EFFECTS OF SLUDGE ADDITION AMOUNT ON SOIL PHYSICO CHEMICAL PROPERTIES AND GROWTH OF MAIZE SEEDLINGS IN ROCKY DESERTIFICATION AREAS OF GUIZHOU PROVINCE

The effects of different proportion of sludge (sludge: soil is 0:1, 1:1, 1:2, 1:3) on soil physico-chemical properties and growth of maize seedlings were analyzed through a pot experiment. The results showed that the addition of sludge could significantly improve the soil fertility and promote the growth of maize seedlings in rocky desertification areas of Guizhou Province. Contents of the soil organic matter, water-holding capacity, available N,available P and the heavy metal were all positively correlated with the amount of sludge added in the mixed-substrate. When the sludge addition ratio is 50%, the indexes were the highest. However, the total amount of Cu, Cd, Pb and Zn of each treatment did not exceed the national secondary standard of "Environmental quality standards for soils" (GB 18918-2008, China). On the other hand, the addition of sludge increased the maximum root length, plant height, biomass, protein, chlorophyll and p-carotene content of maize seedlings. Plants grew best when the proportion was between 25% and 33%, while a high proportion (50%) of the sludge inhibited the growth of maize seedlings due to the high content of heavy metal. After adding sludge, the dominant root microorganism of maize seedlings changed, Ghttamicibacter and Citrobac-ter were the dominant bacterial communities, while Trichosporon and Fusarhtm were the dominant fungal communities.