Relationship between the mass of organic matter and carbon in soil

The quantity of soil organic matter (SOM) was estimated through the determination of soil organic carbon (SOC) times a factor, which assumes that 58 percent of the SOM was formed by carbon. A number of soil samples with wide range of SOC content collected in the state of Paraná, Brazil were evaluated in the laboratory. SOC was measured by Walkley-Black method and the total SOM by loss on ignition. The SOC was positively correlated with SOM. The SOM/SOC ratio varied from 1.91 to 5.08 for the soils. It shows that Brazilian SOM has greater oxidation degree. Although, the SOM and SOC decreased with soil depth the SOM/SOC ratio increased. It showed that SOM in the subsoil contained more oxygen but less carbon than the SOM in the upper soil surface. The CEC/SOC also increased with depth indicating that the functional groups of the SOM increased per unity of carbon.

O teor de matéria orgânica do solo (MOS) é estimado pelo conteúdo de carbono orgânico do solo (COS) vezes um fator, decorrente do pressuposto de que 58 por cento da MOS é formada por carbono. Amostras de solos apresentando grande variação no teor de COS foram avaliadas no laboratório. O COS foi determinado pelo método de Walkley-Black (WB) e a MOS pela perda de massa por ignição (PMI). A MOS foi positivamente correlacionada com o COS. A relação MOS/COS variou de 1,91 a 5,08. Este resultado mostra que a MOS brasileiros apresentam maior grau de oxidação. Embora a MOS e o COS tenham diminuído a relação MOS/COS aumentou com a profundidade do solo. Este resultado demonstrou que a MOS da subsuperfície contem mais oxigênio e menos carbono que a MOS da superfície do solo. A relação CTC/COS também aumentou com a profundidade, indicando um aumento nos grupos funcionais da MOS por unidade de carbono.

Absorçäo de metais pesados do lodo de esgoto pelo feijoeiro (Phaseolus vulgaris L.) / Heavy metal uptake of the sewage sludge by bean plants (Phaseolus vulgaris L.)

Toxicity and uptake of heavy metals of sewage sludge by beans (Phaseolus vulgaris L.) were evaluated in green house experiments. Treatments consisted of 1,0; 2,0 and 5,0 per cent (m/m) of dry sewage sludge, collected from Londrina (Bom Retiro and ETE-Sul) and Curitiba (ETE-Belém and RALF). Bean (variety IAPAR 57) was sown three times at 0, 120 and 240 days after the treatment have been applied. Contents of Cd, Cr, Co, Cu, Ni, and Pb in bean tissues cultivated with 5,0 per cent (m/m) of all sewage sludge were similar to the control and Ba contents were reduced by increasing the quantity of sewage sludge in the soil. The Zn content in tissue bean increased from 86 mg kg -1 of contrrol to 462 mg kg-1 by applying 5 per cent (m/m) of sewage sludge in soil, but plant beans did not show toxicity symptons. The addition of 5 per cent (m/m) of sewage sludge increased Mn content in plants, from 193 mg kg-1 of control to 1.960 mg kg -1, showing toxity in bean leaves when the contents were more than 500 mg kg-1. The addition of sewage sludges in soils increased only avaiable Zn carbonate and Cu organic species