Lead phytostabilization using Stipa ichu assisted by biochar in high-Andean agricultural soil, Puno, Peru

Abstract

The quality of agricultural soils is affected by lead contamination. The capacity of native species such as Stipa ichu to remediate contaminated soils can be optimized through the use of biochar. The objective was to evaluate the effect of biochar on the phytoremediation capacity of Stipa ichu in lead-contaminated soils in a high-Andean area of Puno, Peru. The experiment was conducted in Juliaca, Peru (379519.57 m E, 8287413.04 m S, zone 19 L, and altitude of 3825 m). Six treatments consisting of biochar applications (0 %, 2 %, 4 %, 6 %, 8 %, and 10 %) were evaluated in pots with Stipa ichu plants. A completely randomized experimental design (CRD) was used, with three replicates for each treatment. Pb concentrations in aerial tissues were not detected, since they were below the limit of quantification (<3 mg.kg⁻¹), while in roots they remained between 3.14 and 4.38 mg.kg⁻¹. The application of biochar significantly reduced (p < 0.05) Pb concentrations in the soil, achieving a remediation efficiency of 43 % at doses of 6 - 10 %. The translocation factor (TF<1) and bioconcentration factor (BCF<0.05) values confirmed the phytostabilization mechanism, with preferential retention of the metal in the root system. These findings suggest that biochar promotes the immobilization of Pb in the roots, although its impact on plant absorption was limited.