Combine effects of Broussonetia papyrifera-derived biochar and selenium nanoparticles for lead-polluted saline soils remediation during barley cultivation

Overview

Murtaza and colleagues tested Broussonetia papyrifera-derived biochar and selenium nanoparticle treatments in lead-polluted saline field plots planted with barley. This is mitigation evidence for soil-to-crop lead reduction: it reports extractable soil lead (Pb) and barley root, shoot, and seed Pb under amendment treatments, but it should not be pooled as ordinary product occurrence data.

Key numbers

Starting water and amendment context

The trial used Sadiqia canal irrigation water with reported pH 7.24 and electrical conductivity 0.51 dS/m. The source reports irrigation-water metals as nickel (Ni) 0.776 mg/L, arsenic 0.026 mg/L, chromium (Cr) 0.030 mg/L, aluminum (Al) 0.021 mg/L, cadmium (Cd) 0.35 mg/L, mercury (Hg) 0.021 mg/L, and Pb 0.121 mg/L; the authors compare Pb with a 0.01 mg/L permissible irrigation threshold.

Biochar produced from Broussonetia papyrifera stems and leaves had Pb 0.02 mg/kg, pH 8.9, electrical conductivity 1.24 dS/m, organic matter 27.60%, carbon 530 g/kg, cation exchange capacity 5.01 cmolc/kg, and specific surface area 17.38 m2/g.

Lead concentrations in soil and barley tissues

Table 4 reports extractable soil Pb and barley tissue Pb as mean +/- SD of 3 replicates.

The table reports p < 0.01 for BP-BC and SeNPs main effects across soil, root, shoot, and seed Pb. The interaction term was not significant for soil Pb (p = 0.16) or root Pb (p = 0.13), but was significant for shoot and seed Pb (p < 0.01).

Reported reduction magnitudes

The authors state that BP-BC at 5 and 10 t/ha reduced Pb accumulation by 19.37-35.67% in soil, 34.01-60.39% in shoots, 38.40-4.70% in roots as printed, and 28.29-49.40% in seeds relative to the no-BP-BC control. The root range appears internally inconsistent with the table values and may be a typographical error.

SeNP foliar application at 10 and 20 mg/L reduced Pb buildup by 3.70-3.40% in soil, 29.19-37.18% in shoots, 12.03-13.70% in roots, and 27.40-24.30% in seeds relative to the no-SeNP control.

For combined treatments, the authors report a 59.89% reduction in seed Pb with SeNPs 10 mg/L plus BP-BC 10 t/ha and a 73.88% reduction in shoot Pb with SeNPs 20 mg/L plus BP-BC 10 t/ha relative to the zero-amendment treatment.

Methods (brief)

The field study ran from October 2023 to March 2024 at the Agricultural Research Centre Bahawalpur, Pakistan. Plots were 2 m by 2.5 m and were organized in a completely randomized block design. Barley seeds (Hordeum vulgare JAU-83) were sown at 100 kg/ha and irrigated five times with Sadiqia canal water.

The nine treatments were unamended control, BP-BC at 5 or 10 t/ha, SeNPs at 10 or 20 mg/L, and combinations of those biochar and SeNP doses. Broussonetia papyrifera waste was pyrolyzed at 450 degrees C for 4 h. SeNPs were applied as foliar sprays three times at 15-day intervals starting 30 days after planting. Soil Pb was extracted with EDTA and measured by AAS. Five barley plants were randomly selected from each plot at physiological maturity, digested by Kjeldahl procedure, and analyzed for tissue Pb using AAS.

Related evidence

• Agronomic mitigation
• Remediation evidence — drivers and interventions
• Lead
• Cadmium
• Arsenic, Total
• Chromium
• Aluminum
• Mercury, Total
• Nickel
• Testing

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