above all, when add a small amount of composted sludge (1%, 5% and 10% ) to loess ,it was beneficial for the germination and growth of crops, which was similar with the research results of li guoxue et al19 and singh et al20 . the former discovered that when the application amount of composted sludge was more than 25%, the dry weight yield of crop reduced significantly. the latter found out that sewage sludge can not only improve soil environment, but also increase the crop yield. previous studied 22 demonstrated that in the process from the germ stage to the appearance of radicle, the radicle was required to break through the seed coat to absorb water. as a result, the accumulation of heavy metals in plant roots and their threatening effects were expected to be strengthened, and then their influence on plants was increased. meanwhile, owing to the conductivity of sewage sludge was higher than that of the soil, the application of sewage sludge was expected to increase salinity of soil 23 and further jeopardized the normal germination and growth of plants. when the additive amount of sewage sludge exceeded certain proportion, its adverse effect was expected to outweigh the favorable effects and inevitably posed inhibition on the germination and growth of crops.