Field bioremediation trial data and identifiability analysis code for petroleum-contaminated soil, Kyzylorda region, Kazakhstan

<p dir="ltr">This deposit contains the raw field data and the complete analysis code behind the study of kinetic model identifiability in field-scale bioremediation of petroleum-contaminated soil.</p><p dir="ltr">The field trial was carried out between April and June 2026 at an oil-waste treatment site in the Kyzylorda region, Kazakhstan (45°42′ N, 65°28′ E). Six plots of 2 × 2 m, each holding 200 kg of soil, received one of the following treatments: an untreated control with no oil; oil with no further treatment; oil with mineral fertiliser; oil with fertiliser and reintroduced indigenous degrading strains; oil with fertiliser and a biopreparation based on the same strains; and oil with biochar.

Samples were taken on days 0, 13, 27, 41, 55, 69 and 83 and analysed for total petroleum hydrocarbons, pH, mineralisation, moisture, available nitrogen, phosphorus and potassium, and organic carbon. Air temperature was recorded on site at each sampling date.</p><p dir="ltr">The code fits six kinetic models to these data — zero order, first order, two-compartment, substrate Monod, Haldane and first order with multiplicative nitrogen limitation — and assesses the identifiability of their parameters through standard errors and residual sum-of-squares profiles.