RESUMO
The effectiveness of phytoremediation in Cd-contaminated soils is crucial for enhancing nutrient availability and plant tolerance to Cd. We simulated soil contamination with varying textures and fertilization conditions. Two experiments were conducted: one without liming and fertilization and another with soil fertilization for grasses. The soil types used were Oxisol and Entisol, and the grasses tested were Megathyrsus maximus and Urochloa brizantha at three Cd levels: 0 mg kg-1 (Control), 2 mg kg-1 (Low), and 12 mg kg-1 (High). Soil amendments and fertilization did not significantly change Cd availability. Soil chemical attributes were unaffected by Cd contamination but were influenced by fertilization, which kept the pH below optimal levels. Cd availability was higher in more contaminated soils, with Entisol showing greater concentrations than Oxisol. Dry matter production of the grasses decreased with higher contamination, with U. brizantha being more productive than M. maximus in fertilized soils. Cd accumulation was higher in highly contaminated soils, particularly for U. brizantha. The bioconcentration factor was higher in Entisol, while the translocation factor exceeded 1.0 only for M. maximus in low-contamination Oxisol. Fertilization can mitigate Cd contamination effects, with U. brizantha showing greater tolerance and accumulation capacity in fertilized soils.
Grasses, often seen just as cover crops or forages, can play a vital role in mitigating heavy metal pollution, especially Cd. By comparing the growth, Cd accumulation, and tolerance of different grass species in fertilized versus unfertilized soils, we identify optimal strategies to maximize the effectiveness of phytoremediation without compromising soil health and ecological balance. The findings of the study reveal that the response of grasses to fertilization in contaminated soils varies significantly, directly influencing their capacity to phytoremediate Cd. This discovery suggests that customizing fertilizer use, based on the grass species and specific soil conditions, could be crucial for optimizing the removal of Cd from the environment.