Effects of different modifiers on Cd pollution of lettuce

Taking fly ash, peat, chicken manure, silicon fertilizer, superphosphate and calcium magnesium phosphate as modifiers, and planting lettuce in Cd polluted soil, this paper studied the effects of modifiers on the Cd polluted soil，in order to find out the practical and feasible modifier scheme. The results showed that complex modifiers was better than corresponding pure modifiers clearly as to vegetable biomass and Cd mass fraction in edible part. The improvement effects for Cd pollution in soil from high to low were: fly ash+ superphosphate> superphosphate> fly ash+ chicken manure > calcium magnesium phosphate > fly ash+ peat >silicon fertilizer> chicken manure> fly ash > peat. Different modifiers had obviously different effects on lettuce biomass and Cd mass fraction, whereas the quantity of the modifiers had not that obviously different effects. Modifier type and quantity didn’t affect soil pH. The effect was the best when the ratio of fly ash and superphosphate was 5:1.