Soil Science and Soil Fertility Management
Soil Science and Soil Fertility Management tests soil properties, their diagnosis by sampling and analysis, and the conversion of a laboratory recommendation into an agronomically and legally correct fertilizer programme - the central skill on calcareous Cypriot soils.
Properties that decide everything
- Texture (sand/silt/clay) sets water holding capacity, aeration and workability; structure sets infiltration and erosion risk.
- CEC (cmol(+)/kg) is the reserve of exchangeable cations and rises with clay and organic matter; base saturation shows how much of it is occupied by Ca, Mg, K and Na.
- pH controls availability. Cyprus soils are typically calcareous (free CaCO3, pH 7.5–8.5): phosphate is fixed as calcium phosphate and iron, zinc and manganese become poorly available, giving interveinal chlorosis on citrus and vines.
- Organic matter in Mediterranean arable soils is often below 2%; it is the main lever for structure, CEC and water retention.
- EC (dS/m) of the saturated extract flags salinity; rising EC with a high sodium adsorption ratio points to sodicity and a gypsum requirement.
Sampling and interpretation
Sample 0–30 cm (0–15 cm for pastures), 15–20 cores per uniform zone in a W pattern, avoiding tracks and troughs; air-dry and label. Use Olsen-P for calcareous soils, not Bray. Compare with crop critical values calibrated locally.
Worked example - fertilizer blend
Recommendation: 100 kg N, 50 kg P2O5, 80 kg K2O per ha. Apply 500 kg/ha of 20-10-10 → 100 kg N, 50 kg P2O5, 50 kg K2O. K2O short by 30 kg. Potassium sulphate is 50% K2O → 30 / 0.50 = 60 kg/ha. Total: 500 kg 20-10-10 plus 60 kg potassium sulphate.
Traps
- Reporting P and K as P2O5 and K2O: P × 2.29 = P2O5, K × 1.20 = K2O.
- Broadcasting urea on dry calcareous soil without incorporation - ammonia volatilization.
- Applying phosphate without accounting for fixation; banding or fertigation is more efficient.
- Over-liming an already calcareous soil.
- Sampling a field that is not uniform (different soil, old manure heaps).