Investigating the effects of municipal waste compost and nitrogen application on the yield and concentration of heavy metals in soil and fruit of tomatoe (Solanum lycopersicum)

In order to investigate the effect of different levels of municipal waste compost and nitrogen on the yield of tomatoes and the concentration of heavy metals in fruit and soil, a field experiment was conducted with 9 treatments and three replications in the form of split plot design in Agricultural Research and Education Center of Tehran Province for one year. The main plot consisted of three levels of compost consumption (0, 10 and 20 t ha-1 with a moisture content of 22% by weight). Subplots consisted of three levels of nitrogen application (0, 100 and 200 kg ha-1). The effect of urban waste compost, the effect of nitrogen and their interaction on yield of tomatoes were statistically significant at the level of one percent. The highest yield of fruit 68785 kg ha-1 was obtained from 20 ton.ha-1 compost with 100 kg ha-1 nitrogen. Consumption of 20 tons per hectare of urban waste compost significantly increased the concentration of lead, cadmium and nickel in tomato fruit at 2804, 2400 and 3022 percent, respectively, compared to control. However, the concentration of any of the above elements in fruit was not more than the maximum allowed national standard of the country. Also, municipal waste compost increased the concentration of total lead, nickel and cadmium in soil, which was allowed in this concentration increase. Also, there was a significant correlation between the concentration of lead, cadmium and nickel of tomatoes with total concentration of these elements in the soil.