Magdalena Zaborowska

Using basalt flour and brown algae to improve biological properties of soil contaminated with cadmium.

Zaborowska M., Kucharski J., Wyszkowska J. (2015): Using basalt flour and brown algae to improve biological properties of soil contaminated with cadmium. Soil & Water Res., 10: 181–188. In order to achieve homeostasis of soil, the potential of alleviating substances (two innovative: basalt flour and brown algae extract against two classic compounds: barley straw and compost) were analyzed in soil contaminated with cadmium. The studies thus determined the activity of urease, number of ammonification bacteria, nitrogen-immobilizing bacteria, Arthrobacter sp., Azotobacter sp., and spring barley yield. The analyzed parameters were presented as the following indices: RS – resistance of soil; EF – fertilization effect of an alleviating substance; and R:S – rhizosphere effect. Cadmium was applied as CdCl2∙2.5H2O at the following doses: 0, 4, 40, 80, 120, 160, and 200 mg Cd2+/kg of soil. Straw increased the values of most examined parameters, mainly at lower doses of cadmium. Among the cultivated plants, resistance was most stimulated by compost. Basalt flour and brown algae extract did not play a major role in the recovery of contaminated soil. Ammonification bacteria were the least sensitive to stress associated with the deposition of cadmium in soil, whereas Azotobacter sp. was the most sensitive. Urease was found to be a reliable indicator of soil condition.

Maintenance of Soil Homeostasis under Exposure to Cadmium

This study makes a pioneering attempt to analyze the neutralizing effects of algae extracts and basalt flour on cadmium-contaminated soil with the aim of restoring a healthy soil balance. Their effectiveness was compared with that of straw and compost. The following soil parameters were evaluated to monitor changes in the cadmium-contaminated environment: dehydrogenases and catalase activity and population size of microorganisms. The influence of cadmium on the resistance of spring barley crops was evaluated. Cadmium was applied at doses of 0, 4, 40, 80, 120, 160, and 200 mg Cd2+ kg−1 DM soil. The results of the experiment indicate that algae extract was a less effective soil amendment, whereas basalt flour failed to improve the soil profile. Straw and compost significantly stimulated soil enzymatic activity. An improvement in soil fertility was reported in treatments sown with spring barley, but a significant decrease in crop resistance to contamination was noted.

The possibilities of restoring the enzymatic balance of soil contaminated with cadmium

The effectiveness of four substances, including two innovative products - basalt meal and algae extract, and two conventional soil improvers - barley straw and compost, was evaluated in this study. The activities of soil enzymes (dehydrogenases, urease, acid phosphatase, alkaline phosphatase and catalase) in response to increasing Cd2+ doses were monitored. Enzymatic activity levels were used to calculate indicators of soil resistance (RS) and soil resilience (RL). The evaluated enzymes were classified in the following order based on their sensitivity to soil pollution with Cd2+: dehydrogenases > urease > alkaline phosphatase > acid phosphatase > catalase. Barley straw was most effective in mitigating the adverse impact of Cd2+ on the biochemical properties of soil, whereas algae extract and compost were less effective soil amendments. Compost neutralised the inhibitory effect of Cd2+ on enzymatic activity, but it significantly enhanced the analysed metals negative impact on oat yield. Basalt meal was not an effective soil improver.