Standard operating procedure
Soil-testing SOP by zone
Core and additional tests for every agro-ecological zone — 93 zones across 26 regions. Generated from the recommendation engine.
Showing 93 zones
Acid / low base saturationNear-neutralAlkaline / saline / sodic
JAYAGRIC · Standard Operating Procedure
Soil-Testing SOP by Agro-Ecological Zone
26 regions · 93 zones · 8 core tests/sample · generated 2026-06-06
§1
Field sampling — every sample, every zone
A test is only as good as the sample. Follow these steps for a representative 0–20 cm composite.
- 1Define a uniform sampling unit — one field or management zone of broadly similar soil, slope, colour and cropping history (≈2 ha or less, or a homogeneous part of the GPS-resolved zone). Sample any visibly different patches (wet hollows, white/salt crusts, eroded knolls, old kraals/boma sites) as SEPARATE samples.
- 2Clear surface litter. With a soil auger or clean spade, take a topsoil core at 0–20 cm (0–15 cm on shallow soils). Where rooting depth or salinity/sodicity matters, take a second 20–50 cm subsoil set in its own bag.
- 3Walk a zig-zag (W) pattern across the unit and collect 15–25 cores spread evenly over it — never from one spot, field edges, paths, or under trees.
- 4Combine the cores in a clean plastic bucket. Break up clods, mix thoroughly, and pick out stones, roots and crop residues.
- 5Cone-and-quarter the mixture: heap it, divide into four, keep two opposite quarters, remix, and repeat until ~500 g remains. This is the sample.
- 6Air-dry in shade on clean paper or a clean tray. Do NOT oven-dry, sun-bake, or store near fertiliser, lime, fuel or smoke.
- 7Label every bag with the sample code, GPS coordinates, depth, date and collector name; enter the same on the collection form so the zone resolves correctly.
- 8For salinity/sodicity work, seal the bag and submit promptly; note any visible salt crust, scald patches, crusting or poor drainage on the form.
Timing & re-testing. Sample after harvest and before land preparation. Avoid sampling immediately after liming, fertilising, or manure application (wait one full season). Re-test problem fields every 2–3 years, or one year after a corrective lime/gypsum programme.
§2
Core panel — runs on every sample
These eight tests are measured for every sample regardless of zone. The per-zone panels in §5 are in addition to this core.
| Test | Method | Why it matters | Interpretation |
|---|---|---|---|
| pH (H₂O) | 1:2.5 soil:water suspension, pH electrode | The master variable — it governs nutrient availability, aluminium/manganese toxicity and microbial activity. | <5.5 acidic (aluminium risk) · 5.5–6.5 slightly acid (ideal for most crops) · 6.5–7.3 near-neutral · 7.3–8.5 alkaline · >8.5 sodicity suspected. |
| Organic carbon | Walkley–Black wet oxidation (× 1.724 → organic matter) | Drives nitrogen supply, cation-exchange capacity, structure and water-holding. | <0.6% very low · 0.6–1.2 low · 1.2–2.0 moderate · >2.0 adequate (OC). |
| Total / mineralizable N | Kjeldahl total nitrogen (or anaerobic mineralizable N) | Nitrogen is the most yield-limiting nutrient on most Tanzanian soils. | <0.1% low · 0.1–0.2 moderate · >0.2 adequate (total N). |
| Extractable P | Bray-1 on acid soils; Olsen (NaHCO₃) on neutral/alkaline/calcareous soils | Second most limiting nutrient — the extractant MUST match soil pH or the reading is wrong. | Bray-1: <7 low, 7–20 medium, >20 adequate · Olsen: <5 low, 5–15 medium, >15 adequate (ppm P). |
| Exchangeable K | 1 M ammonium acetate (NH₄OAc) pH 7 | Key cation for water relations, grain fill and crop quality. | <0.2 cmol(+)/kg low · 0.2–0.4 medium · >0.4 adequate. |
| Sulphate-S | Calcium-phosphate extraction, turbidimetric | Increasingly deficient as high-analysis fertilisers replace older S-bearing ones. | <10 ppm low · ≥10 adequate. |
| Texture | Hydrometer (or field feel), USDA class | Governs water/nutrient storage, leaching, workability and how fast lime/gypsum react. | Sandy → low CEC, leaching: split N and K · Clayey → higher CEC and P-fixation, watch drainage and structure. |
| CEC / ECEC | NH₄OAc pH 7 (CEC₇) on high-activity clays; unbuffered salt-sum (ECEC) on low-activity clays | The soil’s nutrient-holding capacity and the basis for base saturation. | <6 low · 6–12 moderate · >12 good. Use ECEC on low-activity-clay soils (Acrisols, Ferralsols, Andosols). |
§3
Additional-test reference
The beyond-core tests referenced in §5, with method and interpretation. Run only the ones listed for your zone.
| Test | Method | Why it matters | Interpretation |
|---|---|---|---|
| Exchangeable acidity & Al saturation | 1 M KCl extraction → exchangeable Al + H; Al saturation = Al ÷ ECEC × 100 | In acid soils the real yield-killer is aluminium toxicity, not low pH itself. | Al saturation >20–30% is toxic to sensitive crops → lime. |
| Lime requirement | KCl-Al method (Cochrane/Kamprath) or base-saturation method | Quantifies the CaCO₃ needed to neutralise toxic Al / raise base saturation — not a guess from pH. | Dose targets Al saturation below ~10–15% (or a crop-specific base-saturation target). |
| Mn / Al toxicity screen | Extractable (DTPA/Mehlich-3) Mn alongside exchangeable Al | Strongly acid soils can express manganese toxicity in addition to aluminium. | Read with Al saturation and crop sensitivity; correct by liming. |
| Molybdenum + Boron (acid soils) | Ammonium-oxalate Mo; hot-water B | Mo availability falls as pH drops (hurts legume N-fixation); B is variable on leached soils. | Mo deficiency common below ~pH 5.5; treat B in a narrow band (deficient ↔ toxic). |
| Bray-1 P | 0.03 N NH₄F + 0.025 N HCl extraction | The correct phosphorus test for ACID soils (Olsen under-reads there). | <7 low · 7–20 medium · >20 adequate (ppm P). |
| Olsen P | 0.5 M NaHCO₃ at pH 8.5 | The correct phosphorus test for neutral, alkaline and calcareous soils. | <5 low · 5–15 medium · >15 adequate (ppm P). |
| Mehlich-3 multi-element | Single Mehlich-3 extractant (P, K, Ca, Mg + micronutrients) | An efficient combined extractant for acid-to-neutral soils. | Use the lab’s Mehlich-3 calibration bands for each element. |
| P sorption / retention | P-sorption index, or oxalate-extractable Al + Fe | Andosols (volcanic) and sesquioxidic soils fix phosphorus strongly. | High sorption → raise P rates and BAND the phosphate near the seed. |
| DTPA micronutrients (Zn, Fe, Mn, Cu) | DTPA extraction at pH 7.3 | High pH locks up Zn/Fe/Mn/Cu; zinc deficiency is widespread in Tanzanian maize and rice. | Zn <0.8 ppm low · Fe <4.5 · Mn <1.0 · Cu <0.2 (DTPA). |
| Hot-water Boron | Hot-water extraction | Boron sits in a narrow window between deficiency and toxicity; toxicity appears on saline/alkaline soils. | <0.4 ppm low · >2–5 ppm toxicity risk (hot-water B). |
| EC — soluble salts (salinity) | Saturated-paste extract (ECe), or 1:2.5 EC | Soluble salts pull water away from roots and cut germination and yield. | ECe <2 none · 2–4 slight · 4–8 moderate · >8 severe (dS/m). |
| ESP / SAR — sodicity | Exchangeable Na ÷ CEC (ESP); or Na ÷ √((Ca+Mg)/2) (SAR) | Sodium destroys soil structure and infiltration — a sodic soil needs gypsum, never lime. | ESP >15 sodic (>6 on swelling clays) · SAR >13 sodic. |
| Gypsum requirement | From ESP and CEC (Ca needed to displace exchangeable Na) | Supplies calcium to replace sodium and reclaim sodic structure. | Apply where ESP exceeds the crop threshold; re-test after one season. |
| Free CaCO₃ / fizz test | Dilute-HCl effervescence (field), or calcimeter (lab) | Carbonate raises pH, fixes phosphorus and induces Zn/Fe deficiency — and means Olsen, not Bray, for P. | Visible fizz → calcareous: use Olsen P and watch Zn/Fe. |
§4
The three soil regimes
Acid / low base saturation
Acid, low-base-saturation soils (Acrisols, Ferralsols, dystric Nitisols, acid-phase Andosols). The limiting factor is aluminium/manganese toxicity and low phosphorus — not pH alone. Run the acidity panel and use Bray-1 for P; salinity tests are not relevant here.
Near-neutral
Near-neutral, adequately-based soils (Lixisols, Luvisols, eutric Cambisols, many Nitisols). Keep the core panel and add micronutrients (zinc especially). Add aluminium/lime only if a measured pH falls below ~5.5; add salinity only if pH rises above ~7.
Alkaline / saline / sodic
Alkaline, calcareous, saline or sodic soils (Solonchaks, Solonetz, Calcisols, high-pH Vertisols, closed depressions and irrigated bottomlands). The risks are soluble salts, sodicity (structural collapse) and carbonate-induced phosphorus and micronutrient lock-up. Run the salinity/sodicity panel, use Olsen P, and skip aluminium/lime.
§5
Per-zone test panels
For each zone: its dominant soil, regime, the P and CEC methods to use, and the additional tests to run, make conditional, or skip — plus the zone’s key limitation. Core panel (§2) always applies.
Njombe7 zones
E7E11H1H2H3H5H6
E7Plateaux (Warm sub-humid)AcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Soil acidity (common here per De Pauw), leaching, erosion on dissected uplands
E11Lacustrine / Rift LowlandsArenosolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients · watch K / S / B / Mg leaching (sandy)
Only ifexchangeable acidity + Al saturation + lime (measured pH ≤ 5.5 OR base saturation < 50%)
⚑ Very low fertility and water/nutrient storage (sandy); erosion on dissected ridges and scarps
H1High Plains & PlateauxAcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Acidity / low base status on Acrisol phases (Al toxicity, low P); erosion on degraded land
H2High Plains & Plateaux (Very humid)NitisolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients · P sorption / retention
Only ifexchangeable acidity + Al saturation + lime (measured pH ≤ 5.5 OR base saturation < 50%)
⚑ Strong leaching, acidity / Al toxicity, P-fixation
H3High Plains & Plateaux (Dissected)AcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Severe erosion and landslide risk, acidity / Al toxicity, shallow depth
H5High Plains & Plateaux (Volcanic)AndosolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients · P sorption / retention
Only ifexchangeable acidity + Al saturation + lime (measured pH ≤ 5.5 OR base saturation < 50%)
⚑ Strong phosphate fixation by active Al; erosion on the dissected hills
H6High Plains & Plateaux (Volcanic)AndosolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients · P sorption / retention
Only ifexchangeable acidity + Al saturation + lime (measured pH ≤ 5.5 OR base saturation < 50%)
⚑ Cold/frost and short warm window; strong P-fixation by active Al; waterlogging in peat hollows
Iringa6 zones
E7E10H1H2H7P2
E7Plateaux (Warm sub-humid)AcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Soil acidity (common here per De Pauw), leaching, erosion on dissected uplands
E10Alluvial PlainsFluvisolsNear-neutralP: Bray-1 · CEC: CEC7
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients
Not neededexchangeable Al / Al saturation · lime requirement
⚑ Seasonal flooding and drainage; low direct rainfall (flood/irrigation-fed)
H1High Plains & PlateauxAcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Acidity / low base status on Acrisol phases (Al toxicity, low P); erosion on degraded land
H2High Plains & Plateaux (Very humid)NitisolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients · P sorption / retention
Only ifexchangeable acidity + Al saturation + lime (measured pH ≤ 5.5 OR base saturation < 50%)
⚑ Strong leaching, acidity / Al toxicity, P-fixation
H7High Plains & Plateaux (Stony)AcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Shallow stony soils, severe erosion/dissection, acidity, limited rooting depth
P2Plateaux (Semi-arid)LixisolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients
Not neededexchangeable Al / Al saturation · lime requirement
⚑ Short, unreliable season and drought; very low fertility, capping and stoniness
Mbeya6 zones
H6H5H4H1P3P2
H6High Plains & Plateaux (Volcanic)AndosolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients · P sorption / retention
Only ifexchangeable acidity + Al saturation + lime (measured pH ≤ 5.5 OR base saturation < 50%)
⚑ Cold nights / short warm window; strong P-fixation by active Al; steep slopes best forested
H5High Plains & Plateaux (Volcanic)AndosolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients · P sorption / retention
Only ifexchangeable acidity + Al saturation + lime (measured pH ≤ 5.5 OR base saturation < 50%)
⚑ Strong phosphate fixation by active Al; erosion on the dissected hills
H4Lacustrine LowlandsFluvisolsNear-neutralP: Bray-1 · CEC: CEC7
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients
Not neededexchangeable Al / Al saturation · lime requirement
⚑ Flooding and impeded drainage on the heavy mottled clays (Gleysol phases)
H1High Plains & PlateauxAcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Acidity / low base status on the Acrisol phases (Al toxicity, low P); erosion where subsoil is exposed
P3Plateaux (Sub-humid)LixisolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients
Not neededexchangeable Al / Al saturation · lime requirement
⚑ Low fertility and weak structure on the sandy uplands (capping, erosion); patchy salinity in bottoms
P2Plateaux (Semi-arid)LixisolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients
Not neededexchangeable Al / Al saturation · lime requirement
⚑ Short, unreliable season and drought; very low fertility, capping and stoniness; high-ESP salt-affected patches (Usangu)
Songwe6 zones
H5H4H1P3P2R1
H5High Plains & Plateaux (Volcanic)AndosolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients · P sorption / retention
Only ifexchangeable acidity + Al saturation + lime (measured pH ≤ 5.5 OR base saturation < 50%)
⚑ Strong phosphate fixation by active Al; erosion on the dissected hills
H4Lacustrine LowlandsFluvisolsNear-neutralP: Bray-1 · CEC: CEC7
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients
Not neededexchangeable Al / Al saturation · lime requirement
⚑ Flooding and impeded drainage on the heavy mottled clays (Gleysol phases)
H1High Plains & PlateauxAcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Acidity / low base status on the Acrisol phases (Al toxicity, low P); erosion where subsoil is exposed
P3Plateaux (Sub-humid)LixisolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients
Not neededexchangeable Al / Al saturation · lime requirement
⚑ Low fertility and weak structure on the sandy uplands (capping, erosion); patchy salinity in bottoms
P2Plateaux (Semi-arid)LixisolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients
Not neededexchangeable Al / Al saturation · lime requirement
⚑ Short, unreliable season and drought; very low fertility, capping and stoniness; high-ESP salt-affected patches (Usangu)
R1Rift FloodplainsSolonchaksAlkaline / saline / sodicP: Olsen · CEC: CEC7
Core panelall 8 core tests run on every sample (see §2)
AdditionalEC (salinity, dS/m) · ESP or SAR (sodicity) · gypsum requirement (if sodic) · free CaCO₃ / fizz test · DTPA micronutrients (Zn, Fe, Mn, Cu — high-pH lock-up) · hot-water B · Olsen P
Not neededexchangeable Al / Al saturation · lime requirement · Mo (not limiting above ~pH 6) · Bray-1 P (under-reads on carbonate)
⚑ Variable flooding and drainage; salinity/sodicity over a large share (Lake Rukwa / Karema); waterlogging
Arusha9 zones
N4N1N2N5N6N3E2E1P2
N4Volcanic HighlandsAndosolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients · P sorption / retention
Only ifexchangeable acidity + Al saturation + lime (measured pH ≤ 5.5 OR base saturation < 50%)
⚑ Strong P-fixation by active Al; steep slopes and erosion; cold/short season upslope
N1Volcanic Highlands (Dissected)AndosolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients · P sorption / retention
Only ifexchangeable acidity + Al saturation + lime (measured pH ≤ 5.5 OR base saturation < 50%)
⚑ Variable acidity and P-fixation; erosion on dissected plateaux; moisture-limited
N2Volcanic Highlands (Cold)PhaeozemsNear-neutralP: Bray-1 · CEC: CEC7
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients
Not neededexchangeable Al / Al saturation · lime requirement
⚑ Cold highland climate and short warm window; shallow stony soils on cones; erosion
N5Volcanic Ash PlainsAndosolsAlkaline / saline / sodicP: Olsen · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalEC (salinity, dS/m) · ESP or SAR (sodicity) · gypsum requirement (if sodic) · free CaCO₃ / fizz test · DTPA micronutrients (Zn, Fe, Mn, Cu — high-pH lock-up) · hot-water B · Olsen P · P sorption / retention
Not neededexchangeable Al / Al saturation · lime requirement · Mo (not limiting above ~pH 6) · Bray-1 P (under-reads on carbonate)
⚑ Mildly alkaline/calcareous in places; P-fixation on allophanic phases; moisture-limited on the drier margin
N6Volcanic Plains (Rain-shadow)AndosolsAlkaline / saline / sodicP: Olsen · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalEC (salinity, dS/m) · ESP or SAR (sodicity) · gypsum requirement (if sodic) · free CaCO₃ / fizz test · DTPA micronutrients (Zn, Fe, Mn, Cu — high-pH lock-up) · hot-water B · Olsen P · P sorption / retention
Not neededexchangeable Al / Al saturation · lime requirement · Mo (not limiting above ~pH 6) · Bray-1 P (under-reads on carbonate)
⚑ Severe rain-shadow drought and very short season; shallow soils; hard-to-till vertisol depressions
N3Saline Lacustrine LowlandsSolonchaksAlkaline / saline / sodicP: Olsen · CEC: CEC7
Core panelall 8 core tests run on every sample (see §2)
AdditionalEC (salinity, dS/m) · ESP or SAR (sodicity) · gypsum requirement (if sodic) · free CaCO₃ / fizz test · DTPA micronutrients (Zn, Fe, Mn, Cu — high-pH lock-up) · hot-water B · Olsen P
Not neededexchangeable Al / Al saturation · lime requirement · Mo (not limiting above ~pH 6) · Bray-1 P (under-reads on carbonate)
⚑ Salinity/sodicity overriding (ESP>15, pH>8.5, EC>4); flooding; high-ESP subsoils
E2Gneissic Plains (Sub-humid)AcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Low fertility and surface sealing/capping; acidity on Acrisol phases; short unreliable season
E1Gneissic Plains (Semi-arid)AcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Severe drought and very short season; low fertility; surface capping
P2Granitic Plains (Semi-arid)LixisolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients
Not neededexchangeable Al / Al saturation · lime requirement
⚑ Short unreliable season and drought; very low fertility, capping and stoniness; patchy salinity in bottoms
Kilimanjaro6 zones
N4E12E2E1E8P5
N4Volcanic Mountain SlopesAndosolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients · P sorption / retention
Only ifexchangeable acidity + Al saturation + lime (measured pH ≤ 5.5 OR base saturation < 50%)
⚑ Strong P-fixation by active Al; steep slopes and severe erosion; cold/short season near the summit
E12Dissected Mountain PlateauxAcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Steep dissected slopes (10-40%) and severe water erosion; acidity / Al toxicity; shallow soils on crests
E2Gneissic Plains (Sub-humid)AcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Low fertility and surface sealing/capping; acidity on Acrisol phases; short unreliable season
E1Gneissic Plains (Semi-arid)AcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Severe drought and very short season; low fertility; surface capping
E8Saline Alluvial FloodplainsSolonchaksAlkaline / saline / sodicP: Olsen · CEC: CEC7
Core panelall 8 core tests run on every sample (see §2)
AdditionalEC (salinity, dS/m) · ESP or SAR (sodicity) · gypsum requirement (if sodic) · free CaCO₃ / fizz test · DTPA micronutrients (Zn, Fe, Mn, Cu — high-pH lock-up) · hot-water B · Olsen P
Not neededexchangeable Al / Al saturation · lime requirement · Mo (not limiting above ~pH 6) · Bray-1 P (under-reads on carbonate)
⚑ Salinity/sodicity overriding (ESP>15, pH>8.5, EC>4); flooding; impervious high-ESP subsoils
P5Granitic Plains (Semi-arid)LixisolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients
Not neededexchangeable Al / Al saturation · lime requirement
⚑ Short unreliable season and drought; low fertility and surface capping on the sands
Manyara3 zones
N1E2E1
N1Volcanic HighlandAndosolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients · P sorption / retention
Only ifexchangeable acidity + Al saturation + lime (measured pH ≤ 5.5 OR base saturation < 50%)
⚑ Variable acidity and P-fixation; erosion on the dissected highland; cold-limited near the top of Hanang
E2Gneissic Plains (Sub-humid)AcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Low fertility and surface sealing/capping; acidity on Acrisol phases; erosion around the Babati lakes
E1Maasai Steppe (Semi-arid)AcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Severe drought and very short season; low fertility; surface capping
Dodoma6 zones
H7E2P1P2P9R4
H7Hill Ranges (Dissected)AcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Steep dissected slopes and erosion; acidity on Acrisol phases; shallow stony soils on the crests
E2Gneissic Plains (Sub-humid)AcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Low fertility and surface sealing/capping; acidity on Acrisol phases; short unreliable season
P1Granitic Plains (Sub-humid)LixisolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients
Not neededexchangeable Al / Al saturation · lime requirement
⚑ Low fertility and weak structure on sands; surface capping; moisture-limited, short season
P2Granitic Plains (Semi-arid)LixisolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients
Not neededexchangeable Al / Al saturation · lime requirement
⚑ Short unreliable season and drought; very low fertility, capping and stoniness; patchy salinity in bottoms
P9Sandy Plains (Continental Deposits)ArenosolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients · watch K / S / B / Mg leaching (sandy)
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Strongly acid (pH 4-6), extremely infertile sands with very low water/nutrient storage; erosion
R4Riverine Alluvial PlainsFluvisolsNear-neutralP: Bray-1 · CEC: CEC7
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients
Not neededexchangeable Al / Al saturation · lime requirement
⚑ Seasonal flooding and drainage; cropping timing governed by the flood regime
Singida2 zones
P2N1
P2Granitic Plains (Semi-arid)LixisolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients
Not neededexchangeable Al / Al saturation · lime requirement
⚑ Short unreliable season and drought; very low fertility, capping and stoniness; patchy salinity in the bottoms
N1Volcanic-ash HighlandAndosolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients · P sorption / retention
Only ifexchangeable acidity + Al saturation + lime (measured pH ≤ 5.5 OR base saturation < 50%)
⚑ Variable acidity and P-fixation on the ash soils; erosion on the dissected plateau; moisture-limited
Mwanza2 zones
P4E2
P4Sukumaland PlainsLixisolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients
Not neededexchangeable Al / Al saturation · lime requirement
⚑ Low fertility and weak structure on the sands; chemical (salt) barriers in some units; mbuga clays hard to till and seasonally waterlogged
E2Sub-humid Lake MarginAcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Acidity on the more-leached Acrisol phases under higher rainfall; low inherent fertility; erosion on island slopes
Geita2 zones
P4E2
P4Sukumaland PlainsLixisolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients
Not neededexchangeable Al / Al saturation · lime requirement
⚑ Low fertility and weak structure on the sands; chemical (salt) barriers in some units; mbuga clays hard to till and seasonally waterlogged
E2Sub-humid Lake MarginAcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Acidity on more-leached Acrisol phases under higher rainfall; low inherent fertility; erosion on hill slopes
Mara2 zones
P8E2
P8Hardpan/Sodic PlainsSolonetzAlkaline / saline / sodicP: Olsen · CEC: CEC7
Core panelall 8 core tests run on every sample (see §2)
AdditionalEC (salinity, dS/m) · ESP or SAR (sodicity) · gypsum requirement (if sodic) · free CaCO₃ / fizz test · DTPA micronutrients (Zn, Fe, Mn, Cu — high-pH lock-up) · hot-water B · Olsen P
Not neededexchangeable Al / Al saturation · lime requirement · Mo (not limiting above ~pH 6) · Bray-1 P (under-reads on carbonate)
⚑ Shallow hardpan and sodic subsoil restricting roots/water; seasonal waterlogging; mbuga clays hard to till
E2Mara HighlandAcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Acidity on more-leached phases under higher rainfall; erosion on highland slopes; low inherent fertility
Simiyu2 zones
P8P7
P8Hardpan/Sodic PlainsSolonetzAlkaline / saline / sodicP: Olsen · CEC: CEC7
Core panelall 8 core tests run on every sample (see §2)
AdditionalEC (salinity, dS/m) · ESP or SAR (sodicity) · gypsum requirement (if sodic) · free CaCO₃ / fizz test · DTPA micronutrients (Zn, Fe, Mn, Cu — high-pH lock-up) · hot-water B · Olsen P
Not neededexchangeable Al / Al saturation · lime requirement · Mo (not limiting above ~pH 6) · Bray-1 P (under-reads on carbonate)
⚑ Shallow hardpan and sodic subsoil; seasonal waterlogging; short unreliable season
P7Lake-sediment Clay PlainsVertisolsAlkaline / saline / sodicP: Olsen · CEC: CEC7
Core panelall 8 core tests run on every sample (see §2)
AdditionalEC (salinity, dS/m) · ESP or SAR (sodicity) · gypsum requirement (if sodic) · free CaCO₃ / fizz test · DTPA micronutrients (Zn, Fe, Mn, Cu — high-pH lock-up) · hot-water B · Olsen P
Not neededexchangeable Al / Al saturation · lime requirement · Mo (not limiting above ~pH 6) · Bray-1 P (under-reads on carbonate)
⚑ Severe drought and very short season; mild alkalinity/salinity; heavy clays hard to till
Shinyanga2 zones
P3P13
P3Granitic PlainsLixisolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients
Not neededexchangeable Al / Al saturation · lime requirement
⚑ Very low fertility and surface capping on the sands; short season; mbuga clays hard to till
P13Inundated LowlandVertisolsNear-neutralP: Bray-1 · CEC: CEC7
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients
Only ifEC / ESP + free CaCO₃ (semi-arid or valley-bottom position, measured pH ≥ 7, or field fizz)
Not neededexchangeable Al / Al saturation · lime requirement
⚑ Seasonal inundation and waterlogging; heavy cracking clays hard to till; drainage governs the season
Kagera2 zones
W1W3
W1Buhaya HighlandAcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Strong acidity and very low inherent fertility (highly weathered); chemical (Al) barriers; steep dissected slopes and erosion
W3Karagwe-Ngara Highland PlainsAcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Acidity and low fertility on the leached plateau soils; erosion on the escarpments; drought on the drier rweya margins
Tabora2 zones
P5P3
P5Miombo PlainsCambisolsNear-neutralP: Bray-1 · CEC: CEC7
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients
Only ifexchangeable acidity + Al saturation + lime (measured pH ≤ 5.5 OR base saturation < 50%)
⚑ Low fertility and surface capping on the sands; mbuga clays hard to till; miombo soils acidify under continuous cropping
P3Semi-arid Granitic PlainsCambisolsNear-neutralP: Bray-1 · CEC: CEC7
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients
Only ifexchangeable acidity + Al saturation + lime (measured pH ≤ 5.5 OR base saturation < 50%)
⚑ Short unreliable season and drought; very low fertility and capping; patchy salinity in the Wembere bottoms
Katavi2 zones
P5R1
P5Miombo PlainsCambisolsNear-neutralP: Bray-1 · CEC: CEC7
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients
Only ifexchangeable acidity + Al saturation + lime (measured pH ≤ 5.5 OR base saturation < 50%)
⚑ Low fertility and surface capping on the sands; mbuga clays hard to till; remoteness limits inputs
R1Rift FloodplainsSolonchaksAlkaline / saline / sodicP: Olsen · CEC: CEC7
Core panelall 8 core tests run on every sample (see §2)
AdditionalEC (salinity, dS/m) · ESP or SAR (sodicity) · gypsum requirement (if sodic) · free CaCO₃ / fizz test · DTPA micronutrients (Zn, Fe, Mn, Cu — high-pH lock-up) · hot-water B · Olsen P
Not neededexchangeable Al / Al saturation · lime requirement · Mo (not limiting above ~pH 6) · Bray-1 P (under-reads on carbonate)
⚑ Variable flooding and drainage; salinity/sodicity over a large share; waterlogging
Kigoma2 zones
P5E2
P5Miombo PlainsFerralsolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients · P sorption / retention
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Low fertility and surface capping on the sands; clay bottoms hard to till; erosion on the lake escarpment
E2Buha HighlandAcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Acidity on more-leached phases under higher rainfall; erosion on highland slopes; low inherent fertility
Rukwa2 zones
UR1
UUfipa HighlandAcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Acidity and low fertility on the leached plateau soils; cold-limited near the top; erosion on slopes
R1Rift FloodplainsSolonchaksAlkaline / saline / sodicP: Olsen · CEC: CEC7
Core panelall 8 core tests run on every sample (see §2)
AdditionalEC (salinity, dS/m) · ESP or SAR (sodicity) · gypsum requirement (if sodic) · free CaCO₃ / fizz test · DTPA micronutrients (Zn, Fe, Mn, Cu — high-pH lock-up) · hot-water B · Olsen P
Not neededexchangeable Al / Al saturation · lime requirement · Mo (not limiting above ~pH 6) · Bray-1 P (under-reads on carbonate)
⚑ Variable flooding and drainage; salinity/sodicity over a large share (Lake Rukwa / Karema); waterlogging
Morogoro3 zones
E7E10E4
E7Gneissic Miombo PlainsAcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Low fertility and acidity on Acrisol phases; erosion on the dissected uplands; surface capping
E10Kilombero FloodplainFluvisolsNear-neutralP: Bray-1 · CEC: CEC7
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients
Not neededexchangeable Al / Al saturation · lime requirement
⚑ Regular flooding and waterlogging; drainage; cropping timing governed by the flood regime
E4Uluguru Uplands & MountainsAcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Steep dissected slopes and severe erosion; acidity / Al on leached phases; shallow soils on crests
Pwani (Coast)3 zones
C2C1C3
C2Coastal PlainsArenosolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients · watch K / S / B / Mg leaching (sandy)
Only ifexchangeable acidity + Al saturation + lime (measured pH ≤ 5.5 OR base saturation < 50%)
⚑ Very low fertility and water/nutrient storage on the sands; capping; flooding on the Rufiji floodplain
C1Coastal PlainsArenosolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients · watch K / S / B / Mg leaching (sandy)
Only ifexchangeable acidity + Al saturation + lime (measured pH ≤ 5.5 OR base saturation < 50%)
⚑ Very low fertility and water/nutrient storage on the sands; each of the two rains is short
C3Coastal Hills (Dissected)AcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Steep dissected slopes and erosion; shallow stony soils; low fertility
Dar es Salaam4 zones
C1C2C3C4
C1Coastal PlainsArenosolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients · watch K / S / B / Mg leaching (sandy)
Only ifexchangeable acidity + Al saturation + lime (measured pH ≤ 5.5 OR base saturation < 50%)
⚑ Very low fertility and water/nutrient storage on the sands; each of the two rain seasons is short
C2Coastal PlainsArenosolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients · watch K / S / B / Mg leaching (sandy)
Only ifexchangeable acidity + Al saturation + lime (measured pH ≤ 5.5 OR base saturation < 50%)
⚑ Very low fertility and weak structure on the sands; capping; depression clays hard to till wet
C3Coastal Hills (Dissected)AcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Steep dissected slopes (10-45%) and erosion; shallow stony soils; low fertility
C4Riverine Floodplains & DeltasFluvisolsNear-neutralP: Bray-1 · CEC: CEC7
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients
Not neededexchangeable Al / Al saturation · lime requirement
⚑ Flooding/waterlogging; salinity in the delta near the sea; drainage
Tanga4 zones
E12E2E1C1
E12Usambara HighlandAcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Steep dissected slopes and severe water erosion; acidity / Al on leached phases; shallow soils on crests
E2Gneissic Plains (Sub-humid)AcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Low fertility and surface sealing/capping; acidity on Acrisol phases; erosion on dissected slopes
E1Gneissic Plains (Semi-arid)AcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Severe drought and very short season; low fertility; surface capping
C1Coastal PlainsArenosolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients · watch K / S / B / Mg leaching (sandy)
Only ifexchangeable acidity + Al saturation + lime (measured pH ≤ 5.5 OR base saturation < 50%)
⚑ Very low fertility and water/nutrient storage on the sands; each of the two rains is short; salinity in the delta fringe
Lindi3 zones
C2C3E3
C2Coastal PlainsArenosolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients · watch K / S / B / Mg leaching (sandy)
Only ifexchangeable acidity + Al saturation + lime (measured pH ≤ 5.5 OR base saturation < 50%)
⚑ Very low fertility and water/nutrient storage on the sands; capping; flooding in the valleys
C3Coastal Hills (Dissected)AcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Steep dissected slopes and erosion; shallow stony soils; low fertility
E3Interior Metamorphic PlainsAcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Acidity on more-leached phases; low fertility; unreliable onset and short-to-medium season
Mtwara2 zones
C2E5
C2Coastal PlainsArenosolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients · watch K / S / B / Mg leaching (sandy)
Only ifexchangeable acidity + Al saturation + lime (measured pH ≤ 5.5 OR base saturation < 50%)
⚑ Very low fertility and water/nutrient storage on the sands; capping; flooding in the river valleys
E5Makonde PlateauAcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Acidity and low fertility on the leached plateau soils; little surface water on the plateau; erosion on the scarp edges
Ruvuma3 zones
H5E7E5
H5Volcanic Highland (Lake Nyasa)AndosolsNear-neutralP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
AdditionalDTPA or Mehlich-3 micronutrients · P sorption / retention
Only ifexchangeable acidity + Al saturation + lime (measured pH ≤ 5.5 OR base saturation < 50%)
⚑ Strong phosphate fixation by active Al; erosion on the dissected hills
E7Sub-humid Southern PlateauAcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Low fertility and acidity on Acrisol phases; erosion on the dissected uplands; surface capping
E5Eastern & Southern Lowland PlainsAcrisolsAcid / low base saturationP: Bray-1 · CEC: ECEC
Core panelall 8 core tests run on every sample (see §2)
Additionalexchangeable acidity + Al saturation · lime requirement (KCl; lime if Al > 20% ECEC) · Mn / Al toxicity screen · Mo + B (acid soils) · Bray-1 P · Mehlich-3 micronutrients
Not neededEC / salinity (not a low-pH problem) · ESP / SAR sodicity · gypsum requirement · free CaCO₃
⚑ Acidity and low fertility on the leached plateau soils; little surface water on the plateau; erosion on the scarp edges