Effects of Phosphorus Fertilizer Type and Rate on Plant Growth and Heavy Metal Content in Lettuce (Lactuca sativa L.) Grown on Calcareous Soil

A field experiment was carried out to investigate effects of phosphorus (P) fertilizer type and rate on plant growth and toxic heavy metals contents (Cd, Pb and As) in head lettuce plant on calcareous soil. Four P fertilizer types {single super phosphate (SSP), di ammonium phosphate (DAP), mono ammonium phosphate (MAP) and a local phosphate rock (PR)} were applied as main plot treatments and five rates of each fertilizer (0, 125, 250, 375, and 500 kg P2O5/ha) as subplot treatments. P fertilizer type, rate and their interaction showed a significant effect on the fresh plant yield and dry matter production. Both P fertilizer type and rate didn’t induce significant differences in heavy metals contents of the plant and soil, as they were within tolerable limits. The examined P fertilizers constitute no potential risks for heavy metals accumulation in the soil-plant system over short-term.