Capacity of Isolates of Six Genera of Filamentous Fungi to Remove Lead, Nickel and Cadmium from Refinery Effluent

Agricultural soils can act as sources and sinks for CO 2 and other greenhouse gases. Whether soils act as a sink or source depends upon the management of the soil. The fluxes of CO 2 between the atmosphere and the soil are an important link in the C cycle, and the processes affect the atmospheric concentration of CO 2 . Therefore, objective of this paper is to review the effect of tillage and crop residue on soil carbon and carbon dioxide emission. Tillage induces the loss of C as CO 2 by breaking up soil aggregates and exposing the protected organic matter to microbes, minimizing soil disturbance decreases SOC decomposition rate, then this change in management practice would cause decreased transfer of C from soil to the atmosphere. Conservation tillage combined with crop residues on the soil surface has been identified as an important for sequestering carbon from the atmosphere. Crop residue management is another important method of sequestering C in soil and increasing the soil OM content and giving protection against erosion. Surface applied crop residues decompose more slowly than those that are incorporated by tillage, because they have less contact with soil microorganisms and soil water. Clay particles tend to remain in a flocculated state reducing the exposure and mineralization of organic carbon adsorbed on clay particle surfaces. Carbon inventories are higher in the soils, which have higher clay content and higher fractions of clay associated with high organic matter, changes in organic matter properties that correlate with soil texture. The greatest reductions in CO 2 emission are associated with those tillage systems having less soil disturbance. Climatic conditions, natural vegetation, soil texture, and drainage all affect the amount and length of time carbon is stored.