Abstract: The study on the ecological effects of intercrops in four cropping patterns showed that with the increase of multiple cropping,the annual increase of soil organic matter,total N,total P and total K was 5%～20%,7%～40%,8%～70% and 15%～80%,respectively. Potato-soybean had the best benefit in soil and water conservation,followed by cole?peanut,potato?watermelon,and wheat. Compared with control,the average soil erosion module and runoff amount of 4 patterns were decreased by 44.19%,39.55%,38.24% and 37.56%,and 22.40%,9.28%,24.11% and 21.16%,respectively. Cole-peanut had the highest biomass,being averaged 100 276 kg·hm^-2 annually,and the second was potato-watermelon,with an average of 73 692 kg·hm^-2. Potato-watermelon had the highest productivity,which averaged 37 565 kg·hm^-2 annually,and the second was potato-soybean,averaged 25 934 kg·hm^-2. The efficiency of energy input was in order of cole-peanut,potato-watermelon,potato-soybean,and wheat,and the value was 2.96,2.08,2.01 and 0.96,respectively.

Key words: Soil-plant system, Heavy metal, Organic pollutant, Combined pollution