Effect of Different Periods of Application of Sewage Sludge and Municipal Solid Wastes Compost on the Amount of Cadmium and Nickel Content of Soil and Borage (Borago officinadis)

In order to study، the amount of cadmium and nickel in different plant organs of borage planted in calcareous، following the application of sewage sludge and municipal solid wastes compost، an experiment was conducted in split-plot design based on complete randomized block design in 2009. The main plot was sewage sludge and municipal solid wastes compost at five levels (control، 20، and 40 ton/ha) and the sub plot was years in six treatments (2006، 2006 and 2007، 2006 and 2008، 2006-2008، 2006 and 2007 and 2009، and 2006-2009). The amount of available Cd and Ni in soil and Cd and Ni accumulated in the roots، leaves and flower of Borage were compared with the control. Results indicated that the application of 40 ton/ha sewage sludge and municipal solid wastes compost increased the available Cd and Ni in soil (about 2 and 2. 5 times، respectively) and the amount of Cd and Ni in the roots of Borage by 5 and 2. 5 times compared to control. The maximum amount of Cd in leaves and flowers of borage was observed in the 40 ton/ha sewage sludge treatment. Furthermore، the treatment of 40 ton/ha sewage sludge and municipal solid wastes compost produced the most amount of Ni in leaves and flowers of Borage، respectively. Meanwhile، the maximum amount of Cd translocated to the shoots was observed in the flower in the 40 ton/ha sewage sludge and Ni in the same organic fertilizer treatments to leaves of borage.