Rehabilitation with forage grasses of an area degraded by urban solid waste deposits

Abstract

-Dry matter yield and chemical composition of forage grasses harvested from an area degraded by urban solid waste deposits were evaluated. A split-plot scheme in a randomized block design with four replicates was used, with five grasses in the plots and three harvests in the subplots. The mineral content and extraction and heavy metal concentration were evaluated in the second cut, using a randomized block design with five grasses and four replicates. The grasses were Brachiaria decumbens cv. Basilisk, Brachiaria ruziziensis, Brachiaria brizantha cv. Marandu and cv. Xaraés, and Panicum maximum cv. Tanzânia, cut at 42 days of regrowth. The dry matter yield per cut reached 1,480 kg ha -1 ; the minimum crude protein content was 9.5% and the average neutral detergent fiber content was 62.3%. The dry matter yield of grasses was satisfactory, and may be an alternative for rehabilitating areas degraded by solid waste deposits. The concentration of heavy metals in the plants was below toxicity levels; the chemical composition was appropriate, except for phosphorus. The rehabilitated areas may therefore be used for grazing.

Availability and accumulation of lead for forage grasses in contaminated soil

“…The Pb doses observed in the DWS, DWSB and DWR of the forage grasses (Table 2) were below the limit of 30 mg kg -1 Pb that was considered acceptable for bovine diets by the NRC (1996), suggesting that these varieties could be used in the feeding of ruminants. Miranda et al (2012), working with the cultivars Basilisk, Marandu, Xaraés, Tanzania and Brachiaria ruziziensis in soil contaminated by the deposition of solid waste, found an average content of 0.48 mg Pb kg -1 in the plants, lower than that observed in the present study. These differences may be related to differences in metabolism, anatomy and physiology between species.…”

Potássio na amenização dos efeitos tóxicos induzidos pelo cádmio no capim tanzânia

“…Nos anos recentes, o capim tanzânia tem sido estudado sob condições de fitotoxicidade e em recuperação de áreas contaminadas por metais pesados (Miranda et al 2012;Monteiro et al 2011;Nascimento et al 2014;Silva et al 2016). A contaminação dos solos por metais pesados é importante problema ambiental devido aos danos causados na qualidade do solo e as graves consequências na saúde animal e humana.…”

“…Em razão da toxicidade do Cd, há necessidade de reduzir a concentração deste metal no ambiente, o que pode ser feito de maneira mais sustentável e menos onerosa por meio da fitoextração. Nesta técnica, o contaminante é absorvido pelas raízes e transportado para a parte aérea da planta, tornando possível sua remoção do solo por meio de cortes das plantas.Nos anos recentes, o capim tanzânia tem sido estudado sob condições de fitotoxicidade e em recuperação de áreas contaminadas por metais pesados(Miranda et al 2012;Nascimento et al 2014;Silva et al 2016). Esse capim apresenta potencial para fitoextração de metais, pois apresenta rápido crescimento, alta produção de biomassa e permite cortes sucessivos durante anos(Gilabel et al 2014;Monteiro et al 2011b).…”