NAITRO · SA1
Bergvlei Grains — Free State, South Africa
🇿🇦 Maize · Soya · Sunflower · 1,240 ha All farms
Overview
Digital twin
How NAITRO works
Soil health score
Poor 0–30 Average 31–60 Optimal 61–100 62 / 100
/100
Optimal — pH correction needed
SOC
1.8%
BNF
22%
Priming risk
High
Compaction
62%
LAN applied
145 kg N/ha
Above optimal
Soil pH
5.1
Acid — target 6.0–6.5
Maize yield
6.8 t/ha
Below 8 t/ha potential
Soil erosion risk
High
Wind + water loss
Critical: Soil acidification detected. pH 5.1 severely limits nutrient availability and microbial activity. Free State ferralsols require targeted lime application (2–4 t/ha dolomitic lime) before any other intervention will be effective. Acid soils also lock up phosphorus — R480/ha wasted annually on P fertiliser that cannot be absorbed.
1
Address soil acidification — lime immediately
Highest impact · pH correction · Free State ferralsols
The science: At pH 5.1, aluminium and manganese toxicity is active in the root zone, directly stunting root development in maize. Microbial activity drops 60% below pH 5.5. Every nutrient input applied at this pH is operating at 40–60% efficiency. Dolomitic lime also adds magnesium — critical for chlorophyll production and often deficient in Free State soils.
The action: Apply 2.5 t/ha dolomitic lime in autumn (March–April) ahead of the planting season. Soil pH correction takes 6–8 months — plan for next season. Repeat soil test after 12 months and reapply if pH has not reached 6.0.
Yield +1.5–2.0 t/ha est. P efficiency +40% Microbial activity ↑60%
2
Introduce cover crops to rebuild SOC
Soil carbon · Erosion control · No-till transition
The science: SOC of 1.8% is critically low for the Free State — the region historically supported 3–4% SOC under natural Highveld grassland. Bare-fallowed monoculture maize has depleted carbon at approximately 0.15%/yr over 20 years. Below 2% SOC, the soil lacks the water-holding capacity to buffer the summer rainfall variability that is intensifying with climate change.
The action: Plant a summer cover crop mix (cowpea, sunhemp, finger millet) after maize harvest. Target 60% soil cover over winter. Transition 20% of hectares to no-till in Year 1, expanding to full no-till by Year 3. Introduce soya beans on rotation to fix atmospheric nitrogen and add root carbon.
SOC +0.2%/yr Erosion risk reduced Water holding +18%
3
Reduce LAN, replace with split liquid urea
N efficiency · Cost reduction · Priming risk
The science: Limestone ammonium nitrate (LAN) at 145 kg N/ha is causing active soil carbon priming in already-depleted soil. The high application rate, combined with low SOC, creates a C:N imbalance that forces microbial burndown of what little soil carbon remains. Priming risk score is currently 7/9.
The action: Reduce total N to 100–110 kg N/ha over two seasons. Switch to split liquid urea application (fertigation or side-dress at V5 and V8 growth stages) to align nitrogen availability with maize demand curve, reducing leaching and priming. Use NAITRO's variable-rate maps to target higher rates only on zones with confirmed N deficiency.
Input cost −R3,200/ha Priming risk 7→4 N leaching −35%
1 m³ soil block · Bergvlei Grains, Free State
Ferralsol · Maize-soya rotation · Semi-arid summer rainfall
High priming risk
time horizon
−10 yr +10 yr
2015 — monoculture + heavy LAN 2020 2035 — cover crop + no-till recovery
inputs
Poor 0–30 Average 31–60 Optimal 61–100 62 / 100
outputs
Select an input or output above
Click any card on the left or right to explore how that variable connects to the soil biology and what decisions can change it.
Scenario:
Score — OBI adapted for SA
21 indicators recalibrated for Free State ferralsols and Highveld climate. pH correction weighted as priority indicator for SA maize belt context. Benchmarked against SA Grain Research Institute soil health norms.
Visualise — digital twin
1m³ soil block models the Fe-Al chemistry of ferralsol soils. Inputs track rainfall variability (400–600 mm summer), LAN application, and lime. Output layer includes wind erosion risk — critical for Free State open-paddock context.
Decide — AI recommendations
AI engine prioritises pH correction before N management — unlike NZ context where N is the primary lever. Covers SA-specific trace mineral deficiencies (Zn and S common in Highveld). Variable-rate lime and LAN maps by paddock block.
Report — HUIGE for SA
Farmer + Tiger Brands / Pioneer Foods supply chain + Absa agri loan risk score + Department of Agriculture compliance + SA NUE tracking aligned to AfCFTA export requirements. One data source, five SA stakeholders.