine for fossil aquifer development; beyond 300 m energy cost usually becomes the binding constraint.
Reading 185 m → state W1 · subclass a
WP-D-02Conveyance Distanceⓘ3.4W1a
The length of pipeline or canal from wellhead to field.
Distinct from distance to source: this is the infrastructure that must actually be built and maintained. Short distances mean lower capital cost and lower transmission loss.
Reading 3.4 km → state W1 · subclass a
E · Basin AllocationW1
WP-E-01Basin Sustainable Yieldⓘ410W1b
How much the basin as a whole can supply without depleting.
A basin-scale figure, not a site one. It sets the ceiling that all abstraction within the basin must collectively respect — no individual licence can be assessed without it.
Reading 410 Mm³/yr → state W1 · subclass b
WP-E-02Allocation Statusⓘ78% allocatedW1b
How much of that basin ceiling is already committed to existing users.
At 78%, the basin retains headroom for new allocation. A licence on this hectare draws on uncommitted capacity rather than competing with established users. Above roughly 90% the basin closes to new abstraction entirely.
Reading 78% allocated → state W1 · subclass b
How W2qy is arrived at. Each of the 15 parameters is rated to a W-state; each group takes its worst member; the source takes the worst group. Groups A, D and E are all W1 — volume, distance, lift and basin headroom are unconstrained. Group B is W2 because the aquifer is non-renewable and its level is falling (subclass y). Group C is W2 because boron is high (subclass q). Both letters travel with the state: W2qy = water usable today, limited by supply sustainability and by quality.
Question 3 — Does the law allow it?
Land Rights & Constraints · 6 checks · 6 authorities
E2(ET) Resolvable
CodeCheckRecord sourceState
EP Protected areasⓘ NCW registerE1
Whether the land sits inside a formally designated conservation area.
Nature reserves and wildlife sanctuaries are declared by royal decree and recorded on the National Center for Wildlife register. Designation bars every activity except conservation, and cannot be lifted administratively.
No overlap with any NCW-declared boundary or its 3 km buffer → E1
EV Rangeland & vegetationⓘ NCVC layerE1
Whether the land carries a rangeland, forest or afforestation designation.
These are held by the National Center for Vegetation Cover on a separate register from NCW. Screening only the first would miss protective status across large areas of rangeland, which is why the two are checked independently.
Outside all NCVC reserve, forest and afforestation zones → E1
ET Ownership & tenureⓘ Watheeq cadastreE2ET
Whether a legal owner is recorded for the parcel.
This is the finding on this hectare. No entry exists in the national cadastre. Nothing prohibits development — but no allocation, licence or transfer can proceed until a holder is established and registered. Across most non-urban land in the Kingdom, no record exists.
No cadastral entry found → E2 — resolvable, administrative
EZ Planning & zoningⓘ MOMAH schemeE1
Whether the land-use designation permits the proposed activity.
Assessed per activity, never once for the hectare — industrial zoning excludes cultivation and favours a processing plant. Here the designation is agricultural, so cultivation is permitted as of right.
Agricultural designation, compatible with cultivation → E1
EX Conflicting designated useⓘ Energy / DefenseE1
Whether another ministry holds a competing claim on the land.
Petroleum blocks, mining concessions and military exclusion zones are set under separate legislation and cannot be overridden by agricultural approval. A military zone cannot be moved; a missing title can.
No active concession or exclusion overlapping the cell → E1
EH Hazard restrictionⓘ NCEC mappingE1
Whether flood, geological or contamination hazard restricts what can be built.
The softest of the six checks — it modifies design standards rather than barring use. Many of the Kingdom’s most productive wadi-margin soils sit in mapped flood zones.
No hazard designation on the cell → E1
Five checks clear, one to resolve. The cause travels with the state: E2(ET) names tenure as the single reason. This hectare falls into the category the study exists to surface — capable, watered, and waiting only on a document.
Question 4 — How well would each crop do?
Suitability · 26 diagnostic factors · 6 groups · 3 crops
S1 S3n S3n palm · wheat · tomato
CodeDiagnostic factorMeasured🌴🌾🍅
A · Soil Physical6 factors
SQ-A-01Available water capacityⓘ132S1S1S1
How much water the soil holds for the plant between waterings.
132 mm/m is a good holding capacity. All three crops rate S1 — none is limited by how much water this soil can store.
Reading 132 mm/m → 🌴 S1   🌾 S1   🍅 S1 · subclass s
SQ-A-02Soil workabilityⓘ86S1S1S1
How easily the soil is tilled and prepared.
Applies to annual crops needing tillage each cycle. Date palm is transplanted once, so this is effectively non-limiting for it.
Reading 86 index → 🌴 S1   🌾 S1   🍅 S1 · subclass s
SQ-A-03Rooting conditionsⓘ118S1S1S1
How deep roots can grow before hitting an obstruction.
118 cm exceeds every threshold: date palm needs >100, wheat >75, tomato >60. Unusually favourable for all three.
Reading 118 cm → 🌴 S1   🌾 S1   🍅 S1 · subclass s
SQ-A-04Surface sealing & crustingⓘ88S1S1S1
Whether the surface forms a crust that blocks emergence.
Matters most for direct-sown crops at germination. Low crusting here, so wheat emergence is unimpeded.
Reading 88 index → 🌴 S1   🌾 S1   🍅 S1 · subclass s
SQ-A-05Soil textureⓘSandy loamS1S1S1
The proportions of sand, silt and clay.
Sandy loam sits in the S1 range for all three crops — it drains freely, works easily, and still holds usable water.
Reading Sandy loam → 🌴 S1   🌾 S1   🍅 S1 · subclass s
SQ-A-06Coarse fragmentsⓘ8S1S1S1
How much gravel and stone occupies the root zone.
8% is low. Above 15% the effective rooting volume starts falling proportionally and tillage equipment suffers.
Reading 8 vol. % → 🌴 S1   🌾 S1   🍅 S1 · subclass s
B · Soil Chemical6 factors
SQ-B-01Salinity (ECe)ⓘ3.5S1S1S2
How salty the soil is.
The tolerances diverge here. Date palm holds S1 to 4.0 dS/m and wheat to 6.0 — both clear. Tomato loses S1 above 2.5, so it drops to S2.
Reading 3.5 dS/m → 🌴 S1   🌾 S1   🍅 S2 · subclass z
SQ-B-02Sodicity (ESP)ⓘ8.5S1S1S1
How much sodium sits on the soil particles.
Below 10% for all three. Above 15% soil structure begins collapsing and infiltration falls regardless of crop.
Reading 8.5 % → 🌴 S1   🌾 S1   🍅 S1 · subclass z
SQ-B-04Toxicity — boronⓘ3.5S1S3S3
Boron concentration, toxic slightly above trace levels.
This factor decides the page. Date palm holds S1 to 4.0 mg/L. Wheat and tomato lose S1 above 2.0 and fall into the S3 band at 3.0–5.0. One reading, three very different verdicts.
Reading 3.5 mg/L → 🌴 S1   🌾 S3   🍅 S3 · subclass n
SQ-B-05Calcium carbonateⓘ14S1S2S2
Lime content, which locks up phosphorus and micronutrients.
14% is typical for KSA. Date palm tolerates it well; wheat and tomato need chelated micronutrient supply above roughly 10%.
Reading 14 % → 🌴 S1   🌾 S2   🍅 S2 · subclass n
SQ-B-06Gypsum contentⓘ3.2S1S1S2
Gypsum, which dissolves and destabilises the profile.
3.2% is modest. Structural risk to buried infrastructure begins above about 10%; tomato's shallower rooting makes it marginally more sensitive.
Reading 3.2 % → 🌴 S1   🌾 S1   🍅 S2 · subclass n
SQ-B-07Soil pHⓘ7.9S1S1S2
Soil reaction — too acid or too alkaline both limit.
7.9 is alkaline, typical of calcareous KSA soils. Within S1 for date palm and wheat; tomato prefers below 7.5 so it drops one class.
Reading 7.9 pH → 🌴 S1   🌾 S1   🍅 S2 · subclass n
C · Water & Drainage3 factors
SQ-C-01Drainage conditionⓘ79S1S1S1
How fast excess water leaves the root zone.
Free-draining. Roots get air as well as water, and salts can be leached below the root zone rather than accumulating.
Reading 79 index → 🌴 S1   🌾 S1   🍅 S1 · subclass w
SQ-C-02Flood hazardⓘ0.4S1S1S1
How often the site is likely to be inundated.
Effectively flood-free. No design constraint on permanent infrastructure or planting layout.
Reading 0.4 events/10 yr → 🌴 S1   🌾 S1   🍅 S1 · subclass f
SQ-C-03Waterlogging riskⓘ7S1S1S1
How long water sits in the root zone after irrigation.
Seven days a year is negligible. Sustained saturation is what kills roots, and this site does not produce it.
Reading 7 days/yr → 🌴 S1   🌾 S1   🍅 S1 · subclass w
D · Topography & Erosion4 factors
SQ-D-01Terrain workabilityⓘ1.1S1S1S1
How steep and even the ground is.
1.1% is nearly flat — suitable for centre pivot, surface irrigation, and full mechanisation without any land forming.
Reading 1.1 slope % → 🌴 S1   🌾 S1   🍅 S1 · subclass t
SQ-D-02Water erosion hazardⓘ3.1S1S1S1
How fast rain and runoff strip topsoil.
Well below the sustainable soil-loss rate. The gentle slope and low rainfall together make this a non-issue.
Reading 3.1 t/ha/yr → 🌴 S1   🌾 S1   🍅 S1 · subclass e
SQ-D-03Wind erosion hazardⓘ18S1S1S1
How fast wind removes soil and sandblasts seedlings.
Low. Windbreaks would be prudent for annual crops at establishment but are not required for viability.
Reading 18 index → 🌴 S1   🌾 S1   🍅 S1 · subclass e
SQ-D-04Sand encroachmentⓘ0.8S1S1S1
How fast mobile sand is advancing onto the site.
Under 1 m/yr — no active dune front nearby. Encroachment management is not a recurring cost here.
Reading 0.8 m/yr → 🌴 S1   🌾 S1   🍅 S1 · subclass d
E · Climate5 factors
SQ-E-01Moisture deficitⓘ0.52S1S1S1
How far rainfall falls short of evaporation.
Large, as everywhere in the Kingdom. It is fully met by irrigation on this hectare, which is why it does not limit — the cost appears in SQ-F-01 instead.
Reading 0.52 aridity index → 🌴 S1   🌾 S1   🍅 S1 · subclass c
SQ-E-02Thermal suitabilityⓘ3,900S1S2S2
Whether the site accumulates the right amount of heat.
Abundant heat suits date palm perfectly. Wheat and tomato are both cool-season here — 3,900 GDD means they must be grown in the winter window or suffer heat stress at flowering.
Reading 3,900 GDD → 🌴 S1   🌾 S2   🍅 S2 · subclass c
SQ-E-03Radiationⓘ26S1S1S1
How much sunlight energy reaches the crop daily.
Among the highest in the world. Radiation is never the limiting factor on open-field production in this setting.
Reading 26 MJ/m²/day → 🌴 S1   🌾 S1   🍅 S1 · subclass c
SQ-E-04Length of growing periodⓘ340S1S1S1
How many days a year growth is possible.
Near year-round. Date palm is perennial so unaffected; for annuals it permits two cycles if water allows.
Reading 340 days → 🌴 S1   🌾 S1   🍅 S1 · subclass c
SQ-E-05Frost riskⓘ0S1S1S1
How often and how severely frost occurs.
Frost-free. No risk to date palm flowering, no kill risk to wheat at anthesis, no protection cost for tomato.
Reading 0 days ≤ 0°C → 🌴 S1   🌾 S1   🍅 S1 · subclass c
F · Crop-Specific2 factors
SQ-F-01Irrigation demand (ETc)ⓘ13,800 / 5,400 / 7,100S1S1S1
How much irrigation water the named crop needs.
Date palm needs 13,800 m³/ha/yr against 14,200 available — met, but with little margin. Wheat and tomato need far less, so all three rate S1 on availability.
Reading 13,800 / 5,400 / 7,100 m³/ha/yr → 🌴 S1   🌾 S1   🍅 S1 · subclass i
SQ-F-02Crop nutrient requirementⓘvaries by cropS1S2S2
The fertiliser input the crop needs to reach target yield.
The soil supplies a moderate baseline. Date palm's demand is met with routine fertilisation; wheat and tomato need higher inputs against a calcareous soil that fixes phosphorus.
Reading varies by crop → 🌴 S1   🌾 S2   🍅 S2 · subclass n
The same readings, three sets of tolerances. Nothing about the hectare changes between the three columns — only the ruler. Date palm rates S1 on all 26 factors. Wheat and tomato both fall to S3n, and the same factor governs both: boron at 3.5 mg/L.
Sample · 02 · Reading the Result
What the numbers actually mean
Sample hectare H-0417-2286 — composite record
C2nz·W2qy·E2(ET)·S1 date palm
C2nz
Moderately capable land
Seventeen of seventeen qualities unconstrained. Limited by boron (n) and salinity (z) together — neither severe.
W2qy
Water usable, constrained
Volume, distance and lift are fine. Limited by a declining non-renewable source (y) and by boron in the water (q).
E2(ET)
Legally resolvable
Five checks clear. No cadastral entry exists. Nothing prohibits development; ownership must be established first.
S1 · S3n · S3n
Date palm · wheat · tomato
One crop highly suitable on all 26 factors. Two marginal — and the same single factor limits both.
›
This is a date palm site, and the numbers say why

The land is good, with one qualification. Seventeen of nineteen land qualities are unconstrained — a deep rooting profile at 118 cm, near-flat ground at 1.1%, no erosion or encroachment hazard, abundant heat and light, a 340-day growing window and no frost. The two constrained qualities are both soil chemical: salinity at 3.5 dS/m and boron at 3.5 mg/L. Neither is severe. Together they make the land C2nz rather than C1.

The single most consequential number on this page is boron at 3.5 mg/L. It is a moderate reading for the land — C2 — and it is decisive for the crop. Date palm holds S1 up to 4.0 mg/L. Wheat and tomato lose S1 above 2.0 and fall into the S3 band between 3.0 and 5.0. The same 3.5 that barely troubles the land assessment drops two of three crops from highly suitable to marginal. This is precisely why capability and suitability are assessed separately: a general threshold and a crop tolerance are different questions, and this hectare is where the difference becomes visible.

The same reading appears twice, in two modules. Boron registers as WP-C-04 in the water assessment and as SQ-B-04 in suitability. That is not duplication — the water module asks whether the supply meets a general irrigation standard, and the suitability module asks whether it meets a named crop’s tolerance. One reading, two questions, and it constrains both answers.

Why this pattern matters beyond one hectare. Boron-rich groundwater is characteristic of deep confined aquifers across large parts of the Kingdom. Date palm’s exceptional boron and salt tolerance is not an incidental fact about the crop — it is a substantial part of why date palm became the dominant perennial in Saudi agriculture, and why land that looks unremarkable on a capability map can be first-class date palm ground.

Water sets the time horizon, not the possibility. W2qy confirms the hectare can be irrigated today with water of acceptable quality. What it does not confirm is for how long. A non-renewable aquifer falling 0.8 m a year with a 28-year remaining horizon means any development carries a defined lifespan. That is a planning parameter, not a disqualification — but it belongs in any investment case, and it argues for a crop whose value justifies the water. Date palm at 13,800 m³/ha/yr against 14,200 available fits, with little margin. Irrigated wheat on this water would be harder to defend.

Nothing legal prevents development. Five of six checks are clear. The sixth — no cadastral entry — blocks allocation but not use, and is administratively resolvable.

Action 1
Register the parcel
Establish and record a legal holder in the national cadastre. The only step between this hectare and allocation, and the fastest to complete.
Action 2
Target date palm, not cereal
Boron makes this land first-class for date palm and marginal for wheat and tomato. Cropping decisions should follow the crop tolerance, not the capability map alone.
Action 3
Confirm the supply horizon
Verify the 28-year estimate at the planned abstraction rate before capital is committed. A perennial planting must be matched against a finite source.
Action 4
Field-verify boron
This one reading determines the entire crop portfolio. It is the single measurement on this hectare where a desk value should be confirmed on the ground before planting.

And what the study does not say. Nothing here indicates whether developing this hectare is profitable. Capital cost, water pricing, yield, distance to market and land value sit outside the assessment entirely. The four answers establish that agriculture here is possible, watered, permitted and suited to a named crop. The economic question is asked separately, deliberately.

08 · Scope and Limits
What this study does not do

Stated plainly, because the value of the assessment depends on it being used for what it can answer.

No field survey
The study is entirely satellite-based and desk-based. No ground truthing or field sampling is conducted, and no finding should be read as a site inspection.
Planning-level screening
Results identify where detailed investigation is warranted. They do not replace site-specific soil survey, hydrogeological study or engineering assessment.
Not a legal opinion
The legal answer screens existing records. It does not confirm title. Every check names the authority holding the record, so a finding can be taken to the right office.
Not an economic appraisal
These findings answer whether agriculture is possible and permitted, not whether it is profitable. Physical and legal questions are kept deliberately separate from cost.
Note on element numbering. LQ-W-03 is an inherited numbering gap. LQ-C-01 moisture deficit and LQ-C-04 length of growing period were retired from capability at version 10.1; their measurements are now SQ-E-01 and SQ-E-04, where they are crop-keyed.

Why they moved. Both are relational — a deficit is a deficit of something, and a growing period is long enough for something. Neither carries meaning until a crop is named, which is what suitability does and capability does not. Thermal regime and radiation remain in capability, because degree-days accumulated and megajoules received are absolute properties of a location, true whatever is planted.

Testing confirmed the problem: with both in capability, every hectare in the Kingdom returned CN, the terminal class, with one of the two always governing. Rainfed growing period is zero across almost the whole country and aridity runs 0.02–0.09 against a C1 boundary of 0.50, so under maximum limitation the national capability map was uniformly terminal and the other seventeen qualities carried no influence anywhere.

Growing period was also redefined. As a capability element it measured days rainfall alone could support a crop — zero almost everywhere. As SQ-E-04 it measures days growth is thermally possible, which in the Kingdom runs 280–365 days.