| A indoor culture experiment was conducted to study the effects of 3 sludges(sampled from Linyi sewage treatment plant,Huozhou sewage treatment plant,and Taiyuan Yangjiapbao's sewage treatment plant respectivelys)on the nutrient and heavy metal contents of 3 different soils(brick red soil,red soil,and calcareous cinnamon soil)and a pot experiment planted two crops of corn was employed to study the effect of sludge on the nutrient and heavy metal contents in calcareous cinnamon soil and plant.In order to provide the basis for the efficient and safe utilization of sludge.(1)The results of indoor culture experiment showed that the effect of sewage sludge on the pH values of different soils was different.The 3 sludges all significantly increased the pH values of brick red soil and red soil,while the pH value of calcareous cinnamon soil decreased slightly applied with the 3 sludges.The 3 sludges all increased the contents of organic matter,total nitrogen,available phosphorus,and available potassium at different degrees in the 3 soils.The contents of organic matter,total nitrogen,available phosphorus,and available potassium in brick red soil increased 0.43-8.06 g·kg-1,0.03-1.00 g·kg-1,6.91-89.79 mg·kg-1,and 5.96-177.58 mg·kg-1 respectively,thai in red soil increased 1.04-15.21 g·kg-1,0.10-1.05 g·kg-1,7.06-105.8 mg·kg-1,and 4.96-121.03 mg·kg-1,and that in calcareous cinnamon soil increased 1.05-13.40 ·kg-1,0.16-1.06 g·kg-1,9.59-145.29 mg·kg-1,and 4.63-178.61 mg·kg-1.The increases of total nitrogen and organic matter in both red soil and calcareous cinnamon soil were higher than that in brick red soil,the increases of available phosphorus were all significant in the 3 soils,and the increases of available potassium in both calcareous cinnamon soil and brick red soil were higher than that in red soil.The effects of sludge on the contents of heavy metals were different in different soils.The increase of Cu was red soil>calcareous cinnamon soil>brick red soil,the increase of Zn was calcareous cinnamon soil>red soil>brick red soil,the increase of Cr was calcareous cinnamon soil>brick red soil>red soil,the increase of Ni was calcareous cinnamon soil>brick red soil>red soil,and the increase of Pb in calcareous cinnamon soil was bigger than that in both brick red soil and red soil.Therefore,the increases of Cu,Zn,Pb,Cr,Ni were all higher in calcareous cinnamon soil.(2)the results of pot experiment showed that the root dry weight and root length of maize both increased with the increase of sludge application dose and the plant height and shoot dry weight both were the highest at the sludge application dose of 60 g·pot-1.When the sludge application amount was 90 g·pot-1,plant height and shoot dry weight decreased.Compared with the two stubble,except the root dry weight,the dry weight,root length,and plant height of second crop were all higher than that of first crop.The contents of soil organic matter,total nitrogen,available phosphorus,and available potassium all increased with the increase of sludge application dose.Soil organic matter,total nitrogen,available phosphorus,and available potassium increased by 1.9-4.81 g·kg-1,0.02-0.18 g·kg-1,0.06-5.97 mg·kg-1,2.70-18.99 mg·kg-1 respectively.The total nitrogen,total phosphorus,and total potassium of the plants were significantly higher than that of CK and all increased with the increase of sludge application dose.The contents of total Cu,Zn,Pb,Cr,Ni,and Cd and available Cu,Zn,Pb,Cr,Ni,and Cd in the soil increased with the increase of sludge application rate.The contents of heavy metals in plants also showed an increasing trend.Except Zn,the accumulation amount of other heavy metals in plant root was higher than that in plant shoot.Compared with the two crops,the contents of the the six heavy metals in the first crop were all lower than that in the second crop.The contents of heavy metals was significantly different from that of CK when the high dosage of sludge application rate of 90 g·pot-1.Taking into account the influence of sludge application on the increase of nutrients and the reduction of heavy metals,the amount of sludge application rate of 60 g·pot-1 was reasonable. |
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